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Burd M. You can't always get what you want from pollinators. THE NEW PHYTOLOGIST 2024; 244:7-9. [PMID: 38840568 DOI: 10.1111/nph.19892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2024]
Abstract
This article is a Commentary on Duncan et al. (2024), 244: 307–317.
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Affiliation(s)
- Martin Burd
- Indiana University Herbarium, East 10th Street, Bloomington, IN, 47408, USA
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2
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Musker SD, Pirie MD, Nürk NM. Pollinator shifts despite hybridisation in the Cape's hyperdiverse heathers (Erica, Ericaceae). Mol Ecol 2024:e17505. [PMID: 39188071 DOI: 10.1111/mec.17505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 06/23/2024] [Accepted: 08/09/2024] [Indexed: 08/28/2024]
Abstract
Interrogating the ecological and geographic factors that influence population divergence dynamics can reveal why some groups of organisms diversify more prolifically than others. One such group is the heathers (Erica, Ericaceae), the largest plant genus in the Cape Floristic Region. We study Erica abietina, a highly variable species complex with four subspecies differing in geographic range, habitat and pollination syndrome. We test for population differentiation, hybridisation, introgression and pollinator-driven divergence using genotyping-by-sequencing on samples across the entire distribution. We find five variably distinct genetic groups, with one subspecies comprising two independent lineages that are geographically isolated and occur on different soil types. Phylogenetic analysis suggests two independent shifts between bird and insect pollination, with accompanying genetic divergence. However, for one pair of populations with different pollinators, we uncover several individuals of hybrid origin at a site of sympatry. These results suggest that floral differentiation driven by divergent selection acts in concert with geographic isolation to maintain reproductive isolation and promote speciation. Our investigations reveal a highly dynamic system whose diversity has been shaped by a variety of interacting forces. We suggest that such a system could be a model for much of the diversification of the Cape flora.
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Affiliation(s)
- Seth D Musker
- Department of Biological Sciences, University of Cape Town, Rondebosch, South Africa
- Department of Plant Systematics, Bayreuth Centre of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany
| | | | - Nicolai M Nürk
- Department of Plant Systematics, Bayreuth Centre of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany
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Yue J, Yan Z, Liu W, Liu J, Yang D. A visual pollination mechanism of a new specialized pollinating weevil-plant reciprocity system. FRONTIERS IN PLANT SCIENCE 2024; 15:1432263. [PMID: 39220015 PMCID: PMC11362035 DOI: 10.3389/fpls.2024.1432263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2024] [Accepted: 07/29/2024] [Indexed: 09/04/2024]
Abstract
Introduction Pollinating flower-consuming mutualisms are considered exemplary models for studying coevolution due to their rarity. Visual cues are considered to have a major role in facilitating the evolution of floral patterns in these systems. We present a new specialized pollinating flower-consuming mutualism from the plant Wurfbainia villosa, which is a traditional Chinese herbal medicine, by a pollinating weevil, Xenysmoderes sp. Methods In this study, We utilized monochrome plates for binary-choice tests to determine weevil color preferences, conducted behavioral choice experiments, using trackballs, photographed flowers and weevils, and employed blue sticky boards to attract weevils in the field. Results Tests were conducted using colorpreferring weevils in both indoor and outdoor field systems, and validation experiments were performed. Behavioral tests were conducted to investigate the role of the visual cues in the pollinator attraction of W. villosa, which is a selfcompatible insect-pollinated plant that relies primarily on the Xenysmoderes sp. weevil for pollination due to its specialized gynandrium-like structure. Behavioral tests demonstrated that a blue color wavelength of 480 nm and the blue color system, as along with the UV-style pattern of the flowers, particularly the parts with specialized gynandrium-like structures in the labellum, were significantly attractive to both male and female weevils. These results were further confirmed through the field blue sticky board trap method. Discussion These findings indicated that the interaction between W. villosa and Xenysmoderes sp. weevil was a novel symbiotic relationship involving pollinator flower consumption. Additionally, Wurfbainia villosa flowers developed specific visual cues of UV patterns and specialized structures that played a crucial role in attracting pollinators.
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Affiliation(s)
- Jianjun Yue
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, China
- School of Traditional Dai-Thai Medicine, West Yunnan University of Applied Sciences, Jinghong, China
| | - Zhen Yan
- Yunnan Key Laboratory of Southern Medicine Utilization, Institute of Medicinal Plant Development Yunnan Branch, Chinese Academy of Medical Sciences and Peking Union Medical College, Jinghong, China
| | - Wei Liu
- School of Traditional Dai-Thai Medicine, West Yunnan University of Applied Sciences, Jinghong, China
| | - Ju Liu
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, China
| | - Depo Yang
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, China
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Hederström V, Ekroos J, Friberg M, Krausl T, Opedal ØH, Persson AS, Petrén H, Quan Y, Smith HG, Clough Y. Pollinator-mediated effects of landscape-scale land use on grassland plant community composition and ecosystem functioning - seven hypotheses. Biol Rev Camb Philos Soc 2024; 99:675-698. [PMID: 38118437 DOI: 10.1111/brv.13040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 12/05/2023] [Accepted: 12/07/2023] [Indexed: 12/22/2023]
Abstract
Environmental change is disrupting mutualisms between organisms worldwide. Reported declines in insect populations and changes in pollinator community compositions in response to land use and other environmental drivers have put the spotlight on the need to conserve pollinators. While this is often motivated by their role in supporting crop yields, the role of pollinators for reproduction and resulting taxonomic and functional assembly in wild plant communities has received less attention. Recent findings suggest that observed and experimental gradients in pollinator availability can affect plant community composition, but we know little about when such shifts are to be expected, or the impact they have on ecosystem functioning. Correlations between plant traits related to pollination and plant traits related to other important ecosystem functions, such as productivity, nitrogen uptake or palatability to herbivores, lead us to expect non-random shifts in ecosystem functioning in response to changes in pollinator communities. At the same time, ecological and evolutionary processes may counteract these effects of pollinator declines, limiting changes in plant community composition, and in ecosystem functioning. Despite calls to investigate community- and ecosystem-level impacts of reduced pollination, the study of pollinator effects on plants has largely been confined to impacts on plant individuals or single-species populations. With this review we aim to break new ground by bringing together aspects of landscape ecology, ecological and evolutionary plant-insect interactions, and biodiversity-ecosystem functioning research, to generate new ideas and hypotheses about the ecosystem-level consequences of pollinator declines in response to land-use change, using grasslands as a focal system. Based on an integrated set of seven hypotheses, we call for more research investigating the putative pollinator-mediated links between landscape-scale land use and ecosystem functioning. In particular, future research should use combinations of experimental and observational approaches to assess the effects of changes in pollinator communities over multiple years and across species on plant communities and on trait distributions both within and among species.
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Affiliation(s)
- Veronica Hederström
- Centre for Environmental and Climate Science, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
| | - Johan Ekroos
- Centre for Environmental and Climate Science, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
| | - Magne Friberg
- Department of Biology, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
| | - Theresia Krausl
- Centre for Environmental and Climate Science, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
| | - Øystein H Opedal
- Department of Biology, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
| | - Anna S Persson
- Centre for Environmental and Climate Science, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
| | - Hampus Petrén
- Department of Biology, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
| | - Yuanyuan Quan
- Centre for Environmental and Climate Science, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
| | - Henrik G Smith
- Centre for Environmental and Climate Science, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
- Department of Biology, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
| | - Yann Clough
- Centre for Environmental and Climate Science, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
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Wenzell KE, Zhang JY, Skogen KA, Fant JB. Adaptive generalization in pollination systems: Hawkmoths increase fitness to long-tubed flowers, but secondary pollinators remain important. Ecol Evol 2024; 14:e11443. [PMID: 38783846 PMCID: PMC11112297 DOI: 10.1002/ece3.11443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 05/02/2024] [Accepted: 05/03/2024] [Indexed: 05/25/2024] Open
Abstract
Selection on floral traits by animal pollinators is important in the evolution of flowering plants, yet whether floral divergence requires specialized pollination remains uncertain. Longer floral tubes, a trait associated with long-tongued pollinators, can also exclude other pollinators from accessing rewards, a potential mechanism for specialization. Across most of its range, Castilleja sessiliflora displays much longer corollas than most Castilleja species, though tube length varies geographically and correlates partially with hawkmoth visitation. To assess whether long corolla tubes reflect adaptation to hawkmoth pollinators, we performed a day/night pollinator exclusion experiment in nine natural populations that varied in corolla length across the range of C. sessiliflora and short-tubed members of the parapatric C. purpurea complex. We compared the fitness contributions of nocturnal and diurnal visitors, revealing that long-tubed populations visited predominantly by hawkmoths experienced greater fruit set at night, in contrast with short-tubed populations or those visited mainly by diurnal pollinators. Next, leveraging a range-wide multiyear dataset of pollinator visitation to these species, we identify that hawkmoth visitation is associated with increased fitness in long-tubed populations overall, and that long tubes are associated with less diverse visitor assemblages. Thus, long corollas represent an adaptation to hawkmoth pollination at the exclusion of diverse pollinators. Nonetheless, while hawkmoths were scarce in the northern range, secondary diurnal pollinators contributed to fruit set across the range, providing reproductive assurance despite possible trait mismatch. This study illustrates adaptive generalization in pollination systems and that floral divergence may proceed along a continuum of generalized and specialized pollinator interactions.
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Affiliation(s)
- Katherine E. Wenzell
- Botany DepartmentCalifornia Academy of SciencesSan FranciscoCaliforniaUSA
- Department of EntomologyUniversity of MarylandCollege ParkMarylandUSA
| | - Johnathan Y. Zhang
- Interdisciplinary Programs BioinformaticsBoston UniversityBostonMassachusettsUSA
| | - Krissa A. Skogen
- Department of Biological SciencesClemson UniversityClemsonSouth CarolinaUSA
| | - Jeremie B. Fant
- Program in Plant Biology and ConservationNorthwestern UniversityEvanstonIllinoisUSA
- Negaunee Institute for Plant Conservation Science and ActionChicago Botanic GardenGlencoeIllinoisUSA
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Smith CI, Leebens-Mack JH. 150 Years of Coevolution Research: Evolution and Ecology of Yucca Moths (Prodoxidae) and Their Hosts. ANNUAL REVIEW OF ENTOMOLOGY 2024; 69:375-391. [PMID: 37758220 DOI: 10.1146/annurev-ento-022723-104346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
Yucca moths (Tegeticula and Parategeticula) are specialized pollinators of yucca plants, possessing unique, tentacle-like mouthparts used to actively collect pollen and deposit it onto the flowers of their hosts. The moths' larvae feed on the developing seeds and fruit tissue. First described in 1873, the yucca-yucca moth pollination system is now considered the archetypical example of a coevolved intimate mutualism. Research conducted over the past three decades has transformed our understanding of yucca moth diversity and host plant interactions. We summarize the current understanding of the diversity, ecology, and evolution of this group, review evidence for coevolution of the insects and their hosts, and describe how the nature of the interaction varies across evolutionary time and ecological contexts. Finally, we identify unresolved questions and areas for future research.
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Chen H, Yuan YW. Genetic basis of nectar guide trichome variation between bumblebee- and self-pollinated monkeyflowers (Mimulus): role of the MIXTA-like gene GUIDELESS. BMC PLANT BIOLOGY 2024; 24:62. [PMID: 38262916 PMCID: PMC10804488 DOI: 10.1186/s12870-024-04736-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 01/09/2024] [Indexed: 01/25/2024]
Abstract
Nectar guide trichomes play crucial ecological roles in bee-pollinated flowers, as they serve as footholds and guides for foraging bees to access the floral rewards. However, the genetic basis of natural variation in nectar guide trichomes among species remains poorly understood. In this study, we performed genetic analysis of nectar guide trichome variation between two closely related monkeyflower (Mimulus) species, the bumblebee-pollinated Mimulus lewisii and self-pollinated M. parishii. We demonstrate that a MIXTA-like R2R3-MYB gene, GUIDELESS, is a major contributor to the nectar guide trichome length variation between the two species. The short-haired M. parishii carries a recessive allele due to non-synonymous substitutions in a highly conserved motif among MIXTA-like MYB proteins. Furthermore, our results suggest that besides GUIDELESS, additional loci encoding repressors of trichome elongation also contribute to the transition from bumblebee-pollination to selfing. Taken together, these results suggest that during a pollination syndrome switch, changes in seemingly complex traits such as nectar guide trichomes could have a relatively simple genetic basis, involving just a few genes of large effects.
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Affiliation(s)
- Hongfei Chen
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, 06269, USA.
| | - Yao-Wu Yuan
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, 06269, USA.
- Institute for Systems Genomics, University of Connecticut, Storrs, CT, 06269, USA.
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Albuquerque-Lima S, Lopes AV, Machado IC. Reproductive isolation between two sympatric bat-pollinated Bauhinia (Leguminosae). JOURNAL OF PLANT RESEARCH 2024; 137:65-77. [PMID: 37991585 DOI: 10.1007/s10265-023-01508-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 11/06/2023] [Indexed: 11/23/2023]
Abstract
Several barriers contribute to reproductive isolation between plant species, which can be classified as pre- or post-pollination. Understanding the strength of these barriers could clarify the factors that maintain reproductive isolation and thus species integrity. In this study, we quantified reproductive isolation between two bat-pollinated co-occurring Bauhinia species (B. acuruana and B. pentandra) with similar flower morphology. Over the course of 18 months, we assessed reproductive isolation between these two Bauhinia species by quantifying the individual strengths and absolute contributions of five pre- and post- pollination barriers. Our data showed that both species are completely isolated in their reproduction by a combination of several barriers. Although they co-occur in a few populations, we found a high degree of geographic isolation between them. And although their flowering periods overlap, there is a significant difference in flowering peaks. Both species have the same pollinating bats, but the interspecific transfer of pollen between the plant species may be reduced due to the different length of the flower stamens, resulting in different pollen deposition on the bats' bodies. We have documented complete incompatibility between taxa and conclude that pre- and post-pollination barriers are important factors in preventing gene flow, even in contact zones between these two species of Bauhinia. We highlight that our work is the first study to use methods to estimate the strength of reproductive isolation barriers between bat-pollinated species.
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Affiliation(s)
- Sinzinando Albuquerque-Lima
- Laboratório de Biologia Floral e Reprodutiva and Programa de Pós-Graduação em Biologia Vegetal, Departamento de Botânica, Universidade Federal de Pernambuco, Recife, 50670-901, Pernambuco, Brazil.
- Kunming Institute of Botany, Chinese Academy of Sciences, 123, Lanhei Road, Panlong District, Kunming, 650201, China.
| | - Ariadna Valentina Lopes
- Laboratório de Biologia Floral e Reprodutiva and Programa de Pós-Graduação em Biologia Vegetal, Departamento de Botânica, Universidade Federal de Pernambuco, Recife, 50670-901, Pernambuco, Brazil
| | - Isabel Cristina Machado
- Laboratório de Biologia Floral e Reprodutiva and Programa de Pós-Graduação em Biologia Vegetal, Departamento de Botânica, Universidade Federal de Pernambuco, Recife, 50670-901, Pernambuco, Brazil.
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Diaz-Martin Z, Cisternas-Fuentes A, Kay KM, Raguso RA, Skogen K, Fant J. Reproductive strategies and their consequences for divergence, gene flow, and genetic diversity in three taxa of Clarkia. Heredity (Edinb) 2023; 131:338-349. [PMID: 37700028 PMCID: PMC10673949 DOI: 10.1038/s41437-023-00649-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 08/25/2023] [Accepted: 08/25/2023] [Indexed: 09/14/2023] Open
Abstract
Differences in reproductive strategies can have important implications for macro- and micro-evolutionary processes. We used a comparative approach through a population genetics lens to evaluate how three distinct reproductive strategies shape patterns of divergence among as well as gene flow and genetic diversity within three closely related taxa in the genus Clarkia. One taxon is a predominantly autonomous self-fertilizer and the other two taxa are predominantly outcrossing but vary in the primary pollinator they attract. In genotyping populations using genotyping-by-sequencing and comparing loci shared across taxa, our results suggest that differences in reproductive strategies in part promote evolutionary divergence among these closely related taxa. Contrary to expectations, we found that the selfing taxon had the highest levels of heterozygosity but a low rate of polymorphism. The high levels of fixed heterozygosity for a subset of loci suggests this pattern is driven by the presence of structural rearrangements in chromosomes common in other Clarkia taxa. In evaluating patterns within taxa, we found a complex interplay between reproductive strategy and geographic distribution. Differences in the mobility of primary pollinators did not translate to a difference in rates of genetic diversity and gene flow within taxa - a pattern likely due to one taxon having a patchier distribution and a less temporally and spatially reliable pollinator. Taken together, this work advances our understanding of the factors that shape gene flow and the distribution of genetic diversity within and among closely related taxa.
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Affiliation(s)
- Zoe Diaz-Martin
- Department of Biology, Spelman College, Atlanta, GA, 30314, USA.
- Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL, 60035, USA.
| | - Anita Cisternas-Fuentes
- Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL, 60035, USA
- Plant Biology and Conservation, Northwestern University, 2205 Tech Drive, Evanston, IL, 60208, USA
- Departamento de Botánica, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción, Chile
| | - Kathleen M Kay
- Department of Ecology and Evolutionary Biology, University of California, 130 McAllister Way, Santa Cruz, CA, 95060, USA
| | - Robert A Raguso
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, USA
| | - Krissa Skogen
- Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL, 60035, USA
- Plant Biology and Conservation, Northwestern University, 2205 Tech Drive, Evanston, IL, 60208, USA
- Department of Biological Sciences, Clemson University, 132 Long Hall, Clemson, SC, 29631, USA
| | - Jeremie Fant
- Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL, 60035, USA
- Plant Biology and Conservation, Northwestern University, 2205 Tech Drive, Evanston, IL, 60208, USA
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Kobayashi S. Evolution of a non-flying mammal-dependent pollination system in Asian Mucuna (Fabaceae). PLANT BIOLOGY (STUTTGART, GERMANY) 2023; 25:833-841. [PMID: 37408380 DOI: 10.1111/plb.13557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 06/01/2023] [Indexed: 07/07/2023]
Abstract
Pollinator shifts are often related to speciation in angiosperms, and the relationship between them has been discussed in several plant taxa. Although limited information on plants pollinated by non-flying mammals in Central and South America and Africa is available, related research has not been conducted in Asia. Herein, I summarize the available knowledge of pollination in Asian Mucuna (Fabaceae), a genus mainly distributed in the tropics, and discuss the evolution of plants pollinated by non-flying mammals in Asia. Nineteen pollinator species have been recorded and pollination systems have been categorized into four types. An examination of the relationship between Mucuna species and their pollinators from the lineage perspective revealed that all species in Mucuna, subgenus Macrocarpa, which are distributed in Asia, are pollinated exclusively by non-flying mammals. Additionally, plants pollinated by non-flying mammals were found to have diverged from bat-pollinated and non-flying mammal-pollinated plants, while plants pollinated by non-flying mammals have evolved multiple times. This is a unique example of evolutionary transition. I hypothesize that the diversification of squirrel species in tropical Asia may have led to the speciation and diversification of Mucuna in Asia. Furthermore, the behavioural and ecological characteristics of bats and birds in Asia differ from the characteristics of those in other regions, implying that Asian Mucuna species do not rely on bat or bird pollinators. The adaptation of floral characteristics to pollinators is not well understood in Asia. Mammal-pollinated plants in Asia may have evolved differently from those in other regions and have unique pollination systems.
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Affiliation(s)
- S Kobayashi
- Faculty of Science, University of the Ryukyus, Nishihara, Okinawa, Japan
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Wessinger CA, Katzer AM, Hime PM, Rausher MD, Kelly JK, Hileman LC. A few essential genetic loci distinguish Penstemon species with flowers adapted to pollination by bees or hummingbirds. PLoS Biol 2023; 21:e3002294. [PMID: 37769035 PMCID: PMC10538765 DOI: 10.1371/journal.pbio.3002294] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 08/11/2023] [Indexed: 09/30/2023] Open
Abstract
In the formation of species, adaptation by natural selection generates distinct combinations of traits that function well together. The maintenance of adaptive trait combinations in the face of gene flow depends on the strength and nature of selection acting on the underlying genetic loci. Floral pollination syndromes exemplify the evolution of trait combinations adaptive for particular pollinators. The North American wildflower genus Penstemon displays remarkable floral syndrome convergence, with at least 20 separate lineages that have evolved from ancestral bee pollination syndrome (wide blue-purple flowers that present a landing platform for bees and small amounts of nectar) to hummingbird pollination syndrome (bright red narrowly tubular flowers offering copious nectar). Related taxa that differ in floral syndrome offer an attractive opportunity to examine the genomic basis of complex trait divergence. In this study, we characterized genomic divergence among 229 individuals from a Penstemon species complex that includes both bee and hummingbird floral syndromes. Field plants are easily classified into species based on phenotypic differences and hybrids displaying intermediate floral syndromes are rare. Despite unambiguous phenotypic differences, genome-wide differentiation between species is minimal. Hummingbird-adapted populations are more genetically similar to nearby bee-adapted populations than to geographically distant hummingbird-adapted populations, in terms of genome-wide dXY. However, a small number of genetic loci are strongly differentiated between species. These approximately 20 "species-diagnostic loci," which appear to have nearly fixed differences between pollination syndromes, are sprinkled throughout the genome in high recombination regions. Several map closely to previously established floral trait quantitative trait loci (QTLs). The striking difference between the diagnostic loci and the genome as whole suggests strong selection to maintain distinct combinations of traits, but with sufficient gene flow to homogenize the genomic background. A surprisingly small number of alleles confer phenotypic differences that form the basis of species identity in this species complex.
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Affiliation(s)
- Carolyn A. Wessinger
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, United States of America
| | - Amanda M. Katzer
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas, United States of America
| | - Paul M. Hime
- Biodiversity Institute and Natural History Museum, University of Kansas, Lawrence, Kansas, United States of America
| | - Mark D. Rausher
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - John K. Kelly
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas, United States of America
| | - Lena C. Hileman
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas, United States of America
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Oldenbeuving A, Gómez‐Zúniga A, Florez‐Buitrago X, Gutiérrez‐Zuluaga AM, Machado CA, Van Dooren TJM, van Alphen J, Biesmeijer JC, Herre EA. Field sampling of fig pollinator wasps across host species and host developmental phase: Implications for host recognition and specificity. Ecol Evol 2023; 13:e10501. [PMID: 37706164 PMCID: PMC10495548 DOI: 10.1002/ece3.10501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 07/28/2023] [Accepted: 08/24/2023] [Indexed: 09/15/2023] Open
Abstract
Previous genetic studies of pollinator wasps associated with a community of strangler figs (Ficus subgenus Urostigma, section Americana) in Central Panama suggest that the wasp species exhibit a range in host specificity across their host figs. To better understand factors that might contribute to this observed range of specificity, we used sticky traps to capture fig-pollinating wasp individuals at 13 Ficus species, sampling at different phases of the reproductive cycle of the host figs (e.g., trees with receptive inflorescences, or vegetative trees, bearing only leaves). We also sampled at other tree species, using them as non-Ficus controls. DNA barcoding allowed us to identify the wasps to species and therefore assign their presence and abundance to host fig species and the developmental phase of that individual tree. We found: (1) wasps were only very rarely captured at non-Ficus trees; (2) nonetheless, pollinators were captured often at vegetative individuals of some host species; (3) overwhelmingly, wasp individuals were captured at receptive host fig trees representing the fig species from which they usually emerge. Our results indicate that wasp occurrence is not random either spatially or temporally within the forest and across these hosts, and that wasp specificity is generally high, both at receptive and vegetative host trees. Therefore, in addition to studies that show chemicals produced by receptive fig inflorescences attract pollinator wasps, we suggest that other cues (e.g., chemicals produced by the leaves) can also play a role in host recognition. We discuss our results in the context of recent findings on the role of host shifts in diversification processes in the Ficus genus.
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Affiliation(s)
- Aafke Oldenbeuving
- Naturalis Biodiversity CenterLeidenThe Netherlands
- Institute of Environmental Sciences (CML)Leiden UniversityLeidenThe Netherlands
| | | | | | | | | | - Tom J. M. Van Dooren
- Naturalis Biodiversity CenterLeidenThe Netherlands
- CNRS, Institute of Ecology and Environmental SciencesParisFrance
| | | | - Jacobus C. Biesmeijer
- Naturalis Biodiversity CenterLeidenThe Netherlands
- Institute of Environmental Sciences (CML)Leiden UniversityLeidenThe Netherlands
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Chen Z, Zhou Z, Guo ZM, Van Do T, Sun H, Niu Y. Historical development of karst evergreen broadleaved forests in East Asia has shaped the evolution of a hemiparasitic genus Brandisia (Orobanchaceae). PLANT DIVERSITY 2023; 45:501-512. [PMID: 37936821 PMCID: PMC10625920 DOI: 10.1016/j.pld.2023.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 01/14/2023] [Accepted: 03/17/2023] [Indexed: 11/09/2023]
Abstract
Brandisia is a shrubby genus of about eight species distributed basically in East Asian evergreen broadleaved forests (EBLFs), with distribution centers in the karst regions of Yunnan, Guizhou, and Guangxi in southwestern China. Based on the hemiparasitic and more or less liana habits of this genus, we hypothesized that its evolution and distribution were shaped by the development of EBLFs there. To test our hypothesis, the most comprehensive phylogenies of Brandisia hitherto were constructed based on plastome and nuclear loci (nrDNA, PHYA and PHYB); then divergence time and ancestral areas were inferred using the combined nuclear loci dataset. Phylogenetic analyses reconfirmed that Brandisia is a member of Orobanchaceae, with unstable placements caused by nuclear-plastid incongruences. Within Brandisia, three major clades were well supported, corresponding to the three subgenera based on morphology. Brandisia was inferred to have originated in the early Oligocene (32.69 Mya) in the Eastern Himalayas-SW China, followed by diversification in the early Miocene (19.45 Mya) in karst EBLFs. The differentiation dates of Brandisia were consistent with the origin of keystone species of EBLFs in this region (e.g., Fagaceae, Lauraceae, Theaceae, and Magnoliaceae) and the colonization of other characteristic groups (e.g., Gesneriaceae and Mahonia). These findings indicate that the distribution and evolution of Brandisia were facilitated by the rise of the karst EBLFs in East Asia. In addition, the woody and parasitic habits, and pollination characteristics of Brandisia may also be the important factors affecting its speciation and dispersal.
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Affiliation(s)
- Zhe Chen
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming 650201, Yunnan, China
| | - Zhuo Zhou
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming 650201, Yunnan, China
| | - Ze-Min Guo
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming 650201, Yunnan, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Truong Van Do
- Vietnam National Museum of Nature, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay 10000, Hanoi, Vietnam
- Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay 10000, Hanoi, Vietnam
| | - Hang Sun
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming 650201, Yunnan, China
| | - Yang Niu
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming 650201, Yunnan, China
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14
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Maguiña‐Conde R, Zuñiga‐Rivas D, Kay KM. An elevational gradient in floral traits and pollinator assemblages in the Neotropical species Costus guanaiensis var. tarmicus in Peru. Ecol Evol 2023; 13:e10314. [PMID: 37529588 PMCID: PMC10375365 DOI: 10.1002/ece3.10314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 07/04/2023] [Indexed: 08/03/2023] Open
Abstract
Different populations of plant species can adapt to their local pollinators and diverge in floral traits accordingly. Floral traits are subject to pollinator-driven natural selection to enhance plant reproductive success. Studies on temperate plant systems have shown pollinator-driven selection results in floral trait variation along elevational gradients, but studies in tropical systems are lacking. We analyzed floral traits and pollinator assemblages in the Neotropical bee-pollinated taxon Costus guanaiensis var. tarmicus across four sites along a steep elevational gradient in Peru. We found variations in floral traits of size, color, and reward, and in the pollinator assemblage along the elevational gradient. We examined our results considering two hypotheses, (1) local adaptation to different bee assemblages, and (2) the early stages of an evolutionary shift to a new pollinator functional group (hummingbirds). We found some evidence consistent with the adaptation of C. guanaiensis var. tarmicus to the local bee fauna along the studied elevational gradient. Corolla width across sites was associated with bee thorax width of the local most frequent pollinator. However, we could not rule out the possibility of the beginning of a bee-to-hummingbird pollination shift in the highest-studied site. Our study is one of the few geographic-scale analyses of floral trait and pollinator assemblage variation in tropical plant species. Our results broaden our understanding of plant-pollinator interactions beyond temperate systems by showing substantial intraspecific divergence in both floral traits and pollinator assemblages across geographic space in a tropical plant species.
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Affiliation(s)
- Rossana Maguiña‐Conde
- Ecology and Evolutionary Biology DepartmentUniversity of California Santa CruzSanta CruzCaliforniaUSA
| | - Dorali Zuñiga‐Rivas
- Laboratorio de EntomologíaUniversidad Nacional San Antonio Abad del CuscoCuscoPeru
| | - Kathleen M. Kay
- Ecology and Evolutionary Biology DepartmentUniversity of California Santa CruzSanta CruzCaliforniaUSA
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15
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Wang L, Filatov DA. Mechanisms of prezygotic post-pollination reproductive barriers in plants. FRONTIERS IN PLANT SCIENCE 2023; 14:1230278. [PMID: 37476168 PMCID: PMC10354421 DOI: 10.3389/fpls.2023.1230278] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Accepted: 06/21/2023] [Indexed: 07/22/2023]
Abstract
Hybridisation between individuals of different species can lead to maladapted or inviable progeny due to genetic incompatibilities between diverging species. On the other hand, mating with close relatives, or self-fertilisation may lead to inbreeding depression. Thus, both too much or too little divergence may lead to problems and the organisms have to carefully choose mating partners to avoid both of these pitfalls. In plants this choice occurs at many stages during reproduction, but pollen-pistil interactions play a particularly important role in avoiding inbreeding and hybridisation with other species. Interestingly, the mechanisms involved in avoidance of selfing and interspecific hybridisation may work via shared molecular pathways, as self-incompatible species tend to be more 'choosy' with heterospecific pollen compared to self-compatible ones. This review discusses various prezygotic post-pollination barriers to interspecific hybridisation, with a focus on the mechanisms of pollen-pistil interactions and their role in the maintenance of species integrity.
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Affiliation(s)
- Ludi Wang
- Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Gogerddan, Aberystwyth, United Kingdom
| | - Dmitry A. Filatov
- Department of Biology, University of Oxford, South Parks Road, Oxford, United Kingdom
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16
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Johnson MA. Phylogenetic and functional trait-based community assembly within Pacific Cyrtandra (Gesneriaceae): Evidence for clustering at multiple spatial scales. Ecol Evol 2023; 13:e10048. [PMID: 37153018 PMCID: PMC10160169 DOI: 10.1002/ece3.10048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 03/07/2023] [Accepted: 04/13/2023] [Indexed: 05/09/2023] Open
Abstract
Tropical rainforest communities are often characterized by a small number of species-rich genera that contribute disproportionately to the alpha diversity in these habitats. In the Pacific Basin, there are nearly 200 species of Cyrtandra, most of which are white-flowered woody shrubs that are single-island endemics. Within these island communities, multiple Cyrtandra species are commonly observed to occur sympatrically in wet forest understories, forming swarms of what appear to be ecologically similar taxa. The aim of this study was to determine whether species of these plants are randomly assembled with respect to phylogenetic relatedness and traits that are ecologically relevant. I examined assembly patterns across three Pacific archipelagoes using a combination of 10 functional traits and a well-resolved phylogeny comprising 34 species of Cyrtandra. Coexisting species were found to be more closely related and more phenotypically similar than would be expected by chance. This pattern was observed at both regional (island) and local (site) spatial scales. The retention of phylogenetic signal in floral traits and the strong influence of these traits on the observed degree of phylogenetic clustering may indicate that generalist insect pollinators act as a biotic filter on oceanic islands, driving selection for similar floral morphology among closely related species of Pacific Cyrtandra. Phylogenetic signal was also detected in leaf size, which contributed to niche clustering at both spatial scales. Coupled with a propensity for long-distance dispersal, and the restricted distribution of Cyrtandra to rainforest understories, this finding suggests that environmental filtering along this trait axis may be more important than dispersal limitation in determining species assemblages. This study supports the theory that plant species are not randomly assembled, and instead, that niche-based processes structure biodiversity at regional and local spatial scales in diverse congeneric species assemblages.
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Affiliation(s)
- Melissa A. Johnson
- Daniel K. Inouye US Pacific Basin Agricultural Research CenterHawaiiHiloUSA
- Rancho Santa Ana Botanic GardenCAClaremontUSA
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17
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Pérez ÁJ, Tobar F, Burgess KS, Henning T. Contributions to Ecuadorian butterworts (Lentibulariaceae, Pinguicula): two new species and a re-evaluation of Pinguiculacalyptrata. PHYTOKEYS 2023; 222:153-171. [PMID: 37252644 PMCID: PMC10209607 DOI: 10.3897/phytokeys.222.98139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 02/27/2023] [Indexed: 05/31/2023]
Abstract
Comparatively few species of the insectivorous genus Pinguicula L. have been recognized in South America so far. In recent years, a number of narrowly endemic taxa from the Andes have been described that simultaneously refined the broad taxonomic concepts of the "historical" species. Here, we describe two striking new species from Southern Ecuador that further condense the circumscription of Pinguiculacalyptrata Kunth. Pinguiculajimburensissp. nov. and P.ombrophilasp. nov. are clearly beyond the taxonomic scope of the known species and consequently described as new to science. The deviating morphological features of the two new taxa are described and illustrated and the remaining morphological spectrum of P.calyptrata in Ecuador is outlined. The two new species add to the exceptional biodiversity in the Amotape-Huancabamba Zone and underline its importance as a biodiversity hotspot in urgent need of protection.
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Affiliation(s)
- Álvaro J. Pérez
- Herbario QCA, Escuela de Ciencias Biológicas, Pontificia Universidad Católica del Ecuador, Av. 12 de Octubre 1076 y Roca, Apartado 17-01-2184, Quito, EcuadorPontificia Universidad Católica del EcuadorQuitoEcuador
| | - Francisco Tobar
- Área de Investigación y Monitoreo de Avifauna, Aves y Conservación-BirdLife en Ecuador, Quito, EcuadorÁrea de Investigación y Monitoreo de AvifaunaQuitoEcuador
- Herbario Nacional del Ecuador, Instituto Nacional de Biodiversidad, Pasaje Rumipamba 341 y Av. de los Shyris, 170135, Quito, Pichincha, EcuadorHerbario Nacional del Ecuador, Instituto Nacional de BiodiversidadQuitoEcuador
| | - Kevin S. Burgess
- Department of Biology, College of Letters & Sciences, Columbus State University, University System of Georgia, 4225 University Ave, Columbus, GA 31907, USAColumbus State UniversityColumbusUnited States of America
| | - Tilo Henning
- Leibniz Centre for Agricultural Landscape Research (ZALF), Eberswalder Str. 84, 15374, Müncheberg, GermanyLeibniz Centre for Agricultural Landscape ResearchMünchebergGermany
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18
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Alpuente N, Miranda MÁ, Cursach J. Pollination biology of Aristolochia bianorii Sennen & Pau: promoting cross-pollination but assuring reproductive success in island ecosystems. PLANT BIOLOGY (STUTTGART, GERMANY) 2023; 25:296-307. [PMID: 36536116 DOI: 10.1111/plb.13497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Accepted: 11/28/2022] [Indexed: 06/17/2023]
Abstract
Deceptive pollination has been reported in the genus Aristolochia, but the floral biology and pollination strategy of A. bianorii, an endemic of the Balearic Islands, have not yet been studied. Here, we investigated floral anthesis, mating system, pollinators and volatile organic compounds (VOCs) emitted by its flowers. Flower buds were marked and monitored daily to define floral stages and their duration. Experimental bagging and hand-pollination were performed to test for autonomous self-pollination, induced self-pollination and cross-pollination. Flowers were collected to analyse the presence of entrapped pollinators. VOCs emitted by flowers were evaluated by means of solid phase microextraction followed by immediate GC-MS. Anthesis lasted between 63 and 96 h, and the species exhibited autonomous self-pollination with moderate inbreeding depression. Pollinators were mainly females of Oscinomorpha longirostris (Diptera; Chloropidae). The number of pollinators inside flowers was affected by floral stage and time of flowering. The most common VOCs were alkanes, oximes, esters, alkenes, cyclic unsaturated hydrocarbons, isocyanates, amides and carboxylic acids. Aristolochia bianorii can set seed by autonomous self-pollination, in contrast to other Aristolochia species, in which both protogyny and herkogamy prevent autonomous self-pollination. However, the species may encourage cross-pollination by attracting female chloropid flies though emission of floral scents that may mimic an oviposition site and, possibly, freshly killed true bugs (i.e. Heteroptera). In conclusion, A. bianorii promotes cross-pollination, but delayed autonomous self-pollination assures reproductive success in the putative absence of pollinators.
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Affiliation(s)
- N Alpuente
- Research Group on Plant Biology Under Mediterranean Conditions, Laboratory of Botany, Department of Biology, Faculty of Sciences, University of Balearic Islands, Palma, Spain
| | - M Á Miranda
- Research Group on Applied Zoology and Animal Conservation, Department of Biology, Faculty of Sciences, University of Balearic Islands, Palma, Spain
| | - J Cursach
- Research Group on Plant Biology Under Mediterranean Conditions, Laboratory of Botany, Department of Biology, Faculty of Sciences, University of Balearic Islands, Palma, Spain
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19
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Moein F, Jamzad Z, Rahiminejad M, Landis JB, Mirtadzadini M, Soltis DE, Soltis PS. Towards a global perspective for Salvia L.: Phylogeny, diversification and floral evolution. J Evol Biol 2023; 36:589-604. [PMID: 36759951 DOI: 10.1111/jeb.14149] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 11/18/2022] [Accepted: 11/22/2022] [Indexed: 02/11/2023]
Abstract
Salvia is the most species-rich genus in Lamiaceae, encompassing approximately 1000 species distributed all over the world. We sought a new evolutionary perspective for Salvia by employing macroevolutionary analyses to address the tempo and mode of diversification. To study the association of floral traits with speciation and extinction, we modelled and explored the evolution of corolla length and the lever-mechanism pollination system across our Salvia phylogeny. We reconstructed a multigene phylogeny for 366 species of Salvia in the broad sense including all major recognized lineages and 50 species from Iran, a region previously overlooked in studies of the genus. Our comprehensive sampling of Iranian species of Salvia provides higher phylogenetic resolution for southwestern Asian species than obtained in previous studies. Our phylogenetic data in combination with divergence time estimates were used to examine the evolution of corolla length, woody versus herbaceous habit, and presence versus absence of a lever mechanism. We investigated the timing and dependence of Salvia diversification related to corolla length evolution through a disparity test and BAMM analysis. A HiSSE model was used to evaluate the dependency of diversification on the lever-mechanism pollination system in Salvia. A medium corolla length (15-18 mm) was reconstructed as the ancestral state for Salvia with multiple shifts to shorter and longer corollas. Macroevolutionary model analyses indicate that corolla length disparity is high throughout Salvia evolution, significantly different from expectations under a Brownian motion model during the last 28 million years of evolution. Our analyses show evidence of a higher diversification rate of corolla length for some Andean species of Salvia compared to other members of the genus. Based on our tests of diversification models, we reject the hypothesis of a direct effect of the lever mechanism on Salvia diversification. Therefore, we suggest caution in considering the lever-mechanism pollination system as one of the main drivers of speciation in Salvia.
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Affiliation(s)
- Fatemeh Moein
- Department of Plant and Animal Biology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, Iran
| | - Ziba Jamzad
- Department of Botany, Research Institute of Forest and Rangelands, Tehran, Iran
| | - Mohammadreza Rahiminejad
- Department of Plant and Animal Biology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, Iran
| | - Jacob B Landis
- School of Integrative Plant Science, Section of Plant Biology and the L.H. Bailey Hortorium, Cornell University, Ithaca, New York, USA.,BTI Computational Biology Center, Boyce Thompson Institute, Ithaca, New York, USA
| | | | - Douglas E Soltis
- Department of Biology, University of Florida, Gainesville, Florida, USA.,Florida Museum of Natural History, University of Florida, Gainesville, Florida, USA.,The Genetics Institute, University of Florida, Gainesville, Florida, USA.,The Biodiversity Institute, University of Florida, Gainesville, Florida, USA
| | - Pamela S Soltis
- Florida Museum of Natural History, University of Florida, Gainesville, Florida, USA.,The Genetics Institute, University of Florida, Gainesville, Florida, USA.,The Biodiversity Institute, University of Florida, Gainesville, Florida, USA
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20
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Coughlan JM. The role of hybrid seed inviability in angiosperm speciation. AMERICAN JOURNAL OF BOTANY 2023; 110:1-14. [PMID: 36801827 DOI: 10.1002/ajb2.16135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2022] [Revised: 01/05/2023] [Accepted: 01/05/2023] [Indexed: 05/11/2023]
Abstract
Understanding which reproductive barriers contribute to speciation is essential to understanding the diversity of life on earth. Several contemporary examples of strong hybrid seed inviability (HSI) between recently diverged species suggest that HSI may play a fundamental role in plant speciation. Yet, a broader synthesis of HSI is needed to clarify its role in diversification. Here, I review the incidence and evolution of HSI. Hybrid seed inviability is common and evolves rapidly, suggesting that it may play an important role early in speciation. The developmental mechanisms that underlie HSI involve similar developmental trajectories in endosperm, even between evolutionarily deeply diverged incidents of HSI. In hybrid endosperm, HSI is often accompanied by whole-scale gene misexpression, including misexpression of imprinted genes which have a key role in endosperm development. I explore how an evolutionary perspective can clarify the repeated and rapid evolution of HSI. In particular, I evaluate the evidence for conflict between maternal and paternal interests in resource allocation to offspring (i.e., parental conflict). I highlight that parental conflict theory generates explicit predictions regarding the expected hybrid phenotypes and genes responsible for HSI. While much phenotypic evidence supports a role of parental conflict in the evolution of HSI, an understanding of the underlying molecular mechanisms of this barrier is essential to test parental conflict theory. Lastly, I explore what factors may influence the strength of parental conflict in natural plant populations as an explanation for why rates of HSI may differ between plant groups and the consequences of strong HSI in secondary contact.
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Affiliation(s)
- Jenn M Coughlan
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, 06511, USA
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21
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Wenzell KE, Skogen KA, Fant JB. Range‐wide floral trait variation reflects shifts in pollinator assemblages, consistent with pollinator‐mediated divergence despite generalized visitation. OIKOS 2023. [DOI: 10.1111/oik.09708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Katherine E. Wenzell
- John Innes Centre Colney Lane Norwich UK
- Northwestern Univ., Program in Plant Biology and Conservation Evanston IL USA
- Negaunee Inst. for Plant Conservation Science and Action, Chicago Botanic Garden Glencoe IL USA
| | - Krissa A. Skogen
- Northwestern Univ., Program in Plant Biology and Conservation Evanston IL USA
- Negaunee Inst. for Plant Conservation Science and Action, Chicago Botanic Garden Glencoe IL USA
- Clemson Univ., Dept of Biological Sciences Clemson SC USA
| | - Jeremie B. Fant
- Northwestern Univ., Program in Plant Biology and Conservation Evanston IL USA
- Negaunee Inst. for Plant Conservation Science and Action, Chicago Botanic Garden Glencoe IL USA
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22
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Floral scent divergence across an elevational hybrid zone with varying pollinators. Oecologia 2023; 201:45-57. [PMID: 36374316 DOI: 10.1007/s00442-022-05289-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 11/08/2022] [Indexed: 11/16/2022]
Abstract
Divergence in floral traits attractive to different pollinators can promote reproductive isolation in related species. When isolation is incomplete, hybridization may occur, which offers the opportunity to explore mechanisms underlying reproductive isolation. Recent work suggests that divergence in floral scent may frequently contribute to reproductive barriers, although such divergence has seldom been examined in species with generalized pollination. Here, we used two closely related Penstemon species, P. newberryi and P. davidsonii, and their natural hybrids from an elevational gradient with pollinator communities that are predicted to vary in their reliance on floral scent (i.e., primarily hummingbirds at low elevation vs. bees at high elevation). The species vary in a suite of floral traits, but scent is uncharacterized. To address whether scent varies along elevation and potentially contributes to reproductive isolation, we genetically characterized individuals collected at field and identified whether they were parental species or hybrids. We then characterized scent amount and composition. Although the parental species had similar total emissions, some scent characteristics (i.e., scent composition, aromatic emission) diverged between them and may contribute to their isolation. However, the species emitted similar compound sets which could explain hybridization in the contact area. Hybrids were similar to the parents for most scent traits, suggesting that their floral scent would not provide a strong barrier to backcrossing. Our study suggests floral scent may be a trait contributing to species boundaries even in plants with generalized pollination, and reinforces the idea that evolutionary pollinator transitions may involve changes in multiple floral traits.
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23
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Koski MH. Pollinators exert selection on floral traits in a pollen-limited, narrowly endemic spring ephemeral. AMERICAN JOURNAL OF BOTANY 2023; 110:e16101. [PMID: 36371765 PMCID: PMC10108127 DOI: 10.1002/ajb2.16101] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 10/27/2022] [Accepted: 10/28/2022] [Indexed: 06/16/2023]
Abstract
PREMISE Floral traits are frequently under pollinator-mediated selection, especially in taxa subject to strong pollen-limitation, such as those reliant on pollinators. However, antagonists can be agents of selection on floral traits as well. The causes of selection acting on spring ephemerals are understudied though these species can experience particularly strong pollen-limitation. I examined pollinator- and antagonist-mediated selection in a narrowly endemic spring ephemeral, Trillium discolor. METHODS I measured pollen limitation in T. discolor across two years and evaluated its breeding system. I compared selection on floral traits (display height, petal size, petal color, flowering time) between open-pollinated, and pollen-supplemented plants to measure the strength and mode of pollinator-mediated selection. I assessed whether natural levels of antagonism impacted selection on floral traits. RESULTS Trillium discolor was self-incompatible and experienced pollen limitation in both years of the study. Pollinators exerted negative disruptive selection on display height and petals size. In one year, pollinator-mediated selection favored lighter petals but in the second year pollinators favored darker petals. Antagonist damage did not alter selection on floral traits. CONCLUSIONS Results demonstrate that pollinators mediate the strength and mode of selection on floral traits in T. discolor. Interannual variation in the strength, mode, and direction of pollinator-mediated selection on floral traits could be important for maintaining of floral diversity in this system. Observed levels of antagonism were weak agents of selection on floral traits.
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Affiliation(s)
- Matthew H. Koski
- Department of Biological SciencesClemson UniversityClemsonSouth Carolina29634USA
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24
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Cornet C, Noret N, Van Rossum F. Pollinator sharing between reproductively isolated genetic lineages of Silene nutans. FRONTIERS IN PLANT SCIENCE 2022; 13:927498. [PMID: 36340351 PMCID: PMC9634645 DOI: 10.3389/fpls.2022.927498] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Accepted: 09/22/2022] [Indexed: 06/16/2023]
Abstract
High reciprocal pollination specialization leading to pollinator isolation can prevent interspecific pollen transfer and competition for pollinators. Sharing pollinators may induce mating costs, but it may also increase pollination services and pollen dispersal and offer more resources to pollinators, which may be important in case of habitat fragmentation leading to pollination disruption. We estimated pollen dispersal and pollinator isolation or sharing between two reproductively isolated genetic lineages of Silene nutans (Caryophyllaceae), which are rare and occur in parapatry in southern Belgium, forming two edaphic ecotypes. As inter-ecotypic crosses may lead to pollen wastage and inviable progeny, pollinator isolation might have evolved between ecotypes. Silene nutans is mainly pollinated by nocturnal moths, including nursery pollinators, which pollinate and lay their eggs in flowers, and whose caterpillars feed on flowers and seeds. Pollinator assemblages of the two ecotypes are largely unknown and inter-ecotypic pollen flows have never been investigated. Fluorescent powdered dyes were used as pollen analogues to quantify intra- and inter-ecotypic pollen transfers and seeds were germinated to detect chlorotic seedlings resulting from inter-ecotypic pollination. Nocturnal pollinators were observed using infrared cameras on the field, and seed-eating caterpillars were collected and reared to identify nursery pollinator species. No pollinator isolation was found: we detected long-distance (up to 5 km) inter-ecotypic dye transfers and chlorotic seedlings, indicating inter-ecotypic fertilization events. The rare moth Hadena albimacula, a nursery pollinator specialized on S. nutans, was found on both ecotypes, as well as adults visiting flowers (cameras recordings) as seed-eating caterpillars. However, S. nutans populations harbor different abundance and diversity of seed predator communities, including other rare nursery pollinators, suggesting a need for distinct conservation strategies. Our findings demonstrate the efficiency of moths, especially of nursery pollinators, to disperse pollen over long distances in natural landscapes, so to ensure gene flow and population sustainability of the host plant. Seed-predator specificities between the two reproductively isolated genetic lineages of S. nutans, and pollinator sharing instead of pollinator isolation when plants occur in parapatry, suggest that conservation of the host plant is also essential for sustaining (rare) pollinator and seed predator communities.
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Affiliation(s)
- Camille Cornet
- Laboratoire d’Ecologie végétale et Biogéochimie, Université libre de Bruxelles, Brussels, Belgium
| | - Nausicaa Noret
- Laboratoire d’Ecologie végétale et Biogéochimie, Université libre de Bruxelles, Brussels, Belgium
| | - Fabienne Van Rossum
- Laboratoire d’Ecologie végétale et Biogéochimie, Université libre de Bruxelles, Brussels, Belgium
- Research Department, Meise Botanic Garden, Meise, Belgium
- Service général de l’Enseignement supérieur et de la Recherche scientifique, Fédération Wallonie-Bruxelles, Brussels, Belgium
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25
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Hassler GW, Gallone B, Aristide L, Allen WL, Tolkoff MR, Holbrook AJ, Baele G, Lemey P, Suchard MA. Principled, practical, flexible, fast: a new approach to phylogenetic factor analysis. Methods Ecol Evol 2022; 13:2181-2197. [PMID: 36908682 PMCID: PMC9997680 DOI: 10.1111/2041-210x.13920] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Biological phenotypes are products of complex evolutionary processes in which selective forces influence multiple biological trait measurements in unknown ways. Phylogenetic comparative methods seek to disentangle these relationships across the evolutionary history of a group of organisms. Unfortunately, most existing methods fail to accommodate high-dimensional data with dozens or even thousands of observations per taxon. Phylogenetic factor analysis offers a solution to the challenge of dimensionality. However, scientists seeking to employ this modeling framework confront numerous modeling and implementation decisions, the details of which pose computational and replicability challenges.We develop new inference techniques that increase both the computational efficiency and modeling flexibility of phylogenetic factor analysis. To facilitate adoption of these new methods, we present a practical analysis plan that guides researchers through the web of complex modeling decisions. We codify this analysis plan in an automated pipeline that distills the potentially overwhelming array of decisions into a small handful of (typically binary) choices.We demonstrate the utility of these methods and analysis plan in four real-world problems of varying scales. Specifically, we study floral phenotype and pollination in columbines, domestication in industrial yeast, life history in mammals, and brain morphology in New World monkeys.General and impactful community employment of these methods requires a data scientific analysis plan that balances flexibility, speed and ease of use, while minimizing model and algorithm tuning. Even in the presence of non-trivial phylogenetic model constraints, we show that one may analytically address latent factor uncertainty in a way that (a) aids model flexibility, (b) accelerates computation (by as much as 500-fold) and (c) decreases required tuning. These efforts coalesce to create an accessible Bayesian approach to high-dimensional phylogenetic comparative methods on large trees.
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Affiliation(s)
- Gabriel W. Hassler
- Department of Computational Medicine, David Geffen School of Medicine at UCLA, University of California, Los Angeles, United States
| | | | - Leandro Aristide
- Ecole Normale Superieure Paris Sciences et Lettres Research University, Institut de Biologie de l’Ecole Normale Superieure, Paris, France
| | - William L. Allen
- Department of Biosciences, Swansea University, Swansea, United Kingdom
| | - Max R. Tolkoff
- Department of Biostatistics, Jonathan and Karin Fielding School of Public Health, University of California, Los Angeles, United States
| | - Andrew J. Holbrook
- Department of Biostatistics, Jonathan and Karin Fielding School of Public Health, University of California, Los Angeles, United States
| | - Guy Baele
- Department of Microbiology and Immunology, Rega Institute, KU Leuven, Leuven, Belgium
| | - Philippe Lemey
- Department of Microbiology and Immunology, Rega Institute, KU Leuven, Leuven, Belgium
| | - Marc A. Suchard
- Department of Computational Medicine, David Geffen School of Medicine at UCLA, University of California, Los Angeles, United States
- Department of Biostatistics, Jonathan and Karin Fielding School of Public Health, University of California, Los Angeles, United States
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Universtiy of California, Los Angeles, United States
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Christie K, Fraser LS, Lowry DB. The strength of reproductive isolating barriers in seed plants: Insights from studies quantifying premating and postmating reproductive barriers over the past 15 years. Evolution 2022; 76:2228-2243. [PMID: 35838076 PMCID: PMC9796645 DOI: 10.1111/evo.14565] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 06/23/2022] [Accepted: 06/30/2022] [Indexed: 01/22/2023]
Abstract
Speciation is driven by the evolution of reproductive isolating barriers that reduce, and ultimately prevent, substantial gene flow between lineages. Despite its central role in evolutionary biology, the process can be difficult to study because it proceeds differently among groups and may occur over long timescales. Due to this complexity, we typically rely on generalizations of empirical data to describe and understand the process. Previous reviews of reproductive isolation (RI) in flowering plants have suggested that prezygotic or extrinsic barriers generally have a stronger effect on reducing gene flow compared to postzygotic or intrinsic barriers. Past conclusions have rested on relatively few empirical estimates of RI; however, RI data have become increasingly abundant over the past 15 years. We analyzed data from recent studies quantifying multiple pre- and postmating barriers in plants and compared the strengths of isolating barriers across 89 taxa pairs using standardized RI metrics. Individual prezygotic barriers were on average stronger than individual postzygotic barriers, and the total strength of prezygotic RI was approximately twice that of postzygotic RI. These findings corroborate that ecological divergence and extrinsic factors, as opposed to solely the accumulation of genetic incompatibilities, are important to speciation and the maintenance of species boundaries in plants. Despite an emphasis in the literature on asymmetric postmating and postzygotic RI, we found that prezygotic barriers acted equally asymmetrically. Overall, substantial variability in the strengths of 12 isolating barriers highlights the great diversity of mechanisms that contribute to plant diversification.
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Affiliation(s)
- Kyle Christie
- Department of Plant BiologyMichigan State UniversityEast LansingMichigan48824,Department of Biological SciencesNorthern Arizona UniversityFlagstaffArizona86011
| | - Linnea S. Fraser
- Department of Plant BiologyMichigan State UniversityEast LansingMichigan48824
| | - David B. Lowry
- Department of Plant BiologyMichigan State UniversityEast LansingMichigan48824
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27
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Luan Y, Tang Y, Wang X, Xu C, Tao J, Zhao D. Tree Peony R2R3-MYB Transcription Factor PsMYB30 Promotes Petal Blotch Formation by Activating the Transcription of the Anthocyanin Synthase Gene. PLANT & CELL PHYSIOLOGY 2022; 63:1101-1116. [PMID: 35713501 DOI: 10.1093/pcp/pcac085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 06/08/2022] [Accepted: 06/14/2022] [Indexed: 06/15/2023]
Abstract
Petal blotches are commonly observed in many angiosperm families and not only influence plant-pollinator interactions but also confer high ornamental value. Tree peony (Paeonia suffruticosa Andr.) is an important cut flower worldwide, but few studies have focused on its blotch formation. In this study, anthocyanins were found to be the pigment basis for blotch formation of P. suffruticosa, and peonidin-3,5-di-O-glucoside (Pn3G5G) was the most important component of anthocyanins, while the dihydroflavonol-4-reductase gene was the key factor contributing to blotch formation. Then, the R2R3-myeloblastosis (MYB) transcription factor PsMYB30 belonging to subgroup 1 was proven as a positive anthocyanin regulator with transcriptional activation and nuclear expression. Furthermore, silencing PsMYB30 in P. suffruticosa petals reduced blotch size by 37.9%, faded blotch color and decreased anthocyanin and Pn3G5G content by 23.6% and 32.9%, respectively. Overexpressing PsMYB30 increased anthocyanin content by 14.5-fold in tobacco petals. In addition, yeast one-hybrid assays, dual-luciferase assays and electrophoretic mobility shift assays confirmed that PsMYB30 could bind to the promoter of the anthocyanin synthase (ANS) gene and enhance its expression. Altogether, a novel MYB transcription factor, PsMYB30, was identified to promote petal blotch formation by activating the expression of PsANS involved in anthocyanin biosynthesis, which provide new insights for petal blotch formation in plants.
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Affiliation(s)
- Yuting Luan
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, Jiangsu, China
| | - Yuhan Tang
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, Jiangsu, China
| | - Xin Wang
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, Jiangsu, China
| | - Cong Xu
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, Jiangsu, China
| | - Jun Tao
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, Jiangsu, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, The Ministry of Education of China, Yangzhou University, Yangzhou 225009, Jiangsu, China
| | - Daqiu Zhao
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, Jiangsu, China
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28
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Armbruster WS. Floral specialization increases pollination precision: the roles of floral orientation, symmetry, fusion and stamen number. THE NEW PHYTOLOGIST 2022; 235:1307-1309. [PMID: 35621012 DOI: 10.1111/nph.18215] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Affiliation(s)
- W Scott Armbruster
- School of Biological Sciences, University of Portsmouth, Portsmouth, PO1 2DY, UK
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA
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29
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Wessinger CA. Small genetic steps lead to mechanical isolation in hummingbird-pollinated gingers. Mol Ecol 2022; 31:4205-4207. [PMID: 35796626 DOI: 10.1111/mec.16605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 07/04/2022] [Indexed: 11/28/2022]
Abstract
Interactions with pollinators are a potent source of natural selection driving the spectacular array of flowering plant diversity on Earth (Kay & Sargent, 2009; Van der Niet et al., 2014). Floral traits play a central role in this process: reliable and effective pollination by animal pollinators depends on complex floral features, including traits that determine pollinator attraction and reward, as well as the mechanics of pollen transfer. Pollinators specify mating events between individuals, and thus differences in flowers have the potential to generate reproductive isolating barriers (floral isolation). A compelling case of floral isolation comes from spiral gingers (Costus), where hummingbird-adapted species have evolved distinct pollen placement strategies (on the bills vs. foreheads of pollinators) due to differences in flower shape and the arrangements of flower parts. This difference in pollen placement causes a mechanical barrier to cross-pollination. In this issue of Molecular Ecology, Kay and Surget-Groba (2022) dissect the genetic basis of these floral differences using a quantitative trait locus (QTL) mapping approach. They find small-effect QTLs that influence multiple correlated traits and allelic effects that suggest a history of directional selection. Their results indicate mechanical isolation reflects adaptive divergence that has built up piecemeal over time.
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30
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Boehm MMA, Guevara‐Apaza D, Jankowski JE, Cronk QCB. Floral phenology of an Andean bellflower and pollination by buff-tailed sicklebill hummingbird. Ecol Evol 2022; 12:e8988. [PMID: 35784085 PMCID: PMC9168340 DOI: 10.1002/ece3.8988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 05/09/2022] [Accepted: 05/13/2022] [Indexed: 11/17/2022] Open
Abstract
The Andean bellflowers comprise an explosive radiation correlated with shifts to specialized pollination. One diverse clade has evolved with extremely curved floral tubes and is predicted to be pollinated exclusively by one of two parapatric species of sicklebill hummingbirds (Eutoxeres). In this study, we focused on the floral biology of Centropogon granulosus, a bellflower thought to be specialized for pollination by Eutoxeres condamini, in a montane cloud forest site in southeastern Peru. Using camera traps and a pollination exclusion experiment, we documented E. condamini as the sole pollinator of C. granulosus. Visitation by E. condamini was necessary for fruit development. Flowering rates were unequivocally linear and conformed to the "steady-state" phenological type. Over the course of >1800 h of monitoring, we recorded 12 E. condamini visits totaling 42 s, indicating traplining behavior. As predicted by its curved flowers, C. granulosus is exclusively pollinated by buff-tailed sicklebill within our study area. We present evidence for the congruence of phenology and visitation as a driver of specialization in this highly diverse clade of Andean bellflowers.
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Affiliation(s)
- Mannfred M. A. Boehm
- Department of BotanyUniversity of British ColumbiaVancouverBritish ColumbiaCanada
- Biodiversity Research CentreUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - David Guevara‐Apaza
- Facultad de Ciencias BiológicasUniversidad San Antonio Abad del CuscoCuscoPeru
| | - Jill E. Jankowski
- Biodiversity Research CentreUniversity of British ColumbiaVancouverBritish ColumbiaCanada
- Department of ZoologyUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Quentin C. B. Cronk
- Department of BotanyUniversity of British ColumbiaVancouverBritish ColumbiaCanada
- Biodiversity Research CentreUniversity of British ColumbiaVancouverBritish ColumbiaCanada
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31
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Hamilton AM, Wessinger CA. Adaptation to lower latitudes and lower elevations precedes the evolution of hummingbird pollination in western North American Penstemon. AMERICAN JOURNAL OF BOTANY 2022; 109:1047-1055. [PMID: 35471733 DOI: 10.1002/ajb2.1857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Revised: 04/12/2022] [Accepted: 04/12/2022] [Indexed: 06/14/2023]
Abstract
PREMISE A switch in pollinator can occur when a plant lineage enters a new habitat where the ancestral pollinator is less common, and a novel pollinator is more common. Because pollinator communities vary according to environmental tolerances and availability of resources, there may be consistent associations between pollination mode and specific regions and habitats. Such associations can be studied in lineages that have experienced multiple pollinator transitions, representing evolutionary replicates. METHODS Our study focused on a large clade of Penstemon wildflower species in western North America, which has repeatedly evolved hummingbird-adapted flowers from ancestral bee-adapted flowers. For each species, we estimated geographic ranges from occurrence data and inferred environmental niches from climate, topographical, and soil data. Using a phylogenetic comparative approach, we investigated whether hummingbird-adapted species occupy distinct geographic regions or habitats relative to bee-adapted species. RESULTS Hummingbird-adapted species occur at lower latitudes and lower elevations than bee-adapted species, resulting in a difference in their environmental niche. Bee-adapted species sister to hummingbird-adapted species are also found in relatively low elevations and latitudes, similar to their hummingbird-adapted sister species, suggesting ecogeographic shifts precede pollinator divergence. Sister species pairs-regardless of whether they differ in pollinator-show relatively little geographic range overlap. CONCLUSIONS Adaptation to a novel pollinator may often occur in geographic and ecological isolation from ancestral populations. The ability of a given lineage to adapt to novel pollinators may critically depend on its ability to colonize regions and habitats associated with novel pollinator communities.
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Affiliation(s)
- Ashley M Hamilton
- Department of Biological Sciences, University of South Carolina, 715 Sumter St, Columbia, SC 29208, USA
| | - Carolyn A Wessinger
- Department of Biological Sciences, University of South Carolina, 715 Sumter St, Columbia, SC 29208, USA
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32
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Cooper BJ, Moore MJ, Douglas NA, Wagner WL, Johnson MG, Overson RP, Kinosian SP, McDonnell AJ, Levin RA, Raguso RA, Flores Olvera H, Ochoterena H, Fant JB, Skogen KA, Wickett NJ. Target enrichment and extensive population sampling help untangle the recent, rapid radiation of Oenothera sect. Calylophus. Syst Biol 2022:6588089. [PMID: 35583314 DOI: 10.1093/sysbio/syac032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/14/2022] [Accepted: 04/22/2022] [Indexed: 11/14/2022] Open
Abstract
Oenothera sect. Calylophus is a North American group of 13 recognized taxa in the evening primrose family (Onagraceae) with an evolutionary history that may include independent origins of bee pollination, edaphic endemism, and permanent translocation heterozygosity. Like other groups that radiated relatively recently and rapidly, taxon boundaries within Oenothera sect. Calylophus have remained challenging to circumscribe. In this study, we used target enrichment, flanking non-coding regions, gene tree/species tree methods, tests for gene flow modified for target-enrichment data, and morphometric analysis to reconstruct phylogenetic hypotheses, evaluate current taxon circumscriptions, and examine character evolution in Oenothera sect. Calylophus. Because sect. Calylophus comprises a clade with a relatively restricted geographic range, we were able to extensively sample across the range of geographic, edaphic and morphological diversity in the group. We found that the combination of exons and flanking non-coding regions led to improved support for species relationships. We reconstructed potential hybrid origins of some accessions and note that if processes such as hybridization are not taken into account, the number of inferred evolutionary transitions may be artificially inflated. We recovered strong evidence for multiple evolutionary origins of bee pollination from ancestral hawkmoth pollination, edaphic specialization on gypsum, and permanent translocation heterozygosity. This study applies newly emerging techniques alongside dense infraspecific sampling and morphological analyses to effectively reconstruct the recalcitrant history of a rapid radiation.
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Affiliation(s)
- Benjamin J Cooper
- The Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, 1000 Lake Cook Rd., Glencoe, IL 60022, USA.,Northwestern University,Program in Plant Biology and Conservation,O.T. Hogan Hall, Room, 6-140B, 2205 Tech Drive, Evanston, IL 60208, USA
| | - Michael J Moore
- Oberlin College, Department of Biology, 119 Woodland St., Oberlin, OH 44074, USA
| | - Norman A Douglas
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
| | - Warren L Wagner
- Department of Botany, MRC-166, Smithsonian Institution, PO Box 37012, Washington, DC 20013-7012, USA
| | - Matthew G Johnson
- The Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, 1000 Lake Cook Rd., Glencoe, IL 60022, USA.,Department of Biological Sciences, Texas Tech University, Box 43131 Lubbock, TX 79409, USA
| | - Rick P Overson
- The Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, 1000 Lake Cook Rd., Glencoe, IL 60022, USA.,School of Sustainability, Arizona State University, PO Box 875502, Tempe, AZ 85287-5502, USA
| | - Sylvia P Kinosian
- The Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, 1000 Lake Cook Rd., Glencoe, IL 60022, USA
| | - Angela J McDonnell
- The Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, 1000 Lake Cook Rd., Glencoe, IL 60022, USA
| | - Rachel A Levin
- Department of Biology, Amherst College, 25 East Drive, Amherst, MA, 01002, USA
| | - Robert A Raguso
- Department of Neurobiology and Behavior, Cornell University, 215 Tower Road, Ithaca, NY 14853, USA
| | - Hilda Flores Olvera
- Departamento de Botánica, Instituto de Biología, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Helga Ochoterena
- Departamento de Botánica, Instituto de Biología, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Jeremie B Fant
- The Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, 1000 Lake Cook Rd., Glencoe, IL 60022, USA.,Northwestern University,Program in Plant Biology and Conservation,O.T. Hogan Hall, Room, 6-140B, 2205 Tech Drive, Evanston, IL 60208, USA
| | - Krissa A Skogen
- The Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, 1000 Lake Cook Rd., Glencoe, IL 60022, USA.,Northwestern University,Program in Plant Biology and Conservation,O.T. Hogan Hall, Room, 6-140B, 2205 Tech Drive, Evanston, IL 60208, USA
| | - Norman J Wickett
- The Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, 1000 Lake Cook Rd., Glencoe, IL 60022, USA.,Northwestern University,Program in Plant Biology and Conservation,O.T. Hogan Hall, Room, 6-140B, 2205 Tech Drive, Evanston, IL 60208, USA
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Steenwyk JL, Phillips MA, Yang F, Date SS, Graham TR, Berman J, Hittinger CT, Rokas A. An orthologous gene coevolution network provides insight into eukaryotic cellular and genomic structure and function. SCIENCE ADVANCES 2022; 8:eabn0105. [PMID: 35507651 PMCID: PMC9067921 DOI: 10.1126/sciadv.abn0105] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 03/16/2022] [Indexed: 06/14/2023]
Abstract
The evolutionary rates of functionally related genes often covary. We present a gene coevolution network inferred from examining nearly 3 million orthologous gene pairs from 332 budding yeast species spanning ~400 million years of evolution. Network modules provide insight into cellular and genomic structure and function. Examination of the phenotypic impact of network perturbation using deletion mutant data from the baker's yeast Saccharomyces cerevisiae, which were obtained from previously published studies, suggests that fitness in diverse environments is affected by orthologous gene neighborhood and connectivity. Mapping the network onto the chromosomes of S. cerevisiae and Candida albicans revealed that coevolving orthologous genes are not physically clustered in either species; rather, they are often located on different chromosomes or far apart on the same chromosome. The coevolution network captures the hierarchy of cellular structure and function, provides a roadmap for genotype-to-phenotype discovery, and portrays the genome as a linked ensemble of genes.
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Affiliation(s)
- Jacob L. Steenwyk
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Megan A. Phillips
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Feng Yang
- Shmunis School of Biomedical and Cancer Research, Tel Aviv University, Ramat Aviv, Israel
- Department of Pharmacology, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China
| | - Swapneeta S. Date
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Todd R. Graham
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Judith Berman
- Shmunis School of Biomedical and Cancer Research, Tel Aviv University, Ramat Aviv, Israel
| | - Chris Todd Hittinger
- Laboratory of Genetics, DOE Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, Center for Genomic Science Innovation, J.F. Crow Institute for the Study of Evolution, University of Wisconsin-Madison, Madison, WI, USA
| | - Antonis Rokas
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
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34
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Burgin G, Hopkins R. A missing link: Connecting plant and pollinator population structure. AMERICAN JOURNAL OF BOTANY 2022; 109:668-671. [PMID: 35421258 DOI: 10.1002/ajb2.1844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 03/07/2022] [Accepted: 03/08/2022] [Indexed: 06/14/2023]
Affiliation(s)
- Grace Burgin
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
- Arnold Arboretum of Harvard University, Boston, MA, 02131, USA
| | - Robin Hopkins
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
- Arnold Arboretum of Harvard University, Boston, MA, 02131, USA
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35
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Hopkins R. Predicting how pollinator behavior causes reproductive isolation. Ecol Evol 2022; 12:e8847. [PMID: 35462980 PMCID: PMC9019001 DOI: 10.1002/ece3.8847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 04/06/2022] [Indexed: 11/07/2022] Open
Abstract
Pollinator behavior is an important contributor to plants speciation, yet how variation in pollinator behavior causes variation in reproductive isolation (RI) is largely uncharacterized. Here I present a model that predicts how two aspects of pollinator behavior, constancy and preference, contribute to a barrier to reproduction in plants. This model is motivated by two observations: most co‐occurring plants vary in frequency over space and time, and most plants have multiple pollinators that differ in behavior. Thus, my goal was to understand how relative frequencies of plants and pollinators in a community influence ethological RI between co‐occurring plants. I find that RI for a focal plant generally increases with increasing relative plant frequency, but the shape of this relationship is highly dependent on the strength of pollinator behavior (constancy and preference). Additionally, when multiple pollinators express different behavior, I find that pollinators with stronger preference disproportionately influence RI. But, I show that RI caused by constancy is the average RI predicted from constancy of each pollinator weighted by pollinator frequency. I apply this model to examples of pollinator‐mediated RI in Phlox and in Ipomopsis to predict the relationships between plant frequency and ethological RI in natural systems. This model provides new insights into how and why pollinator specialization causes RI, and how RI could change with changing biological communities.
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Affiliation(s)
- Robin Hopkins
- The Department of Organismic and Evolutionary Biology and The Arnold ArboretumHarvard UniversityBostonMassachusettsUSA
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36
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Uluer DA, Forest F, Armbruster S, Hawkins JA. Reconstructing an historical pollination syndrome: keel flowers. BMC Ecol Evol 2022; 22:45. [PMID: 35413792 PMCID: PMC9004149 DOI: 10.1186/s12862-022-02003-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 04/05/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Keel flowers are bilaterally symmetrical, pentamerous flowers with three different petal types and reproductive organs enclosed by keel petals; generally there is also connation of floral parts such as stamens and keel petals. In this study, the evolution of keel flowers within the order Fabales is explored to investigate whether the establishment of this flower type within one of the species-rich families, the Fabaceae (Leguminosae), preceded and could have influenced the evolution of keel flowers in the Polygalaceae. We conducted molecular dating, and ancestral area and ancestral state analyses for a phylogeny constructed for 678 taxa using published matK, rbcL and trnL plastid gene regions.
Results
We reveal the temporal and spatial origins of keel flowers and traits associated with pollinators, specifically floral symmetry, the presence or absence of a pentamerous corolla and three distinct petal types, the presence or absence of enclosed reproductive organs, androecium types, inflorescence types, inflorescence size, flower size, plant height and habit. Ancestral area reconstructions show that at the time keel flowers appeared in the Polygaleae, subfamily Papilionoideae of the Fabaceae was already distributed almost globally; at least eight clades of the Papilionoideae had keel flowers with a functional morphology broadly similar to the morphology of the first evolving Polygaleae flowers.
Conclusions
The multiple origins of keel flowers within angiosperms likely represent convergence due to bee specialization, and therefore pollinator pressure. In the case of the Fabales, the first evolving keel flowers of Polygaleae have a functional morphology that corresponds with keel flowers of species of the Papilionoideae already present in the environment. These findings are consistent with the keel-flowered Polygaleae exploiting pollinators of keel-flowered Papilionoideae. The current study is the first to use ancestral reconstructions of traits associated with pollination to demonstrate that the multiple evolutionary origins of the keel flower pollinator syndrome in Fabales are consistent with, though do not prove, mimicry.
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Sun T, Rao S, Zhou X, Li L. Plant carotenoids: recent advances and future perspectives. MOLECULAR HORTICULTURE 2022; 2:3. [PMID: 37789426 PMCID: PMC10515021 DOI: 10.1186/s43897-022-00023-2] [Citation(s) in RCA: 89] [Impact Index Per Article: 44.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Accepted: 01/03/2022] [Indexed: 10/05/2023]
Abstract
Carotenoids are isoprenoid metabolites synthesized de novo in all photosynthetic organisms. Carotenoids are essential for plants with diverse functions in photosynthesis, photoprotection, pigmentation, phytohormone synthesis, and signaling. They are also critically important for humans as precursors of vitamin A synthesis and as dietary antioxidants. The vital roles of carotenoids to plants and humans have prompted significant progress toward our understanding of carotenoid metabolism and regulation. New regulators and novel roles of carotenoid metabolites are continuously revealed. This review focuses on current status of carotenoid metabolism and highlights recent advances in comprehension of the intrinsic and multi-dimensional regulation of carotenoid accumulation. We also discuss the functional evolution of carotenoids, the agricultural and horticultural application, and some key areas for future research.
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Affiliation(s)
- Tianhu Sun
- Robert W. Holley Center for Agriculture and Health, USDA-Agricultural Research Service, Cornell University, Ithaca, NY, 14853, USA
- Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA
| | - Sombir Rao
- Robert W. Holley Center for Agriculture and Health, USDA-Agricultural Research Service, Cornell University, Ithaca, NY, 14853, USA
- Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA
| | - Xuesong Zhou
- Robert W. Holley Center for Agriculture and Health, USDA-Agricultural Research Service, Cornell University, Ithaca, NY, 14853, USA
- State Key Laboratory of Crop Genetics & Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Li Li
- Robert W. Holley Center for Agriculture and Health, USDA-Agricultural Research Service, Cornell University, Ithaca, NY, 14853, USA.
- Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA.
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Medina M, Baker DM, Baltrus DA, Bennett GM, Cardini U, Correa AMS, Degnan SM, Christa G, Kim E, Li J, Nash DR, Marzinelli E, Nishiguchi M, Prada C, Roth MS, Saha M, Smith CI, Theis KR, Zaneveld J. Grand Challenges in Coevolution. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2021.618251] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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Boehm MMA, Jankowski JE, Cronk QCB. Plant-Pollinator Specialization: Origin and Measurement of Curvature. Am Nat 2021; 199:206-222. [DOI: 10.1086/717677] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- Mannfred M. A. Boehm
- Department of Botany, University of British Columbia, 3156-6270 University Boulevard, Vancouver, British Columbia V6T 1Z4, Canada
- Biodiversity Research Centre, University of British Columbia, 2212 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada
| | - Jill E. Jankowski
- Biodiversity Research Centre, University of British Columbia, 2212 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Zoology, University of British Columbia, 4200-6270 University Boulevard, Vancouver, British Columbia V6T 1Z4, Canada
| | - Quentin C. B. Cronk
- Department of Botany, University of British Columbia, 3156-6270 University Boulevard, Vancouver, British Columbia V6T 1Z4, Canada
- Biodiversity Research Centre, University of British Columbia, 2212 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada
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40
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Stimpson ML, Whalley RDB, McLean L, Sadgrove NJ, Padilla-Gonzalez GF, Van Wyk BE, Clay J, Bruhl JJ. Colour of floral styles in the Banksia spinulosa Sm complex (Proteaceae) relates to the anthocyanin and flavonol profile, not soil pH. PHYTOCHEMISTRY 2021; 192:112931. [PMID: 34478991 DOI: 10.1016/j.phytochem.2021.112931] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 08/18/2021] [Accepted: 08/21/2021] [Indexed: 06/13/2023]
Abstract
The cylindrical conflorescences of the Banksia spinulosa Sm complex have several different colour types, i.e., black, red, maroon, lemon, and yellow. It is unknown if colour variation is due to extrinsic factors, importantly soil pH. Recent morphological observations have indicated that style colour are not contiguous, so follow-up chemical and soil analysis was conducted to further characterize the colour difference with respect to putative taxa and abiotic factors. Conflorescences of all known colours were sampled from across the eastern Australian distribution of B. spinulosa, and the respective soils were sampled and analysed for pH and total nitrogen. Regression analyses of this data demonstrated that pH and nitrogen gave nil and limited predictability for style colour respectively, i.e., only the taxa with black styles demonstrated a correlation, which was to a soil with slightly higher nitrogen content (p < 0.05). Furthermore, differences of pH were more often between taxa with conflorescences of the same colour. For chemical characterisation, the coloured styles were removed from conflorescences, extracted, and analysed by liquid chromatography-mass spectrometry (HPLC-MS/MS-DAD). Ten anthocyanin and twelve flavonol monoglycosides were identified by mass spectral fragmentation patterns (MS1 and MS2) and retention times. The data demonstrates that style colour differences are caused by the concentration of anthocyanins and their specific chemistry. It remains to be determined if the differences of anthocyanin expression are caused by other abiotic factors, or if it is intrinsic to the respective taxon.
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Affiliation(s)
- Margaret L Stimpson
- School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351, Australia
| | - Ralph D B Whalley
- School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351, Australia
| | - Lynette McLean
- School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351, Australia
| | - Nicholas J Sadgrove
- Plant Biotechnology and Botany, University of Johannesburg, Auckland Park, Johannesburg, 2006, South Africa; Jodrell Science Laboratory, Royal Botanic Gardens Kew, Richmond, Surrey, TW9 3DS, UK; School of Science and Technology, University of New England, Armidale, NSW, 2351, Australia.
| | | | - Ben-Erik Van Wyk
- Plant Biotechnology and Botany, University of Johannesburg, Auckland Park, Johannesburg, 2006, South Africa
| | - Jonathon Clay
- School of Science and Technology, University of New England, Armidale, NSW, 2351, Australia
| | - Jeremy J Bruhl
- School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351, Australia
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41
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Stanley A, Martel C, Arceo-Gómez G. Spatial variation in bidirectional pollinator-mediated interactions between two co-flowering species in serpentine plant communities. AOB PLANTS 2021; 13:plab069. [PMID: 34804469 PMCID: PMC8598379 DOI: 10.1093/aobpla/plab069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 10/19/2021] [Indexed: 06/13/2023]
Abstract
Pollinator-mediated competition and facilitation are two important mechanisms mediating co-flowering community assembly. Experimental studies, however, have mostly focused on evaluating outcomes for a single interacting partner at a single location. Studies that evaluate spatial variation in the bidirectional effects between co-flowering species are necessary if we aim to advance our understanding of the processes that mediate species coexistence in diverse co-flowering communities. Here, we examine geographic variation (i.e. at landscape level) in bidirectional pollinator-mediated effects between co-flowering Mimulus guttatus and Delphinium uliginosum. We evaluated effects on pollen transfer dynamics (conspecific and heterospecific pollen deposition) and plant reproductive success. We found evidence of asymmetrical effects (one species is disrupted and the other one is facilitated) but the effects were highly dependent on geographical location. Furthermore, effects on pollen transfer dynamics did not always translate to effects on overall plant reproductive success (i.e. pollen tube growth) highlighting the importance of evaluating effects at multiple stages of the pollination process. Overall, our results provide evidence of a spatial mosaic of pollinator-mediated interactions between co-flowering species and suggest that community assembly processes could result from competition and facilitation acting simultaneously. Our study highlights the importance of experimental studies that evaluate the prevalence of competitive and facilitative interactions in the field, and that expand across a wide geographical context, in order to more fully understand the mechanisms that shape plant communities in nature.
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Affiliation(s)
- Amber Stanley
- Department of Biological Sciences, East Tennessee State University, Johnson City, TN 37614, USA
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Carlos Martel
- Department of Biological Sciences, East Tennessee State University, Johnson City, TN 37614, USA
- Instituto de Ciencias Ómicas y Biotecnología Aplicada, Pontificia Universidad Católica del Perú, San Miguel 15088, Lima, Peru
| | - Gerardo Arceo-Gómez
- Department of Biological Sciences, East Tennessee State University, Johnson City, TN 37614, USA
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42
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Dorchin A, Shafir A, Neumann FH, Langgut D, Vereecken NJ, Mayrose I. Bee flowers drive macroevolutionary diversification in long-horned bees. Proc Biol Sci 2021; 288:20210533. [PMID: 34547912 PMCID: PMC8515878 DOI: 10.1098/rspb.2021.0533] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The role of plant–pollinator interactions in the rapid radiation of the angiosperms have long fascinated evolutionary biologists. Studies have brought evidence for pollinator-driven diversification of various plant lineages, particularly plants with specialized flowers and concealed rewards. By contrast, little is known about how this crucial interaction has shaped macroevolutionary patterns of floral visitors. In particular, there is currently no empirical evidence that floral host association has increased diversification in bees, the most prominent group of floral visitors that essentially rely on angiosperm pollen. In this study, we examine how floral host preference influenced diversification in eucerine bees (Apidae, Eucerini), which exhibit large variations in their floral associations. We combine quantitative pollen analyses with a recently proposed phylogenetic hypothesis, and use a state speciation and extinction probabilistic approach. Using this framework, we provide the first evidence that multiple evolutionary transitions from host plants with accessible pollen to restricted pollen from ‘bee-flowers’ have significantly increased the diversification of a bee clade. We suggest that exploiting host plants with restricted pollen has allowed the exploitation of a new ecological niche for eucerine bees and contributed both to their colonization of vast regions of the world and their rapid diversification.
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Affiliation(s)
- Achik Dorchin
- The National Natural History Collections, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem 9190401, Israel
| | - Anat Shafir
- School of Plant Sciences and Food Security, George S. Wise Faculty of Life Sciences, The Edmond J. Safra Center for Bioinformatics, Tel Aviv University, Tel Aviv 69978, Israel
| | - Frank H Neumann
- Evolutionary Studies Institute, University of the Witwatersrand, Braamfontein 2050, Johannesburg, South Africa
| | - Dafna Langgut
- Department of Archaeology and Ancient Near Eastern Cultures, and The Steinhardt Museum of Natural History, Tel Aviv University, Israel
| | | | - Itay Mayrose
- School of Plant Sciences and Food Security, George S. Wise Faculty of Life Sciences, The Edmond J. Safra Center for Bioinformatics, Tel Aviv University, Tel Aviv 69978, Israel
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43
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Kay KM, Surget-Groba Y. The genetic basis of floral mechanical isolation between two hummingbird-pollinated Neotropical understorey herbs. Mol Ecol 2021; 31:4351-4363. [PMID: 34487383 DOI: 10.1111/mec.16165] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 07/29/2021] [Accepted: 08/31/2021] [Indexed: 12/29/2022]
Abstract
Floral divergence can contribute to reproductive isolation among plant lineages, and thus provides an opportunity to study the genetics of speciation, including the number, effect size, mode of action and interactions of quantitative trait loci (QTL). Moreover, flowers represent suites of functionally interrelated traits, but it is unclear to what extent the phenotypic integration of the flower is underlain by a shared genetic architecture, which could facilitate or constrain correlated evolution of floral traits. Here, we examine the genetic architecture of floral morphological traits involved in an evolutionary switch from bill to forehead pollen placement between two species of hummingbird-pollinated Neotropical understorey herbs that are reproductively isolated by these floral differences. For the majority of traits, we find multiple QTL of relatively small effect spread throughout the genome. We also find substantial colocalization and alignment of effects of QTL underlying different floral traits that function together to promote outcrossing and reduce heterospecific pollen transfer. Our results are consistent with adaptive pleiotropy or linkage of many co-adapted genes, either of which could have facilitated a response to correlated selection and helped to stabilize divergent phenotypes in the face of low levels of hybridization. Moreover, our results indicate that floral mechanical isolation can be consistent with an infinitesimal model of adaptation.
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Affiliation(s)
- Kathleen M Kay
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Yann Surget-Groba
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA, USA.,Département de Biologie, Université du Québec en Outaouais, Ripon, QC, Canada
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44
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Wenzell KE, McDonnell AJ, Wickett NJ, Fant JB, Skogen KA. Incomplete reproductive isolation and low genetic differentiation despite floral divergence across varying geographic scales in Castilleja. AMERICAN JOURNAL OF BOTANY 2021; 108:1270-1288. [PMID: 34289081 DOI: 10.1002/ajb2.1700] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 05/18/2021] [Indexed: 06/13/2023]
Abstract
PREMISE Divergence depends on the strength of selection and frequency of gene flow between taxa, while reproductive isolation relies on mating barriers and geographic distance. Less is known about how these processes interact at early stages of speciation. Here, we compared population-level differentiation in floral phenotype and genetic sequence variation among recently diverged Castilleja to explore patterns of diversification under different scenarios of reproductive isolation. METHODS Using target enrichment enabled by the Angiosperms353 probe set, we assessed genetic distance among 50 populations of four Castilleja species. We investigated whether patterns of genetic divergence are explained by floral trait variation or geographic distance in two focal groups: the widespread C. sessiliflora and the more restricted C. purpurea species complex. RESULTS We document that C. sessiliflora and the C. purpurea complex are characterized by high diversity in floral color across varying geographic scales. Despite phenotypic divergence, groups were not well supported in phylogenetic analyses, and little genetic differentiation was found across targeted Angiosperms353 loci. Nonetheless, a principal coordinate analysis of single nucleotide polymorphisms revealed differentiation within C. sessiliflora across floral morphs and geography and less differentiation among species of the C. purpurea complex. CONCLUSIONS Patterns of genetic distance in C. sessiliflora suggest species cohesion maintained over long distances despite variation in floral traits. In the C. purpurea complex, divergence in floral color across narrow geographic clines may be driven by recent selection on floral color. These contrasting patterns of floral and genetic differentiation reveal that divergence can arise via multiple eco-evolutionary paths.
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Affiliation(s)
- Katherine E Wenzell
- Program in Plant Biology and Conservation, Northwestern University, O.T. Hogan Hall, Room 6-140B, 2205 Tech Drive, Evanston, IL, 60208, USA
- Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL, 60022, USA
- John Innes Centre, Norwich Research Park, Colney Lane, Norwich, NR4 7UH, UK
| | - Angela J McDonnell
- Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL, 60022, USA
| | - Norman J Wickett
- Program in Plant Biology and Conservation, Northwestern University, O.T. Hogan Hall, Room 6-140B, 2205 Tech Drive, Evanston, IL, 60208, USA
- Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL, 60022, USA
| | - Jeremie B Fant
- Program in Plant Biology and Conservation, Northwestern University, O.T. Hogan Hall, Room 6-140B, 2205 Tech Drive, Evanston, IL, 60208, USA
- Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL, 60022, USA
| | - Krissa A Skogen
- Program in Plant Biology and Conservation, Northwestern University, O.T. Hogan Hall, Room 6-140B, 2205 Tech Drive, Evanston, IL, 60208, USA
- Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL, 60022, USA
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45
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Christie K, Doan JP, Mcbride WC, Strauss SY. Asymmetrical reproductive barriers in sympatric jewelflowers: are floral isolation, genetic incompatibilities and floral trait displacement connected? Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blab027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
Floral visitors influence reproductive interactions among sympatric plant species, either by facilitating assortative mating and contributing to reproductive isolation, or by promoting heterospecific pollen transfer, potentially leading to reproductive interference or hybridization. We assessed preference and constancy of floral visitors on two co-occurring jewelflowers [Streptanthus breweri and Streptanthus hesperidis (Brassicaceae)] using field arrays, and quantified two floral rewards potentially important to foraging choice – pollen production and nectar sugar concentration – in a greenhouse common garden. Floral visitors made an abundance of conspecific transitions between S. breweri individuals, which thus experienced minimal opportunities for heterospecific pollen transfer from S. hesperidis. In contrast, behavioural isolation for S. hesperidis was essentially absent due to pollinator inconstancy. This pattern emerged across multiple biotic environments and was unrelated to local density dependence. S. breweri populations that were sympatric with S. hesperidis had higher nectar sugar concentrations than their sympatric congeners, as well as allopatric conspecifics. Previous work shows that S. breweri suffers a greater cost to hybridization than S. hesperidis, and here we find that it also shows asymmetrical floral isolation and floral trait displacement in sympatry. These findings suggest that trait divergence may reduce negative reproductive interactions between sympatric but genetically incompatible relatives.
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Affiliation(s)
- Kyle Christie
- Department of Evolution and Ecology, University of California Davis, One Shields Avenue, Davis, CA, USA
- Center for Population Biology, University of California Davis, One Shields Avenue, Davis, CA, USA
| | - Jonathan P Doan
- Department of Evolution and Ecology, University of California Davis, One Shields Avenue, Davis, CA, USA
| | - Wendy C Mcbride
- Deaver Herbarium, Northern Arizona University, Flagstaff, AZ, USA
| | - Sharon Y Strauss
- Department of Evolution and Ecology, University of California Davis, One Shields Avenue, Davis, CA, USA
- Center for Population Biology, University of California Davis, One Shields Avenue, Davis, CA, USA
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Rahim SA, Kodandaramaiah U, Kulkarni A, Barua D. Striking between-population floral divergences in a habitat specialized plant. PLoS One 2021; 16:e0253038. [PMID: 34181672 PMCID: PMC8238184 DOI: 10.1371/journal.pone.0253038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 05/27/2021] [Indexed: 11/19/2022] Open
Abstract
When the habitat occupied by a specialist species is patchily distributed, limited gene flow between the fragmented populations may allow population differentiation and eventual speciation. 'Sky islands'-montane habitats that form terrestrial islands-have been shown to promote diversification in many taxa through this mechanism. We investigate floral variation in Impatiens lawii, a plant specialized on laterite rich rocky plateaus that form sky islands in the northern Western Ghats mountains of India. We focus on three plateaus separated from each other by ca. 7 to 17 km, and show that floral traits have diverged strongly between these populations. In contrast, floral traits have not diverged in the congeneric I. oppositifolia, which co-occurs with I. lawii in the plateaus, but is a habitat generalist that is also found in the intervening valleys. We conducted common garden experiments to test whether the differences in I. lawii are due to genetic differentiation or phenotypic plasticity. There were strong differences in floral morphology between experimental plants sourced from the three populations, and the relative divergences between population pairs mirrored that seen in the wild, indicating that the populations are genetically differentiated. Common garden experiments confirmed that there was no differentiation in I. oppositifolia. Field floral visitation surveys indicated that the observed differences in floral traits have consequences for I. lawii populations, by reducing the number of visitors and changing the relative abundance of different floral visitor groups. Our results highlight the role of habitat specialization in diversification, and corroborates the importance of sky islands as centres of diversification.
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Affiliation(s)
- Sumayya Abdul Rahim
- IISER-TVM Centre for Research and Education in Ecology and Evolution (ICREEE), Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, Kerala, India
| | - Ullasa Kodandaramaiah
- IISER-TVM Centre for Research and Education in Ecology and Evolution (ICREEE), Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, Kerala, India
| | - Aboli Kulkarni
- Department of Biology, Indian Institute of Science Education and Research, Pune, Maharashtra, India
| | - Deepak Barua
- Department of Biology, Indian Institute of Science Education and Research, Pune, Maharashtra, India
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Abstract
Pollen-pistil interactions serve as important prezygotic reproductive barriers that play a critical role in mate selection in plants. Here, we highlight recent progress toward understanding the molecular basis of pollen-pistil interactions as reproductive isolating barriers. These barriers can be active systems of pollen rejection, or they can result from a mismatch of required male and female factors. In some cases, the barriers are mechanistically linked to self-incompatibility systems, while others represent completely independent processes. Pollen-pistil reproductive barriers can act as soon as pollen is deposited on a stigma, where penetration of heterospecific pollen tubes is blocked by the stigma papillae. As pollen tubes extend, the female transmitting tissue can selectively limit growth by producing cell wall-modifying enzymes and cytotoxins that interact with the growing pollen tube. At ovules, differential pollen tube attraction and inhibition of sperm cell release can act as barriers to heterospecific pollen tubes.
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Affiliation(s)
- Amanda K Broz
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523-1878, USA; ,
| | - Patricia A Bedinger
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523-1878, USA; ,
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Petrén H, Toräng P, Ågren J, Friberg M. Evolution of floral scent in relation to self-incompatibility and capacity for autonomous self-pollination in the perennial herb Arabis alpina. ANNALS OF BOTANY 2021; 127:737-747. [PMID: 33555338 PMCID: PMC8103803 DOI: 10.1093/aob/mcab007] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 01/08/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND AND AIMS The transition from outcrossing to selfing is a frequent evolutionary shift in flowering plants and is predicted to result in reduced allocation to pollinator attraction if plants can self-pollinate autonomously. The evolution of selfing is associated with reduced visual floral signalling in many systems, but effects on floral scent have received less attention. We compared multiple populations of the arctic-alpine herb Arabis alpina (Brassicaceae), and asked whether the transition from self-incompatibility to self-compatibility has been associated with reduced visual and chemical floral signalling. We further examined whether floral signalling differ between self-compatible populations with low and high capacity for autonomous self-pollination, as would be expected if benefits of signalling decrease with reduced dependence on pollinators for pollen transfer. METHODS In a common garden we documented flower size and floral scent emission rate and composition in eight self-compatible and nine self-incompatible A. alpina populations. These included self-compatible Scandinavian populations with high capacity for autonomous self-pollination, self-compatible populations with low capacity for autonomous self-pollination from France and Spain, and self-incompatible populations from Italy and Greece. KEY RESULTS The self-compatible populations produced smaller and less scented flowers than the self-incompatible populations. However, flower size and scent emission rate did not differ between self-compatible populations with high and low capacity for autonomous self-pollination. Floral scent composition differed between self-compatible and self-incompatible populations, but also varied substantially among populations within the two categories. CONCLUSIONS Our study demonstrates extensive variation in floral scent among populations of a geographically widespread species. Contrary to expectation, floral signalling did not differ between self-compatible populations with high and low capacity for autonomous self-pollination, indicating that dependence on pollinator attraction can only partly explain variation in floral signalling. Additional variation may reflect adaptation to other aspects of local environments, genetic drift, or a combination of these processes.
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Affiliation(s)
- Hampus Petrén
- Department of Biology, Lund University, Sölvegatan 37, SE-223 62 Lund, Sweden
- Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
| | - Per Toräng
- Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
- SLU Swedish Species Information Centre, Box 7007, SE-750 07 Uppsala, Sweden
| | - Jon Ågren
- Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
| | - Magne Friberg
- Department of Biology, Lund University, Sölvegatan 37, SE-223 62 Lund, Sweden
- Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
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49
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Hernández-Hernández T, Miller EC, Román-Palacios C, Wiens JJ. Speciation across the Tree of Life. Biol Rev Camb Philos Soc 2021; 96:1205-1242. [PMID: 33768723 DOI: 10.1111/brv.12698] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 02/13/2021] [Accepted: 02/16/2021] [Indexed: 01/04/2023]
Abstract
Much of what we know about speciation comes from detailed studies of well-known model systems. Although there have been several important syntheses on speciation, few (if any) have explicitly compared speciation among major groups across the Tree of Life. Here, we synthesize and compare what is known about key aspects of speciation across taxa, including bacteria, protists, fungi, plants, and major animal groups. We focus on three main questions. Is allopatric speciation predominant across groups? How common is ecological divergence of sister species (a requirement for ecological speciation), and on what niche axes do species diverge in each group? What are the reproductive isolating barriers in each group? Our review suggests the following patterns. (i) Based on our survey and projected species numbers, the most frequent speciation process across the Tree of Life may be co-speciation between endosymbiotic bacteria and their insect hosts. (ii) Allopatric speciation appears to be present in all major groups, and may be the most common mode in both animals and plants, based on non-overlapping ranges of sister species. (iii) Full sympatry of sister species is also widespread, and may be more common in fungi than allopatry. (iv) Full sympatry of sister species is more common in some marine animals than in terrestrial and freshwater ones. (v) Ecological divergence of sister species is widespread in all groups, including ~70% of surveyed species pairs of plants and insects. (vi) Major axes of ecological divergence involve species interactions (e.g. host-switching) and habitat divergence. (vii) Prezygotic isolation appears to be generally more widespread and important than postzygotic isolation. (viii) Rates of diversification (and presumably speciation) are strikingly different across groups, with the fastest rates in plants, and successively slower rates in animals, fungi, and protists, with the slowest rates in prokaryotes. Overall, our study represents an initial step towards understanding general patterns in speciation across all organisms.
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Affiliation(s)
- Tania Hernández-Hernández
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A.,Catedrática CONACYT asignada a LANGEBIO-UGA Cinvestav, Libramiento Norte Carretera León Km 9.6, 36821, Irapuato, Guanajuato, Mexico
| | - Elizabeth C Miller
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A
| | - Cristian Román-Palacios
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A
| | - John J Wiens
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A
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50
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Wessinger CA. From pollen dispersal to plant diversification: genetic consequences of pollination mode. THE NEW PHYTOLOGIST 2021; 229:3125-3132. [PMID: 33159813 DOI: 10.1111/nph.17073] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 11/02/2020] [Indexed: 06/11/2023]
Abstract
Pollinators influence patterns of plant speciation, and one intuitive hypothesis is that pollinators affect rates of plant diversification through their effects on pollen dispersal. By specifying mating events and pollen flow across the landscape, distinct types of pollinators may cause different opportunities for allopatric speciation. This pollen dispersal-dependent speciation hypothesis predicts that pollination mode has effects on the spatial context of mating events that scale up to impact population structure and rates of species formation. Here I consider recent comparative studies, including genetic analyses of plant mating events, population structure and comparative phylogenetic analyses, to examine evidence for this model. These studies suggest that highly mobile pollinators conduct greater gene flow within and among populations, compared to less mobile pollinators. These differences influence patterns of population structure across the landscape. However, the effects of pollination mode on speciation rates is less predictable. In some contexts, the predicted effects of pollen dispersal are outweighed by other factors that govern speciation rates. A multiscale approach to examine effects of pollination mode on plant mating system, population structure and rates of diversification is key to determining the role of pollen dispersal on plant speciation for model clades.
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Affiliation(s)
- Carolyn A Wessinger
- Department of Biological Sciences, University of South Carolina, Columbia, SC, 27708, USA
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