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Feller AF, Burgin G, Lewis N, Prabhu R, Hopkins R. Mismatch between pollen and pistil size causes asymmetric mechanical reproductive isolation across Phlox species. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.08.593106. [PMID: 38766021 PMCID: PMC11100701 DOI: 10.1101/2024.05.08.593106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
In flowering plants, pollen-pistil interactions can serve as an important barrier to reproduction between species. As the last barrier to reproduction before fertilization, interactions between these reproductive organs are both complex and important for determining a suitable mate. Here, we test whether differences in style length generate a post-mating prezygotic mechanical barrier between five species of perennial Phlox wildflowers with geographically overlapping distributions. We perform controlled pairwise reciprocal crosses between three species with long styles and two species with short styles to assess crossing success (seed set). We find that heterospecific seed set is broadly reduced compared to conspecific cross success and reveal a striking asymmetry in heterospecific crosses between species with different style lengths. To determine the mechanism underlying this asymmetric reproductive isolating barrier we assess pollen tube growth in vitro and in vivo. We demonstrate that pollen tubes of short-styled species do not grow long enough to reach the ovaries of long-styled species. We find that short-styled species also have smaller pollen and that both within and between species pollen diameter is highly correlated with pollen tube length. Our results support the hypothesis that the small pollen of short-styled species lacks resources to grow pollen tubes long enough to access the ovaries of the long-styled species, resulting in an asymmetrical, mechanical barrier to reproduction. Such mechanisms, combined with additional pollen-pistil incompatibilities, may be particularly important for closely related species in geographic proximity that share pollinators.
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Affiliation(s)
- Anna F. Feller
- Department of Organismic and Evolutionary Biology & Arnold Arboretum, Harvard University, Cambridge, MA 02138, USA
| | - Grace Burgin
- Department of Organismic and Evolutionary Biology & Arnold Arboretum, Harvard University, Cambridge, MA 02138, USA
| | - Nia Lewis
- Department of Organismic and Evolutionary Biology & Arnold Arboretum, Harvard University, Cambridge, MA 02138, USA
| | - Rohan Prabhu
- Department of Organismic and Evolutionary Biology & Arnold Arboretum, Harvard University, Cambridge, MA 02138, USA
- Northeastern University, Boston, MA 02115, USA
| | - Robin Hopkins
- Department of Organismic and Evolutionary Biology & Arnold Arboretum, Harvard University, Cambridge, MA 02138, USA
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2
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Harenčár J, Vargas OM, Escalona M, Schemske DW, Kay KM. Genome assemblies and comparison of two Neotropical spiral gingers: Costus pulverulentus and C. lasius. J Hered 2023; 114:286-293. [PMID: 36928286 PMCID: PMC10212132 DOI: 10.1093/jhered/esad018] [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: 02/22/2023] [Accepted: 03/15/2023] [Indexed: 03/18/2023] Open
Abstract
The spiral gingers (Costus L.) are a pantropical genus of herbaceous perennial monocots; the Neotropical clade of Costus radiated rapidly in the past few million years into over 60 species. The Neotropical spiral gingers have a rich history of evolutionary and ecological research that can motivate and inform modern genetic investigations. Here, we present the first 2 chromosome-level genome assemblies in the genus, for C. pulverulentus and C. lasius, and briefly compare their synteny. We assembled the C. pulverulentus genome from a combination of short-read data, Chicago and Dovetail Hi-C chromatin-proximity sequencing, and alignment with a linkage map. We annotated the genome by mapping a C. pulverulentus transcriptome and querying mapped transcripts against a protein database. We assembled the C. lasius genome with Pacific Biosciences HiFi long reads and alignment to the C. pulverulentus genome. These 2 assemblies are the first published genomes for non-cultivated tropical plants. These genomes solidify the spiral gingers as a model system and will facilitate research on the poorly understood genetic basis of tropical plant diversification.
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Affiliation(s)
- Julia Harenčár
- Ecology and Evolutionary Biology Department, University of California, Santa Cruz, Santa Cruz, CA, United States
| | - Oscar M Vargas
- Department of Biological Sciences, California State Polytechnic University, Humboldt, Arcata, CA, United States
| | - Merly Escalona
- Department of Biomolecular Engineering, University of California, Santa Cruz, Santa Cruz, CA, United States
| | - Douglas W Schemske
- Department of Plant Biology, Michigan State University, East Lansing, MI, United States
| | - Kathleen M Kay
- Ecology and Evolutionary Biology Department, University of California, Santa Cruz, Santa Cruz, CA, United States
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3
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Maas PJM, Maas-van de Kamer H, André T, Skinner D, Valderrama E, Specht CD. Eighteen new species of Neotropical Costaceae (Zingiberales). PHYTOKEYS 2023; 222:75-127. [PMID: 37252638 PMCID: PMC10210046 DOI: 10.3897/phytokeys.222.87779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 01/19/2023] [Indexed: 05/31/2023]
Abstract
In preparation for a full taxonomic revision of the Neotropical genera of Costaceae (i.e., Chamaecostus, Costus, Dimerocostus, and Monocostus), we present the description of 17 new species of Neotropical Costus and one new species of the Neotropic endemic genus Chamaecostus with notes on their distribution and ecology, vernacular names (when known), and diagnostic characters for identification. Distribution maps are included for all species, and each description is accompanied by photographic plates illustrating diagnostic characters.
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Affiliation(s)
- Paul J. M. Maas
- Naturalis Biodiversity Centre, Botany, P.O. Box 9517, 2300 RA Leiden, NetherlandsNaturalis Biodiversity CentreLeidenNetherlands
| | - Hiltje Maas-van de Kamer
- Naturalis Biodiversity Centre, Botany, P.O. Box 9517, 2300 RA Leiden, NetherlandsNaturalis Biodiversity CentreLeidenNetherlands
| | - Thiago André
- Universidade de Brasília, Departamento de Botânica, Campus Universitário Darcy Ribeiro, Asa Norte, Brasília (DF), BrazilUniversidade de BrasíliaBrasíliaBrazil
| | - David Skinner
- Le Jardin Ombragé, Tallahassee, (Private botanical garden, Botanic Gardens Conservation International – BGCI – registration ID 50148), Florida, USALe Jardin OmbragéTallahasseeUnited States of America
| | - Eugenio Valderrama
- Cornell University, Section of Plant Biology and the L.H.Bailey Hortorium, School of Integrative Plant Science, Ithaca, NY, USACornell UniversityIthacaUnited States of America
| | - Chelsea D. Specht
- Cornell University, Section of Plant Biology and the L.H.Bailey Hortorium, School of Integrative Plant Science, Ithaca, NY, USACornell UniversityIthacaUnited States of America
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4
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Kay KM, Grossenbacher DL. Evolutionary convergence on hummingbird pollination in Neotropical Costus provides insight into the causes of pollinator shifts. THE NEW PHYTOLOGIST 2022; 236:1572-1583. [PMID: 36068995 PMCID: PMC9826479 DOI: 10.1111/nph.18464] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 08/10/2022] [Indexed: 06/15/2023]
Abstract
The evolution of hummingbird pollination is common across angiosperms throughout the Americas, presenting an opportunity to examine convergence in both traits and environments to better understand how complex phenotypes arise. Here we examine independent shifts from bee to hummingbird pollination in the Neotropical spiral gingers (Costus) and address common explanations for the prevalence of transitions from bee to hummingbird pollination. We use floral traits of species with observed pollinators to predict pollinators of unobserved species and reconstruct ancestral pollination states on a well-resolved phylogeny. We examine whether independent transitions evolve towards the same phenotypic optimum and whether shifts to hummingbird pollination correlate with elevation or climate. Traits predicting hummingbird pollination include small flower size, brightly colored floral bracts and the absence of nectar guides. We find many shifts to hummingbird pollination and no reversals, a single shared phenotypic optimum across hummingbird flowers, and no association between pollination and elevation or climate. Evolutionary shifts to hummingbird pollination in Costus are highly convergent and directional, involve a surprising set of traits when compared with other plants with analogous transitions and refute the generality of several common explanations for the prevalence of transitions from bee to hummingbird pollination.
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Affiliation(s)
- Kathleen M. Kay
- Department of Ecology and Evolutionary BiologyUniversity of California, Santa CruzSanta CruzCA95060USA
| | - Dena L. Grossenbacher
- Department of BiologyCalifornia Polytechnic State UniversitySan Luis ObispoCA93401USA
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5
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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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6
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Gorman CE, Li Y, Dorken ME, Stift M. No evidence for incipient speciation by selfing in North American Arabidopsis lyrata. J Evol Biol 2021; 34:1397-1405. [PMID: 34228843 DOI: 10.1111/jeb.13901] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 05/01/2021] [Accepted: 07/03/2021] [Indexed: 01/01/2023]
Abstract
Self-fertilization inherently restricts gene flow by reducing the fraction of offspring that can be produced by inter-population matings. Therefore, mating system transitions from outcrossing to selfing could result in reproductive isolation between selfing and outcrossing lineages and provide a starting point for speciation. In newly diverged lineages, for example after a transition to selfing, further reproductive isolation can be caused by a variety of prezygotic and post-zygotic mechanisms that operate before, during and after pollination. In animals, prezygotic barriers tend to evolve faster than post-zygotic ones. This is not necessarily the case for plants, for which the relative importance of post-mating, post-fertilization and early-acting post-zygotic barriers has been investigated far less. To test whether post-pollination isolation exists between populations of North American Arabidopsis lyrata that differ in breeding (self-incompatible versus self-compatible) and mating system (outcrossing versus selfing), we compared patterns of seed set after crosses made within populations, between populations of the same mating system and between populations with different mating systems. We found no evidence for post-pollination isolation between plants from selfing populations (self-compatible, low outcrossing rates) and outcrossing populations (self-incompatible, high outcrossing rates) via either prezygotic or early-acting post-zygotic mechanisms. Together with the results of other studies indicating the absence of reproductive barriers acting before and during pollination, we conclude that the transition to selfing in this study system has not led to the formation of reproductive barriers between selfing and outcrossing populations of North American A. lyrata.
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Affiliation(s)
| | - Yan Li
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
| | - Marcel E Dorken
- Department of Biology, Trent University, Peterborough, ON, Canada
| | - Marc Stift
- Department of Biology, University of Konstanz, Konstanz, Germany
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7
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Rushworth CA, Mitchell-Olds T. The Evolution of Sex is Tempered by Costly Hybridization in Boechera (Rock Cress). J Hered 2020; 112:67-77. [PMID: 33211850 DOI: 10.1093/jhered/esaa041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 10/03/2020] [Indexed: 12/17/2022] Open
Abstract
Despite decades of research, the evolution of sex remains an enigma in evolutionary biology. Typically, research addresses the costs of sex and asexuality to characterize the circumstances favoring one reproductive mode. Surprisingly few studies address the influence of common traits that are, in many organisms, obligately correlated with asexuality, including hybridization and polyploidy. These characteristics have substantial impacts on traits under selection. In particular, the fitness consequences of hybridization (i.e., reduced fitness due to interspecific reproductive isolation) will influence the evolution of sex. This may comprise a cost of either sex or asexuality due to the link between hybridity and asexuality. We examined reproductive isolation in the formation of de novo hybrid lineages between 2 widespread species in the ecological model system Boechera. Seventeen percent of 664 crosses produced F1 fruits, and only 10% of these were viable, suggesting that postmating prezygotic and postzygotic barriers inhibit hybrid success in this system. The postmating prezygotic barrier was asymmetrical, with 110 of 115 total F1 fruits produced when Boechera stricta acted as maternal parent. This asymmetry was confirmed in wild-collected lineages, using a chloroplast phylogeny of wild-collected B. stricta, Boechera retrofracta, and hybrids. We next compared fitness of F2 hybrids and selfed parental B. stricta lines, finding that F2 fitness was reduced by substantial hybrid sterility. Multiple reproductively isolating barriers influence the formation and fitness of hybrid lineages in the wild, and the costs of hybridization likely have profound impacts on the evolution of sex in the natural environment.
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Affiliation(s)
- Catherine A Rushworth
- Department of Evolution and Ecology, Storer Hall, University of California Davis, Davis, CA.,Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN.,University and Jepson Herbaria, University of California Berkeley, Berkeley, CA.,Department of Biology and Center for Genomic and Computational Biology, Duke University, Box, Durham, NC
| | - Tom Mitchell-Olds
- Department of Biology and Center for Genomic and Computational Biology, Duke University, Box, Durham, NC
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8
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Misiewicz TM, Simmons TS, Fine PVA. The contribution of multiple barriers to reproduction between edaphically divergent lineages in the Amazonian tree Protium subserratum (Burseraceae). Ecol Evol 2020; 10:6646-6663. [PMID: 32724539 PMCID: PMC7381562 DOI: 10.1002/ece3.6396] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 03/30/2020] [Accepted: 04/22/2020] [Indexed: 11/09/2022] Open
Abstract
Disentangling the strength and importance of barriers to reproduction that arise between diverging lineages is central to our understanding of species origin and maintenance. To date, the vast majority of studies investigating the importance of different barriers to reproduction in plants have focused on short-lived temperate taxa while studies of reproductive isolation in trees and tropical taxa are rare. Here, we systematically examine multiple barriers to reproduction in an Amazonian tree, Protium subserratum (Burseraceae) with diverging lineages of soil specialist ecotypes. Using observational, molecular, distributional, and experimental data, we aimed to quantify the contributions of individual prezygotic and postzygotic barriers including ecogeographic isolation, flowering phenology, pollinator assemblage, pollen adhesion, pollen germination, pollen tube growth, seed development, and hybrid fitness to total reproductive isolation between the ecotypes. We were able to identify five potential barriers to reproduction including ecogeographic isolation, phenological differences, differences in pollinator assemblages, differential pollen adhesion, and low levels of hybrid seed development. We demonstrate that ecogeographic isolation is a strong and that a combination of intrinsic and extrinsic prezygotic and postzygotic barriers may be acting to maintain near complete reproductive isolation between edaphically divergent populations of the tropical tree, P. subserratum.
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Affiliation(s)
- Tracy M. Misiewicz
- Department of Integrative Biology, University and Jepson HerbariaUniversity of CaliforniaBerkeleyCAUSA
| | - Tracey S. Simmons
- Department of Biological SciencesSan Jose State UniversitySan JoseCAUSA
| | - Paul V. A. Fine
- Department of Integrative Biology, University and Jepson HerbariaUniversity of CaliforniaBerkeleyCAUSA
- Department of Integrative BiologyEssig Museum of EntomologyUniversity and Jepson HerbariaUniversity of CaliforniaBerkeleyCAUSA
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9
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Kay KM, Woolhouse S, Smith BA, Pope NS, Rajakaruna N. Sympatric serpentine endemic
Monardella
(Lamiaceae) species maintain habitat differences despite hybridization. Mol Ecol 2018; 27:2302-2316. [DOI: 10.1111/mec.14582] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 02/09/2018] [Accepted: 02/20/2018] [Indexed: 01/09/2023]
Affiliation(s)
- Kathleen M. Kay
- Department of Ecology and Evolutionary Biology University of California Santa Cruz California
| | - Suzie Woolhouse
- Department of Biological Sciences San José State University San José California
| | - Brett A. Smith
- Department of Ecology and Evolutionary Biology University of California Santa Cruz California
| | - Nathaniel S. Pope
- Department of Integrative Biology The University of Texas at Austin Austin Texas
| | - Nishanta Rajakaruna
- Biological Sciences Department California Polytechnic State University San Luis Obispo California
- Unit for Environmental Sciences and Management North‐West University Potchefstroom South Africa
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10
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Missagia CCC, Alves MAS. Does beak size predict the pollination performance of hummingbirds at long and tubular flowers? A case study of a Neotropical spiral ginger. J Zool (1987) 2018. [DOI: 10.1111/jzo.12539] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Caio C. C. Missagia
- Programa de Pós‐Graduação em Ecologia e Evolução Universidade do Estado do Rio de Janeiro Rio de Janeiro RJ Brazil
| | - Maria Alice S. Alves
- Departamento de Ecologia Universidade do Estado do Rio de Janeiro Rio de Janeiro RJBrazil
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11
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Lyu N, Du W, Wang XF. Unique growth paths of heterospecific pollen tubes result in late entry into ovules in the gynoecium of Sagittaria (Alismataceae). PLANT BIOLOGY (STUTTGART, GERMANY) 2017; 19:108-114. [PMID: 27687794 DOI: 10.1111/plb.12508] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 09/24/2016] [Indexed: 06/06/2023]
Abstract
Pollen-pistil interactions are a fundamental process in the reproductive biology of angiosperms and play a particularly important role in maintaining incipient species that exist in sympatry. However, the majority of previous studies have focused on species with syncarpous gynoecia (fused carpels) and not those with apocarpous gynoecia (unfused carpels). In the present study, we investigated the growth of conspecific pollen tubes compared to heterospecific pollen tubes in Sagittaria species, which have apocarpous gynoecia. We conducted controlled pollinations between S. pygmaea and S. trifolia and observed the growth of conspecific and heterospecific pollen tubes under a fluorescence microscope. Heterospecific and conspecific pollen tubes arrived at locules within the ovaries near simultaneously. However, conspecific pollen tubes entered into the ovules directly, whereas heterospecific tubes passed through the carpel base and adjacent receptacle tissue, to ultimately fertilize other unfertilized ovules. This longer route taken by heterospecific pollen tubes therefore caused a delay in the time required to enter into the ovules. Furthermore, heterospecific pollen tubes displayed similar growth patterns at early and peak pollination. The growth pattern of heterospecific pollen tubes at late pollination was similar to that of conspecific pollen tubes at peak pollination. Heterospecific and conspecific pollen tubes took different routes to fertilize ovules. A delayed entry of heterospecific pollen into ovules may be a novel mechanism of conspecific pollen advantage (CPA) for apocarpous species.
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Affiliation(s)
- N Lyu
- College of Life Sciences, Wuhan University, Wuhan, China
| | - W Du
- College of Life Sciences, Wuhan University, Wuhan, China
| | - X-F Wang
- College of Life Sciences, Wuhan University, Wuhan, China
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12
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Wang L, Clarke LA, Eason RJ, Parker CC, Qi B, Scott RJ, Doughty J. PCP-B class pollen coat proteins are key regulators of the hydration checkpoint in Arabidopsis thaliana pollen-stigma interactions. THE NEW PHYTOLOGIST 2017; 213:764-777. [PMID: 27596924 PMCID: PMC5215366 DOI: 10.1111/nph.14162] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 07/23/2016] [Indexed: 05/09/2023]
Abstract
The establishment of pollen-pistil compatibility is strictly regulated by factors derived from both male and female reproductive structures. Highly diverse small cysteine-rich proteins (CRPs) have been found to play multiple roles in plant reproduction, including the earliest stages of the pollen-stigma interaction. Secreted CRPs found in the pollen coat of members of the Brassicaceae, the pollen coat proteins (PCPs), are emerging as important signalling molecules that regulate the pollen-stigma interaction. Using a combination of protein characterization, expression and phylogenetic analyses we identified a novel class of Arabidopsis thaliana pollen-borne CRPs, the PCP-Bs (for pollen coat protein B-class) that are related to embryo surrounding factor (ESF1) developmental regulators. Single and multiple PCP-B mutant lines were utilized in bioassays to assess effects on pollen hydration, adhesion and pollen tube growth. Our results revealed that pollen hydration is severely impaired when multiple PCP-Bs are lost from the pollen coat. The hydration defect also resulted in reduced pollen adhesion and delayed pollen tube growth in all mutants studied. These results demonstrate that AtPCP-Bs are key regulators of the hydration 'checkpoint' in establishment of pollen-stigma compatibility. In addition, we propose that interspecies diversity of PCP-Bs may contribute to reproductive barriers in the Brassicaceae.
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Affiliation(s)
- Ludi Wang
- Department of Biology and BiochemistryUniversity of BathClaverton DownBathBA2 7AYUK
| | - Lisa A. Clarke
- Department of Biology and BiochemistryUniversity of BathClaverton DownBathBA2 7AYUK
| | - Russell J. Eason
- Department of Biology and BiochemistryUniversity of BathClaverton DownBathBA2 7AYUK
| | | | - Baoxiu Qi
- Department of Biology and BiochemistryUniversity of BathClaverton DownBathBA2 7AYUK
| | - Rod J. Scott
- Department of Biology and BiochemistryUniversity of BathClaverton DownBathBA2 7AYUK
| | - James Doughty
- Department of Biology and BiochemistryUniversity of BathClaverton DownBathBA2 7AYUK
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13
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Baek YS, Royer SM, Broz AK, Covey PA, López-Casado G, Nuñez R, Kear PJ, Bonierbale M, Orillo M, van der Knaap E, Stack SM, McClure B, Chetelat RT, Bedinger PA. Interspecific reproductive barriers between sympatric populations of wild tomato species (Solanum section Lycopersicon). AMERICAN JOURNAL OF BOTANY 2016; 103:1964-1978. [PMID: 27864262 DOI: 10.3732/ajb.1600356] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 10/21/2016] [Indexed: 05/09/2023]
Abstract
PREMISE OF THE STUDY Interspecific reproductive barriers (IRBs) often prevent hybridization between closely related species in sympatry. In the tomato clade (Solanum section Lycopersicon), interspecific interactions between natural sympatric populations have not been evaluated previously. In this study, we assessed IRBs between members of the tomato clade from nine sympatric sites in Peru. METHODS Coflowering was assessed at sympatric sites in Peru. Using previously collected seeds from sympatric sites in Peru, we evaluated premating prezygotic (floral morphology), postmating prezygotic (pollen-tube growth), and postzygotic barriers (fruit and seed development) between sympatric species in common gardens. Pollen-tube growth and seed development were examined in reciprocal crosses between sympatric species. KEY RESULTS We confirmed coflowering of sympatric species at five sites in Peru. We found three types of postmating prezygotic IRBs during pollen-pistil interactions: (1) unilateral pollen-tube rejection between pistils of self-incompatible species and pollen of self-compatible species; (2) potential conspecific pollen precedence in a cross between two self-incompatible species; and (3) failure of pollen tubes to target ovules. In addition, we found strong postzygotic IRBs that prevented normal seed development in 11 interspecific crosses, resulting in seed-like structures containing globular embryos and aborted endosperm and, in some cases, overgrown endothelium. Viable seed and F1 hybrid plants were recovered from three of 19 interspecific crosses. CONCLUSIONS We have identified diverse prezygotic and postzygotic IRBs that would prevent hybridization between sympatric wild tomato species, but interspecific hybridization is possible in a few cases.
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Affiliation(s)
- You Soon Baek
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523-1878, USA
| | - Suzanne M Royer
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523-1878, USA
| | - Amanda K Broz
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523-1878, USA
| | - Paul A Covey
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523-1878, USA
| | - Gloria López-Casado
- Department of Plant Biology, Cornell University, Ithaca, New York 14853, USA
| | - Reynaldo Nuñez
- Department of Horticulture and Crop Science, Ohio State University, Wooster, Ohio 44691, USA
| | - Philip J Kear
- Quality and Nutrition Laboratory, Centro Internacional de la Papa, Perú Postal 1558, Lima, Peru
| | - Merideth Bonierbale
- Quality and Nutrition Laboratory, Centro Internacional de la Papa, Perú Postal 1558, Lima, Peru
| | - Matilde Orillo
- Quality and Nutrition Laboratory, Centro Internacional de la Papa, Perú Postal 1558, Lima, Peru
| | - Esther van der Knaap
- Department of Horticulture and Crop Science, Ohio State University, Wooster, Ohio 44691, USA
- Department of Horticulture, University of Georgia, Athens, Georgia 30602, USA
| | - Stephen M Stack
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523-1878, USA
| | - Bruce McClure
- Department of Biochemistry, University of Missouri-Columbia, Columbia, Missouri 65211, USA
| | - Roger T Chetelat
- Department of Plant Sciences, University of California Davis, Davis, California 95616, USA
| | - Patricia A Bedinger
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523-1878, USA
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14
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Keller B, de Vos JM, Schmidt‐Lebuhn AN, Thomson JD, Conti E. Both morph- and species-dependent asymmetries affect reproductive barriers between heterostylous species. Ecol Evol 2016; 6:6223-44. [PMID: 27648239 PMCID: PMC5016645 DOI: 10.1002/ece3.2293] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 06/03/2016] [Accepted: 06/07/2016] [Indexed: 12/13/2022] Open
Abstract
The interaction between floral traits and reproductive isolation is crucial to explaining the extraordinary diversity of angiosperms. Heterostyly, a complex floral polymorphism that optimizes outcrossing, evolved repeatedly and has been shown to accelerate diversification in primroses, yet its potential influence on isolating mechanisms remains unexplored. Furthermore, the relative contribution of pre- versus postmating barriers to reproductive isolation is still debated. No experimental study has yet evaluated the possible effects of heterostyly on pre- and postmating reproductive mechanisms. We quantify multiple reproductive barriers between the heterostylous Primula elatior (oxlip) and P. vulgaris (primrose), which readily hybridize when co-occurring, and test whether traits of heterostyly contribute to reproductive barriers in unique ways. We find that premating isolation is key for both species, while postmating isolation is considerable only for P. vulgaris; ecogeographic isolation is crucial for both species, while phenological, seed developmental, and hybrid sterility barriers are also important in P. vulgaris, implicating sympatrically higher gene flow into P. elatior. We document for the first time that, in addition to the aforementioned species-dependent asymmetries, morph-dependent asymmetries affect reproductive barriers between heterostylous species. Indeed, the interspecific decrease of reciprocity between high sexual organs of complementary floral morphs limits interspecific pollen transfer from anthers of short-styled flowers to stigmas of long-styled flowers, while higher reciprocity between low sexual organs favors introgression over isolation from anthers of long-styled flowers to stigmas of short-styled flowers. Finally, intramorph incompatibility persists across species boundaries, but is weakened in long-styled flowers of P. elatior, opening a possible backdoor to gene flow through intramorph pollen transfer between species. Therefore, patterns of gene flow across species boundaries are likely affected by floral morph composition of adjacent populations. To summarize, our study highlights the general importance of premating isolation and newly illustrates that both morph- and species-dependent asymmetries shape boundaries between heterostylous species.
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Affiliation(s)
- Barbara Keller
- Department of Systematic and Evolutionary BotanyUniversity of ZürichZollikerstrasse 1078008ZürichSwitzerland
| | - Jurriaan M. de Vos
- Department of Ecology and Evolutionary BiologyBrown University80 Waterman StreetBox G‐WProvidenceRhode Island02912USA
- Present address: Comparative Plant and Fungal Biology DepartmentRoyal Botanic GardensKewRichmondSurreyTW9 3AE UK
| | | | - James D. Thomson
- Ecology and Evolutionary Biology DepartmentUniversity of Toronto25 Harbord St.TorontoOntarioM5S 3G5Canada
| | - Elena Conti
- Department of Systematic and Evolutionary BotanyUniversity of ZürichZollikerstrasse 1078008ZürichSwitzerland
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Johnson SL, Villarroel M, Rosengrave P, Carne A, Kleffmann T, Lokman PM, Gemmell NJ. Proteomic analysis of chinook salmon (Oncorhynchus tshawytscha) ovarian fluid. PLoS One 2014; 9:e104155. [PMID: 25089903 PMCID: PMC4121310 DOI: 10.1371/journal.pone.0104155] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 07/10/2014] [Indexed: 11/18/2022] Open
Abstract
The ovarian, or coelomic, fluid that is released with the egg mass of many fishes is increasingly found to play an important role in several biological processes crucial for reproductive success. These include maintenance of oocyte fertility and developmental competence, prolonging of sperm motility, and enhancing sperm swimming speed. Here we examined if and how the proteome of chinook salmon (Oncorhynchus tshawytscha) ovarian fluid varied among females and then sought to examine the composition of this fluid. Ovarian fluid in chinook salmon was analyzed using 1D SDS PAGE and LC-MS/MS tryptic digest screened against Mascot and Sequest databases. We found marked differences in the number and concentrations of proteins in salmon ovarian fluid across different females. A total of 174 proteins were identified in ovarian fluid, 47 of which were represented by six or more peptides, belonging to one of six Gene Ontology pathways. The response to chemical stimulus and response to hypoxia pathways were best represented, accounting for 26 of the 174 proteins. The current data set provides a resource that furthers our understanding of those factors that influence successful egg production and fertilisation in salmonids and other species.
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Affiliation(s)
- Sheri L. Johnson
- Allan Wilson Centre for Molecular Ecology and Evolution and Department of Anatomy, University of Otago, Dunedin, New Zealand
- Department of Zoology, University of Otago, Dunedin, New Zealand
| | - Marsha Villarroel
- Allan Wilson Centre for Molecular Ecology and Evolution and Department of Anatomy, University of Otago, Dunedin, New Zealand
| | - Patrice Rosengrave
- Allan Wilson Centre for Molecular Ecology and Evolution and Department of Anatomy, University of Otago, Dunedin, New Zealand
| | - Alan Carne
- Centre for Protein Research, Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Torsten Kleffmann
- Centre for Protein Research, Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - P. Mark Lokman
- Department of Zoology, University of Otago, Dunedin, New Zealand
| | - Neil J. Gemmell
- Allan Wilson Centre for Molecular Ecology and Evolution and Department of Anatomy, University of Otago, Dunedin, New Zealand
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Turelli M, Lipkowitz JR, Brandvain Y. On the Coyne and Orr-igin of species: effects of intrinsic postzygotic isolation, ecological differentiation, x chromosome size, and sympatry on Drosophila speciation. Evolution 2014; 68:1176-87. [PMID: 24325145 DOI: 10.1111/evo.12330] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 11/27/2013] [Indexed: 12/30/2022]
Abstract
Coyne and Orr found that mating discrimination (premating isolation) evolves much faster between sympatric than allopatric Drosophila species pairs. Their meta-analyses established that this pattern, expected under reinforcement, is common and that Haldane's rule is ubiquitous in Drosophila species divergence. We examine three possible contributors to the reinforcement pattern: intrinsic postzygotic isolation, dichotomized as to whether hybrid males show complete inviability/sterility; host-plant divergence, as a surrogate for extrinsic postzygotic isolation; and X chromosome size, whether roughly 20% or 40% of the genome is X-linked. We focus on "young" species pairs with overlapping ranges, contrasted with allopatric pairs. Using alternative criteria for "sympatry" and tests that compare either level of prezygotic isolation in sympatry or frequency of sympatry, we find no statistically significant effects associated with X chromosome size or our coarse quantifications of intrinsic postzygotic isolation or ecological differentiation. Although sympatric speciation seems very rare in animals, the pervasiveness of the reinforcement pattern and the commonness of range overlap for close relatives indicate that speciation in Drosophila is often not purely allopatric. It remains to determine whether increased premating isolation with sympatry results from secondary contact versus parapatric speciation and what drives this pattern.
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Affiliation(s)
- Michael Turelli
- Department of Evolution and Ecology and Center for Population Biology, University of California, Davis, California, 95616.
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Carlson AL, Gong H, Toomajian C, Swanson RJ. Parental genetic distance and patterns in nonrandom mating and seed yield in predominately selfing Arabidopsis thaliana. PLANT REPRODUCTION 2013; 26:317-28. [PMID: 23843176 PMCID: PMC3825607 DOI: 10.1007/s00497-013-0228-5] [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: 05/16/2013] [Accepted: 07/03/2013] [Indexed: 05/09/2023]
Abstract
In this study, we ask two questions: (1) Is reproductive success independent of parental genetic distance in predominately selfing plants? (2) In the absence of early inbreeding depression, is there substantial maternal and/or paternal variation in reproductive success in natural populations? Seed yield in single pollinations and proportion of seeds sired in mixed pollinations were studied in genetically defined accessions of the predominately selfing plant Arabidopsis thaliana by conducting two diallel crosses. The first diallel was a standard, single pollination design that we used to examine variance in seed yield. The second diallel was a mixed pollination design that utilized a standard pollen competitor to examine variance in proportion of seeds sired. We found no correlation between reproductive success and parental genetic distance, and self-pollen does not systematically differ in reproductive success compared to outcross pollen, suggesting that Arabidopsis populations do not experience embryo lethality due to early-acting inbreeding or outbreeding depression. We used these data to partition the contributions to total phenotypic variation from six sources, including maternal contributions, paternal contributions and parental interactions. For seed yield in single pollinations, maternal effects accounted for the most significant source of variance (16.6 %). For proportion of seeds sired in mixed pollinations, the most significant source of variance was paternal effects (17.9 %). Thus, we show that population-level genetic similarities, including selfing, do not correlate with reproductive success, yet there is still significant paternal variance under competition. This suggests two things. First, since these differences are unlikely due to early-acting inbreeding depression or differential pollen viability, this implicates natural variation in pollen germination and tube growth dynamics. Second, this strongly supports a model of fixation of pollen performance genes in populations, offering a focus for future genetic studies in differential reproductive success.
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Affiliation(s)
- Ann L. Carlson
- Department of Biology, Valparaiso University, Valparaiso, IN 46383 USA
| | - Hui Gong
- Department of Mathematics and Computer Science, Valparaiso University, Valparaiso, IN 46383 USA
| | | | - Robert J. Swanson
- Department of Biology, Valparaiso University, Valparaiso, IN 46383 USA
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Abstract
BACKGROUND Our understanding of the processes and dynamics of allopolyploid speciation, the long-term consequences of ploidal change, and the genetic and chromosomal changes in new emerged allopolyploids has substantially increased during the past few decades. Yet we remain uncertain about the time since lineage divergence when two taxa are capable of spawning such entities. Indeed, the matter has seemed intractable. Knowledge of the window of opportunity for allopolyploid production is very important because it provides temporal insight into a key evolutionary process, and a temporal reference against which other modes of speciation may be measured. SCOPE This Viewpoint paper reviews and integrates published information on the crossability of herbaceous species and the fertility of their hybrids in relation to species' divergence times. Despite limitations in methodology and sampling, the estimated times to hybrid sterility are somewhat congruent across disparate lineages. Whereas the waiting time for hybrid sterility is roughly 4-5 million years, the waiting time for cross-incompatibility is roughly 8-10 million years, sometimes considerably more. Strict allopolyploids may be formed in the intervening time window. The progenitors of several allopolyploids diverged between 4 and 6 million years before allopolyploid synthesis, as expected. This is the first study to propose a general temporal framework for strict allopolyploidy. This Viewpoint paper hopefully will stimulate interest in studying the tempo of speciation and the tempo of reproductive isolation in general.
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Christianini AV, Forzza RC, Buzato S. Divergence on floral traits and vertebrate pollinators of two endemic Encholirium bromeliads. PLANT BIOLOGY (STUTTGART, GERMANY) 2013; 15:360-8. [PMID: 22882351 DOI: 10.1111/j.1438-8677.2012.00649.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Shifts in pollen vectors favour diversification of floral traits, and differences in pollination strategies between congeneric sympatric species can contribute to reproductive isolation. Divergence in flowering phenology and selfing could also reduce interspecific crossing between self-compatible species. We investigated floral traits and visitation rates of pollinators of two sympatric Encholirium species on rocky outcrops to evaluate whether prior knowledge of floral characters could indicate actual pollinators. Data on flowering phenology, visitation rates and breeding system were used to evaluate reproductive isolation. Flowering phenology overlapped between species, but there were differences in floral characters, nectar volume and concentration. Several hummingbird species visited flowers of both Encholirium spp., but the endemic bat Lonchophylla bokermanni and an unidentified sphingid only visited E. vogelii. Pollination treatments demonstrated that E. heloisae and E. vogelii were partially self-compatible, with weak pollen limitation to seed set. Herbivores feeding on inflorescences decreased reproductive output of both species, but for E. vogelii the damage was higher. Our results indicate that actual pollinators can be known beforehand through floral traits, in agreement with pollination syndromes stating that a set of floral traits can be associated with the attraction of specific groups of pollinators. Divergence on floral traits and pollinator assemblage indicate that shifts in pollination strategies contribute to reproductive isolation between these Encholirium species, not divergence on flowering phenology or selfing. We suggest that hummingbird pollination might be the ancestral condition in Encholirium and that evolution of bat pollination made a substantial contribution to the diversification of this clade.
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Affiliation(s)
- A V Christianini
- Universidade Federal de São Carlos, Campus Sorocaba, Rua do Matão 321, Sorocaba, SP, Brazil
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