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Dunivant TS, Singh V, Livingston KE, Ross JD, Hileman LC. CYCLOIDEA paralogs function partially redundantly to specify dorsal flower development in Mimulus lewisii. Am J Bot 2024; 111:e16271. [PMID: 38265745 DOI: 10.1002/ajb2.16271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 11/09/2023] [Accepted: 11/10/2023] [Indexed: 01/25/2024]
Abstract
PREMISE Duplicated genes (paralogs) are abundant in plant genomes, and their retention may influence the function of genetic programs and contribute to evolutionary novelty. How gene duplication affects genetic modules and what forces contribute to paralog retention are outstanding questions. The CYCLOIDEA(CYC)-dependent flower symmetry program is a model for understanding the evolution of gene duplication, providing multiple examples of paralog partitioning and novelty. However, a novel CYC gene lineage duplication event near the origin of higher core Lamiales (HCL) has received little attention. METHODS To understand the evolutionary fate of duplicated HCL CYC2 genes, we determined the effects on flower symmetry by suppressing MlCYC2A and MlCYC2B expression using RNA interference (RNAi). We determined the phenotypic effects on flower symmetry in single- and double-silenced backgrounds and coupled our functional analyses with expression surveys of MlCYC2A, MlCYC2B, and a putative downstream RADIALIS (MlRAD5) ortholog. RESULTS MlCYC2A and MlCYC2B jointly contribute to bilateral flower symmetry. MlCYC2B exhibits a clear dorsal flower identity function and may additionally function in carpel development. MlCYC2A functions in establishing dorsal petal shape. Further, our results suggest an MlCYC2A-MlCYC2B regulatory interaction, which may affect pathway homeostasis. CONCLUSIONS Our results suggest that CYC paralogs specific to higher core Lamiales may be selectively retained for their joint contribution to bilateral flower symmetry, similar to the independently derived CYC paralogs in the Lamiales model for bilateral flower symmetry research, Antirrhinum majus (snapdragon).
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Affiliation(s)
- Taryn S Dunivant
- Department of Ecology and Evolutionary Biology, University of Kansas, 1200 Sunnyside Avenue, Lawrence, KS, 66045, USA
| | - Vibhuti Singh
- Department of Ecology and Evolutionary Biology, University of Kansas, 1200 Sunnyside Avenue, Lawrence, KS, 66045, USA
| | - Kaylee E Livingston
- Department of Ecology and Evolutionary Biology, University of Kansas, 1200 Sunnyside Avenue, Lawrence, KS, 66045, USA
| | - Jack D Ross
- Department of Ecology and Evolutionary Biology, University of Kansas, 1200 Sunnyside Avenue, Lawrence, KS, 66045, USA
| | - Lena C Hileman
- Department of Ecology and Evolutionary Biology, University of Kansas, 1200 Sunnyside Avenue, Lawrence, KS, 66045, USA
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Chi X, Chen R, Zhang F, Chen S. Comparative plastomes of species from Phrymaceae and Mazaceae: insights into adaptive evolution, codon usage bias, and phylogenetic relationships. Genome 2023; 66:281-294. [PMID: 37159948 DOI: 10.1139/gen-2023-0014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The phylogeny of the species from Phrymaceae and Mazaceae has undergone many adjustments and changes in recent years. Moreover, there is little plastome information on the Phrymaceae. In this study, we compared the plastomes of six species from the Phrymaceae and 10 species from the Mazaceae. The gene order, contents, and orientation of the 16 plastomes were found to be highly similar. A total of 13 highly variable regions were identified among the 16 species. An accelerated rate of substitution was found in the protein-coding genes, particularly cemA and matK. The combination of effective number of codons, parity rule 2, and neutrality plots revealed that the codon usage bias is affected by mutation and selection. The phylogenetic analysis strongly supported {Mazaceae [(Phrymaceae + Wightiaceae) + (Paulowniaceae + Orobanchaceae)]} relationships in the Lamiales. Our findings can provide useful information to analyze the phylogeny and molecular evolution within the Phrymaceae and Mazaceae.
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Affiliation(s)
- Xiaofeng Chi
- Qinghai Provincial Key Laboratory of Crop Molecular Breeding, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China
| | - Ronglian Chen
- Qinghai Provincial Key Laboratory of Crop Molecular Breeding, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Faqi Zhang
- Qinghai Provincial Key Laboratory of Crop Molecular Breeding, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China
| | - Shilong Chen
- Qinghai Provincial Key Laboratory of Crop Molecular Breeding, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China
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Muir CD, Van Den Elzen CL, Angert AL. Selection on early survival does not explain germination rate clines in Mimulus cardinalis. Am J Bot 2022; 109:1811-1821. [PMID: 36317645 DOI: 10.1002/ajb2.16076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 07/11/2022] [Accepted: 07/11/2022] [Indexed: 06/16/2023]
Abstract
PREMISE Many traits covary with environmental gradients to form phenotypic clines. While local adaptation to the environment can generate phenotypic clines, other nonadaptive processes may also. If local adaptation causes phenotypic clines, then the direction of genotypic selection on traits should shift from one end of the cline to the other. Traditionally, genotypic selection on non-Gaussian traits like germination rate have been hampered because it is challenging to measure their genetic variance. METHODS Here we used quantitative genetics and reciprocal transplants to test whether a previously discovered cline in germination rate showed additional signatures of adaptation in the scarlet monkeyflower (Mimulus cardinalis). We measured genotypic and population level covariation between germination rate and early survival, a component of fitness. We developed a novel discrete log-normal model to estimate genetic variance in germination rate. RESULTS Contrary to our adaptive hypothesis, we found no evidence that genetic variation in germination rate contributed to variation in early survival. Across populations, southern populations in both gardens germinated earlier and survived more. CONCLUSIONS Southern populations have higher early survival but it is not caused by faster germination. This pattern is consistent with nonadaptive forces driving the phenotypic cline in germination rate, but future work will need to assess whether there is selection at other life stages. This statistical framework should help expand quantitative genetic analyses for other waiting-time traits.
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Affiliation(s)
- Christopher D Muir
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- School of Life Sciences, University of Hawai'i, Honolulu, HI, 96822, USA
| | - Courtney L Van Den Elzen
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, 80309, USA
| | - Amy L Angert
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
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Nelson TC, Muir CD, Stathos AM, Vanderpool DD, Anderson K, Angert AL, Fishman L. Quantitative trait locus mapping reveals an independent genetic basis for joint divergence in leaf function, life-history, and floral traits between scarlet monkeyflower (Mimulus cardinalis) populations. Am J Bot 2021; 108:844-856. [PMID: 34036561 DOI: 10.1002/ajb2.1660] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Accepted: 01/12/2021] [Indexed: 06/12/2023]
Abstract
PREMISE Across taxa, vegetative and floral traits that vary along a fast-slow life-history axis are often correlated with leaf functional traits arrayed along the leaf economics spectrum, suggesting a constrained set of adaptive trait combinations. Such broad-scale convergence may arise from genetic constraints imposed by pleiotropy (or tight linkage) within species, or from natural selection alone. Understanding the genetic basis of trait syndromes and their components is key to distinguishing these alternatives and predicting evolution in novel environments. METHODS We used a line-cross approach and quantitative trait locus (QTL) mapping to characterize the genetic basis of twenty leaf functional/physiological, life history, and floral traits in hybrids between annualized and perennial populations of scarlet monkeyflower (Mimulus cardinalis). RESULTS We mapped both single and multi-trait QTLs for life history, leaf function and reproductive traits, but found no evidence of genetic co-ordination across categories. A major QTL for three leaf functional traits (thickness, photosynthetic rate, and stomatal resistance) suggests that a simple shift in leaf anatomy may be key to adaptation to seasonally dry habitats. CONCLUSIONS Our results suggest that the co-ordination of resource-acquisitive leaf physiological traits with a fast life-history and more selfing mating system results from environmental selection rather than functional or genetic constraint. Independent assortment of distinct trait modules, as well as a simple genetic basis to leaf physiological traits associated with drought escape, may facilitate adaptation to changing climates.
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Affiliation(s)
- Thomas C Nelson
- Division of Biological Sciences, University of Montana, Missoula, Montana, 59812, USA
| | - Christopher D Muir
- Departments of Botany and Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada
- School of Life Sciences, University of Hawai'i, Honolulu, Hawai'i, 96822, USA
| | - Angela M Stathos
- Division of Biological Sciences, University of Montana, Missoula, Montana, 59812, USA
| | - Daniel D Vanderpool
- Division of Biological Sciences, University of Montana, Missoula, Montana, 59812, USA
| | - Kayli Anderson
- Division of Biological Sciences, University of Montana, Missoula, Montana, 59812, USA
| | - Amy L Angert
- Departments of Botany and Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada
| | - Lila Fishman
- Division of Biological Sciences, University of Montana, Missoula, Montana, 59812, USA
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Popovic D, Lowry DB. Contrasting environmental factors drive local adaptation at opposite ends of an environmental gradient in the yellow monkeyflower (Mimulus guttatus). Am J Bot 2020; 107:298-307. [PMID: 31989586 DOI: 10.1002/ajb2.1419] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 09/13/2019] [Indexed: 05/22/2023]
Abstract
PREMISE Identifying the environmental factors responsible for natural selection across different habitats is crucial for understanding the process of local adaptation in plants. Despite its importance, few studies have successfully isolated the environmental factors driving local adaptation in nature. In this study, we evaluated the agents of selection responsible for local adaptation of the monkeyflower Mimulus guttatus to California's coastal and inland habitats. METHODS We implemented a manipulative reciprocal transplant experiment at coastal and inland sites, where we excluded aboveground stressors in an effort to elucidate their role in the evolution of local adaptation. RESULTS Excluding aboveground stressors, most likely a combination of salt spray and herbivory, completely rescued inland annual plant fitness when transplanted to coastal habitat. The exclosures in inland habitat provided a benefit to the performance of coastal perennial plants. However, the exclosures are unlikely to provide much fitness benefit to the coastal plants at the inland site because of their general inability to flower in time to escape from the summer drought. CONCLUSIONS Our study demonstrates that a distinct set of selective agents (aboveground vs. belowground) are responsible for local adaptation at opposite ends of an environmental gradient.
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Affiliation(s)
- Damian Popovic
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA
- Program in Ecology, Evolutionary Biology, and Behavior, Michigan State University, East Lansing, MI, 48824, USA
| | - David B Lowry
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA
- Program in Ecology, Evolutionary Biology, and Behavior, Michigan State University, East Lansing, MI, 48824, USA
- Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA
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Chase MA, Stankowski S, Streisfeld MA. Genomewide variation provides insight into evolutionary relationships in a monkeyflower species complex (Mimulus sect. Diplacus). Am J Bot 2017; 104:1510-1521. [PMID: 29885225 DOI: 10.3732/ajb.1700234] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 09/11/2017] [Indexed: 06/08/2023]
Abstract
PREMISE OF THE STUDY Evolutionary radiations provide excellent opportunities to study the origins of biodiversity, but rapid divergence and ongoing gene flow make inferring evolutionary relationships among taxa difficult. Consequently, combining morphological and genomic analyses will be necessary to clarify the evolutionary history of radiations. We used an integrative approach to shed light on relationships within a diverse radiation of monkeyflowers (Mimulus section Diplacus) with a controversial taxonomic history. METHODS We used genomewide single nucleotide polymorphism data and a combination of phylogenetic and population genomic analyses to infer the evolutionary relationships within the group. Tests for hybridization were performed to reveal sources of shared variation, and multivariate analyses of floral trait data were conducted to examine the correspondence between phenotypic and phylogenetic data. KEY RESULTS We identified four primary clades with evidence for some shared variation among them. We also detected evidence for recent gene flow between closely related subclades and populations. Strong discordance between floral trait and molecular data provides evidence for divergent and convergent phenotypic evolution. CONCLUSIONS Mimulus section Diplacus has all the hallmarks of a rapid radiation, including diverse taxa that are at different stages of divergence, extensive shared variation among taxa, and complex patterns of phenotypic evolution. Our findings will direct future evolutionary research and have important taxonomic implications that highlight the need for a new revision of section Diplacus.
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Affiliation(s)
- Madeline A Chase
- Institute of Ecology and Evolution, 335 Pacific Hall 5289, University of Oregon, Eugene, Oregon 97405 USA
| | - Sean Stankowski
- Institute of Ecology and Evolution, 335 Pacific Hall 5289, University of Oregon, Eugene, Oregon 97405 USA
| | - Matthew A Streisfeld
- Institute of Ecology and Evolution, 335 Pacific Hall 5289, University of Oregon, Eugene, Oregon 97405 USA
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Peng F, Byers KJRP, Bradshaw HD. Less is more: Independent loss-of-function OCIMENE SYNTHASE alleles parallel pollination syndrome diversification in monkeyflowers (Mimulus). Am J Bot 2017; 104:1055-1059. [PMID: 28724593 DOI: 10.3732/ajb.1700104] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Accepted: 06/14/2017] [Indexed: 06/07/2023]
Abstract
PREMISE OF THE STUDY Pollinator-mediated selection on flower phenotypes (e.g., shape, color, scent) is key to understanding the adaptive radiation of angiosperms, many of which have evolved specialized relationships with a particular guild of animal pollinators (e.g., birds, bats, moths, bees). E-β-Ocimene, a monoterpene produced by OCIMENE SYNTHASE (OS) in Mimulus lewisii, is a floral scent important in attracting the species' bumblebee pollinators. The taxa closely related to M. lewisii have evolved several different pollination syndromes, including hummingbird pollination and self pollination (autogamy). We are interested in how floral scent variation contributed to species diversification in this clade. METHODS We analyzed variation in E-β-ocimene emission within this Mimulus clade and explored its molecular basis through a combination of DNA sequencing, reverse transcriptase PCR, and enzyme functional analysis in vitro. KEY RESULTS We found that none of the taxa, other than M. lewisii, emitted E-β-ocimene from flowers. But the molecular basis underlying loss of E-β-ocimene emission is unique in each taxon, including deletion, missense, or frameshift mutations in the OS gene, and potential posttranscriptional downregulation. CONCLUSIONS The molecular evidence suggests that parallel loss-of-function in OS is the best explanation for the observed pattern of E-β-ocimene emission, likely as the result of natural selection.
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Affiliation(s)
- Foen Peng
- Department of Biology, Box 351800, University of Washington, Seattle, Washington 98195 USA
| | - Kelsey J R P Byers
- Department of Biology, Box 351800, University of Washington, Seattle, Washington 98195 USA
- Department of Zoology, Downing Street, University of Cambridge, Cambridge, CB2 3EJ England, UK
| | - Harvey D Bradshaw
- Department of Biology, Box 351800, University of Washington, Seattle, Washington 98195 USA
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Friedman J, Hart KS, den Bakker MC. Losing one's touch: Evolution of the touch-sensitive stigma in the Mimulus guttatus species complex. Am J Bot 2017; 104:335-341. [PMID: 28202451 DOI: 10.3732/ajb.1600394] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 01/30/2017] [Indexed: 06/06/2023]
Abstract
PREMISE OF THE STUDY The stigmas of several species are touch sensitive and respond to pressure by closing. Previous research suggests that stigma closure could prevent self pollination within a flower during a pollinator's visit or enhance male function by increasing pollen export. Both factors could be favored in outcrossers, and neither would be beneficial in selfers. METHODS We investigated variation in stigma-closing and the duration of closure in annual and perennial populations of the variable species Mimulus guttatus and whether four closely related selfing species (M. cupriphilus, M. laciniatus, M. nasutus, and M. pardalis) have lost their touch sensitivity. We grew plants in a controlled environment and performed experiments with and without the addition of pollen to the stigma. KEY RESULTS In M. guttatus, the speed of stigma-closing was rapid and unaffected by the deposition of pollen. Populations varied significantly in closing speed, which may reflect their geographic location. For annual populations only, anther-stigma separation significantly affected closing speed. Also, stigmas that closed quickly stayed closed longer, and stigmas that received pollen remained closed longer. Finally, in the selfing species, stigma-closing was more variable; some populations have entirely lost the ability to respond to touch. CONCLUSIONS We discuss our results in the context of traits that promote outcrossing and traits that are under selection during the evolution of selfing. This is the first characterization of variation in touch responses across multiple populations within a species and the first to demonstrate the loss of touch sensitivity in selfing lineages.
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Affiliation(s)
- Jannice Friedman
- Department of Biology, Syracuse University, 110 College Place, Syracuse, New York 13244 USA
| | - Katherine S Hart
- Department of Biology, Syracuse University, 110 College Place, Syracuse, New York 13244 USA
| | - Meghan C den Bakker
- Department of Biology, Syracuse University, 110 College Place, Syracuse, New York 13244 USA
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Tian Z, Zhang F, Liu H, Gao Q, Chen S. Development of SSR markers for a Tibetan medicinal plant, Lancea tibetica ( Phrymaceae), based on RAD sequencing. Appl Plant Sci 2016; 4:apps1600076. [PMID: 27843726 PMCID: PMC5104527 DOI: 10.3732/apps.1600076] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 09/14/2016] [Indexed: 06/06/2023]
Abstract
PREMISE OF THE STUDY Lancea tibetica (Phrymaceae), a Tibetan medicinal plant, is endemic to the Qinghai-Tibet Plateau. The over-exploitation of wild L. tibetica has led to the destruction of many populations. To enhance protection and management, biological research, especially population genetic studies, should be carried out on L. tibetica. Simple sequence repeat (SSR) markers of L. tibetica were developed to analyze population diversity. METHODS AND RESULTS Four thousand four hundred and forty-one SSR loci were identified for L. tibetica based on restriction-site associated DNA (RAD) sequencing on the Illumina HiSeq platform. One hundred SSR loci were arbitrarily selected for primer design, and 38 of them were successfully amplified. These markers were tested on 56 individuals from three populations of L. tibetica, and 10 markers displayed polymorphisms. The total number of alleles per locus ranged from three to eight, and observed and expected heterozygosities ranged from 0.200 to 1.000 and 0.683 to 0.879, respectively. We tested for cross-amplification of these 10 markers in the related species L. hirsuta and found that nine could be successfully amplified. CONCLUSIONS The SSR markers characterized here are the first to be developed and tested in L. tibetica. They will be useful for future population genetic studies on L. tibetica and closely related species.
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Affiliation(s)
- Zunzhe Tian
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Xining 810001, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing 100039, People’s Republic of China
| | - Faqi Zhang
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Xining 810001, People’s Republic of China
| | - Hairui Liu
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Xining 810001, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing 100039, People’s Republic of China
| | - Qingbo Gao
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Xining 810001, People’s Republic of China
| | - Shilong Chen
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Xining 810001, People’s Republic of China
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10
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Stanton K, Valentin CM, Wijnen ME, Stutstman S, Palacios JJ, Cooley AM. Absence of postmating barriers between a selfing vs. outcrossing Chilean Mimulus species pair. Am J Bot 2016; 103:1030-1040. [PMID: 27283023 DOI: 10.3732/ajb.1600079] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 05/10/2016] [Indexed: 06/06/2023]
Abstract
PREMISE OF THE STUDY Reproductive isolation between sympatric species pairs may be maintained by both pre- and postmating barriers. Here we evaluate potential barriers to mating between the outcrossing Mimulus luteus and its more highly selfing sympatric congener, M. cupreus, two members of the South American luteus complex of Mimulus. METHODS Seed set was compared following autonomous self-pollination, manual pollination, conspecific outcrossing, and sympatric and allopatric hybridization, for laboratory-maintained inbred lines and wild-collected accessions. Survival and reproductive fitness of hybrids relative to parental species were examined across environments that differed with respect to temperature and soil nutrients, two factors that vary across the ranges of M. luteus and M. cupreus. KEY RESULTS Mimulus luteus was minimally capable of autonomous self-fertilization, consistent with reliance on an animal pollinator, whereas M. cupreus was a successful selfer across all tested accessions. Postmating barriers to hybridization are negligible, in both low- and high-stress environments, across multiple sympatric and allopatric populations. CONCLUSION As in the North American M. guttatus-M. nasutus species pair, postmating barriers contribute little to isolation between M. luteus and M. cupreus. This result reinforces the importance of premating barriers, specifically species differences in reliance on, and accessibility to, animal pollinators. A unique aspect of the M. luteus-M. cupreus pair is the recent gain of red floral anthocyanin pigmentation in M. cupreus. On the basis of species differences in vegetative anthocyanin production, a facultative stress-protective response, we propose a potential stress-protective role for the constitutive floral anthocyanins of M. cupreus.
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Affiliation(s)
- Kimmy Stanton
- Whitman College Biology Department, Walla Walla, Washington 99362 USA
| | - Celine M Valentin
- Whitman College Biology Department, Walla Walla, Washington 99362 USA
| | - Marijke E Wijnen
- Whitman College Biology Department, Walla Walla, Washington 99362 USA
| | - Sage Stutstman
- Whitman College Biology Department, Walla Walla, Washington 99362 USA
| | | | - Arielle M Cooley
- Whitman College Biology Department, Walla Walla, Washington 99362 USA
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11
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Wipf HML, Meindl GA, Ashman TL. A first test of elemental allelopathy via heterospecific pollen receipt. Am J Bot 2016; 103:514-521. [PMID: 26451033 DOI: 10.3732/ajb.1500187] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 06/11/2015] [Indexed: 06/05/2023]
Abstract
PREMISE OF THE STUDY Coflowering plants often share pollinators and may receive mixed species pollen loads. Although detrimental effects of heterospecific pollen receipt have been documented, trait-based modifiers of interactions on the stigma remain largely unknown. Chemicals that mediate interactions between sporophytes could also influence pollen-pollen or pollen-style interactions. We test for the first time whether nickel (Ni) accumulation in pollen can lead to "elemental allelopathy" and intensify the fitness consequences of heterospecific pollen receipt. METHODS We grew Ni-hyperaccumulator Streptanthus polygaloides in soils augmented with three concentrations of Ni, measured pollen Ni concentration, and hand-pollinated non-Ni hyperaccumulator Mimulus guttatus. We assayed pollen germination, tube growth and seeds of M. guttatus after pure and mixed species pollinations. KEY RESULTS Streptanthus polygaloides pollen accumulated Ni in proportion to soil availability and at levels significantly greater than M. guttatus pollen. Although receipt of S. polygaloides pollen increased M. guttatus pollen germination, it decreased the proportion of pollen tubes reaching the ovary and seed number. Increased Ni in pollen, however, did not significantly intensify the effect of S. polygaloides pollen receipt on M. guttatus seed production. CONCLUSIONS Different levels of Ni in the pollen of S. polygaloides achieved in the greenhouse did not significantly reduce the fitness of M. guttatus. Stigma tolerance to Ni may also have contributed to the lack of response to increased Ni in heterospecific pollen. This study paves the way for additional tests in other metal hyperaccumulators and recipients, and to identify mechanisms of interactions on the stigma.
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Affiliation(s)
- Heidi M-L Wipf
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 USA
| | - George A Meindl
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 USA
| | - Tia-Lynn Ashman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 USA
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12
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Peterson ML, Miller TJ, Kay KM. An ultraviolet floral polymorphism associated with life history drives pollinator discrimination in Mimulus guttatus. Am J Bot 2015; 102:396-406. [PMID: 25784473 DOI: 10.3732/ajb.1400415] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
UNLABELLED • PREMISE OF THE STUDY Ultraviolet (UV) floral patterns are common in angiosperms and mediate pollinator attraction, efficiency, and constancy. UV patterns may vary within species, yet are cryptic to human observers. Thus, few studies have explicitly described the distribution or ecological significance of intraspecific variation in UV floral patterning. Here, we describe the geographic distribution and pattern of inheritance of a UV polymorphism in the model plant species Mimulus guttatus (Phrymaceae). We then test whether naturally occurring UV phenotypes influence pollinator interactions within M. guttatus.• METHODS We document UV patterns in 18 annual and 19 perennial populations and test whether UV pattern is associated with life history. To examine the pattern of inheritance, we conducted crosses within and between UV phenotypes. Finally, we tested whether bee pollinators discriminate among naturally occurring UV phenotypes in two settings: wild bee communities and captive Bombus impatiens.• KEY RESULTS Within M. guttatus, perennial populations exhibit a small bulls-eye pattern, whereas a bilaterally symmetric runway pattern occurs mainly in annual populations. Inheritance of UV patterning is consistent with a single-locus Mendelian model in which the runway phenotype is dominant. Bee pollinators discriminate against unfamiliar UV patterns in both natural and controlled settings.• CONCLUSIONS We describe a widespread UV polymorphism associated with life history divergence within Mimulus guttatus. UV pattern influences pollinator visitation and should be considered when estimating reproductive barriers between life history ecotypes. This work develops a new system to investigate the ecology and evolution of UV floral patterning in a species with extensive genomic resources.
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Affiliation(s)
- Megan L Peterson
- Ecology and Evolutionary Biology, University of California Santa Cruz, 1156 High Street, Santa Cruz, California 95064 USA
| | - Timothy J Miller
- Ecology and Evolutionary Biology, University of California Santa Cruz, 1156 High Street, Santa Cruz, California 95064 USA
| | - Kathleen M Kay
- Ecology and Evolutionary Biology, University of California Santa Cruz, 1156 High Street, Santa Cruz, California 95064 USA
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