Homing in on heterostyly

Gilmartin, Philip M.; Li, J

doi:10.1038/hdy.2010.69

Cited by 12 publications

(13 citation statements)

References 13 publications

(20 reference statements)

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“…‘Supergenes,’ another important concept in the animal CP literature, have been discussed for plants mainly in the context of alternative morphs in incompatibility systems (e.g. Gilmartin & Li 2010) rather than colour variants.…”

Section: Box 1 Plant Colour Polymorphismsmentioning

confidence: 99%

Colour polymorphism and correlated characters: genetic mechanisms and evolution

2010

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Colour polymorphisms (CP's) continue to be of interest to evolutionary biologists because of their general tractability, importance in studies of selection and potential role in speciation. Since some of the earliest studies of CP, it has been evident that alternative colour morphs often differ in features other than colour. Here we review the rapidly accumulating evidence concerning the genetic mechanisms underlying correlations between CP and other traits in animals. We find that evidence for genetic correlations is now available for taxonomically diverse systems and that physical linkage and regulatory mechanisms including transcription factors, cis-regulatory elements, and hormone systems provide pathways for the ready accumulation or modification of these correlations. Moreover, physical linkage and regulatory mechanisms may both contribute to genetic correlation in some of the best-studied systems. These results raise the possibility that negative frequency-dependent selection and disruptive selection might often be acting on suites of traits and that the cumulative effects of such selection, as well as correlational selection, may be important to CP persistence and evolution. We consider additional evolutionary implications. We recommend continued efforts to elucidate the mechanisms underlying CP-correlated characters and the more frequent application of comparative approaches, looking at related species that vary in character correlations and patterns of selection. We also recommend efforts to elucidate how frequency-dependent selection may act on suites of characters.

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Section: Box 1 Plant Colour Polymorphismsmentioning

confidence: 99%

Colour polymorphism and correlated characters: genetic mechanisms and evolution

2010

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“…Distyly promotes cross‐fertilization between compatible, heteromorphic flowers via the transfer of pollen onto distinct positions of the pollinator's body corresponding to the heights of the receiving stigmas ( i.e., disassortative pollination), decreasing gamete wastage to self‐fertilization and sexual interference (Barrett ). In the best known distylous system, that is primroses ( Primula L.; Barrett and Shore ; Gilmartin and Li ), a single Mendelian, diallelic locus ( i.e., S‐locus) controls distyly, with L‐plants being homozygous ( ss ) and S‐plants heterozygous ( Ss ). This genetic system, coupled with disassortative mating between morphs, maintains equal morph ratios ( i.e., isoplethy) in sufficiently large populations (Dowrick ; Lewis and Jones ).…”

Section: Introductionmentioning

confidence: 99%

Both morph‐ and species‐dependent asymmetries affect reproductive barriers between heterostylous species

Keller

Vos

Schmidt‐Lebuhn

et al. 2016

Ecology and Evolution

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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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“…Heteromorphic SI, where alternate floral morphs are produced (e.g. long-and short-style Primula vulgaris; Darwin, 1877;Gilmartin and Li, 2010), is common, but outcrossing is achieved by structural barriers and not pollen-pistil interactions. In SI species with homomorphic flowers, the S-locus encodes pistilexpressed genes that provide for the recognition and rejection of self-pollen or the favoring of nonself pollen.…”

Section: Intraspecific Reproductive Barriers: Simentioning

confidence: 99%