Divergent selection drives genetic differentiation in an R2R3-MYB transcription factor that contributes to incipient speciation in Mimulus aurantiacus.

Publisher: Public Library of Science Country of Publication: United States NLM ID: 101239074 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1553-7404 (Electronic) Linking ISSN: 15537390 NLM ISO Abbreviation: PLoS Genet Subsets: MEDLINE

Original Publication: San Francisco, CA : Public Library of Science, c2005-

Biological Evolution* ; Flowers*/cytology ; Flowers*/genetics ; Flowers*/growth & development ; Genetic Speciation*; Pigmentation/*genetics ; Plant Proteins/*genetics ; Transcription Factors/*genetics; Arabidopsis Proteins/genetics ; Biodiversity ; California ; Ecosystem ; Genetics, Population ; Mimulus/genetics ; Mimulus/growth & development ; Mutation

Identifying the molecular genetic basis of traits contributing to speciation is of crucial importance for understanding the ecological and evolutionary mechanisms that generate biodiversity. Despite several examples describing putative "speciation genes," it is often uncertain to what extent these genetic changes have contributed to gene flow reductions in nature. Therefore, considerable interest lies in characterizing the molecular basis of traits that actively confer reproductive isolation during the early stages of speciation, as these loci can be attributed directly to the process of divergence. In Southern California, two ecotypes of Mimulus aurantiacus are parapatric and differ primarily in flower color, with an anthocyanic, red-flowered morph in the west and an anthocyanin-lacking, yellow-flowered morph in the east. Evidence suggests that the genetic changes responsible for this shift in flower color have been essential for divergence and have become fixed in natural populations of each ecotype due to almost complete differences in pollinator preference. In this study, we demonstrate that a cis-regulatory mutation in an R2R3-MYB transcription factor results in differential regulation of enzymes in the anthocyanin biosynthetic pathway and is the major contributor to differences in floral pigmentation. In addition, molecular population genetic data show that, despite gene flow at neutral loci, divergent selection has driven the fixation of alternate alleles at this gene between ecotypes. Therefore, by identifying the genetic basis underlying ecologically based divergent selection in flower color between these ecotypes, we have revealed the ecological and functional mechanisms involved in the evolution of pre-mating isolation at the early stages of incipient speciation.
Competing Interests: The authors have declared that no competing interests exist.

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0 (Arabidopsis Proteins)
0 (BOTRYTIS SUSCEPTIBLE1 protein, Arabidopsis)
0 (Plant Proteins)
0 (Transcription Factors)

Date Created: 20130405 Date Completed: 20130625 Latest Revision: 20211021

20231215

PMC3605050

10.1371/journal.pgen.1003385

23555295