title: Unlinked Mendelian inheritance of red and black pigmentation in snakes: Implications for Batesian mimicry.
abstract: Identifying the genetic basis of mimetic signals is critical to understanding both the origin and dynamics of mimicry over time. For species not amenable to large laboratory breeding studies, widespread color polymorphism across natural populations offers a powerful way to assess the relative likelihood of different genetic systems given observed phenotypic frequencies. We classified color phenotype for 2175 ground snakes (Sonora semiannulata) across the continental United States to analyze morph ratios and test among competing hypotheses about the genetic architecture underlying red and black coloration in coral snake mimics. We found strong support for a two-locus model under simple Mendelian inheritance, with red and black pigmentation being controlled by separate loci. We found no evidence of either linkage disequilibrium between loci or sex linkage. In contrast to Batesian mimicry systems such as butterflies in which all color signal components are linked into a single "supergene," our results suggest that the mimetic signal in colubrid snakes can be disrupted through simple recombination and that color evolution is likely to involve discrete gains and losses of each signal component. Both outcomes are likely to contribute to the exponential increase in rates of color evolution seen in snake mimicry systems over insect systems.
authors.affiliation: Department of Ecology and Evolutionary Biology and Museum of Zoology, University of Michigan, 1109 Geddes Avenue, Ann Arbor, Michigan, 48109. ardr@umich.edu.|Department of Integrative Biology and Museum of Vertebrate Zoology, University of California, Berkeley, California, 94720. ardr@umich.edu.
authors.forename: Alison R
authors.initials: AR
authors.lastname: Davis Rabosky
authors.affiliation: Department of Biology, Georgia Southern University, PO Box 8042, Statesboro, Georgia 30460.
authors.forename: Christian L
authors.initials: CL
authors.lastname: Cox
authors.affiliation: Department of Ecology and Evolutionary Biology and Museum of Zoology, University of Michigan, 1109 Geddes Avenue, Ann Arbor, Michigan, 48109.
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Rabosky
mesh_terms: D000818:Animals; D005075:Biological Evolution; D000067558:Biological Mimicry; D017812:Colubridae / Q000235:genetics*; D005260:Female; D056426:Genetic Loci; D040582:Inheritance Patterns; D015810:Linkage Disequilibrium; D008297:Male; D008957:Models, Genetic; D010641:Phenotype; D010858:Pigmentation / Q000235:genetics*
keywords: Color polymorphism; Sonora semiannulata; coloration genetics; coral snake mimicry; linkage disequilibrium; supergene