Person:
Vignieri, Sacha

Profile Picture

Email Address

AA Acceptance Date

Birth Date

Research Projects

Organizational Units

Job Title

Last Name

Vignieri

First Name

Sacha

Name

Vignieri, Sacha
Author's Publications: search.filters.isAuthorOfPublication.c5b1e831-5e3e-4adf-84d3-36532aa6c8c8

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Publication
    The selective advantage of cryptic coloration in mice
    (Wiley-Blackwell, 2010) Vignieri, Sacha; Larson, Joanna G.; Hoekstra, Hopi
    The light color of mice that inhabit the sandy dunes of Florida's coast have served as a textbook example of adaptation for nearly a century, despite the fact that the selective advantage of crypsis has never been directly tested or quantified in nature. Using plasticine mouse models of light and dark color, we demonstrate a strong selective advantage for mice that match their local background substrate. Further our data suggest that stabilizing selection maintains color matching within a single habitat, as models that are both lighter and darker than their local environment are selected against. These results provide empirical evidence in support of the hypothesis that visual hunting predators shape color patterning in Peromyscus mice and suggest a mechanism by which selection drives the pronounced color variation among populations.
  • Thumbnail Image
    Publication
    Adaptive basis of geographic variation: genetic, phenotypic and environmental differences among beach mouse populations
    (The Royal Society, 2009) Mullen, L. M.; Vignieri, Sacha; Gore, J. A.; Hoekstra, Hopi
    A major goal in evolutionary biology is to understand how and why populations differentiate, both genetically and phenotypically, as they invade a novel habitat. A classical example of adaptation is the pale colour of beach mice, relative to their dark mainland ancestors, which colonized the isolated sandy dunes and barrier islands on Florida's Gulf Coast. However, much less is known about differentiation among the Gulf Coast beach mice, which comprise five subspecies linearly arrayed on Florida's shoreline. Here, we test the role of selection in maintaining variation among these beach mouse subspecies at multiple levels—phenotype, genotype and the environments they inhabit. While all beach subspecies have light pelage, they differ significantly in colour pattern. These subspecies are also genetically distinct: pair-wise Fst-values range from 0.23 to 0.63 and levels of gene flow are low. However, we did not find a correlation between phenotypic and genetic distance. Instead, we find a significant association between the average ‘lightness’ of each subspecies and the brightness of the substrate it inhabits: the two most genetically divergent subspecies occupy the most similar habitats and have converged on phenotype, whereas the most genetically similar subspecies occupy the most different environments and have divergent phenotypes. Moreover, allelic variation at the pigmentation gene, Mc1r, is statistically correlated with these colour differences but not with variation at other genetic loci. Together, these results suggest that natural selection for camouflage—via changes in Mc1r allele frequency—contributes to pigment differentiation among beach mouse subspecies.
  • Thumbnail Image
    Publication
    Population Structure as Revealed by mtDNA and Microsatellites in Northern Fur Seals, Callorhinus ursinus, throughout Their Range
    (Public Library of Science, 2010) Dickerson, Bobette R.; Ream, Rolf R.; Vignieri, Sacha; Bentzen, Paul
    Background: The northern fur seal (Callorhinus ursinus; NFS) is a widely distributed pinniped that has been shown to exhibit a high degree of philopatry to islands, breeding areas on an island, and even to specific segments of breeding areas. This level of philopatry could conceivably lead to highly genetically divergent populations. However, northern fur seals have the potential for dispersal across large distances and have experienced repeated rapid population expansions following glacial retreat and the more recent cessation of intensive harvest pressure. Methodology/Principal Findings: Using microsatellite and mitochondrial loci, we examined population structure in NFS throughout their range. We found only weak population genetic structure among breeding islands including significant FST and ΦST values between eastern and western Pacific islands. Conclusions: We conclude that insufficient time since rapid population expansion events (both post glacial and following the cessation of intense harvest pressure) mixed with low levels of contemporary migration have resulted in an absence of genetic structure across the entire northern fur seal range.