Presentation Title

Population Genetics, Form, and Function of Loggerhead Shrikes in California

Faculty Mentor

Diego Sustaita, Arun Sethuraman

Start Date

23-11-2019 1:00 PM

End Date

23-11-2019 1:15 PM

Location

Markstein 103

Session

oral 3

Type of Presentation

Oral Talk

Subject Area

biological_agricultural_sciences

Abstract

Population genetics studies of Loggerhead Shrikes (Laniidae: Lanius ludovicianus) in California have indicated considerable intraspecific genetic differentiation. Other morphological and behavioral studies have also shown geographic phenotypic variation. However, the concordance between genetic and phenotypic differentiation remains obscure. Here we explore the extent to which genetic differences among populations are correlated with phenotypic differences (beak shape and bite force) among populations of Loggerhead Shrikes throughout California. Feather samples were collected from shrikes in locations along an approximately 950 km range. Genomic DNA was then extracted and we genotyped each individual at 6 different nuclear microsatellite loci. We performed Mantel tests for correlations between pairwise phenotypic and genetic distance matrices among populations, and principle components analysis (PCA) of beak shape and microsatellite loci to explore patterns of variation among individuals. Mantel tests showed significant correlations between pairwise morphological and performance distances with genetic distances, among populations. These three distance matrices were also correlated with pairwise geographic distances, suggesting a model of isolation by distance. Despite these correlations, the PCAs show more phenotypic, than genetic, variability among geographic groups. This result suggests that the phenotypes may be influenced by the high rate of inbreeding, (as indicated by high heterozygosity deficiencies we observed), local adaptation, or phenotypic plasticity. We expect that by increasing our genotyping with more microsatellite loci and sampling more individuals across California, we can perform more rigorous analyses of population structure that will shed light on the relative roles of local adaptation and plasticity in shaping differences in feeding morphology and function.

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Nov 23rd, 1:00 PM Nov 23rd, 1:15 PM

Population Genetics, Form, and Function of Loggerhead Shrikes in California

Markstein 103

Population genetics studies of Loggerhead Shrikes (Laniidae: Lanius ludovicianus) in California have indicated considerable intraspecific genetic differentiation. Other morphological and behavioral studies have also shown geographic phenotypic variation. However, the concordance between genetic and phenotypic differentiation remains obscure. Here we explore the extent to which genetic differences among populations are correlated with phenotypic differences (beak shape and bite force) among populations of Loggerhead Shrikes throughout California. Feather samples were collected from shrikes in locations along an approximately 950 km range. Genomic DNA was then extracted and we genotyped each individual at 6 different nuclear microsatellite loci. We performed Mantel tests for correlations between pairwise phenotypic and genetic distance matrices among populations, and principle components analysis (PCA) of beak shape and microsatellite loci to explore patterns of variation among individuals. Mantel tests showed significant correlations between pairwise morphological and performance distances with genetic distances, among populations. These three distance matrices were also correlated with pairwise geographic distances, suggesting a model of isolation by distance. Despite these correlations, the PCAs show more phenotypic, than genetic, variability among geographic groups. This result suggests that the phenotypes may be influenced by the high rate of inbreeding, (as indicated by high heterozygosity deficiencies we observed), local adaptation, or phenotypic plasticity. We expect that by increasing our genotyping with more microsatellite loci and sampling more individuals across California, we can perform more rigorous analyses of population structure that will shed light on the relative roles of local adaptation and plasticity in shaping differences in feeding morphology and function.