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Linking a mutation fo survival in wild mice (Tests (Examined and…
Linking a mutation fo survival in wild mice
Changes in agouti ser allele through space and time
Negative selection on Ser allele (light pigmentation on dark substrates)
Genetic consequences of selection on pigmentation
sequenced all 481 mice
2442 variable in or near Agouti gene
53507 variable genome wide
Functional & ecological effects of a deletion mutation in Agouti
Ser associated with dorsal brightness
highest level of genetic differentiation
has an effect on pigmentation
Ser mice had lighter coats than mice with WT
Ser mice had lower amounts of pheomelanin
decreases strength of attractin interactions
reduces pheomelanin production
increases brightness of dorsal coat
Found on conserved region of agouti protein
required for agouti production
Divergent selection in experimental enclosures
481 wild mice from dark and light sites
75-100 mice introduced
Diffs in 5 pigment traits
Ventral brightness
Ventral chroma
Dorsal chroma
Tail pattern
Dorsal brightness
Mark & re-caputure approach
Compared colonizing population survivors from time 1
Discussion
Have a lot of data
strength of selection acting on phenotype s
statistical signatures of selection on the genome
when genetic variation is available, natural selection brings on evolutionary change on ecological time scales
can help predict evolution under ecological conditions
Tests
Resampling procedure
how many SNPS expected to show significant changes by chance
Amino acid mutation Ser in Agouti
to test functional links
Examined and quantified pigment in dorsal hair
Pheomelanin content analyzed
liquid chromatography
Scatchard analysis
analyzed equilibrium binding levels
WT domain had smaller Kd thank Ser domain
WT has greater binding affinity to attractin
Taqman assay
measured frequency of Ser allele between enclosures and over time
genotyped all individuals
Results
Light enclosures
surviving mice 1.44 times lighter
nonrandom genotype frequencies at 353 SNPs
idiosyncratic changes in allele frequency
2/3 showed expected increases of Ser allele
Dark enclosures
surviving mice 1.98 times darker
non random genotype frequencies at 549 SNPs
rejected null hypothesis
Decreases in Ser allele
Divergent natural selection acting on dorsal brightness
SNPs associated with dorsal brightness should experience selection
4/7 SNPs had differentiation between light and dark habitats
3 linkage blocks
Field experiments
owls hunting at experimental sites
dorsal brightness and survival driven by higher rates of avian predation