Water Snakes in Lake Erie Water snakes Nerodia

Water Snakes in Lake Erie • Water snakes (Nerodia sipedon) in Lake Erie come in two color phases: banded and unbanded • This is a two allele system • Banded partially dominant to unbanded • The mainland has really only banded • The islands may have both • King & Lawson, 1995

A –unbanded B & C – intermediate D – strongly banded

Lake Erie water snakes • It was found that, when basking on islands, the unbanded snakes are more cryptic and thus remain hidden better. • Why wouldn’t selection cause the unbanded pattern to go to fixation? • Migration. Every year, banded snakes migrate from the mainland introduce fresh banded alleles • Therefore, migration offsets selection

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Genetic Drift

Founder Effect • small founding populations have less allelic diversity Silvereye (Zosterops lateralis) • Clegg, et al, 2002

Silvereye colonization • Clegg, et al, 2002

Founder Effect on Allelic Diversity of the Silvereye

Alleles Randomly Fixed

Alleles Randomly Fixed

Average Heterogosity Decreases

Effective Population Size 20

Alleles Randomly fixed in the field Collared Lizard (Crotaphytus collaris) • Templeton, et al, 2002

Multilocus Genotyping of Collared Lizards in the Ozarks

Randomly Fixed Alleles in Isolated Collared Lizard Populations

Alcohol Dehydrogenase (ADH) Gene Alignment in Drosophilia

The Vertebrate Mitochondrial Genetic Code

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