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 dominant to

unbanded• The mainland has really only

banded• The islands may have both

• King & Lawson, 1995

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 and introduce fresh banded alleles

• Therefore, migration offsets selection

Genetic Drift

Founder Effect• small founding populations have less allelic diversity

• Clegg, et al, 2002

Silvereye (Zosterops lateralis)

Silvereye colonization

• Clegg, et al, 2002

Founder Effect on Allelic Diversity of the Silvereye

Alleles Randomly Fixed

Average Heterogosity Decreases

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

The Vertebrate Mitochondrial Genetic Code

Alcohol Dehydrogenase (ADH) Gene Alignment in Drosophilia

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