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EVOLUTIONBiology 145

Lecture 13 – Speciation

FOUNDER EFFECT

In a population with AA, Aa, and aa individuals, if ONE founds a subpopulation, it might well be a HOMOZYGOTE

Polydactyly –AmishAllele 1:14 versus 1:1000

General: 1:180,000PA Mennonites 1:176

Maple Syrup Urine Disease

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Genetic BOTTLENECKS

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SPECIATION

Gene flow must be interrupted!.

Anagenesis versus cladogenesis (speciation)

Chronospecies

Anageneticchange

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Allopatric speciation

Gene flow interrupted by a physical barrier

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Sciurus aberti aberti Sciurus aberti kaibabensis

Parapatric Speciation

Agrostis

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Sympatric speciation

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RIMS   Reproductive Isolating Mechanisms

RIMS – pleiotropy

Food type

Song

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Ring species