Molecular population genetics of adaptive color variation

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Molecular population geneticsof adaptive color
variation
Chaetodipus intermedius Rock Pocket Mouse
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Credit - Sean B. Carroll
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Chaetodipus intermediusRock Pocket Mouse
sandy
chocolate

• Native to the southwestern United States
• Burrow in soil close to or under rocks
• Feed by gathering seeds
• Favorite prey item for owls

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Predators have been effective.

• 99 of pocket mice on lava flows are chocolate
• 99 of pocket mice in the non-volcanic rocky
  regions are sandy

Filled circles represent lava flows and open
circles are non-volcanic rocky regions.
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The MC1R genedetermines color variation.

• Sandy mice have two copies of the ancestral
  light allele.
• Chocolate mice have either one or two copies of
  the mutant dark allele.

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An advantageous mutation

• The soil in the lava flow areas is richer in
  nutrients and supports more vegetation.
• The chocolate mutant allele is advantageous in
  these areas.
• The sandy allele is disadvantageous in these
  areas.
• Natural selection acts to match the pocket mouse
  coat color to its habitat.
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