Disruptive selection and the genetic basis of bill size polymorphism in the African finch Pyrenestes

Article Abstract:

Bill size in the African finch Pyrenestes seems to vary according to a single genetic factor, and to be influenced by disruptive selection. Pyrenestes is the only bird known to have differing bill sizes not determined by sex. Bill size determines the variety and hardness of sedge seed the birds can most efficiently eat, from 13 Newtons of hardness for the small size to 299 N for the 'megabilled' finch. Birds of different bill sizes sometimes mate together.

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Density cycles and offspring quantity and quality game driven by natural selection

Article Abstract:

An example of a genetic rate of increase versus carrying capacity selection, promoting stable population cycles in lizards, is presented.

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Natural selection and sympatric divergence in the apple maggot Rhagoletis pomenella

Article Abstract:

The apple maggot Rhagoletis pomonella was studied for natural selection and sympatric divergence.

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