Term of Award

Spring 1994

Degree Name

Master of Science in Biology

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Committee Chair

Michael P. Moulton

Committee Member 1

D. Kelly McLain

Committee Member 2

John W. Parrish


Patterns of plumage dimorphism were examined among species of passerines native to 19 West Indian islands. Based on sexual selection theory, the predictions were made that dimorphic species: (1) occur on fewer and larger islands than monomorphic species due to reduced colonization ability and reduced survivorship imposed by sexual selection pressure, and (2) should be added to island communities disproportionately as area increases, an idea which was tested using linear models.

No significant difference was observed between number of islands or minimum island area occupied by dimorphics versus monomorphics. The traditional ANCOVA model best fits the data and suggests that dimorphics do not add a disproportionate number of species as island area increases.

I suggest that the force of sexual selection is not an important force in the structuring of these West Indian bird communities.

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