1. Department of Zoology, University of Hawaii at Manoa, 2538 McCarthy Mall, Edmonson 152, Honolulu, Hawaii 96822, USA
2. Department of Mathematics, Campus Box 1146
3. Department of Biology, Campus Box 1137, Washington University, St Louis, Missouri 63130, USA
4. Present address: Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, Massachusetts 02138, USA.

Correspondence to: Marguerite A. Butler¹ Correspondence and requests for materials should be addressed to M.A.B. (Email: mbutler@hawaii.edu).

Abstract

Sexual dimorphism is widespread and substantial throughout the animal world^{1, 2}. It is surprising, then, that such a pervasive source of biological diversity has not been integrated into studies of adaptive radiation, despite extensive and growing attention to both phenomena^{1, 3, 4, 5, 6, 7}. Rather, most studies of adaptive radiation either group individuals without regard to sex or focus solely on one sex. Here we show that sexual differences contribute substantially to the ecomorphological diversity produced by the adaptive radiations of West Indian Anolis lizards: within anole species, males and females occupy mostly non-overlapping parts of morphological space; the overall extent of sexual variation is large relative to interspecific variation; and the degree of variation depends on ecological type. Thus, when sexual dimorphism in ecologically relevant traits is substantial, ignoring its contribution may significantly underestimate the adaptive component of evolutionary radiation. Conversely, if sexual dimorphism and interspecific divergence are alternative means of ecological diversification, then the degree of sexual dimorphism may be negatively related to the extent of adaptive radiation.

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