Gender-specific differences fuel biodiversity

Many factors, such as habitat, behaviour and diet, contribute to biological diversity. But researchers now have an unexpected addition to this list — sexual differences. A study of the Anolis lizards of the Greater Antilles suggests that morphological differences between males and females are linked to increased biodiversity.
The Anolis lizards of Puerto Rico, Jamaica, Cuba and Hispaniola evolved independently on their respective islands into species that occupy particular niches, such as the short-legged twig dwellers and the long-legged open space dwellers. But males and females of the same species can be very different — in some species the sexes are the same size, but in others adult males can be three times bigger than females.
Marguerite A. Butler and colleagues studied five sexually dimorphic characteristics from male and female adults of different niche specialists living on two of the islands. They find that sexual dimorphism contributes substantially to biodiversity, helping to fuel the bursts of ‘adaptive radiation’ that produced the different niche-adapted species.
Most studies of adaptive radiation ignore sexually dimorphic traits, the authors say. But its place in evolutionary ecology should not be underestimated.
CONTACT
Marguerite A. Butler (University of Hawaii at Manoa, Honolulu, HI, USA)
Tel: +1 808 956 4713; E-mail: mbutler@hawaii.edu