Parasites and the evolution of extravagant male characters: Anolis lizards on Caribbean islands as a test of the Hamilton-Zuk hypothesis.

Anolis lizards from Puerto Rico (five species from one site), Curaçao and Aruba in the southern Caribbean (2 populations), and 22 populations from 14 islands in the eastern Caribbean were surveyed for blood parasites (two species of Plasmodium and haemogregarines). Literature records for gut helminths from nine of these populations were added to the data set. Dorsal body color and dewlap color of males were also observed and classified into objective classes with no subjective view of showiness. These data were used to test the among-species prediction of the Hamilton-Zuk hypothesis which states that species harboring more harmful parasites over their evolutionary history will be more likely to evolve extravagant sexually dimorphic traits. Critics have noted important shortcomings in previous tests of the prediction; here we corrected for these errors. Parasite loads (prevalence and number of species) and dorsal and dewlap color varied substantially among the populations sampled. However, there was no association of parasite load with color either in a broad analysis or when correcting for phylogenetic relationships among the lizard species.