Exceptional Convergence on the Macroevolutionary Landscape in Island Lizard Radiations

Playing the Tape of Life Should the tape of life be replayed, would it produce the same music? Many influential evolutionary biologists, notably Stephen J. Gould, have argued that the answer is “no.” However, patterns of convergence among different species filling similar niches all over the world have argued that the answer is neither so simple nor perhaps so negative. Classic cases of convergence, such as marsupials on the Australian continent or cichlids across the African rift lakes, have demonstrated that similar ecological pressures can result in species with similar ecological traits. Such classic examples, however, do not allow for the influence of niche filling based purely on chance. Mahler et al. (p. 292 ) take advantage of the well-studied species clades of Caribbean anoles to examine patterns of adaptation and niche filling across species and islands. Across-islands convergence on a few distinct adaptive peaks (or niches) has driven diversification of species. Anomalies from these ecotypes are only found on the largest, most diverse islands. Thus, ecological niches powerfully shape species and convergence on particular forms is an inherent component of adaptation. Thus, it seems that the tape of life might play the same music, despite being produced by different instruments.