Ecological Morphology of Caribbean Anoles

Abstract

Anoles have evolved independently on each island in the Greater Antilles, producing a suite of morphologically-distinct species that utilize different microhabitats. Comparisons among islands indicate that the same set of ecomorphs-distantly related species that are similar in morphology, ecology, and behavior-has evolved on each island. Despite considerable work on anoles over the past three decades, much remains to be learned about evolution of the ecomorphs. In particular, previous studies have focused on external measurements of gross limb proportions, tail length, mass, and number of lamellae. Using a variety of techniques, we examined these char- acters in greater detail and investigated a wide variety of other characters. We found that the ecomorph classes represent distinct entities in morphological space when morphological characters are examined in greater detail (e.g., each limb element was treated separately). In addition, we found that the ecomorphs differ in a variety of characters not previously examined, including toe pad area, pectoral and pelvic girdle dimensions, head dimensions, and tail shape. These differences were apparent regardless of how we defined body size, although comparisons of particular characters were affected by which body size variable was used. This finding indicates that convergence in ecomorph evolutibn extends beyond traits directly linked to habitat use and locomotion. We also examined a number of other taxa that have not traditionally been considered to be members of any ecomorph class. We found that many descendants of ecomorphs living on small islands near the Greater Antilles no longer belong to the ecomorph class of their ancestor. Many Lesser Antillean anoles appear to ibe trunk-crown anoles, whereas others do not belong to any ecomorph class. Montane anoles of the Greater Antilles and Chamaelinorops also do not belong to any ecomorph class, but Chamaeleolis, and possibly Phenacosaurus, are twig anoles.