Caribbean Birds

Contemporary Expansion Phase of Island Populations Classified by Continental versus Island Origin

Genetic distances representing the initiation of the contemporary phase of expansion within the Lesser Antilles. We have classified species into four groups (A-D) based on endemism and geographical distribution (relatively widespread or restricted) within the Lesser Antilles. Groups A (widespread) and B (restricted) have continental or Greater Antillean origins; Groups C (widespread) and D (restricted) have Lesser Antilles origins. The age distributions of groups show that taxa with extensive distributions (mostly taxon cycle stage 1 and 2 species) are young and that Lesser Antillean endemics with restricted distributions (Group D; stage 3 and 4 species) are significantly older. The fact that restricted group B species are also young supports the notion that their distributions have been limited by colonization rather than extinction. For group C species, the relative timing of the contemporary expansion phase and the initial colonization of the Lesser Antilles are indicated. Data are presented as means and standard deviations. Differences in relative ages of most recent expansions are statistically significant (F = 12.9, df = 3, 21, P = 0.0001, R2 = 0.65).