MOLECULAR EVOLUTION AND POPULATION-GENETICS OF GREATER CARIBBEAN GREEN TURTLES (CHELONIA-MYDAS) AS INFERRED FROM MITOCHONDRIAL-DNA CONTROL REGION SEQUENCES

The molecular evolution and population genetics of migratory green tur tles (Chelonia mydas) in the Greater Caribbean were examined with mito chondrial DNA (mtDNA) control region I sequences. A total of 488 base positions (bp) per individual were aligned for 44 individuals from fou r nesting populations in Florida, Costa Rica, Aves Island (Venezuela), and Surinam. Twelve sequence polymorphisms were detected, representin g ten transitions, one transversion, and one 10-bp repeat. Sequence an alyses of within- and between-population diversity revealed a deep div ergence between western and eastern Caribbean nesting colonies and an inverse relationship between reproductive female population size and m tDNA diversity. In small populations, genetic admixture was important to maintaining high diversity, whereas larger populations appear to ha ve experienced historical bottlenecks or resulted from founder effects . Mitochondrial DNA sequences of the control region offer an order of magnitude greater resolution than restriction site data for addressing questions about mtDNA variation, both within and between populations of green turtles.