Connectivity and the development of population genetic structure in Indo-West Pacific coral reef communities

Abstract

Aim: To identify connectivity patterns among coral reefs of the Indo-West Pacific. Projecting connectivity forward in time provides a framework for studying long-term source–sink dynamics in the region, and makes it possible to evaluate the manner in which migration shapes population genetic structure at regional scales. This information is essential for addressing critical gaps in knowledge for conservation planning efforts in one of the most biologically diverse regions on earth. Location: Coral reefs of the Indo-West Pacific, ranging from 15° S to 30° N and 95° E to 140° E. Methods: Individual-based biophysical dispersal models were used in conjunction with matrix projection to identify the expected patterns of exchange between coral reefs over time. Results: Present-day oceanographic conditions lead to the transport of larvae from the South China Sea into the Coral Triangle region via the Sulu Sea, and from northern Papua New Guinea and the Solomon Islands via Halmahera. The directionality of the system leads to the expected accumulation of organisms from outlying areas into the Coral Triangle region over time, particularly in the vicinity of the Maluku Islands and eastern Sulawesi. Coral reefs in Papua New Guinea, the Sulu Archipelago and areas within the Philippines are expected to be areas of high diversity as well. Main conclusions: Biophysical dispersal models, used in conjunction with matrix projection, provide an effective means of simulating connectivity structure across the Indo-West Pacific and thereby evaluating the directionality of genetic diversity. Migration appears to have a significant influence on population genetic structure in the region. Based on present-day ocean currents, coral reefs in the South China Sea, northern Papua New Guinea and the Solomon Islands are contributing to high levels of diversity in the Coral Triangle.