Footprints on water: the genetic wake of dispersal among reefs

Analysis of genetic data can reveal past and ongoing demographic connections between reef populations. The history, extent, and geography of isolation and exchange help to determine which populations are evolutionarily distinct and how to manage threatened reefs. Here the genetic approaches undertaken to understand connectivity among reefs are reviewed, ranging from early allozyme studies on genetic subdivision, through the use of sequence data to infer population histories, to emerging analyses that pull the influences of the past connections away from the effects of ongoing dispersal. Critically, some of these new approaches can infer migration and isolation over recent generations, thus offering the opportunity to answer many questions about reef connectivity and to better collaborate with ecologists and oceanographers to address problems that remain.