Comparative Phylogeography of Two Scrobridae in Indonesia Archipelago: Understanding the Dispersal Dynamics of a Pelagic Species

Abstract

Purpose: The purpose of this study was to examine and compare the genetic connectivity between two pelagic (open-ocean) species of tuna, Rastrelliger kanagurta and Katsuwonus pelamis, in the Indonesia Archipelago (IA). Hypothesis: Assuming a positive correlation between dispersal and genetic connectivity, we predicted that K. pelamis and R. kanagurta will have similar levels of genetic structure. Background: The quintessence of pelagic taxa is the ability to disperse; therefore divergence should rarely arise in a pelagic species. However, recent studies have indicated that species diversity is considerably more common in pelagic species than previously inferred. To help sustain marine populations, conservation efforts have been focused on understanding connectivity and establishing interconnected reserve networks. Marine reserves are one proven strategy to improve the biomass and abundance of reef organisms (Russ and Alcala, 1996). Because dispersal is the primary means of demographic and genetic exchange among marine populations (i.e. connectivity), understanding patterns of dispersal and connectivity has been identified as one of the key components in developing sustainable marine reserves (Sale et. al., 2005). Direct observation of marine dispersal is difficult. However, population genetics have become particularly helpful in understanding connectivity and dispersal among marine organisms (Grosberg and Cunningham, 2003). By understanding how species disperse and where genetic barriers have developed and reduced connectivity, reserves can be adjusted and scaled for optimal revenue, while still ensuring stability in a population (Palumbi, 2001).