Meeting Abstract

74.5  Friday, Jan. 7  The Calanoids of Sulawesi: Exploring Speciation Patterns in Ancient Lakes VAILLANT, JJ*; CRISTESCU, ME; HAFFNER, GD; University of Windsor; University of Windsor; University of Windsor vaillanj@uwindsor.ca

Ancient lakes (>1 million years old) have recently become recognized as excellent systems for the study of speciation because of their long-term existence and isolation from other systems. The ancient lakes of Sulawesi, Indonesia are an ideal study system because of their varying degrees of geographic isolation and unique geological history. The purpose of this study is to characterize the evolutionary history of the island’s endemic calanoid species and identify the patterns and processes that underlie their cryptic adaptive radiation and speciation using a combination of phylogenetic and morphological data. Copepod samples were gathered from 7 of the island’s lakes, for a total of 23 sites. Neighbour-joining and Bayesian phylogenetic reconstructions were conducted using DNA sequence data from the mitochondrial CO1 and nuclear 18s, ITS1, and 28s markers. The results show deep divergences in the mitochondrial and nuclear DNA between populations in lakes Tondano, Poso, and the Malili lakes, a set of 3 hydrologically connected lakes, indicating a long history of isolation corresponding to about 6.5 Mys. Surprisingly, Lake Towuti, the lowest in the Malili lake system, contains a distinct divergent mitochondrial lineage despite homogeneity across nuclear markers for all the Malili lakes, suggesting that unidirectional hybridization may be occurring between the lakes of the Malili system. The presence of divergent lineages between connected lakes is extremely rare and calls for further study into the possible explanations for these patterns. Future studies in this system combining population genetics, genomics, geochemical, and geological approaches will provide valuable information about the evolutionary forces that drive speciation in pelagic invertebrates.