Meeting Abstract

P3.120  Thursday, Jan. 6  A multilocus phylogeographic study of a rodent (Eliurus myoxinus) distributed throughout western Madagascar HEILMAN, AM*; CHAN, LM; RAKOTOMALALA, Z; GOODMAN, SM; YODER, AD; Duke University; Duke University; Vahatra; Field Museum; Duke University amy.heilman@duke.edu

Madagascar boasts an unprecedented abundance of diverse species and small-scale endemism suggesting the presence of unique mechanisms contributing to the evolutionary processes. To determine what these factors are, it is essential to study species from a diversity of clades. One such species is Eliurus myoxinus, which belongs to the rodent clade, Nesomyinae. Its wide-ranging habitat and the increasing amount of forest fragmentation presents the possibility that the species may be separated into divergent populations. To explore this proposed scenario, members of this study sequenced three loci (cytochrome b, and introns of the growth hormone receptor and beta fibrinogen). These loci were used to construct gene trees in the program MrBayes and run through the program Isolation with Migration (IM). The mtDNA gene tree yielded two distinct clades coincident with capture localities in the north and south respectively. Additionally, it revealed a more recent monophyletic north clade and more ancestral paraphyletic south clade. The two nuclear intronic sequences each produced gene trees lacking any signal of reciprocal monophyly. Multiple and varied iterations of the IM analysis provided evidence for a bottleneck by giving a large ancestral population and smaller current populations. The migration rates supported an asymmetrical movement northwards. From a number of possible scenarios, the results pose that the species began in the southern region of Madagascar and at some point in the past, a substantial proportion moved northwardly. Currently, there is minor directional gene flow between the geographically separated subpopulations, which is maintaining one cohesive species.