Sulawesi's divergent tarsiers: The who, Why and How of gene flow in a secondary contact zone

• Applicant: Dr. Stefan Merker
• Subject Area: Evolution, Anthropology
• Term: from 2011 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 191700999

Sulawesi’s microplate tectonic history gave rise to a remarkable diversification of many of the island’s endemic animals. But what happens when closely related allopatric taxa come into secondary contact? Recent research on the enigmatic primate genus Tarsius provided evidence of strongly skewed introgressive hybridisation between parapatric species. Strictly unidirectional mtDNA introgression contrasts with a lack of Y-DNA exchange between Dian’s and Lariang tarsiers. This study is set to reveal the rationale for this asymmetric gene flow, especially to identify premating or postzygotic isolating mechanisms. Do tarsiers actively disperse into heterospecific ranges or is the observed pattern rooted in hybridisation at the boundary and subsequent gene introgression? In a hybrid zone with no extrinsic barrier to dispersal, 60 tarsiers will be captured and 32 of these – mostly predispersing subadults – will be radio-tracked over the course of six months to trace cross-boundary migration. Playback trials will be conducted to test the significance of duet songs for mate recognition thereby seeking traces of potentially reinforced receiver selectivity in the hybrid zone. Genotyping tarsiers at various autosomal, Y-chromosomal and mitochondrial loci will shed further light on the genetics of reproductive isolation.

• DFG Programme: Research Grants