Impacts of forest fragmentation on the genetic diversity and population structure of Pachycondyla obscurans in Sabah

The impact of forest fragmentation on genetic diversity of Pachycondyla obscurans, a predatory forest-specialist ant species, was investigated in six forest locations using Amplified Fragment Length Polymorphism (AFLP) fingerprinting. There was little difference in genetic diversity between three large forest locations (two locations in continuous forest, plus one 120,000 ha fragment) and three small forest fragments (151-320 ha). Populations from two locations approximately 60 km apart in continuous forest showed little genetic differentiation, but genetic differences between all other locations (35-164 km apart), which are separated by oil palm plantations, were much greater. There was no significant relationship between geographical distance and genetic distance (pairwise F ST values) between locations. Overall, we conclude that the genetic diversity of P. obscurans has not been affected by habitat fragmentation over the past fifty years, but locations separated by forest were more genetically similar than those separated by agricultural areas. This implies that an inhospitable intervening matrix may prevent ant dispersal, and may result in genetic erosion of insect populations in the longer term.