Differences in patterns of dispersal and population structure in congeneric species in the Mekong River basin

The Mekong is the most extensive river in Southeast Asia. It is a relatively young drainage formed by amalgamation of many drainage rearrangement events as recently as the Pleistocene (1.8mya). This talk will compare the patterns of mitochondrial DNA diversity observed in four freshwater fish species across 2000km of contiguous freshwater habitat in the Mekong Basin.

 Two species, the small Siamese mud carp, Henicorhynchus siamensis, and congeneric H. lobatus, are extremely similar in morphology. Their life history includes pelagic larval stages and annual tropic migrations that are linked integrally with movement to and from seasonal habitat. In contrast, two snakehead fish species, the chevron snakehead, Channa striata, and Giant snakehead, C. micropeltes, are largely sedentary nest builders that exercise high levels of parental care. Unlike the Siamese mud carp, snakehead fishes aestivate in response to annual fluctuations in available habitat.

 The species display strikingly different spatial patterns of genetic diversity, even among species within genera, which result from both differences in dispersal ability and historical processes that have influenced drainage re-arrangement in mainland Southeast Asia.