Evidence of small-scale vicariance in Caridina lanceolata (Decapoda:Atyidae) from the Malili Lakes, Sulawesi

摘要

Question: Are dispersal ability and vicariance influential factors regulating population divergence and the formation of new species? Hypothesis: Barriers can lead to dramatic population divergence even over small geographic distances, especially when such barriers prevent dispersal and ultimately gene flow among closely related populations. Organism: Caridina lanceolata Woltereck, 1937. Field site: Lake Matano (Sulawesi, Indonesia) is the hydrological head of the Malili Lakes and is separated from downstream lakes by the Petea River, which negotiates a 72-m change in elevation, part of which consists of highly flowing rapids. Methods: We use morphological traits and genetic data to assess relationships among populations that occur above and below this barrier. Conclusions: The lack of morphological and phylogenetic differentiation among populations within lakes indicates no barriers to gene flow within lake systems. Elevated phylogentic differences between lakes, however, coupled with subtle morphological discontinuities indicates strong differentiation across the Petea River. Thus, dispersal and gene flow of C. lanceolata is restricted by the Petea River, leading to significant population structure among sampled populations. The magnitude of the cross-river genetic differentiation coupled with overall general morphological similarities among populations is consistent with cryptic sibling species.