Divergensi Morfologi Antar Populasi Simpatrik Ikan Baung (Hemibagrus velox Tan et Ng) di Danau Singkarak Sumatera Barat.
ABSTRACT Hemibagrus velox is one of new potential catfishes species found in Sumatra. In order to explore intraspecific variation and morphological differentiation among sympatric populations of this species in Singkarak Lake at West Sumatra, field study and morphological analysis were conducted using direct observation and morphometric methods on three populations in Singkarak Lake (Sumani, Muaro Pingai and Sumpur) and one population in Ombilin River (outflow of Singkarak Lake). Unweighted Pair Group Method Aritmatic Average (UPGMA) was used to identify the pattern of morphological divergence and two nonparametric statistical tests (Kruskall-Wallis test and Mann-Whitney U test) were generated to analyze the morphological variations and differentiations. It was found some morphological divergences among sympatric populations with clear separation between lake and river populations, Sumani and Batang Ombilin River were the most different sympatric populations morphologicaly. There were three characters with highly significant variation and differentiation among populations such as second mandibular barbel length (PSB2), distance between anterior part of pectoral fin base to anterior part of dorsal fin base (T15), and distance between anterior part of pelvic fin base to anterior part of dorsal fin base (T17). These morphological divergences could be induced by ecological differentiations among populations.