Population structure in Banggai cardinalfish, Pterapogon kauderni, a coral reef species lacking a pelagic larval phase

Previous studies on two reef fish lacking a pelagic larval phase (Acanthochromis polyacanthus and Embiotoca jacksoni) revealed features that may be characteristic of their lifestyle: (1) low levels of gene flow, (2) frequent population bottlenecks, and (3) strong phylogeographic breaks, all within their over 1,000 km coastal geographic ranges. The present study tested the predictive nature of these three characteristics in another species lacking a pelagic larval stage.. but with a very restricted distribution (< 10,000 km(2)). The Banggai cardinalfish, Pterapogon kauderni Koumans, 1933, is a mouthbrooding species occurring in the Banggai Archipelago (eastern Indonesia). Fish were captured in January and February (2001, 2002). The mitochondrial control region of 122 individuals from 22 locations was sequenced P. kauderni individuals clustered in two reciprocally monophyletic clades corresponding to a southwestern population (restricted to the southwest of Bangkulu Island) and all northern and eastern populations, which included all the remaining samples. Data were compatible with reduced gene flow and the presence of severe bottlenecks; however, small sample sizes and limited genetic variability in P. kauderni prevented a definitive conclusion. Further studies using larger samples and more rapidly evolving molecular markers may provide enough power to conclusively test our hypotheses.