Comparative Genetic Structure of the Threatened Tenebrionid Beetle Oplocephala haemorrhoidalis and its Common Relative Bolitophagus reticulatus

We used RAPD and allozyme genetic markers to compare the genetic structures of a threatened saproxylic tenebrionid beetle, Oplocephala haemorrhoidalis, and its common relative (different subfamilies), Bolitophagus reticulatus, to evaluate the relative importance of habitat fragmentation on the occurrence of the two species. O. haemorrhoidalis showed significantly higher levels of genetic differentiation between sites than B. reticulatus for both types of genetic marker. Patterns of isolation by distance were consistent with (B. reticulatus) or close to (O. haemorrhoidalis) theoretical expectations for equilibrium between gene flow and genetic drift. For O. haemorrhoidalis, the RAPD-patterns also showed a steeper increase in isolation by distance where geographic distances were small than at larger distances. This suggests that gene flow between the populations of O. haemorrhoidalis has declined as an effect of recent habitat fragmentation and is probably relatively restricted at present. For B. reticulatus, levels of genetic differentiation were low, suggesting that B. reticulatus readily moves over large areas. Genetic variability was not low in either species. Genetic differentiation among and relatedness within fruiting bodies varied substantially within sites for both species. This variation was probably due to founder events: when levels of relatedness were close to zero, genetic differentiation was also low.