Phylogenetic and Habitat Influences on Mating System Structure in the Humbug Damselfishes (Dascyllus, Pomacentridae)

The darnselfish genus Dascyllus contains nine species and exhibits protogynous sex change and/or functional gonochorism with variation both interspecifically and possibly intraspecifically between habitats. The genus can be divided into three species complexes and along lines of both descent and body size: 1) five species in two species complexes (complexes 1 and 2) are relatively small-bodied, closely associate with branching coral throughout life, and commonly exhibit resource defense polygyny and associated protogynous sex change, 2) three species in a third species complex (complex 3) reach larger body size, closely associate with branching coral only as juveniles, and do not exhibit resource defense polygyny, and 3) D. flavicaudus, a large-bodied member of the otherwise small-bodied species complex 2. Dascyllus flavicaudus and D. albisella (complex 3) are both large bodied, but differ in their responses to habitat type. Dascyllus flavicaudus shows differences in sex ratio, space use and mating system between a discontinuous coral cover habitat (female-biased sex ratio, resource defense polygyny) and continuous coral cover habitat (non-biased sex ratio, no resource defense polygyny) while D. albisella does not (non-biased sex ratio, no apparent resource defense polygyny in either habitat type), suggesting that both ecological factors and phylogenetic history influence these characters.