The island biogeography and metapopulation dynamics of ants (Hymenoptera: Formicidae).

摘要

The ant faunas of three remote Polynesian islands were censused using hand collecting techniques. Known ant species richnesses were increased by factors of 2.3, 3.7, and 4.3. The large increase in species numbers is apparently due to inadequate earlier censuses rather than recent immigrations. Tests of species associations revealed more positive than negative interactions among species. A multiple regression analysis of known ant species richness against area and distance for Polynesian islands that have been surveyed relatively thoroughly for ants revealed area is always highly significant but distance is only marginally significant. Remote Polynesian islands appear neither to be as depauperate in ant species as previously thought, nor possess an unusual potential for evolutionary increase in species numbers.; Three species displayed a complementary distribution pattern, resulting from both habitat affinities and negative interspecific interactions. These species were numerically and behaviorally dominant to other species in the communities where they occurred. Each dominant species was commonly positively associated with a group of subordinate species (and negatively associated with others), forming a large-scale mosaic-like distribution pattern of dominant and subordinate species. Baiting experiments demonstrated that the presence of dominant species decreases: (1) the proportion of baits occupied by subordinate species, and (2) overall ant species diversity, at rich food resources. The patterns of community organization observed in this relatively newly assembled fauna are very similar to those reported from studies of older, coevolved ant communities in mainland areas.; The ant species inhabiting 129 small Bahamian islands were censused annually over a five-year period. Mean annual relative turnover was low and variable, ranging from 0.83 to 22.37% yr{dollar}{bsol}sp{lcub}-1{rcub}{dollar} on a per species basis, and from 2.13 to 5.70% yr{dollar}{bsol}sp{lcub}-1{rcub}{dollar} on a per island basis. A comparison of immigration and extinction rates indicated the existence of a dynamic equilibrium between these two processes. Observed turnover is lower than that reported from other, more limited studies of insular ants and from studies of insular arthropods in general, and is more similar to documented vertebrate turnover. Stepwise multiple regression analyses revealed plant species number or vegetation height to be the best single predictor of ant species number.