Bat metacommunity structure on Caribbean islands and the role of endemics


Steven J. Presley, Center for Environmental Sciences and Engineering, University of Connecticut, 3107 Horsebarn Hill Road, Storrs, CT 06269-4210, USA.


Aim  We evaluate characteristics of species ranges (i.e. coherence, species turnover and range boundary clumping) to determine the structure of bat metacommunities and metaensembles from Caribbean islands. We evaluate the effects of endemic species on that structure, and quantify associations between island characteristics and latent environmental gradients that structure these metacommunities and metaensembles.

Location  Sixty-five Caribbean islands throughout the Bahamas, Greater Antilles and Lesser Antilles.

Methods  Metacommunity structure is an emergent property of a set of ecological communities at different sites defined by species distributions across geographic or environmental gradients. We analysed elements of metacommunity structure (coherence, range turnover and range boundary clumping) to determine the best-fit pattern for metacommunities from all Caribbean islands, as well as from the Bahamas, the Greater Antilles and the Lesser Antilles separately. For each island group, analyses were conducted for all bats and for each of two broadly defined guilds (i.e. carnivores and herbivores). In addition, analyses were conducted for all species and for a subset in which endemic species were removed from the fauna. Spearman rank correlations identified island characteristics (area, elevation, latitude, longitude) that were associated significantly with island scores for ordination axes based on reciprocal averaging.

Results  Metacommunity structure for all bats and for carnivores was similar for each island group, with Clementsian distributions (i.e. discrete communities with groups of species replacing other groups of species along the gradient) for all islands, the Bahamas and the Lesser Antilles, but with nested distributions for the Greater Antilles. Herbivore distributions were random for the Bahamas, but were Clementsian for all other island groups. Removal of endemic species affected the best-fit model of metacommunity structure in only 3 of 12 cases. In general, ordination scores for islands were correlated with longitude or latitude, but not with island area or elevation.

Main conclusions  Characteristics of bat species ranges and associated metacommunity structure were primarily dependent on the number and geographic arrangement of primary sources of colonization, and not on interspecific interactions, species-specific levels of environmental tolerance, or the physical characteristics of islands. Endemic species did not greatly affect metacommunity structure in Caribbean bats.