Is the Taxonomic Composition of Landbird Communities in Mexico Predictable

Some bird families are more widespread than others both in geography and in habitat use (high-incidence fami- lies). The number of Mexican species in a bird family was found to be strongly correlated with the number of communi- ties that possess representatives of that family. This effect did not result from a higher probability of larger families hav- ing more widespread species or having species with broader diets or habitat preferences, nor from body size, abundance or clutch size, other factors which tend to correlate with the incidence of species. Instead, number of species per se (a trait of families) strongly influenced family incidence and thereby community composition. Therefore, community composition is influenced not only by ecological assembly rules at the species level, but also by the result of macroevolutionary proc- esses above the species level. This pattern may be related to species-area curves and provides an opportunity for coevolu- tion to occur even in situations in which species-specific coadaptation is not possible. This pattern increases the predict- ability of species composition of communities.