Evaluation of character displacement among plants in two tropical pollination guilds.

Abstract

In cloud forest at Monteverde, Costa Rica, 2 guilds of bird-pollinated plants exist, one pollinated by long-billed hummingbirds, primarily green hermit Phaethornis guy and one by short-billed hummingbirds, primarily purple-throated mountain-gem Lampornis calolaema. Plants were assigned to guilds based on hummingbird visit patterns. Neither guild exhibited pronounced character displacement. Absence of pattern is attributed to the following aspects of biological variability: 1) within any one year, density-dependent competition for pollination is sporadic, and is not clearly related to flowering season or morphological similarity; 2) the nature of interspecific interactions varies among years, as neither the relative intensities of flowering nor the flowering seasons themselves are consistent from year to year; 3) the nature of interspecific interactions varies with changes in species composition, which occur over short distances; 4) the assemblage of species is probably not stable over long time spans.-from Authors