Abstract

Tropical mountains are formed by mosaics of environmental gradients, leading to biotic radiation and adaptive divergence. Species can respond to changes in elevational gradients in different ways, leading to different patterns of richness variation and metacommunity structure. The insect family Membracidae - treehoppers -, are widely distributed along mountains. Previous works in treehoppers suggested that richness decreases with elevation, and also suggested that variation in life histories is an important factor shaping these patterns. Despite these earlier contributions, some aspects of treehopper ecology such as metacommunity structure and richness trends at different taxonomic levels along elevational gradients, remain unexplored to date. Therefore, we searched for treehoppers along two elevational gradients in Colombia, to assess the variation in species richness, beta-diversity, and to describe the structure of treehopper metacommunities along these elevational gradients. We found that richness of all treehopper taxa decreased linearly with an increase in elevation, but with different trends among treehopper tribes. The proportion of species endemic to Colombia increased with elevation. Both gradients studied exhibited a Clementsian metacommunity structure, defined by clumped species boundaries and compositional unity along different portions of the elevational gradients, resulting in three discrete groups of communities or compartments. Each gradient and compartment exhibited different variation in beta-diversity richness and replacement components. These results provide insights into the mechanisms underlying treehopper elevational diversity pattern