Research

Species richness and range distribution patterns along parallel disturbed and undisturbed elevational gradients

I found that dung beetle species richness decreases monotonically with elevation in southeast Peru. Closely related species exhibit distinct non-overlapping altitudinal segregation of their ranges along an undisturbed elevational gradient. However, along a nearby parallel gradient, this pattern is strongly disrupted in response to habitat degradation (e.g. pasture, coffee, citrus, corn, secondary forest). Species range amplitude may increase or decrease, and species average ranges may shift up or down in elevation. Overall abundance of all species decreases dramatically in disturbed areas, implying the disruption of ecological functioning for the dung beetle-mediated processes of nutrient cycling and seed dispersal. The high availability of domestic animal dung along the disturbed transect suggests that factors other than resource availability may be influencing dung beetle distribution and abundance. The pattern of shifting interspecific range boundaries in response to disturbance could serve as a useful monitoring tool for measuring the effects of global warming on animal distributions. Maintaining a forested connection along the steep climatic gradient from the lowlands into the mountains will be necessary for the movement of species with global warming.