Using ecological niche modeling to examine the influence of host specificity on species distribution in the leaf beetle Microrhopala floridana and its host plant

The Florida leaf beetle, Microrhopala floridana, is known to be host-specific on narrowleaf silkgrass Pityopsis graminifolia and the distribution of both beetle and plant includes the state of Florida. To test the hypothesis that the distribution of M. floridana is limited to the distribution of its host plant, the niche modeling algorithm ‘Maximum entropy’ (MaxEnt) was used to generate hypothesized species distributions for both organisms based on known georeferenced collection sites and correlate these with the presence of various environmental information layers. Statistical measures of model accuracy were better than random and the predicted range of the beetle was smaller than that of the plant. The environmental variables that showed the highest degree of correlation with the known presence of these organisms were vegetation type, soil texture, and surficial geology. Missing environmental data, small sample size, collecting bias, and undetected subpopulations are discussed as possible obstacles to accurately predicting species distributions.