Diversity and eco-geographical distribution of insects

This chapter presents an integrative analysis on diversity levels, distributional patterns, and the implications of habitat preferences and geographic distributions of insect groups in the Yucatán Peninsula. Over 3000 insect species have been documented in the Yucatán Peninsula. Yet the number of species recorded may represent no more than 20-30 % of the total number of species. Taxonomic orders that recorded the highest number of species were: diurnal Lepidoptera (N¼510 species), Hymenoptera (602), and Coleoptera (478). Differences in insect species numbers for the three peninsular states were largely due to differences in sampling efforts. Maximum entropy models that were applied to a range of insect species showed that most suitable areas were fairly well distributed towards central and southern areas of the Yucatán Peninsula, with some spatial distributions matching "El Petén" or arid/dry Yucatán, while some others showed rather 'idiosyncratic' distributions. The habitat and geographic categories analysis of 221 butterfly species revealed a declining proportion of species that were restricted to primary habitats with increasing geographic range (χ2¼11.23, df¼2, p¼0.004), and an increasing proportion of widespread butterfly species that make use of modified habitats (χ2¼40.7, df¼2, p<0.001). The present status of butterfly diversity (and perhaps many other insects) in the Yucatán Peninsula revealed important changes in species composition (i.e. the prevalence of a large fraction of weedy species). It is possible that dramatic habitat changes over much of the peninsula throughout the course of its history, together with the current accelerated impact of habitat modification might have precipitated changes in species composition and diversity.