Diversity, resource partitioning, and species turnover in Neotropical saproxylic beetles (Coleoptera: Cerambycidae, Curculionidae) associated with trees in the Brazil nut family (Lecythidaceae)

Deforestation and global changes in temperature and moisture associated with rising levels of greenhouse gases are expected to have strong, direct effects on abundance of wood-boring beetles through loss of larval feeding substrates, and indirect effects through climate and microclimate change. This dissertation examines Neotropical saproxylic beetle (Coleoptera: Curculionidae) diversity, niche breadth, and resource partitioning, and predicts possible impacts of climate change. Data from beetle rearing experiments conducted in French Guiana and Peru were analyzed to assess species richness, abundance, host specificity, seasonality and stratification of wood-boring beetles associated with the Brazil nut family (Lecythidaceae). Niche stability was assessed over time (French Guiana 1995-96, 2007-08) and space (Peru 2003-05). In French Guiana, resource partitioning was analyzed among the most abundant subfamilies of Curculionidae (Conoderinae, Scolytinae, Platypodinae) and Cerambycidae (Cerambycinae, Lamiinae). Species richness was higher in Peru than French Guiana, with high beta-diversity between sites; largely due to the prevalence of rare species in Peru. In both localities, most beetle species were disproportionately associated with the host Eschweilera coriacea (DC) S.A. Mori. In French Guiana, comparatively large cerambycids were more abundant during the dry season and seemed relatively drought tolerant. Small-bodied curculionids were most abundant during the rainy season, with weevils and platypodines best represented at ground stratum. In Peru, weevils were more abundant during the dry season. Cerambycinae, which are preferentially associated with the dry season canopy stratum, are expected to thrive should regional climates become warmer and drier. Lamiinae may respond by seasonally alternating stratum. Many Neotropical weevils and bark/ambrosia beetles seem strongly moisture-dependent, and populations are expected to be negatively impacted by increased drought. The Brazil nut family is threatened by both habitat fragmentation and climate change. The favored host species, E. coriacea, has a wide geographic distribution that extends into western Amazonia, which is not expected to experience severe precipitation changes, and could provide refuge for saproxylic beetles currently associated with Lecythidaceae. Saproxylic beetles, especially curculionids, may be less impacted by direct effects of host loss than indirect effects of climate change, especially northeast Amazonia which is expected to experience declining precipitation and longer dry seasons.