Effects of climate and deforestation on velvet ants (Hymenoptera: Mutillidae) assemblages in southeastern Amazonia

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James Pitts


Tropical forests are among the most threatened ecosystems, due to the combined effects of habitat loss and climate change, which are presumably the primary drivers of the global biodiversity crisis. In Amazonia, deforestation may promote major environmental change over large scales, especially in southeastern Amazonia where the expansion of agricultural land is concentrated along the "arc of deforestation", a vast and understudied region, mostly at the Amazonian-Cerrado transition. This ecotone is most likely the first portion of Amazonia to show early signals of climate impacts. Herein I investigate the influence of climate change and habitat loss on the diversity and structure of velvet ant assemblages in forest fragments at the headwaters of the Xingu basin, eastern Mato Grosso, southeastern Amazonia. In each of two forest fragments, I placed 25 "Y" shaped arrays of pitfall traps along a 0.5 km transect, where I recorded ten environmental and two microclimate parameters. Within a month, I collected ~1,000 individuals, belonging to 30 velvet ants species. According to Principal Component Analysis, canopy openness and stem density were the environmental parameters that better described the habitat and were positively correlated with distance to forest edge. Mean temperature was inversely proportional to humidity and a Multiple Linear Regression Analysis suggested that leaf litter mass explained most of the variance in microclimate. The influence of the above-mentioned parameters on velvet ants assemblages will be investigated.

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