Efeitos do micro-habitat sobre a temperatura critica maxima de formigas no gradiente borda-nucleo de um fragmento de floresta tropical pluvial

Abstract

Forest fragmentation modifies the physiological limits of species by altering microclimatic gradients at multiple spatial and temporal scales. This study investigated the variation in thermal tolerance of tropical ants according to their foraging stratum (ground or vegetation) and landscape position (edge or core), considering the independent effects of vertical structure and spatial configuration of the forest. Collections were carried out in Mata do Pau Ferro, a remnant of seasonal forest located in the municipality of Areia, Paraíba, Brazil, where workers were sampled using honey-baited traps at points distributed between the edge and the interior. Thermal tolerance was determined experimentally, and the data analyzed by two-way ANOVA. It was found that arboreal ants exhibit a higher critical maximum temperature (CTmax) than those from the ground, and that species from the core are more heat tolerant than those from the edge, with no interaction between the factors. These results reveal the parallel, yet complementary, roles of vertical and horizontal thermal gradients in the selection of physiological traits. The difference between the hotter edge and the presence of species with lower thermal tolerance in that environment suggests that thermal variability, rather than absolute temperature, acts as an ecological filter, possibly influenced by the higher proportion of arboreal species in the core.