Dinâmicas eco-evolutivas e evolução de atributos fenotípicos em populações de anuros ao longo de um gradiente de urbanização

Abstract

The urbanization process increases habitat fragmentation, produces heat islands effect, noise, light, and chemical pollution, and introduces new pathogens. These environmental alterations can change phenotypic traits, which in turn affect ecoevolutionary dynamics, with potential negative effects on organismal fitness. However, it remains unclear how urbanization impacts biodiversity in tropical countries. Furthermore, little is known about how animals with low dispersal abilities, such as amphibians, respond to urbanization in the tropics. Amphibians occupy both aquatic and terrestrial environments, are ectothermic, have cutaneous respiration, and their calling behavior is used in mate attraction. Therefore, they are highly prone to respond to changes inherent to cities. To study the impact of urbanization on the morphological, acoustic, physiological, and behavioral traits of anurans, this thesis was divided into three chapters. In the first chapter, we tested how the direct and indirect effects of urbanization rate, local environmental heterogeneity, land surface temperature, and spatial gradient affect the mean and variance of morphological traits related to resource acquisition and dispersal ability. We found that in more urbanized ponds, the mean body size increased, while body size and head shape variability decreased. Also, the leg length variability has decreased with increasing surface temperature. However, there was no clear spatial pattern of trait variation along urbanization gradient, suggesting a relaxed natural selection, which could be explained by a recent urbanization process. In the second chapter, we were interested in testing how acoustic traits vary along an urbanization gradient and whether these traits are under different natural selection regimes. The mean dominant frequency (DF) did not change between areas, but the variability was lower in urban ones. Additionally, rural and urban populations seem to be under a weak directional selection regime, in which individuals that vocalize at higher frequencies had lower fitness. Our results suggest a weak selection regime in urban areas despite the lower variability in DF. Furthermore, lower fitness in high frequency calling suggests that urbanization may directly impact sexual selection in these organisms. In the third chapter, we investigated how behavior and morphophysiological traits change in response to divergent pace of life environments. We found that animals from urban areas displayed less intense escape behavior, indicating possible habituation to human presence. Elevated values in hepatosomatic indices and glucose suggest chronic stress and exposure to xenobiotics. Darker coloration and thicker skin layers in urban areas provide a stronger response to dehydration and protection against pathogens. Additionally, older animals in urban areas had a decrease in white and red blood cells, which may be associated with oxidative stress and potential immunosenescence. Our results together contribute to enlighten the effects of urbanization on different phenotype axes in tropical cities, especially those that change eco-evolutionary dynamics.