Anthropogenic perturbation modifies interactions between mammals and fruits in a tropical forest of southern Mexico

Studies of tropical mammal defaunation highlight the loss of species as well as their reduction in abundance and diversity; however, there is a complex series of effects associated with this anthropogenic disruption, including increases in the relative abundance of disturbance-tolerant mammals and the arrival of alien mammals whose effects on biotic interactions have been poorly studied. We compared the species richness, composition, interaction strength, and patterns of daily activity of mammals that consume the fruits of Pouteria sapota on the forest floor, both inside and outside of the Los Tuxtlas Field Station (LTFS) in Veracruz, southern Mexico. Using camera traps, we recorded eight mammal species interacting with the fruits inside the LTFS (n= 4 trees) and nine species interacting outside (n = 7 trees). Alien species such as Canis lupus familiaris were recorded both inside and outside of the LTFS, whereas Bos taurus was only recorded outside. Medium-sized generalist mammals were overrepresented both inside and outside of the LTFS, evidencing an impoverishment of the fauna, when compared to the mammal assemblage reported to interact with P. sapota fruits in a more intact forest. The daily activity patterns of the mammals that interacted strongly with P. sapota fruits were different inside and outside the LTFS, particularly in the case of Cuniculus paca. Our results show that the impact of human activity is highly pervasive, directly affecting the mammalian fauna at different levels and indirectly affecting the biotic interactions in which these animals are involved.