Traços morfológicos contrastantes em assembleias de formigas ao longo de um gradiente ambiental na Bacia Amazônica

Abstract

Environmental gradients may select species, resulting in assemblies with contrasting functional traits at the ends of the gradient. We used a vegetation type gradient as an indicator for environmental complexity of the litter and tested as a predictor of morphological traits of soil ants. The sampling design covered 8 collection sites located in a latitudinal gradient of 1,050 km in the Amazon Basin with different phytophysiognomies. We selected six morphological traits of ants related to foraging and predation. The generalized linear mixed model was used to predict how environmental complexity is affecting the functional traits of litter ants. Structurally less complex environments (eg Amazonian savannah) harbored smaller ants, with small jaws and petioles, and relatively large eyes and femur. In complex environments the ants exhibited larger size with relatively large mandibles and petioles and relatively minor eyes and femur. The greatest difference in traits was between the extremes of the environmental complexity gradient (forests and savannas). Among the forest types, the traits were, on average, more similar making the relationship between the savanna / forest relationship be better represented by a curve. The environmental conditions can act as "filters" in certain characteristics of the species that inhabit it. The functional approach focused on each individual trait can link traits to behavior revealing which ant foraging strategies are most well established in a particular habitat type.