Revealing the influence of climatic variables on the distribution of legume dispersal traits in the Chaco

Abstract

Climate influences species distribution and selects different morphological traits. The Chaco biome has climatic gradients, leading us to question morphological trait distribution. Using Fabaceae as a study model, we aimed to understand how the dispersal traits of this family, such as fruit types, dispersal syndromes and dispersal units, are distributed along the climatic gradients in the Chaco. We performed a spatial analysis in order to generate spatial predictors and thus identify on which spatial scales climate and soil variables are relevant to the distribution of the traits. Also, we used Threshold indicator rate analysis to identify the variation of the traits along the gradients. Temperature seasonality, precipitation seasonality, and annual mean precipitation are significant predictors of the distribution of the analyzed traits. Anemochory and barochory show the occurrence of reductions in intermediate gradient values for temperature seasonality. Regarding precipitation seasonality, craspedium showed greater reductions. At intermediate values of the rainfall gradient, we observed an increase in the occurrence of drupes and follicles. Craspedium increases in drier regions. Understanding the dispersion patterns of Fabaceae, a group of significant ecological and ethnological relevance in the Chaco, should contribute to the consolidation of conservation plans in different dry forest areas in South America.