Incorporating symmetrical and asymmetrical dispersal into Ecological Niche Models in freshwater environments

Incorporando dispersão simétrica e assimétrica em Modelos de Nicho Ecológico em ambientes de água doce

Abstract:

Aim  Ecological niche models (ENMs) are based mainly on environmental (mostly climatic) and occurrence data to predict the potential distribution of species. In freshwater habitats, species dispersal is not restricted only by physical barriers but also by the directional movement of the hydrographic network, which can be considered through spatial predictors. Here, we aim to evaluate the effect of including asymmetrical and symmetrical spatial predictors in the potential geographic distribution of a freshwater fish in the Tocantins-Araguaia River basin, Brazil.

Methods  For this, we built models with seven variable sets representing the climatic and spatial models, as well as their interactions.

Results  We found that the overall best models (higher evaluation and lower variation among modeling methods) are those built using AEM (asymmetrical dispersal [i.e., dispersal along the river flow path]), either alone or in combination with environmental variables (ENV). Moreover, the inclusion of asymmetrical dispersal variables, taking into account dispersal limitations of species, decreased the overprediction to climatically suitable but disconnected areas through rivers.

Conclusions  Therefore, future ENM studies, especially those using species groups with directional dispersal, should consider the inclusion of asymmetrical spatial predictors to increase the model’s accuracy and ecological reality.

Keywords:  Asymmetric Eigenvector Maps; Ecological Niche Models; directional dispersal; Principal Coordinates of Neighbour Matrices; spatial modeling