Climatic Niche Evolution in the Arremon brunneinucha Complex (Aves: Passerellidae) in a Mesoamerican Landscape

The identification of mechanisms that have generated biodiversity is one of the major tasks in biogeography and evolutionary biology. Here, using a set of environmental variables and historical presence records, we assessed whether closely related allopatric lineages in the Arremon brunneinucha (Aves: Passerellidae) complex are either more ecologically similar or different throughout their distribution in Mesoamerica. Using PCA-env approximation, niche similarity tests, and comparative approaches, we analysed niche evolution in this species complex and the relative role of geographic and environmental factors on shaping lineage divergence. Our results suggest that most (95.24%) of the evolutionary lineages included in the A. brunneinucha complex have a null to low climatic niche overlap ( Schoener ’s D = 0.0–0.2), in addition, our data rejected the hypothesis of niche similarity among these lineages in 17 paired comparison cases (80.94%). We found that allopatric and nearly parapatric lineages both show evidence that their ecological niches have been maintained by sharp climatic gradients. These patterns suggest that divergence in these evolutionary lineages has been promoted due to different environmental conditions and evolutionary pressures, which in concert with geographical barriers to gene flow, have led to diversification in the A. brunneinucha complex throughout Mesoamerica.