Distribution patterns of limno-terrestrial and freshwater tardigrades in the Neotropics: a multistrategic approach using Parsimony Analysis of Endemicity (PAE) and Endemicity Analysis (EA)

Biogeographical studies traditionally use macroscopic animals as models for delimiting areas of endemism while neglecting microinvertebrates. This reflects the false assumption that all microorganisms are everywhere, making it impossible to study their distribution patterns. Here, we identified the distribution patterns and endemic areas of non-marine Tardigrada found in the Neotropics using a Parsimony Analysis of Endemism (PAE) and Endemicity Analysis (EA). In addition, we also tested the impact of using different grid cell sizes, the biogeographical provinces included in the Neotropics, and quantified the spatial association among these regions. Considering both tests and all the grid sizes, 30 endemic areas were identified using PAE, and 22 areas of consensus were identified using NDM/VNDM. The results of both methods were considerably congruent, delimiting possible regions of endemism, such as southeastern, southwest-south, and northern South America, as well as southern Central America. More areas of endemism are likely to be identified in the future due to the incomplete and biased sampling previously done in the region. It is also expected that the areas of endemism delimited here will remain resilient with increased sampling efforts in the Neotropics, increasing the robustness of the distribution patterns found here.