Patterns of Rotifer Diversity in the Chihuahuan Desert

Patrick D Brown,Robert L Wallace,Roberto Rico-Martinez,Thomas Schröder,Marcelo Silva-Briano,Judith V Ríos-Arana,Elizabeth J Walsh

doi:10.3390/d12100393

Abstract

Desert aquatic systems are widely separated, lack hydrologic connections, and are subject to drought. However, they provide unique settings to investigate distributional patterns of micrometazoans, including rotifers. Thus, to understand rotifer biodiversity we sampled 236 sites across an array of habitats including rock pools, springs, tanks, flowing waters, playas, lakes, and reservoirs in the Chihuahuan Desert of the USA (n = 202) and Mexico (n = 34) over a period of >20 years. This allowed us to calculate diversity indices and examine geographic patterns in rotifer community composition. Of ~1850 recognized rotifer species, we recorded 246 taxa (~13%), with greatest diversity in springs (n = 175), lakes (n = 112), and rock pools (n = 72). Sampling effort was positively related to observed richness in springs, lakes, rivers, and tanks. Nestedness analyses indicated that rotifers in these sites, and most subsets thereof, were highly nested (support from 4 null models). Distance was positively correlated with species composition dissimilarity on small spatial scales. We predicted species richness for unsampled locations using empirical Bayesian kriging. These findings provide a better understanding of regional rotifer diversity in aridlands and provide information on potential biodiversity hotspots for aquatic scientists and resource managers.

Highlights

Delineating patterns of species distributions is important for understanding basic and applied questions in biogeography, ecology, and evolutionary biology [1,2]
We described the sites at Big Bend National Park (BIBE) (Brewster Co., Alpine, TX, USA) in our previous work [53,54,88]
The matrix is rearranged to achieve the densest grouping of species in the habitats [111]. We employed both the Temperature calculator (T◦ ) and nestedness metrics based on overlap and decreasing fill (NODF) [109], but because the packing is only marginally different, here we report T◦

Summary

Introduction

Delineating patterns of species distributions is important for understanding basic and applied questions in biogeography, ecology, and evolutionary biology [1,2]. Species distributions can be used in modeling current communities and in predicting outcomes to both short-term (e.g., acute pollution episodes) and long-term events (e.g., increases in temperature due to climate change). They inform biogeography and macroecology [3]. As members of the Syndermata, rotifers offer a good example of this challenge While they comprise an important component of freshwater ecosystems and contribute to both the microbial loop and typical aquatic food webs, it is unclear whether their distribution follows ubiquity theory [4,5], or whether they exhibit some level of endemicity [6,7,8,9]

Methods

Results

Discussion

Conclusion