Understanding the diversity and community structure of bdelloid rotifer soil communities

Rotifers, though very important to the microbial food-web and energy flux of a system, are still poorly understood in terms of their taxonomy and geographical distributions. Rotifers pose problems for taxonomists and evolutionary biologists due to the difficulties associated with isolation, identification and enumeration of organisms that have few distinguishing morphological characters. This lack of morphological information and their extreme abundance of micro-invertebrates make identification of rare, or even common cryptic, taxa a large and unwieldy task as only painstaking microscopy can be used to identify synapomorphies. To overcome these problems I made use of environmental DNA sequencing to perform large- scale surveys of bdelloid rotifer communities. The goal of this study was to describe the diversity and distribution of bdelloid rotifer communities as they relate to space, soil environment, and co-occurring bacterial communities. I found that bdelloid rotifers are significantly limited in their dispersal capabilities on the order of 100 meters, despite historically being viewed as having easy-to-disperse propagules. Although dispersal limitation is a significant contributor to the diversity structure of bdelloid communities, its influence constitutes much less of an effect than local biogeochemistry. In contrast, co-occurring bacterial communities are less affected by both dispersal limitation and local habitat. However, both bdelloid rotifer and bacterial communities share patterns of diversity between three ecologically distinct sites within the Niwot Ridge LTER. Comparisons of the diversity and distribution of microscopic animal communities to bacterial communities have been anecdotal, and have not made direct comparisons among samples, as done here. Analyses comparing soil invertebrate communities to co- occurring microbial communities remain in their infancy, indicating that more inclusive concepts and theories are needed to explain observed patterns of distribution and diversity