Using Whiptail Lizards to Understand the Integration of Environmental and Host Genetic Effects on Host-Associated Microbiota

Animals, including humans, harbor large numbers of different microbes on and in their bodies – so called host-associated microbiota. Recently, scientists have begun to realize that host-associated microbiota are important determinants of host health. Microbes in an animal’s gut, for instance, help digestion and can even help determine whether the animal is lean or obese.

Meanwhile, microbes on an animal’s skin can influence everything from wound healing to susceptibility to cutaneous disease. Despite the importance of host-associated microbiota to host health, there is a surprising amount of variation in the microbiota on one host relative to another. How do these differences emerge?

More specifically, are these differences a result of nature (i.e., host genetics) or nurture (i.e., host environment)? Because most animals are genetically unique, it can be hard to determine whether inter-individual differences in host-associated microbiota are a result of host genetics, environment or both. In whiptail lizards, there are entire populations of genetically identical clones.

What’s more, these clones are closely related to other, sexually reproducing whiptail lizard species where each individual lizard is genetically unique. By comparing inter-individual variation in host-associated microbiota across different environments in clonal lizard populations versus sexually reproducing lizard populations, it will be possible to assess the relative importance of both host genetics and environment on host-associated microbiota.

This research also provides an opportunity to train undergraduate students in research and scientific communication to help train the next generation workforce in STEM.

The strategy for this project is to use 16S rRNA gene sequencing to characterize and compare intraspecific variation in the bacterial and archaeal gut and skin microbiota of four hybrid parthenogenetic Aspidoscelis species and their bisexual parents. Microbiota of each lizard complex (parthenogen + bisexual parent(s)), will be examined within a single vegetation community (low environmental variation), across different vegetation communities (intermediate environmental variation) and, for a subset of systems, across broad geographic ranges (high environmental variation).

The first hypothesis is that variation will be smaller in parthenogens as compared to their bisexual parents. The second hypothesis is that inter-individual variation in lizard microbiota is driven by the environment, and that microbiome variation will be smaller at lower levels of environmental heterogeneity. Determining the underlying causes of inter-individual variation in host-associated microbiota will identify rules governing host-associated microbial community assembly and, by extension, host health, fitness and ecological success.

Results from this work will have implications for both understanding microbial community assembly and guiding host conservation. As an example, knowledge of the factors that promote healthy host microbiomes will help to clarify trade-offs between preserving landscape diversity versus host genetic diversity during reserve selection. Undergraduate students who are supported by this proposal will have the chance to perform research and to also develop podcasts about biology research to broaden participation and to train students for careers in the sciences.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.