Grantee: Dave Daversa

Institution: University of California, Los Angeles, United States

Grant amount: $30,000

Grant type: Small grants

Focal species: Western toad (Anaxyrus boreas)

Conservation status: Least concern

Disciplines: Physiology, herpetology, animal welfare science, population ecology, genetics/genomics

Research location: United States

Project summary

A major challenge in wild animal welfare science lies in developing composite assays that consider the full breadth of factors collectively shaping the subjective experiences of animals. This project will apply epigenetic tools to develop minimally invasive and aggregate measures of wild animal welfare. Specifically, the researchers aim to demonstrate proof of concept for a DNA methylation (DNAm)-based model of wild animal welfare. DNAm joins other measurements such as telomere attrition as a biomarker of biological aging, because DNA becomes methylated as a function of both chronological age (time) and accumulated stress. This project will characterize DNAm in western toads (Anaxyrus boreas) from wild populations in southern California, testing the influence of infection with the fungal pathogen Batrachochytrium dendrobatidis (Bd) on DNAm, and its covariance with demographic factors such as age and sex, as well as with body condition, a common metric of physical health in wild animals. Captive-reared toads representing all life stages will be sampled to characterize DNAm under controlled conditions, providing a standardized profile of DNAm rates over toad life stages. The researchers will then sample toads from wild populations experiencing starkly different levels of environmental stress (Bd infection), with accelerated biological aging signaling elevated stress and impaired welfare. 

Project objectives

Objective 1: Determine the relationship between DNAm and basic risk factors linked to welfare: chronological age, sex, weight, and infection status.

Objective 2: Determine the effect of environmental stressors on epigenetic age.

Why we funded this project

We funded this project because we are interested in the potential for biological aging biomarkers to be used as very long-term, integrative metrics of animals’ lifetime welfare. DNAm is one such potential biomarker that has received relatively little attention in a welfare context. However, DNAm may potentially be easier to measure than more commonly discussed measures of biological age — or at least, be more familiar for mainstream ecological genetics researchers — because DNA methylation is already of interest for other reasons in biological science. We were particularly enthusiastic about this project because it focuses on a species belonging to a large species complex of amphibians, including both common and threatened species, offering broad transferability and potential impact. Amphibians are also relatively neglected in terms of welfare research. We appreciate that this project aims to establish baseline age-specific differences in biological aging rate in order to then assess age-specific differences attributable to different exposures (i.e., age-specific differences in welfare), which connects to the concept of “welfare expectancy” developed by Wild Animal Initiative researcher Luke Hecht.

Find Dave’s other project, studying western fence lizards, here.

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