Amphibian Skin Breathing

Linking skin structure to function

Amphibians rely on their skin to breathe. We study how amphibians breathe across their skin and how they adapt to different environments by adjusting skin breathing.

Flow of oxygen, carbon dioxide, and water

Figure 1

Skin as a barrier

Amphibian skin must do two things that often work against each other: let oxygen diffuse inward while slowing water loss outward. This produces a fundamental trade-off between breathing and hydration.

Oxygen uptake: the absorption of oxygen across respiratory tissue
Water balance: evaporative demand + skin permeability determine the water loss rate
Trade-offs: traits that help one function can constrain the other

Cartoon of histology workflow and measurements

Figure 2

Skin structure

We use histology to characterize skin structure to connect morphology to physiology. Depending on the question, this can include epidermal thickness, gland densities, capillary density, and other features that influence diffusion and resistance.

What we measure

Thickness, layer organization, surface complexity, and features associated with permeability and hydration.

Cartoon phylogeny with frog species at the tips

Figure 3

Comparative approach: linking traits to evolution

We use the comparative phylogenetic method to ask how skin structure and environment shape skin breathing across species. By combining trait data with evolutionary relationships, we can test whether phenotype differences between species are driven by natural selection or shared ancestry.

Across species: quantify skin traits and gas flux in multiple lineages
Comparative method: account for relatedness when understanding species' differences
Inference: identify repeated evolutionary shifts that point to selection

Cartoon linking traits to predictions across environments

Figure 4

Why it matters

Rates of water loss and gas exchange serve an imporant link between organism fitness and environmental change. By understanding variation in these rates across species, we can improve forecasts of dehydration risk and physiological performance across microclimates — and better understand how amphibians respond to environmental change.

Big picture

Traits → performance → energy and water balance. This is the bridge from physiology to ecology.

Methods snapshot

Histology

Sampling, sectioning, staining, imaging, and standardized morphometric measurements.

Skin flux

Skin-specific measurements of gas exchange and water loss using respirometry.

Integration

Mechanistic niche models to identify which structures explain functional variation.

Interested in collaborating?

If you’re working on amphibian physiology, skin structure, diffusion barriers, or dehydration ecology, feel free to reach out: riddell@unc.edu.