The common coquí frog is a small but iconic species in Puerto Rico. Their melodic “co-quí” call is a lullaby for people on the island.

But it’s far less welcome in places like Florida and Hawaii, where the species is invasive. In those states, these little frogs can seem impossible to get rid of.

But in fact, a deadly fungal pathogen has been contributing to declines in more than 500 amphibian species worldwide, including the common coquí.

In Puerto Rico, where this pathogen has been present since 1976, infected frogs tend to be smaller than healthy ones. Smaller frogs of any species are more likely to die.

For tiny frogs, survival is a high-stakes game with no pause button. Any energy put toward immune defense to prevent infection cannot be used to grow, and vice versa. And for young frogs, this energy allocation game is especially critical because getting it wrong can mean game over.

So what processes are driving differences in size and survival between infected and healthy frogs?

We are part of a team of researchers at the University of Florida who study how disease shapes wildlife populations. In our latest research, we integrated field data and mathematical models to examine how young coquís allocate energy as they grow while coping with infection.

We wanted to understand how these trade-offs play out over time and whether the season – that is, whether it’s warm or cool — when frogs hatch from their eggs affects their chances of surviving to maturity and their lifetime reproduction.

Tiny frogs, big challenges

Coquí frogs lay eggs on land, skipping the........

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