Research led by the University of Southampton and published in the Journal of Biogeography shows how temperate prey species are adapting to changing water temperatures, which carry the threat of warm-water predators encroaching into their territory. The paper is titled "Predator-induced defenses under tropicalization: A biogeographic approach."

As global sea-surface temperatures rise and the number of marine heat waves increase under global heating, coastal marine communities are changing. Warm-water predators that were restricted to subtropical and tropical regions are now establishing themselves in more temperate waters. This phenomenon is known as "tropicalization."

As these predators push out from the equator towards the poles, temperate prey species, like the barnacle Tetraclita rubescens, are encountering new, larger, predators. Researchers wanted to know how this barnacle species might adapt their defenses in response to tropicalization.

Specifically, they studied the prevalence of 'bent morphs'—individual barnacles that morph into a bent shape, obscuring an opening in their shells which can be attacked by predatory sea snails (muricids). Bent morphs have slower growth and lower reproduction than the standard cone-shaped barnacles, but this could be a necessary trade-off in the face of increased predation.