Niche width predicts extinction from climate change and vulnerability of tropical species.

Climate change may be a major threat to global biodiversity, especially to tropical species. Yet, why tropical species are more vulnerable to climate change remains unclear. Tropical species are thought to have narrower physiological tolerances to temperature, and they have already experienced a higher estimated frequency of climate-related local extinctions.

Upper thermal limits are repeatable in Trinidadian guppies.

Measurements of thermal tolerance are critical for predicting species vulnerability to climate change. Critical thermal maximum (CTmax) is a measure of an animal's upper thermal tolerance, but there is limited evidence for how repeatable it is within individuals over time. We measured the CTmax of Trinidadian guppies (Poecilia reticulata) across six consecutive trials, each a week apart.