Every animal has a weapon of one sort or another, but the overwhelming majority of weapons stay small. Yet, sprinkled through the tree of life are species where weapons become extreme.

Choosing a mate is one of the most important decisions an animal can make. The fitness costs and benefits of mate choice have been analysed extensively in the context of sexual selection, and the neural and hormonal bases of mate choice have provided insights into how animals make such decisions.

Athena Aktipis discusses how an evolutionary approach to understanding and treating cancer can transform it from being a disease that threatens our lives to one we can live with.

Studying physiological responses in animals can tell us a lot about how much environmental stress animals can tolerate, helping to improve our understanding of animal biology and inform conservation management actions.

Bob Wong considers the role that behaviour plays in determining the fate of species under human-induced environmental change.

In anisogamous mating systems, males and females play different roles. This results in sexual differences in morphology and behaviour.