Editor's choice FebruarySubmitted by editor on 16 February 2017.
Organisms respond to predation risk in multiple ways. Induced defences are not restricted to plants in response to herbivore attack, but are also prominently present in vertebrates and arthropods. Induced responses can be of behavioural or morphological origin and jointly expressed. ecological and experimental determinants of inducible defence expression have been especially studies in tadpoles. Hossie and colleagues present a meta-analysis showing the multi-conditional nature of such responses. When both morphological and behavioural responses are measured, they are highly consistently co-expressed. The absence of a trade-off between both shows that tadpoles are capable to maximise survival through the optimisation of several independent defence traits.
The forum paper by Salewski & Watt, Bergmann's rule: a biophysiological rule examined in birds bring synthesis on the definition and understanding of Bergmann’s rules. This rule is now very commonly used as a mechanism to explain latitudinal and altitudinal variation in size, within and among species, in ecto- and endotherms. Bergmann used an empirical data of more than 300 bird species belonging to 86 genera to demonstrate that when everything but size is equal, the smaller animals should live in warmer areas. This definition does not match its current use. The authors therefore make concrete recommendations on the use and reference to Bergmann’s seminal work in contemporary ecology.