Post-reproductive senescence in moths as a consequence of kin selection: Blest's theory revisited

Abstract

In 1963 Blest reported that cryptic, palatable moth species had faster rates of post-reproductive senescence than conspicuous, unpalatable (aposematic) moth species. He argued that these defence-dependent differences could be explained as a consequence of selection to reduce predation on conspecifics in both cases; this hypothesis was later reformulated by Hamilton in terms of kin selection. Here we re-analyse Blest's original data, and test his underlying assumption that the presence of conspecifics affects predation rates on similar-looking prey using a combination of laboratory work on humans and fieldwork with wild birds. The collective evidence for Blest's theory is weak at best, and we propose a more general hypothesis that post-reproductive senescence rates in cryptic and aposematic prey are a by-product of extrinsic mortality imposed by predation. © 2011 The Linnean Society of London.