Publication

Predation risk as a driving force for phenotypic assortment: a cross-population comparison

Authors: Croft DP, Darden SK, Ruxton GD.

Year: 2009

Journal: Proceedings of the Royal Society B-biological Sciences Volume: 276(1663) Pages: 1899-1904

Publisher: Royal Soc; 6-9 Carlton House Terrace

Abstract:

Frequency-dependent predation has been proposed as a general mechanism driving the phenotypic assortment of social groups via the 'oddity effect', which occurs when the presence of odd individuals in a group allows a predator to fixate on a single prey item, increasing the predator's attack-to-kill ratio. However, the generality of the oddity effect has been debated and, previously, there has not been an ecological assessment of the role of predation risk in driving the phenotypic assortment of social groups. Here, we compare the levels of body length assortment of social groups between populations of the Trinidadian guppy (Poecilia reticulata) that experience differences in predation risk. As predicted by the oddity effect hypothesis, we observe phenotypic assortment by body length to be greater under high predation risk. However, we found that a number of low-predation populations were also significantly assorted by body length, suggesting that other mechanisms may have a role to play.

Keywords: confusion effect, frequency-dependent selection, guppy, oddity effect, Poecilia reticulata