Past Event

Dr. Tom Sherratt of Carleton University will be giving a colloquium talk on Thursday, March 27th, at noon, in room 2203 of Dunton Tower. Refreshments will be available before the talk. All are welcome.

Animal cognition and the evolution of anti-predator defence

In this talk I describe quantitative tests of three long-held beliefs about the role of animal cognition in shaping anti-predator defence.  First, Fritz Müller argued that predators would always sample a fixed number of unpalatable prey types of any given appearance before rejection, a phenomenon that would lead to selection on unpalatable prey types to evolve similar warning colour patterns (Müllerian mimicry).  Second, Abbott Thayer argued that contrasting patterns serve to break up an object’s characteristic outline, thereby hindering their recognition (disruptive coloration).  Third, Henry Bates argued that imperfect mimicry would persist whenever predators are not motivated to be too discriminatory (imperfect Batesian mimicry). I show using mathematical modelling that Müller was wrong (although right in the limit).  Next, eyetracking experiments with humans demonstrate that contrasting patterns do indeed impair object recognition, even at the cost of reducing background matching.  Finally, a comparative analysis of imperfect mimicry in hover flies (Diptera: Syrphidae) suggests that Bates may have been correct that relaxed selection can explain imperfect mimicry, at least in this group.