Great tit predation on colour morphs of the wood tiger moth at different relative frequencies

Polymorphic warning signals in aposematic systems are enigmatic because
predator learning should favor the most common form, creating positive
frequency-dependent survival. However, many populations exhibit variation
in warning signals. There are various selective mechanisms which can
counter positive frequency-dependent selection and lead to temporal or
spatial warning signal diversification. Examining these mechanisms and
their effects requires first confirming whether the most common morphs are
favored at both local and regional scales. Empirical examples of this are
uncommon and often include potentially confounding factors such as a lack
of knowledge of predator identity and behavior. We tested how bird
behavior influences the survival of three coexisting morphs of the
aposematic wood tiger moth Arctia plantaginis offered to a sympatric
predator (great tits, Parus major) at different frequencies. We found that
although positive frequency-dependent selection is present, its strength
is affected by predator characteristics and varying prey
profitability.  These results highlight the need to understand
predator foraging in natural communities with variable prey defences, in
order to better examine how behavioral interactions shape evolutionary
outcomes.