Biology and environmental sciense
Centre of Excellence in Biological Interactions
Survontie 9 Ambiotica 4th floor
Jyväskylä, PO Box 35, FI-40014 University of Jyväskylä
Abstracts (first author)
Snake head shape mimicry: implications to the conservation of the endangered mimic
Most research on the adaptive significance of warning signals has focused on the colouration and patterns of prey animals. However, behaviour, odour and body shape can also have signal functions and thereby reduce predators’ willingness to attack defended prey. For example, European vipers all have a distinctive triangular head shape and they are all venomous. Several non-venomous snakes are known to flatten their heads (head triangulation) when disturbed. Also many Lepidopteran larvae enhance their resemblance to tree vipers by concealing their heads and inflating their thorax or abdomen to express a false, sometimes triangular-shaped head. Even though anecdotal evidence of significance of snake head mimicry is dated back to the Henry Bates (1862), the role of body shape recognition is rarely experimentally investigated. Here we present data from field experiments and show that the triangular head shape can be recognized and avoided by predators. We also discuss the significance of this finding on population dynamics of snakes and its application their conservation. The smooth snake (Coronella austriaca) is non-venomous endangered species. By head triangulation it mimics vipers (Vipera sp.) which are not always protected by law. Because vipers are heavily killed by humans, it is possible that this asymmetric conservation program will be flawed because deceptive mimicry only works if the relative density and frequency of model species is higher than mimics. Based on the experimental evidence, we suggest that vipers should be protected at least in the locations where they co-exist with endangered mimic species.