Variation in morphology and performance of predator-sensing system in wild cricket populations

Abstract

SUMMARY Even though variation in morphology is known to translate into variation in performance, studies looking at structural variability of a sensor to predict its consequences on the performance of animals are exceedingly rare. We investigated the morphological variability of air-flow-sensing receptors in wild populations of wood crickets (Nemobius sylvestris) sampled in a wide variety of habitats differing in latitude, litter structure, vegetation and predator communities. These hair receptors act as predator sensors. The observed levels of hair morphological variation were then incorporated into a biomechanical model of the hair canopy response to air flow to predict their influence on cricket predator perception. Cricket populations differ from each other, often strongly so, in the total number of hairs and in the number of hairs longer than 1 mm, which are the hairs most sensitive for the perception of approaching predators. The hair canopy response, the output of the biomechanical model, sums up over the entire canopy the angles of deflection at which a neurophysiological response is triggered and represents the sensitivity of the cercal system. It is 35% higher in the most sensitive population, compared with the least sensitive population. These large differences in perception sensitivity for a given predator signal translate into larger distances at which predators could be perceived. Thus, differences in morphology at the sensor level seem to be translated both at the perception level and subsequently at the performance level of crickets.

Danger detection and escape behaviour in wood crickets

“…Younger crickets show better performance than older ones. This result, previously observed in field experiments (Dangles et al, 2005), is confirmed here under controlled laboratory conditions.…”

“…In recent years, the wood-cricket, Nemobius sylvestris, started to be the subject of diverse studies focusing on prey-predator interactions, functional neuroanatomy, and modelling of the detection of a predator by the cercal sensory system (Dangles et al, 2005(Dangles et al, , 2006aInsausti et al, 2008Insausti et al, , 2011Magal et al, 2006;Steinmann et al, 2006). The main predator of this cricket species in the area of Tours, France, where most of these studies were conducted, are wolf spiders of the genus Pardosa (Dangles et al, 2006a), whose aerodynamics of attack has also been characterized in detail .…”

Responses of cricket cercal interneurons to realistic naturalistic stimuli in the field

“…Over the last few years, the wood cricket Nemobius sylvestris (Bosc 1792) has been the subject of studies focusing on its ecology (Dangles et al, 2006a), its escape behavior (Dupuy et al, 2011), the neuroanatomy of the cercal sensory system (Insausti et al, 2008;Insausti et al, 2011), the anatomy of cerci (Dangles et al, 2005), mathematical modeling of the movement of mechanoreceptive hairs (Magal et al, 2006) and air movements around hairs on cerci (Steinmann et al, 2006). Nemobius sylvestris crickets live in the litter of forests, an easily accessible environment for field experiments.…”

Variability in Sensory Ecology: Expanding the Bridge Between Physiology and Evolutionary Biology

“…Dangles et al (2005) quantified the natural phenotypic variation in structure and performance of the air-flow sensing cercal system in five cricket populations from diverse habitats and predator communities. These cricket populations differed markedly from one another, such as in the total number of air-flow sensitive hairs and in the number of hairs longer than 1000 m-the hairs most sensitive for the perception of predatory air flow signals.…”