Genotype–environment interaction expressed in the foraging behaviour of dogwhelks,Nucella lapillus(L.), under simulated environmental hazard

Abstract

SUMMARYThe foraging behaviour of sub-adult ucella lapillus originating from different field populations, was monitored for ten alternating, biweekly, periods of calm and wave action simulated in a tidal aquarium. Because the dogwhelks were reared under standard laboratory conditions, any behavioural differences among the experimental populations could reasonably be inferred to be linked to some genetically based mechanism. In order to forage, the dogwhelks had to leave a refugium, traverse empty ' habitat ' and enter a patch of mussels serving as prey. Wave action markedly depressed foraging activity, increased foraging latency and lowered the patch-residence-time index. Dogwhelks derived from populations naturally occurring on shores exposed to wave action reduced their foraging activity less strongly than those derived from sheltered-shore populations, but geographical origin (Plymouth or Anglesey) had no significant influence on foraging behaviour. A simple interpretation was offered, linking the differential behavioural response to habitat-specific shell morphology, known to be heritable. According to this interpretation, all dogwhelks react similarly to the drag forces generated by wave action, but the relatively shorter-spired shells of exposed-shore dogwhelks cause weaker resultant forces than the taller-spired shells of shelteredshore individuals. Consequently, exposed-shore dogwhelks tolerate higher levels of wave action than sheltered-shore morphs before suppressing their foraging behaviour. As exposed-shore dogwhelks have greater tenacity associated with relatively larger pedal area, the increased tolerance of wave action extends opportunities for foraging without incurring extra risk of dislodgement. The sheltered-shore morphology, which imparts greater resistance to desiccation, coincidentally increases drag and so makes dogwhelks more likely to seek refuge during occasional periods of heavy wave action. Exposed-and sheltered-shore morphologies therefore represent genotype-environment interaction that is apparently adaptive, in part, through its effect on foraging behaviour.

Life on the edge: do biomechanical and behavioral adaptations to wave-exposure correlate with habitat partitioning in predatory whelks?

“…S. haemastoma has a squatter shell shape, which is typical of waveexposed phenotypes of other snails (Trussell et al 1993, Hughes & Taylor 1997, Trussell 1997. Thus, the drag force acting on it by water should be smaller and the risk of dislodgment lower than that acting on H. trunculus.…”

“…Comparison among snail populations from protected and exposed sites demonstrated phenotypic plasticity as an adaptation to risk of dislodgment. Periwinkles (Trussell et al 1993, Trussell 1997, topshells (Frid & Fordham 1994) and whelks (Gibbs 1993, Hughes & Taylor 1997 on wave-exposed shores have squatter shells, and larger shell aperture and foot, than their conspecifics on wave-protected shores.…”

Corticosterone manipulation reveals differences in hierarchical organization of multidimensional reproductive trade‐offs in r‐strategist and K‐strategist females

“…Acquisition rate may not depend on overall resource availability, a general environmental effect (Lynch & Walsh, 1998), but may be a special environmental effect as a result of microhabitat differences in resource availability. Because resource acquisition is often behavioural, it can also have a strong genetic component resulting from individual differences in foraging behaviour, which may interact with microhabitat differences, resulting in a G × E (genetic by environmental) interaction (Hughes & Taylor, 1997). Furthermore, resource acquisition itself is involved in trade‐offs with biotic interactions with predators or conspecifics that limit feeding rates (Brown & Kotler, 2004).…”

Microstructural differences in the reinforcement of a gastropod shell against predation

“…Since crab predators are rare and inefficient on wave-swept shores, the usefulness of the crossed-lamellar layer might be related to the tradeoff between shell thickness and internal volume (body size, fecundity). Food availability is greater on exposed shores (Etter 1989), but intense wave action reduces foraging time and efficiency, causing snails on exposed Table 2 shores to grow more slowly (Menge 1978, Brown & Quinn 1985, Etter 1989, Hughes & Taylor 1997. Both slow growth and lack of predation reduce the viability of rapid growth to a size refuge.…”

“…The proportional difference obviously reflects the thinner homogeneous shell layer on exposed shores and thus may not be adaptive in nature. However, if energy is limited on exposed shores, as suggested by reduced growth (Menge 1978, Brown & Quinn 1985, Etter 1989, Hughes & Taylor 1997, it is puzzling that snails do not reduce the thickness of the more expensive microstructure.…”