More sharing when there is less: insights on spider sociality from an orb-weaver's perspective.

FLORENCIA FERNÁNDEZ CAMPÓN

ANIMAL BEHAVIOUR

Elsevier Ltd.

Año: 2008 vol. 75 p. 1063 - 1073

0003-3472

 I examined the potential genetic and environmental determinants of population differences in the foraging behaviour of the colonial spider Parawixia bistriata by using reciprocal transplant and prey manipulation experiments. The population differences noted from a previous study are primarily associated with the degree to which this spider captures prey as a group: P. bistriata show a higher frequency of group capture of prey in dry habitats with lower prey levels than in wet habitats where prey levels are higher. I recorded data on the tendency to capture and feed in groups and the number of individuals feeding on that prey. The transplant experiments revealed population differences in the tendency to capture prey as a group. Dry-origin individuals in dry habitat showed a higher tendency to exhibit group capture and feeding than wet-origin individuals in wet habitat and groups transplanted to both dry and wet habitats. In addition, there were differences in the size of capture and feeding groups depending on the habitat type individuals were found. Because wet-origin individuals transplanted to dry habitat show the same tendency to attack prey as in their native habitat, they represent an ecotype that lacks behavioural plasticity. On the other hand, dry-origin individuals do show a plastic response. Potential causes of the behavioural plasticity exhibited by spiders of dry habitat are discussed. Group foraging behaviour can have a significant effect on the fitness of these spiders as suggested by their success under low prey conditions.