Maternal care and subsocial behaviour in spiders

Abstract

While most spiders are solitary and opportunistically cannibalistic, a variety of social organisations has evolved in a minority of spider species. One form of social organisation is subsociality, in which siblings remain together with their parent for some period of time but disperse prior to independent reproduction. We review the literature on subsocial and maternal behaviour in spiders to highlight areas in which subsocial spiders have informed our understanding of social evolution and to identify promising areas of future research. We show that subsocial behaviour has evolved independently at least 18 times in spiders, across a wide phylogenetic distribution. Subsocial behaviour is diverse in terms of the form of care provided by the mother, the duration of care and sibling association, the degree of interaction and cooperation among siblings, and the use of vibratory and chemical communication. Subsocial spiders are useful model organisms to study various topics in ecology, such as kin recognition and the evolution of cheating and its impact on societies. Further, why social behaviour evolved in some lineages and not others is currently a topic of debate in behavioural ecology, and we argue that spiders offer an opportunity to untangle the ecological causes of parental care, which forms the basis of many other animal societies.

Empathy: Gender effects in brain and behavior

“…It is unclear whether empathy is a key factor in motivating such behaviors, given that, in most of these cases, parent intervention is not triggered by the needs of the offspring (which could reveal sensitivity to others’ internal states), but rather by external danger stimuli activating defensive behavioral responses (Rosenblatt, 2003). For example, in some species of spiders the young remain with the mother for an extended period, during which time the mothers provide food and defense (Yip and Rayor, in press). Mammals evolved more complex behavioral strategies to cope with immature offspring, possibly because such prolonged maternal care is necessary to facilitate offspring weaning and independence (Olazábal et al, 2013).…”

Social Recognition in the Arachnida

“…Ultimately, permanent sociality is achieved by the complete elimination of pre-mating dispersal. Maternal care is widespread amongst arachnids (Yip and Rayor 2014) and it seems likely that extended maternal care and the resulting formation of family sibling groups is a pre-condition for sociality to evolve . For the maintenance of group cohesion, juvenile dispersal has to be delayed to prolong the time of intraspecific interaction, mainly between mother and offspring, to allow selection to act on behaviours that facilitate further social evolution.…”

“…This might well be an artefact of a biased investigation, but it may also underpin the importance of kin recognition to facilitate the evolution of sociality in these animals. In spiders, kin recognition mechanisms are subtle and comprise a number of specific behaviours that are often highly contextdependent (Yip and Rayor 2014). Those mechanisms may be used to direct help towards related individuals in social groups or to discriminate against foreigners.…”

“…Perhaps, once permanent sociality has evolved, there may be additional selective forces that maintain cooperation. For example, high and predictable genetic relatedness among group members may relax selection for maintaining kin recognition Yip and Rayor 2014). Also, mutualistic benefits of cooperation (see Kokko et al 2001) and infrequent encounters with competing groups would reduce the need for a kin recognition system (Waldman 1988).…”

Social network structure in group-feeding spiders

“…Subsocial and social spiders communally hunt and feed on large prey items (Avilés 1997;Lubin and Bilde 2007;Yip and Rayor 2014), and it has been shown that competition is reduced when group members are closely related (Schneider and Bilde 2008;Ruch et al 2009). …”