Spiders are not often social animals, but those exhibiting genetic and neurological similarities to other social species help us understand collectivity more fully.
Of the 50,000 species of spiders worldwide, the great majority are extremely solitary and frequently consume potential or actual mates. While some are categorized as “subsocial,” a small number coexist peacefully in colonies and even share food. Examining the variations between these spiders and their relatives revealed similarities with the genes that give rise to other social animals.
“One of the conditions for social animals is that they have a bigger brain size,” said Professor Alexander Mikheyev of the Australian National University in an emailed statement. “Not only do they need to store information about the physical environment, but also the social one.”
Stegodyphus dumicola take sociability among spiders further than almost any other species, but they are not the only arachnids to have at least some social traits, and the commonalities tell us a lot. Image Credit: Bernard Dupont
As Mikheyev pointed out, Spiders don’t have brains; their neurons are dispersed throughout their bodies. The neural systems of social spiders are more advanced than those of their most closely related solitary counterparts, according to Mikheyev and co-authors in Nature Communications.
Despite being unusual, sociability has independently evolved multiple times, leading the authors to focus on the genes related to it in spiders. By comparison, they note that; “Bees are often described as ideal study systems because they include the full range of social complexity….However, there are only estimated two-three independent origins of sociality within bees.”
The Kalahari, where big colonies create enormous webs, is where the most well-known instance of spider friendliness may be seen. The practice of Delena cancer ides mothers shielding their young, which the publication refers to as subsocial behavior, was the subject of a recent study. Mikheyev and co-authors examined the genetic makeup of 22 social and subsocial species. However, they were unable to identify any common amino acid alterations.
However, they discovered a few genes whose modifications were frequently linked to social behavior, such as the Bromodomain-containing protein 4 gene, discovered in five social and two subsocial spider species, many of which were not closely related. In contrast, research on insect genetics has discovered little overlap in the genes linked to social evolution in social bees from several lineages.
Additionally, social spider species often underwent faster genome-wide molecular evolution than their non-social counterparts. This is due to unbalanced sex ratios and inbreeding, according to the authors.
Despite the enormous evolutionary gap between arachnids and mammals, the discovery could provide us with much insight into who we are. Autism susceptibility candidate 2 is the name given to a gene that has undergone intense selection in social spiders due to the consequences of variations found in mice and humans.
Some creatures develop social relationships to engage in cooperative hunting, which is especially useful when pursuing larger prey. There have been horrifying instances like this. Mikheyev claimed that D. cancel rides, the Australian huntsman spiders that he is most familiar with and which reside in colonies beneath the bark of acacia trees, don’t do this but have instead been observed feeding their neighbors.
Nevertheless, Mikheyev told IFLScience: “To a large extent, we are seeing a tolerance rather than co-operation. It’s not like ants.” Still, he noted, “If we think about the basis of spider behavior, they are very aggressive, so it does not take much to attack each other.” Spiders find sharing a space difficult, much less allowing others to participate in their hunting activities.
Numerous factors, including information exchanged within a colony concerning predators or food supplies, can contribute to the evolution of sociability. Mikheyev asserted that spiders are more inclined to exploit scarce resources, including nesting locations.
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