Nav: Home

Untangling the social lives of spiders

March 31, 2020

The idea of a complex spider society--in which thousands of spiders live, hunt, and raise their young together in a single colony--is unsettling to many of us. We are perhaps lucky then that this scene is relatively rare among arachnids. Among the 40,000 known species of spiders, the vast majority live solitary lives and will often show aggression toward other spiders they encounter, even within their own species. There are fewer than 25 known species of social spiders, distributed broadly across 6 different families and 9 different genera. Not only do these spiders live in social groups, but they produce populations that grow over time as new offspring are added to the nest, enabling the capture of increasingly large prey as the colony expands, and even give rise to new daughter colonies. As social creatures ourselves, humans have long been interested in the evolutionary innovations that enable social cooperation. In a new article in Genome Biology and Evolution titled "
The research, led by Dr. Chao Tong, a postdoc in the lab of Dr. Timothy Linksvayer at the University of Pennsylvania, represents one of the first comparative genomic studies to be conducted in spiders. According to Dr. Tong, "The high complexity and large size of spider genomes has constrained the development of genomic resources for spiders." Because of this, earlier studies compared individual spider genomes to insect genomes and sought mainly to identify venom and silk genes. In the new study, however, a curiosity about the genetic basis of social life led Dr. Tong and his colleagues to compare the genomes of 7 spider species: two social species in the genus Stegodyphus that evolved sociality independently, and five solitary species in the genera Parasteatoda, Acanthoscurria, Nephila, Loxosceles, and Latrodectus.

The analysis revealed a number of interesting findings. First, rapidly evolving genes in the two social species were involved not only in behavior but also in immunity, indicating that group living may require better defenses against pathogens that spread more easily in dense social groups. In contrast, genes that were rapidly evolving in the solitary species were enriched for energy metabolism processes. Dr. Tong notes that this is the opposite pattern from what is observed in social insects such as bees and ants, in which metabolic genes evolve more rapidly. Still, in both insects and spiders, there appear to be metabolic differences between solitary and social organisms that may reflect differences in hunting and feeding behaviors.

In addition, the researchers found that the genomes of the two social spiders exhibited a higher rate of evolution overall than those of the solitary species. While this might reflect a greater number of genes under positive selection, the authors are quick to point out that this pattern may also stem from demographic features that characterize social spiders, such as a female-skewed sex ratio (social spiders have more female offspring than males) and high levels of inbreeding. Perhaps most interesting of all, the new study identified a set of rapidly evolving genes that showed brain-specific expression and were enriched for social behavioral processes. These genes represent top candidates for those that influence social behavior and may have been involved in the evolution of spider sociality.

The researchers note an important limitation of their analysis: since the two social spiders they studied are from the same genus and they did not have access to a solitary spider from this genus, it is difficult to untangle which patterns are directly related to sociality and which may simply characterize spiders in the genus Stegodyphus--both social and non-social species. Thus, the group has already started their next comparative genomics project to verify the above patterns in a larger set of species, including more social spiders and their solitary relatives within the same genus. Realizing that the success of this endeavor may require establishing new collaborations due to the scarcity of spider genomic resources, Dr. Tong would like to put out a call to other researchers: "We welcome samples from other researchers, as we want to include as many spiders as possible in future studies, including social, subsocial, and solitary spider samples from multiple genera."

Molecular Biology and Evolution (Oxford University Press)

Related Spiders Articles:

Untangling the social lives of spiders
Scientists begin to unravel the genetic mechanism by which a solitary spider becomes a social one.
Freshwater insects recover while spiders decline in UK
Many insects, mosses and lichens in the UK are bucking the trend of biodiversity loss, according to a comprehensive analysis of over 5,000 species led by UCL and the UK Centre for Ecology & Hydrology (UKCEH), and published in Nature Ecology & Evolution.
Cave fights for food: Voracious spiders vs. assassin bugs
Killing and eating of potential competitors has rarely been documented in the zoological literature, even though this type of interaction can affect population dynamics.
Spiders and ants inspire a metallic structure that refuses to sink
University of Rochester researchers have created a metallic structure that is so hydrophobic, it refuses to sink - no matter how often it is forced into water or how much it is damaged or punctured.
Compact depth sensor inspired by spiders
Inspired by jumping spiders, researchers at the Harvard John A.
Researchers find hurricanes drive the evolution of more aggressive spiders
Researchers at McMaster University who rush in after storms to study the behavior of spiders have found that extreme weather events such as tropical cyclones may have an evolutionary impact on populations living in storm-prone regions, where aggressive spiders have the best odds of survival.
Baby spiders really are watching you
Baby jumping spiders can hunt prey just like their parents do because they have vision nearly as good.
Solitude breeds aggression in spiders (rather than vice versa)
Spiders start out social but later turn aggressive after dispersing and becoming solitary, according to a study publishing July 2 in the open-access journal PLOS Biology by Raphael Jeanson of the National Centre for Scientific Research (CNRS) in France, and colleagues.
Spiders risk everything for love
A biology study finds that blue jays can easily spot wolf spiders engaged in their courtship rituals.
Hold the mustard: What makes spiders fussy eaters
It might be one of nature's most agile and calculating hunters, but the wolf spider won't harm an insect that literally leaves a bad taste in its mouth, according to new research by a team of Wake Forest University sensory neuroscientists, including C.J.
More Spiders News and Spiders Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Our Relationship With Water
We need water to live. But with rising seas and so many lacking clean water – water is in crisis and so are we. This hour, TED speakers explore ideas around restoring our relationship with water. Guests on the show include legal scholar Kelsey Leonard, artist LaToya Ruby Frazier, and community organizer Colette Pichon Battle.
Now Playing: Science for the People

#569 Facing Fear
What do you fear? I mean really fear? Well, ok, maybe right now that's tough. We're living in a new age and definition of fear. But what do we do about it? Eva Holland has faced her fears, including trauma and phobia. She lived to tell the tale and write a book: "Nerve: Adventures in the Science of Fear".
Now Playing: Radiolab

First things first: our very own Latif Nasser has an exciting new show on Netflix. He talks to Jad about the hidden forces of the world that connect us all. Then, with an eye on the upcoming election, we take a look back: at two pieces from More Perfect Season 3 about Constitutional amendments that determine who gets to vote. Former Radiolab producer Julia Longoria takes us to Washington, D.C. The capital is at the heart of our democracy, but it's not a state, and it wasn't until the 23rd Amendment that its people got the right to vote for president. But that still left DC without full representation in Congress; D.C. sends a "non-voting delegate" to the House. Julia profiles that delegate, Congresswoman Eleanor Holmes Norton, and her unique approach to fighting for power in a virtually powerless role. Second, Radiolab producer Sarah Qari looks at a current fight to lower the US voting age to 16 that harkens back to the fight for the 26th Amendment in the 1960s. Eighteen-year-olds at the time argued that if they were old enough to be drafted to fight in the War, they were old enough to have a voice in our democracy. But what about today, when even younger Americans are finding themselves at the center of national political debates? Does it mean we should lower the voting age even further? This episode was reported and produced by Julia Longoria and Sarah Qari. Check out Latif Nasser's new Netflix show Connected here. Support Radiolab today at