Climate change is making spiders mean

And the angry spiders shall inherit the Earth.

At least, that’s the conclusion Canadian scientists came to after watching how spiders in storm-prone regions responded to extreme weather events.

Although climate change may not spell more storms, scientists suspect it may ratchet up the intensity — and lead to more extreme weather outbursts known as “black swan” events.

“It is tremendously important to understand the environmental impacts of these ‘black swan’ weather events on evolution and natural selection,” lead author Jonathan Pruitt of McMaster University notes in a release.

“As sea levels rise, the incidence of tropical storms will only increase. Now more than ever we need to contend with what the ecological and evolutionary impacts of these storms will be for non-human animals.”

And how, you might ask, does climate change affect spiders? It turns out, in very profound ways. Severe winds, for example, can shatter trees, strip them of leaves and dramatically alter the forest floor.

For creepy-crawler kind, it’s nothing short of a tsunami, devastating colonies. And who should be left to pick up the pieces? Certainly, not the mellow spiders. Researchers noted the aggressive ones — the spiders that had no qualms about cannibalizing their own kind, hoarding supplies and attacking anyone that got in their way — were the ones to rebuild.

In other words, it was survival of the meanest.

For their study, published this week in the journal Nature, the researchers observed 240 colonies of the species Anelosimus studiosus — a North American spider known for living communally, with hundreds sharing the same web.

Anelosimus studiosus also pitch their webs over lakes and rivers, making them especially vulnerable to storms.

The scientists compared colonies before and after they were hit by three major tropical storms in 2018. The team also monitored a control group of spiders that didn’t experience any extreme weather. They were the lucky ones.

The Anelosimus studiosus in its web. Anelosimus studiosus can share its web with hundreds in a colony — until the going gets tough. (Photo: Judy Gallagher [CC BY 2.0]/Flickr)

When the storms broke out, smashing their house of silk, it was no more Mr. Nice Spider. Communal living, researchers note, went out the window, as two types of spiders emerged: the aggressive, downright mean ones and the peace-loving hippies.

Most spider colonies already have representatives of each, often determining the overall aggressiveness of a colony. But when push comes to tsunami, the mellow members of the population get shoved aside — and the killing and marauding and eating-each-other’s-babies begins.

It’s “Hunger Games,” spider-style. But most importantly, it’s a survival mechanism. The scientists noted that the aggro-spiders were “better at acquiring resources when scarce but are also more prone to infighting when deprived of food for long periods of time or when colonies become overheated.”

And to better equip future generations for “black swan” events, spiders passed on those survival tools — a.k.a. the killing and pillaging gene — to their offspring.

“Tropical cyclones likely impact both of these stressors by altering the numbers of flying prey and increasing sun exposure from a more open canopy layer,” Pruitt explains. “Aggressiveness is passed down through generations in these colonies, from parent to daughter, and is a major factor in their survival and ability to reproduce.”

In other words, climate change is giving us an angry new world. And spiders are learning how to navigate it, no matter what it takes.

Climate change is making spiders mean

New research finds mean spiders know what it takes to survive extreme weather.


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