If you’re one of the millions of people terrified of spiders, then now might be a good time to sit up and take notice of climate change because it could have a terrifying effect on creepy crawlies.
As if some people weren’t already perturbed enough by the creatures, the increasingly warming climate could be making our spiders extra aggressive, according to new reports.
Global warming has already been linked to intensifying tropical storms, as well as seeing an increase in ‘black swan’ weather events, which are named due to their ferocity.
In turn, scientists predict a rise in aggressive spiders, as these are most likely to survive such tempestuous weather, essentially breeding stronger social spiders.
As per Insider, evolutionary biologist Jonathan Pruitt from McMaster University said:
It is tremendously important to understand the environmental impacts of these ‘black swan’ weather events on evolution and natural selection.
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.
The evidence of this evolutionary spider trait, Pruitt claims, is found in the arachnid called Anelosimus studiosus. They can be found living in North and South America, including the east coasts and the gulf, which see tropical cyclones coming in from the Atlantic Ocean between May and November.
Insider reports that these spiders live in three-dimensional tangle webs which can house up to a few hundred females, overhanging rivers and lakes.
However, these creatures don’t just all live in harmony, as the species come with two distinct behavioural phenotypes. Some of the spiders are placid and tolerant, while others are more aggressive.
The spiders live side-by-side in the same colony, and the more aggressive spiders living within that space, the more aggressive the colony becomes as a whole. This aggression can also be inherited.
Aggressive spiders are far more likely to respond to both predators and prey, however they’re also known to attack their fellow spiders, cannibalising their own eggs and the males of their species.
The researchers explained:
Colony aggressiveness in A. studiosus is transmitted down colony generations from parent to daughter colony, and is a major determinant of spiders’ survival and fecundity in habitat- and site-specific manners.
More broadly, aggressiveness in spiders is correlated with habitat resources, which also fluctuate in response to tropical cyclones.
Researchers waited until a storm was predicted before sampling spider colonies in that location to determine the effect the weather was having. They then came back to the same location within 48 hours of the storm passing and sampled the colonies again.
They also recorded the number of egg cases in each colony, and the survival rate of the spiderlings.
The study found 75.42 per cent of colonies survived the initial cyclone strike, and while the number of egg cases produced actually fell, this wasn’t evenly distributed between aggressive and placid colonies.
Tropical cyclones selected for more aggressive colony phenotypes. Following tropical cyclones, colonies with more aggressive foraging responses produced more egg cases and had more spiderlings survive into early winter, whereas the opposite trend emerged in control sites.
This trend is consistent across multiple storms that varied in both size, duration and intensity. This shows that these effects are not idiosyncratic but are robust evolutionary responses that hold across storms and at sites occupying a spread of 5-degree latitude.
We only have ourselves to blame really.
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Emma Rosemurgey is an NCTJ trained Journalist at UNILAD. She graduated from the University of Central Lancashire in Preston and started her career in regional newspapers before joining the LADbible Group team in 2017.