Spiders ‘are getting more aggressive in response to climate change’ as they are better equipped to survive the aftermath of hurricanes
- Experts examined female colonies of the spider known as Anelosimus studiosus
- It lives along the Gulf and Atlantic coasts of the United States and Mexico
- This region is directly in the path of tropical cyclones that form in the Atlantic
- Raging winds can demolish trees, defoliate entire canopies and scatter debris
Tropical cyclones and other extreme weather events may be shaping the evolutionary future of spiders by making them more aggressive, research suggests.
Aggressive spiders – such as Anelosimus studiosus, which lives along the Gulf and Atlantic coasts of the United States and Mexico – have the best odds of survival.
Raging winds can demolish trees, defoliate entire canopies and scatter debris across forest floors, researchers warn.
This radically alters a spider species habitat and reshapes the evolutionary pressures on a variety of wildlife found in that ecosystem, they say.
Consensus among scientists suggest that an increase in this type of extreme weather is linked to man-made climate change.
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Tropical cyclones and other extreme weather events may be shaping the evolutionary future of spiders by making them more aggressive, research suggests. Aggressive colonies of spiders – such as those of Anelosimus studiosus (pictured) – have the best odds of survival
Researchers from McMaster University examined female colonies of the spider known as Anelosimus studiosus.
This species lives along the Gulf and Atlantic coasts of the United States and Mexico, directly in the path of tropical cyclones that form in the Atlantic basin from May to November.
‘It is tremendously important to understand the environmental impacts of these “black swan” weather events on evolution and natural selection,’ says lead author Jonathan Pruitt, an evolutionary biologist at McMasters.
‘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.’
Scientists had to tackle many logistical and methodological challenges which included anticipating the trajectory of the tropical cyclones to conduct the research.
Once a storm’s path was determined, they sampled populations before landfall, then returned to the sites within 48 hours.
They sampled 240 colonies throughout the storm-prone coastal regions, and compared them to control sites.
They paid particular interest in determining if extreme weather caused particular spider traits to prevail over others.
In this case they looked at areas disturbed in 2018 by subtropical storm Alberto, Hurricane Florence and Hurricane Michael.
Raging winds can demolish trees, defoliate entire canopies and scatter debris across forest floors, researchers warn. Pictured: A nest of the spider known as Anelosimus studiosus, which lives along the Gulf and Atlantic coasts of the United States and Mexico
As a species, A. studiosus is divided into two sets of inherited personality traits – docile and aggressive.
The aggressiveness of a colony is determined by the speed and number of attackers that respond to prey, the tendency to cannibalise males and eggs, the vulnerability to infiltration by predatory foreign spiders, among other characteristics.
Aggressive colonies are 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.
‘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,’ added Professor Pruitt.
‘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.’
The analysis suggested that after a tropical cyclone event, colonies with more aggressive foraging responses produced more egg cases and had more spiderlings survive into early winter.
The trend was consistent across multiple storms that varied in size, duration and intensity, suggesting the effects are robust evolutionary responses.
The full findings of the study were published in the journal Nature Ecology & Evolution.
Experts paid particular interest in determining if extreme weather – in this case areas disturbed in 2018 by subtropical storm Alberto, Hurricane Florence and Hurricane Michael – caused particular spider traits to prevail over others (stock image)
