More aggressive spiders

Parts of the U.S. where hurricanes occur most frequently may have another problem to worry about: the evolution of more-aggressive spiders. During last year’s hurricane season, researchers examined more than 200 colonies of Anelosimus studiosus spiders before and after three big storms in the Southeast. Anelosimus studiosus colonies are either relatively docile, with mothers working together to rear offspring, or much more combative, with a higher ratio of aggressive females. The researchers found that about 75 percent of the colonies survived the storm—and that the more-aggressive ones were much more likely to do so, probably because they outcompeted other spiders for the food and resources made scarce by the storm. The obvious evolutionary implication is that over time spiders will adapt to harsher weather events by becoming more aggressive—and that other species may also evolve in the same way. “As sea levels rise, the incidence of tropical storms will only increase,” lead author Jonathan Pruitt, from McMaster University in Canada, tells CNN.com. “We need to contend with what the ecological and evolutionary impacts of these storms will be for nonhuman animals.” ■