Tropical storms make spiders more aggressive

A group of researchers has discovered that tropical storms make spiders more aggressive. Researchers Jonathan Pruitt and Alexander Little from the University of California at Santa Barbara have analyzed the effects of the tropical storm Florence that struck North Carolina and that of the south and the east coast of the United States. They discovered that the most aggressive spiders had survived the storm, compared to the more “docile” ones, and this caused an evolutionary push which in turn led to colonies of more daring, aggressive and courageous spiders.

This is one of the few studies that analyzes the effects of hurricanes and tropical storms not on humans but on wildlife.

The researchers have in particular analyzed the Anelosimus studiosus, a species of spider that is already known because it is characterized by aggressive or docile behavior. The most aggressive specimens attack the prey very quickly and in large numbers while the most docile specimens spend a greater number of hours in the den.

These are behaviors that evidently on an evolutionary level are increasingly corroborating and diversifying, from one generation to another. The researchers thought that tropical storms and heavy rain combined with very strong winds could be the basis of this behavioral diversification.

Visiting 240 insect colonies in seven states, from Carolina to Florida to pass through Louisiana, they collected various data “measuring” the aggressiveness of spiders near their burrows. Comparing this data with the steps of tropical storms or cyclones, they found that the regions with a greater number of these atmospheric phenomena saw the presence of more aggressive spider colonies.

According to the researchers, that is to say in the fact that the colonies with specimens with more aggressive genetic traits are, for reasons not yet known, more suitable to survive these atmospheric phenomena and these aggressive traits passed from generation to generation to a greater extent than the traits transmitted by the most “docile” spiders who evidently cannot survive in equal numbers.

The study was published in Nature Ecology & Evolution.