October 13, 2012
Spider Dads Suffer No Ill Effects From Caring For Babies
Alan McStravick for redOrbit.com - Your Universe Online
The idea of the stay-at-home-dad has been getting its legs lately. Sure, we started off with quaint 80´s comedies, like ℠Mr. Mom´ and ℠Three Men and a Baby´, but, like the subject of this article, we are slowly evolving past focusing on the hijinx and silliness of the situation and viewing the caring paternal relationship in a more real light. We have experts, pundits and private-citizens who are arguing the merits of the stay-at-home-dad trend that, according to Forbes, has seen its ranks more than double over the past decade. While we debate the pros and cons of this, one species has apparently rendered its decision.New research conducted by Gustavo Santos Requena and his colleagues at the University of Sao Paolo shows the costs and benefits of exclusive paternal care, the rarest form of parental investment in nature, in the harvestman spider Iporangaia pustulosa. Their research was published earlier this week in the open access journal PLOS ONE and shows that the males of this species, who are exclusively responsible for guarding eggs, actually enjoy survival benefits rather than suffering any detriment to their health or mating privileges.
Over the course of a year, the researchers focused their study in the forests of southeastern Brazil. It was here they tracked I. pustulosa in the hopes of observing how the caring behavior of the males would affect their chances of survival or body condition. The researchers fully expected to see the role these spiders played one of martyrdom. It was well known the male spiders in the caring role eat less than other spiders of the species. Pairing that with a degradation in body condition, and one would expect the caring spiders would also suffer deleterious consequences in the field of natural selection. Why would a female want to mate with a sickly, scrawny male?
Well, let me tell you why. Through their research, Requena and his team noted the spider, despite their sedentary behavior during the caring period, suffered no long-term decrease in body condition. In fact, it´s that sedentary behavior that also lessens their chances of being eaten by predators, which is a big indicator in the reduction to their mortality risk. They went on also to suggest that simply by providing a female cost-free care for their offspring might actually make the caring male more attractive to females. This would, therefore, improve greatly their chances for reproductive success.
The authors, in reviewing their findings, believe the reduction in mortality risk when combined with the genetic advantages of improving survival of their offspring both played an important role in favoring the evolution of paternal care in insects.