Natural selection favors snails with slower metabolisms . Roberto Nespolo and Paulina Artacho, from the Austral University of Valdivia, have reached this conclusion after studying almost a hundred garden snails ( Helix aspersa ) and comparing their base metabolic rate (SMR), an index of the minimum energy they need an animal to stay alive.
The results reveal that snails that survived for at least seven months had 20% slower metabolism than those with only the shell left. As Nespolo and Artacho explain in the latest issue of Evolution magazine, snails with slower metabolisms are ahead because they have greater energy reserves to devote to other activities , such as growth or reproduction . In this way, an old biological hypothesis that links energy expenditure to life expectancy has been confirmed, and that previously had been tried without success in rodents. With the snails it has been different because it is easier to keep track of them. "We were able to recover the dead because the snails leave their shells behind, and because they do not move more than a couple of meters per year," the authors of the research explain. Now it only remains for them to find out if the slow metabolism is also related to the parsimony of the movements of these gastropods.
E.Sanz
