Roost size for multilevel selection of altruism among vampire bats

Abstract

In this paper we analyse the roosting effect among artificial vampires as a way to preserve altruism from cheaters exploitation. We simulate the formation and maintenance of new social structures (roosts) from initial populations as a consequence of both demographic growth and social organisation. Food-sharing among vampire bats (Desmodus Rotundus) is a well-known form of altruism, necessary for the survival of this species, supported by wide ethological evidence. By means of simulation, we study the performance of the system under varying mutation rate (giving rise to cheaters that exploit the altruistic mechanism) and roost size. Results show that the roosting effect can cope with sensible mutation levels. Moreover, the most robust size of roosts indicated by our simulations is shown to be comparable with the size actually found in nature. © Springer-Verlag Berlin Heidelberg 2007.