CLINAL VARIATION IN MALE-TO-MALE ANTAGONISM AND WEAPONRY IN A SUBSOCIAL MITE.

Male aggressiveness is highly variable among populations of a subsocial spider mite that occurs throughout Japan. The average level of aggressiveness is positively correlated with mean winter temperature and with the relative size among males of leg I, which is used as a weapon in this species. The relatedness of males within nests is influenced by rates of overwinter survival, with high survivorship leading to low relatedness, increased aggressiveness, and larger legs I. Within this species, variation in the intensity of sexual selection may therefore be influenced both by natural selection and by kin selection. © 1995 The Society for the Study of Evolution.