Reproductive consequences of male body mass and aggressiveness depend on females' behavioral types

• Published in: Behavioral ecology and sociobiology 2011-10, Vol.65 (10), p.1957-1966
• Main Authors: Pruitt, Jonathan N., Riechert, Susan E., Harris, David J.
• Format: Article
• Language: English
• Subjects: Animal behavior; Animal Ecology; Animal reproduction; Araneae; Behavioral Sciences; Biomedical and Life Sciences; Egg masses; Eggs; Female animals; Females; Human aggression; Life Sciences; Male animals; Mating behavior; Original Paper; Phenotypic traits; Reproduction; Reproductive success; Risk reduction; Sexual selection; Spiders; Zoology
• ISSN: 0340-5443; 1432-0762
• DOI: 10.1007/s00265-011-1205-3

Relatively few investigations explicitly test for concordant versus conflicting selection pressures from intrasexual versus intersexual selection. Here, we examine the effects of male body mass and behavioral type (BT) on reproductive success in the spider Anelosimus studiosus, with emphasis placed on the potential interaction between intrasexual and intersexual selection influences. Female A. studiosus exhibit either an aggtvssive-active or docile passive BT, both of which co-occur in multifemale colonies. Males, in contrast, exhibit a more continuous distribution of behavioral tendencies. We investigated the male traits favored by females in five trial types: one docile female, one aggressive female, four docile females, four aggressive females, and two docile and two aggressive females. Male reproductive success was estimated by the number eggs produced by females following staged mating trials. In previous work, it was established that large aggressive males are favored in male-male contests, an intrasexual effect. However, large aggressive males were not universally favored here. We failed to detect an effect of male body mass or aggressiveness on reproductive success in trials with all docile females; however, in situations involving aggressive females, large aggressive males experienced diminished reproductive success relative to small docile males. Large, aggressive males were also more likely to be attacked and killed by aggressive females in the first 20 min of staged encounters and were more likely to be found dead after 72 h of unobserved interactions. Taken together, our data suggest that the reproductive consequences of male traits differ based on (1) the aspect of sexual selection being considered (intrasexual versus intersexual) and (2) the BT of their prospective mates: large aggressive males enjoy advantages in intrasexual selection and when courting docile females and small docile males experience reduced risk of cannibalism and increased reproductive success with aggressive females.