Diet and environment determine bacterial community composition in a socially polymorphic spider.
Emma I Dietrich, Emma Dietrich
University of Texas at Austin, USA ; University of Texas at Austin, USA
Though rare, sociality in spiders presents unique opportunities for studying invertebrate social evolution. One especially interesting species is Anelosimus studiosus, a socially polymorphic spider that lives in Central America and the Southeastern United States. Throughout most of its range, A. studiosus females are subsocial; adult females care for their young through trophallaxis, web maintenance, and protection from predators, juveniles cooperate in their natal nest, and adult females are aggressive toward other adult females. However, in higher latitudes, adults are occasionally found living in large colonies in which adults will cooperate in web maintenance, prey capture, and brood care. Despite many studies describing the behavioral ecology of this species, no study has been published on the bacterial communities it harbors, or how its social behavior could influence those bacterial communities. In this study, I used 16S rRNA metagenomics to investigate the structure of bacterial communities in wild-caught and lab-raised subsocial A. studiosus across latitudes in Central TX. In wild-caught individuals, I found that bacterial communities were largely determined by environment, as measured by sequencing the bacteria on their silk webs. In lab-raised individuals, I specifically measured the effects of diet, natal web, and molting behavior, and found that diet was a strong predictor of bacterial communities, if individuals did not harbor maternally inherited endosymbionts. In addition, preliminary studies show that social A. studiosus do not harbor more similar bacterial communities if in proximity for short periods of time. Current studies are following up on this research, to determine if certain bacteria identified in the 16s surveys are skewing sex ratios in social A. studiosus populations. In all, it is becoming clearer that this species may have a complex relationship with microorganisms that has been largely ignored until now.