Meeting Abstract
92.1 Monday, Jan. 6 13:30 Coloniality in rotifers: Implications for survival and fitness WALLACE, R.L.*; WALSH, E.J.; WEBER, K.; RICO MARTINEZ, R.; DAS, S.; Ripon College; University of Texas at El Paso; University of Texas at El Paso; University of Texas at El Paso; University of Texas at El Paso wallacer@ripon.edu
Colonial life in rotifers presents significant tradeoffs. In terms of survival, it provides protection from tactile predators with limited gape size; however, their larger size puts colonies at risk from visual predators. Here we investigate the role of epidermal warts found at the anterior of Sinantherina socialis as deterrents to predation. We hypothesized that both individuals and colonies are rejected as prey due to a defense mechanism related to the warts. Wart morphology was investigated using lipid specific stains to elucidate compounds within the wart. In predation experiments, colonies showed increased survival rates in the presence of predators as compared to alternate prey (Daphnia). Individuals also showed increased survival in the presence of predators, but were consumed slightly more than colonies. Nearly all prey survived in the absence of a predator, indicating some level of protection afforded to individuals, but that it is not as strong as in intact colonies. In addition, we found high concentration of lipids in warts supporting the hypothesis that the warts hold unpalatable substances that function in defense. Unpalatable lipids have been observed in other animals, including mites, and may function in a similar way in S. socialis. Coloniality also poses challenges to mating. In solitary species, males circle females before mating, but in colonies access to a female may be impeded. Mating in S. socialis differed in two ways. (1) Duration of the circling phase is protracted for males encountering colonial v. solitary females. Males encountering single females behave similarly to those of solitary species. (2) Duration of copulation in S. socialis is the shortest reported for any rotifer species. The rarity of coloniality in rotifers may be a consequence of these tradeoffs.
