Competition Between Native and Exotic Daphnia
Date of Graduation
Master of Science in Biology
Parasites can influence traits related to the fitness of the host, including host behavior. I studied the behavior of the Ozark zigzag salamander (Plethodon angusticlavius), that was naturally infected with the larval stage of an ectoparasitic mite (Hannemania eltoni) to determine if parasitism was associated with altered behavioral patterns. Experiments were designed to answer three specific questions: (1) Can level of parasitism be detected via chemical cues by conspecifics? (2) Does level of parasitism influence agonistic behavior of males in male-male interactions? and (3) Is parasitism associated with altered foraging behavior of females? In experiment 1, males and females were tested in separate two-choice experiments in the following test conditions: (a) fecal pellet of male with low parasite load versus fecal pellet of male with high parasite load, (b) fecal pellet of male with low parasite load versus control (chemical blank) pellet, and (c) fecal pellet of male with high parasite load versus control pellet. Non-parasitized females spent significantly more time near fecal pellets of males with low parasite loads in test condition (a). Males with low parasite loads spent significantly more time near control pellets, whereas males with high parasite loads spent significantly more time near fecal pellets of males with high parasite loads in test condition (c). Behavior of males and females was influenced by their levels of infection. In experiment 2, levels of aggression for males with low parasite loads were not different between symmetric and asymmetric contests (where the asymmetry was the level of parasitic infection). However, males with high parasite loads were significantly less aggressive in asymmetrical contests thatn in symmetrical contests. Furthermore, males with high parasite loads were overall less aggressive than males with low parasite loads. Finally, in experiment 3, the latency to first capture was significantly longer for infected females than non-infected females, although the total number of prey captured was not different between the two groups of females. These data taken together indicate that subtle alterations in behavior of infected individuals may have potential fitness consequences.
© Jennifer Lynne Cacka
Cacka, Jennifer Lynne, "Competition Between Native and Exotic Daphnia" (1998). MSU Graduate Theses. 92.