Role of the isopod Anilocra partiti in the health, behavior and mating success of the bicolor damselfish, Stegastes partitus

Date of Award




Degree Name

Doctor of Philosophy (Ph.D.)



First Committee Member

Steven M. Green - Committee Chair


Parasites not only reduce the health and fecundity of their hosts but they can also reduce host fitness by changes in the behavior of hosts and in mate selection by potential mates. The mate of a parasitized individual can suffer via direct parasite transfer to itself or its offspring, reduced fecundity of its mate, diminished parental care provided by the parasitized mate, or poor quality offspring if parasitism indicates genetic quality.I examined the relationship between the large, ectoparasitic isopod Anilocra partiti that was found on 15.0% of its host, the bicolor damselfish, Stegastes partitus, in St. Ann's Bay, Jamaica. Parasitized individuals suffered reduced hematocrit but no immunological response was detectable. Relative to non-parasitized fish, parasitized fish were in poorer condition and females suffered a 21.3% decrease in ovary mass.There did not appear to be any effect of microscopic ectoparasites on the health or mating success, as measured by the amount of eggs obtained, of their hosts, and the presence of A. partitidid not seem to affect the presence of these parasites. Naturally and experimentally parasitized male S. partitus had much lower mating success that non-parasitized conspecifcs. When experimentally parasitized, male hosts experienced an apparent, immediate decrease in mating success. This decrease occurred before changes in health or courtship rate were apparent implying that females selected against parasitized males solely on the presence of Anilocra rather than its effects on the male's health. The courtship rate of parasitized males eventually diminished. Some parasitized males mated successfully after three months. A smaller proportion of parasitized than non-parasitized males acquired eggs, but those parasitized males that mated successfully received as many eggs as the non-parasitized males. The reduced courtship rate in parasitized males was partially responsible for their reduced mating success, but the presence of the parasite alone also contributed to this reduction. Parasitized males did not differ in their success at rearing eggs to hatching. Although these males differed somewhat in their egg care behaviors, they did not differ in the amount of time spent in the nest when eggs were present.


Biology, Ecology; Biology, Oceanography; Biology, Zoology

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