AbstractsBiology & Animal Science

Higher ectoparasite richness and abundance in introduced red lionfish («Pterois volitans») at low latitudes: implications for biotic resistance and enemy release

by Andrew Sellers Lara

Institution: McGill University
Department: Department of Biology
Degree: MS
Year: 2014
Keywords: Biology - Ecology
Record ID: 2045454
Full text PDF: http://digitool.library.mcgill.ca/thesisfile127160.pdf


Several hypotheses have been proposed to explain the role of parasites and pathogens in biological invasions, however two fundamentally related hypotheses are most prevalent in the literature: the Enemy Release Hypothesis (ERH) and the Biotic Resistance Hypothesis (BRH). The ERH predicts that introduced species escape the negative effects of parasites present in their native range. This release is postulated to benefit invaders when interacting with native species in their introduced range. On the other hand, parasites in the introduced range can colonize and accumulate in the introduced host if they are able to shift from closely related native host species; this accumulation of parasites in the introduced range can potentially offset the benefits of enemy release. Thus, in contrast to the ERH, the BRH predicts that biotic interactions, such as parasitism, can limit the success of introduced species in their new range. This resistance by enemies in the introduced range is thought to be stronger at low tropical latitudes compared to higher latitudes. For the first component of my thesis I used the rapid and widespread invasion by the Indo-Pacific lionfish as a natural experiment to determine whether introduced lionfish accumulate more parasites and experience a greater effect of parasites at low latitudes. I compared the diversity, abundance, and impact of parasites infecting this invader across latitudes from Florida to Panama. I predicted that while overall lionfish would be infected by few parasites, their abundance and species richness would increase at low tropical latitudes. The second part of this thesis considers the accumulation of parasites from native hosts onto the invasive lionfish and begins to examine one prediction of the enemy release hypothesis. For this I compared parasite richness and abundance between lionfish and three ecologically similar native fishes. I expected that some parasites from native hosts would colonize lionfish, but predicted that natives will be more heavily parasitized and experience a stronger effect of parasites overall.My results are consistent with previous studies of latitudinal patterns of parasitism in native fish; ectoparasite diversity and abundance increased at low latitudes, but endoparasites did not follow a latitudinal pattern. Although ectoparasite species richness and abundance increased at low latitudes I did not find a significant effect of parasite abundance on the condition of lionfish. In comparing parasitism across host species, both native hosts were infected by a greater species richness and abundance of parasites compared to introduced lionfish. Furthermore, parasite abundance had a significant effect on the condition of the native grouper Cephalopholis cruentata, but I did not detect such an effect on the lionfish. Combined, my results show that introduced lionfish accumulate more parasites at lower latitudes, however parasitism in the invader may be too low to generate biotic resistance. Relative to lionfish, native hosts were more heavily parasitized,…