A Global Assessment of Parasite Diversity in Galaxiid Fishes

Rachel A Paterson,Gustavo P Viozzi,Carlos A Rauque,Robert Poulin,Verónica R Flores

doi:10.3390/d13010027

Abstract

Free-living species often receive greater conservation attention than the parasites they support, with parasite conservation often being hindered by a lack of parasite biodiversity knowledge. This study aimed to determine the current state of knowledge regarding parasites of the Southern Hemisphere freshwater fish family Galaxiidae, in order to identify knowledge gaps to focus future research attention. Specifically, we assessed how galaxiid–parasite knowledge differs among geographic regions in relation to research effort (i.e., number of studies or fish individuals examined, extent of tissue examination, taxonomic resolution), in addition to ecological traits known to influence parasite richness. To date, ~50% of galaxiid species have been examined for parasites, though the majority of studies have focused on single parasite taxa rather than assessing the full diversity of macro- and microparasites. The highest number of parasites were observed from Argentinean galaxiids, and studies in all geographic regions were biased towards the highly abundant and most widely distributed galaxiid species, Galaxias maculatus. Parasite diversity generally increased with the number of studies and individual fish examined, however studies which examined parasites from all body tissues could overcome the effects of low study effort. In order to promote further understanding of galaxiid–parasite biodiversity, we provide a series of recommendations, including the use of molecular techniques to verify parasite identity, and highlight the future roles both fish biologists and parasitologists can play.

Highlights

Parasites represent an often neglected, yet numerically and functionally important, component of global biodiversity [1]
Whilst a greater number of parasite taxa were documented from Argentinean galaxiids overall (Figure 1a), pairwise comparisons of slope estimates demonstrated that the number of parasites reported from Argentinean galaxiids showed the least variation from the least to the most studied galaxiid species (n studies/n parasite taxa: A. zebra 3/18; Ga. maculatus 48/37) compared to all other geographic regions (Tables A1 and A2)
An increasing number of studies had the strongest influence on the number of parasite taxa reported from Chilean galaxiids, ranging from a single A. taeniatus study reporting one parasite to 23 parasite taxa recognized from 14 Ga

Summary

Introduction

Parasites represent an often neglected, yet numerically and functionally important, component of global biodiversity [1]. At the geographic region scale, parasite diversity is strongly linked to the number of potential host species, which in turn is associated to a region’s size (e.g., [9,10]), with larger geographical regions supporting a greater number of both host and parasite species. At the host species scale, parasite diversity is often linked to a series of host-specific ecological traits (e.g., body size, geographical range, diet), phylogenetic history (e.g., evolutionary age or distinctness), and environmental factors (e.g., latitude [11,12]). Host body size, geographical range size, and population density have been shown to be consistent drivers of parasite species richness across a wide range of host groups [13], with a greater variety of parasites likely to be encountered for those host species which occupy large geographical ranges and/or are large-bodied [14,15]

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Conclusion