Richness, structure and functioning in metazoan parasite communities

Abstract

Ecosystem functioning, characterized by components such as productivity and stability, has been extensively linked with diversity in recent years, mainly in plant ecology. The aim of our study was thus to quantify general relationships between diversity, community structure and ecosystem functions in metazoan parasite communities. We used data on parasite communities from 15 species of marine fish hosts from coastal Chile. The volumetric abundance (volume of all parasite species per individual host, in mm 3 ) was used as a surrogate for productivity. Species diversity was measured using both species richness and evenness, while community structure was estimated using the co-occurrence indices V-ratio, C-score and a new C-score s index standardized for the number of host replicates. After correcting for fish size, 47% of host species show no relationship, 13% show a hump shaped curve and 40% show positive monotonic relationships between productivity and parasite richness across all host individuals in a sample. We obtained a logarithmically decreasing relationship between evenness and productivity for all fish species, and propose a 'dominance-resistance' hypothesis based on immunity to explain this pattern. The stability of the parasite community, measured as the coefficient of variation in productivity among individual hosts, was strongly and positively related to mean species richness across the 15 host species. The C-score s index, based on the number of checkerboard units in the host-parasite presence/absence matrix, increases linearly with mean productivity across the 15 host species, suggesting that parasite communities tend to be more structured when they are more productive. This is the likely reason why linear relationships between richness and productivity were not observed consistently in all fish species. Parasite communities provide some clear patterns for the diversity Á/ecosystem functioning debate in ecology, although other factors, such as the history of community assembly, may also influence these patterns.

Male hosts drive infracommunity structure of ectoparasites

“…We used the C score (Stone and Roberts 1990) as a metric of co-occurrence for each presence/absence matrix). The C score is a statistically powerful metric (Gotelli 2000) which is commonly used in null model analyses for a variety of plant and animal assemblages (Gotelli and McCabe 2002;Gotelli and Rohde 2002;Mouillot et al 2005;Krasnov et al 2006a;Tello et al 2008;Rooney 2008;Ellwood et al 2009). Detailed descriptions of the statistical properties and performance of the C score can be found in Gotelli (2000) and Gotelli and Rohde (2002).…”

Effects of small weirs on fish parasite communities

“…To assign the probability value to an observed C score, we used randomisation to construct a null distribution for the C score (Gotelli and Graves 1996). We selected the fixed-fixed algorithm (see Gotelli 2000 for more details) recently used by Gotelli and Rohde (2002), Mouillot et al (2005) to study parasites communities of marine fishes. For each presence-absence matrix, we created 5,000 random matrices by reshuffling the elements of each row of the matrix.…”

The importance of the compound community on the parasite infracommunity structure in a small benthic fish

“…During the last few decades, an increasing amount of metaanalyses and macroecological studies have been accumulated by parasite ecologists in an attempt to identify the key determinants of parasite community structure (Gotelli and Rohde 2002;Poulin 2004Poulin , 2007Mouillot et al 2005;Luque and Poulin 2008) searching for recurrent and predictable patterns to determine whether general rules determine the structure of parasite assemblages (Poulin 2007).…”

“…Species richness may be the single most important feature of a community (Poulin and Rohde 1997); however, it does not include all aspects of diversity ) and other features of parasitism, such as parasite abundance, measured either as number or biomass of parasites per host (George-Nascimento et al 2004;Mouillot et al 2005;Poulin and George-Nascimento 2007) as well as the use of average taxonomic distances between parasite species in an assemblage ) have been thus considered as an alternative measurement of diversity in parasite communities.…”