IIMYC   23581
INSTITUTO DE INVESTIGACIONES MARINAS Y COSTERAS
Unidad Ejecutora - UE
artículos
Título:
Ontogenetic changes in heterogeneity of parasite communities of fish: disentangling the relative role of compositional versus abundance variability
Autor/es:
TIMI, JUAN T.; LANFRANCHI, ANA L.
Revista:
PARASITOLOGY
Editorial:
CAMBRIDGE UNIV PRESS
Referencias:
Lugar: Cambridge; Año: 2013 p. 309 - 317
ISSN:
0031-1820
Resumen:
In order
to determine how much of the variability in parasite assemblages is driven by
differences in composition or in abundance we used multivariate dispersions (average distance from infracommunities to their size class centroid
in the multivariate space) as a measurement of β-diversity in infracommunities of
Conger orbignianus, applying a set of dissimilarity measures with different
degrees of emphasis on composition versus relative abundance information. To
evaluate comparatively the rate of such changes, we also analysed the effect of
host size by regressing differences in β-diversity among size classes against
differences in mean fish size. Multivariate dispersions varied along an
ontogenetic gradient, its significance depending on the measurement used.
Larger fish showed higher richness and abundance; however, smaller fish displayed
lower variations in abundance but higher in composition. This could be caused
by stochastic encounters at low densities due to the overdispersion of
parasites in previous hosts. As fish grow, the composition of their parasite
assemblages becomes homogenized by repeated exposure, with abundance thus
arising as the main source of variability. Both variables act at different
rates, with the exponential decay in the compositional variability as differences
in fish size increase being about twice as steep as the decay in abundance
variability, indicating that compositional homogeneity is reached faster than abundance
heterogeneity as fish grow. Discerning between both variables is crucial in
order to understand how community structure is formed by size-dependent
variability of host populations.