Detalle de: Niche segregation factors in an assemblage of pelagic rotifers of a deep high-mountain lake (Redon, Pyrenees)

The niche space of a species has been defined as the region in N-dimensional \nenvironmental hyperspace in which the fitness of the individuals is positive. In zooplankton \nassemblages, there has been little consideration of how different density-dependent (i.e. resources) \nand density-independent (i.e. conditions) environmental factors relate to fitness components in the \nfield, namely survival and reproduction. We studied the abundance and reproduction (egg ratio) \nvariability of seven species of pelagic rotifers living in a high-mountain lake and their relation to a \nnumber of environmental factors by means of partial canonical correspondence analyses. The \ngenerally higher explanatory capacity of conditions over resources suggests that habitat \npartitioning among species largely relies on historical processes, which are internalised in life \nhistory traits of spatial and temporal habitat use. However, the increase in the relevance of \nresources when considering reproduction, as compared to abundance, indicates that there is still an \non-going interactive niche segregation process among rotifer species, which affects present and \nfuture rotifer assemblages in the lake. Our study shows the value of considering measurements \nclose to fitness components (e.g. egg ratio) for detecting on-going niche segregation processes in \nzooplankton, which may help to resolve paradoxes in relation to species coexistence in natural \nassemblages.