Elements of fish metacommunity structure in Neotropical freshwater streams

The identification of the mechanisms underlying co-occurrence
patterns of species is
a way to identify which processes
(niche, neutral or both) structure metacommunities. In this
paper, our goals are to identify patterns of co-occurrence in
neotropical stream fish and determine which
processes structure the metacommunity
and the gradients that underlie this
structure.  Our results pointed out
that the metacommunity formed by the total pool of species is
structured by a nested pattern (Hyperdispersed Species Loss) of
co-occurrence and the mass effect mechanism. On the other
hand, a set of core species displays a
Clementisian pattern and is structured by the species
sorting mechanism. Both, hyperdispersed species
loss and the Clementisian patterns point to a discrete
set of communities in the metacommunity. These communities could be
isolated by physicochemical conditions, or physical barriers, like dams or
waterfalls.