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Free keywords:
diversification; competitors; resource competition; niche pre-emption;
adaptive radiation
Abstract:
Competitors are known to be important in governing the outcome of evolutionary
diversification during an adaptive radiation, but the precise
mechanisms by which they exert their effects remain elusive. Using the
model adaptive radiation of Pseudomonas fluorescens, we show experimentally
that the effect of competition on diversification of a focal lineage
depends on both the strength of competition and the ability of the competitors
to diversify. We provide evidence that the extent of diversification in the
absence of interspecific competitors depends on the strength of resource
competition. We also show that the presence of competitors can actually
increase diversity by increasing interspecific resource competition. Competitors
that themselves are able to diversify prevent diversification of the focal
lineage by removing otherwise available ecological opportunities. These
results suggest that the progress of an adaptive radiation depends ultimately
on the strength of resource competition, an effect that can be exaggerated or
impeded by the presence of competitors.
