Abstract
Behavioral variation within a population is generally maintained by
frequency dependent selection allowing various personalities to coexist.
Bolder individuals usually engage in more risky behaviors that can gain
fitness benefits such as growth under certain conditions. Therefore, it
has been suggested that there should be a link between personality and
dietary niches, but the results so far are inconsistent. In addition,
the equilibrium of the distribution of behavioral traits and the trophic
niche of native populations may shift following the introduction of an
invasive species. Here, using the invasive brook trout (Salvelinus
fontinalis) and native brown trout (Salmo trutta) as model species in
two different natural streams in Sweden, we aimed to test whether 1) the
trophic niche of native brown trout living in allopatry and brown trout
living in sympatry with brook trout differ and 2) bolder brown trout
individuals utilize a different foraging niche. Our results suggest that
there is a dietary niche convergence between brown trout and brook
trout, which likely is a result of brook trout invasion, but that the
trophic niche of native brown trout varies across streams, possibly due
to difference invasion impact (varying ratio of brook trout to brown
trout). We also found a strong positive correlation between trophic
position and personality of brown trout irrespective of the presence of
brook trout.