Sammendrag
Wild animal populations experience selection pressures from both natural and anthropogenic
sources. The availability of extensive pedigrees is increasing along with
our ability to quantify the heritability and evolvability of phenotypic traits and thus
the speed and potential for evolutionary change in wild populations. The environment
may also affect gene expressions in individuals, which may in turn affect the
potential of phenotypic traits to respond to selection. Knowledge about the relationship
between the genetic and environmental components of phenotypic variation is
particularly relevant, given ongoing anthropogenically driven global change. Using a
quantitative genetic mixed model, we disentangled the genetic and environmental
components of phenotypic variance in a large carnivore, the brown bear (Ursus arctos).
We combined a pedigree covering ~1,500 individual bears over seven generations
with location data from 413 bears, as well as data on bear density, habitat
characteristics, and climatic conditions. We found a narrow‐sense heritability of 0.24
(95% CrI: 0.06–0.38) for brown bear head size, showing that the trait can respond to
selection at a moderate speed. The environment contributed substantially to phenotypic
variation, and we partitioned this into birth year (5.9%), nonadditive among‐individual
genetic (15.0%), and residual (50.4%) environmental effects. Brown bear
head circumference showed an evolvability of 0.2%, which can generate large
changes in the trait mean over some hundreds of generations. Our study is among
the first to quantify heritability of a trait in a hunted large carnivore population. Such
knowledge about the degree to which species experiencing hunting can respond to
selection is crucial for conservation and to make informed management decisions.
We show that including important environmental variables when analyzing heritability
is key to understanding the dynamics of the evolutionary potential of phenotypic
traits.
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