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Free keywords:
adaptation; environmental change; insular evolution; invasive species;
morphometrics; rodent; Sub-Antarctic island
Abstract:
Adaptation to new environments is a key feature in evolution promoting
divergence in morphological structures under selection. The house mouse
(Mus musculus domesticus) introduced on the Sub-Antarctic Guillou Island
(Kerguelen Archipelago) had and still has to face environmental conditions
that likely shaped the pattern and pace of its insular evolution. Since mouse
arrival on the island, probably not more than two centuries ago, ecological
conditions dramatically differed from those available to their Western European
commensal source populations. In addition, over the last two decades,
the plant and animal communities of Guillou Island were considerably modified
by the eradication of rabbits, the effects of climate change and the
spread of invasive species detrimental to native communities. Under such a
changing habitat, the mouse response was investigated using a morphometric
quantification of mandible and molar tooth, two morphological structures
related to food processing. A marked differentiation of the insular mice
compared with their relatives from Western Europe was documented for
both mandibles and molar shapes. Moreover, these shapes changed through
the 16 years of the record, in agreement with expectations of drift for the
molar, but more than expected by chance for the mandible. These results
suggest that mice responded to the recent changes in food resources, possibly
with a part of plastic variation for the mandible prone to bone remodelling.
This pattern exemplifies the intricate interplay of evolution, ecology
and plasticity that is a probable key of the success of such an invasive
rodent facing pronounced shifts in food resources exploitation under
a changing environment.
