engleski

Possible character displacement of an introduced mongoose and native marten on Adriatic Islands, Croatia

Aim: Character displacement and release can occur quickly in novel environments and communities. Species introductions are "natural experiments" in which evolutionary changes can be studied as community composition varies. We asked whether morphologies of the introduced small Indian mongoose (Herpestes auropunctatus) and the larger native stone marten (Martes foina) on Adriatic islands where they are sympatric or allopatric are consistent with hypotheses of character displacement and release, respectively. Location: The mongoose is native to Asia and has been introduced to over 60 islands. We measured specimens from several island groups and the native region. The marten is native to Eurasia and several European islands, and we have measurements throughout most of its native range. Methods: We measured skull length and the maximum diameter of the upper canine tooth in both species on Adriatic islands and compared these traits with those in other sites. Results: The mongoose has smaller canines and skulls on the three Adriatic islands it co-occupies with the marten compared with other islands of introduction, are consistent with the hypothesis of character displacement. It is not larger on the Adriatic island where it is the sole carnivore than on other Adriatic islands, which contradicts the hypothesis of character release. Marten skulls are shorter on three islands with no mongooses than on one island where the mongoose is present, and this is consistent with the hypothesis of character release. However, marten canine diameters are similar across the Adriatic islands. Main conclusions: On the Adriatic islands, interspecific competition between the mongoose and the marten is most likely the driving force that maintains small size in the mongoose and prevents character release observed on the other islands of introduction that are lacking mammalian competitors. The marten may have undergone character displacement because of the mongoose introduction on at least one Adriatic island and possibly all three islands where the species co-occur.

Adriatic islands ; body size ; character release ; co-existence ; competition ; Herpestes auropunctatus ; insular carnivores ; mammals ; Martes foina ; sexual dimorphism

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