Offering European minks a better chance of survival in the wild
The European mink (Mustela lutreola) is one of the most endangered mammal species in Europe. The main reasons for its decline were habitat degradation and extensive hunting. The arrival of the invasive American mink was the last straw. Brought to Europe for fur farming, the American mink escaped and displaced the smaller European species throughout Europe. Research data suggest that American minks outcompete their European counterparts through interspecific aggression. Owing to their larger size and higher capability to adapt, American minks are always the winners when the two species interact in the habitats they both want to occupy.
A complex relationship between skull morphology, biting mechanics and foraging
“Knowledge of the biting mechanics (feeding biomechanics) of alien and invasive species could largely contribute to preserving the European mink. First, it could help us identify areas where the available food items promote the survival of the European mink. Second, it could facilitate the development of innovative target-specific solutions to controlling American mink populations,” notes Philip Cox, associate professor in the Centre of Integrative Anatomy at the University College London and coordinator of MINKS, a project funded by the Marie Skłodowska-Curie Actions programme. In the context of MINKS, researchers used a large sample of mink skulls and lower jaws (over 200) borrowed from certain natural history museums across Europe. These specimens were scanned using microcomputed tomography. The variation in shape across the samples was analysed with geometric morphometrics – a landmark-based statistical shape analysis methodology. To elucidate the relationship between morphology and feeding biomechanics, researchers analysed the attachment sites of the muscles closing the jaw on the skull. The study allowed them to determine how efficient each muscle is at converting muscle force to biting force. The findings served as input for creating theoretical dietary profiles for each sex and species.
Findings assisting conservation strategies
“We found that European mink jaws are optimised for fast jaw closures and strong bites with their shearing teeth, whereas the American mink jaws are built for strong bites at the front teeth and powerful crushing with their back teeth,” explains Eloy Gálvez-López, the Marie-Curie fellow working on MINKS. These differences in mandible shape and mechanics suggest that European minks are better suited to hunting aquatic prey, whereas their counterparts are better at small terrestrial vertebrates. Regardless of species and sex, morphological features in larger minks demonstrated increased capabilities for feeding on a wider range of prey. “In both species, larger individuals captured and processed a wider range of prey. Overall, this suggests that the invasive American minks (being larger) have a competitive advantage over the native European species. In particular, in the presence of American minks, female European minks are likely to be displaced from the optimal food sources necessary to survive and rear their young,” remarks Cox. “MINKS findings are expected to enhance understanding of the severe decline of the European mink in the presence of the invasive American mink. Importantly, they should assist conservation workers in identifying the habitats where European minks will most likely thrive. Furthermore, we deem that MINKS will provide a blueprint for studying other replacement instances of a native species by an invasive competitor,” concludes Cox.
Keywords
MINKS, European mink, American mink, jaw, skull, feeding biomechanics, mandible
