Cranial shape variation in mink: Separating two highly similar species

Area of Science:

• Zoology
• Comparative Anatomy
• Evolutionary Biology

Background:

• European (Mustela lutreola) and American (Neovison vison) mink exhibit similar ecology and morphology.
• American mink, a generalist predator, are outcompeting European mink in introduced ranges, threatening native survival.
• Investigating morphological differences, specifically cranial shape, may explain the American mink's competitive success.

Purpose of the Study:

• To analyze cranial shape variation in European and American mink using 3D geometric morphometrics.
• To determine if morphological differences contribute to the American mink's competitive advantage.
• To study sexual dimorphism in size and shape within both species.

Main Methods:

• Utilized 3D geometric morphometrics with 38 landmarks and 107 semilandmarks.
• Analyzed cranial shape variation between and within European and American mink species.
• Assessed the influence of size on shape variation and studied sexual dimorphism.

Main Results:

• Significant cranial shape differences exist between species, but not size.
• European mink possess shorter faces, rounder foreheads, and wider orbits compared to American mink.
• Sexual dimorphism in shape is significant in American mink but not European mink; both species show size-related dimorphism.

Conclusions:

• Cranial shape differences, particularly related to masticatory muscle volume and bite force, likely contribute to the American mink's broader dietary range and competitive success.
• Morphological variations influence adaptation to anthropized environments and prey selection.
• Differences in muscle force and dietary range are evident between species, sexes, and individuals of varying sizes.