Variability of native and invasive raccoon dogs’ Nyctereutes procyonoides populations: looking at translocation from a morphological point of view

Abstract

We have studied metric variability of two indigenous and five invasive populations of the raccoon dog (Nyctereutes procyonoides ussuriensis) by using 21 dental and cranial size-adjusted measurements. Material consisted of 532 the raccoon dog skulls. Sexual size dimorphism (SSD) in total was statistically significant for 12 characteristics. Males were larger than females by up to 7 %. In some populations, SSDs were not explicit. A relatively low SSD is a result of life strategy and characteristics of the raccoon dog as monogamous species with wide ecological niche. Females have more obviously interpopulation structure than males due to 10 significantly different measurements while males differ by eight measurements. In addition, females where correctly classified by discriminatory analysis in populations totalling 60.4 % and males in 52 % of cases. Introduced populations are characterised by bigger measurements in skull width in relation to indigenous ones. Raccoon dogs from Europe show increase of general length of the skull. Our study does not support definite geographical or temporal variation of the raccoon dog because its linear size did not correlate with geoclimatic parameters. The one exception is a dental measurement of females which depends on temperature and latitude predictors. Size variation of the raccoon dog in areas of origin and colonised regions should be discussed from different points of view. The main factors to shape spatial and temporal skull variation in the raccoon dog are net primary production of ecosystems, adaptability to ecologically different regions and stochastic factors such as founder effect, isolation of populations due to by human activity. Observed metric variability is not deep morphological segregation and stands mainly in frames of ancestral subspecies.