Sex and age differences in skull size in Myodes glareolus from Slovakia

The results of a craniometric analysis of the bank vole (Myodes glareolus) were evaluated in this study. Twenty cranial variables were measured and evaluated on 149 skulls (78 males, 71 females) with respect to sex and age. The main aim of this study was to test the sexual dimorphism in skull size. Overall, our results showed that on average, the values for adult and subadult females of M. glareolus were higher than for males. Results presented here thus reveal sexual differences in the measured cranial traits, most expressed for the length of the mandible and the height of the mandible. The effect size was very large for the length of the first upper molar. Comparison of our results with those from other countries confirmed that there are regional differences. These findings highlight the need for craniometric analysis of species also at the regional level.

Craniometric Analysis of European Rabbit (Oryctolagus Cuniculus) Breeds to Trace out Intraspecific and Inter Gender Morphometric Variations

The family Liproidae expresses the significant variation of morphometric features at species level. In already available literature on the European rabbit (Oryctolagus cuniculus) the idea is proposed that there can be variation in the morphometric character of different breeds of Oryctolagus cuniculus but there are negligible scientific research base evidences for it. So in this study interbreed craniometric comparison of the European rabbit is carried out to trace out their intergender and intraspecific morphometric variations. The study material consists of 32 sexually mature rabbits belong to two breeds of European rabbit that are New Zealand rabbit (eight males and eight females) and American Dutch rabbit (eight males and eight females) collected from different districts of the Punjab, Pakistan. There were 29 different measurements taken from the skull and mandible of both breeds by using digital and manual verniar calipers. The results of this study have revealed that there is significant interbreed variation in the nasal length measurement of the New Zealand and American Dutch rabbit. This significant interbreed difference in nasal length is observed in both female as well as male rabbits (p=0.0059 and 0.0069 respectively). The current study also depicts that inter gender craniometric variations exist in the New Zealand as well as American Dutch rabbit. The standard deviation of the foramen magnum index of the both included breeds is comparatively higher than all the other included morphometric features. This study provides the baseline data on interbreed craniometric variations in the Oryctolagus cuniculus.

Biomes, geology and past climate drive speciation of laminate-toothed rats on South African mountains (Murinae: Otomys)

Mitochondrial DNA sequences (1137 bp) of the cytochrome b gene and craniodental and craniometric data were used to investigate the evolutionary relationships of six putative rodent taxa of Otomys (family Muridae: subfamily Murinae: tribe Otomyini) co-occurring in the Western Cape and Eastern Cape provinces of South Africa. Phylogenetic analysis of 20 new sequences together with craniodental and craniometric characters of 94 adult skulls reveal the existence of a unique lineage of Otomys cf. karoensis (named herein Otomys willani sp. nov.) from the Sneeuberg Centre of Floristic Endemism in the southern Drakensberg Mountain Range. Craniometric analysis distinguished O. karoensis from O. willani and identified a further four localities in the range of the latter species. We document southern range extensions of both Sloggett’s ice rat, Otomys sloggetti, and the vlei rat Otomys auratus to the Sneeuberg Mountain Range, in addition to appreciable genetic divergence between Sneeuberg and southern and central Drakensberg populations of O. sloggetti. Our results demonstrate parallel patterns of cryptic speciation in two co-occurring species complexes (Otomys irroratus s.l. and O. karoensis s.l.) associated closely with the boundaries of biomes (fynbos vs. grassland biomes) and geological formations (Cape Fold Belt vs. Great Escarpment).