Morphometric analysis of mandibles of rats, genus Rattus (Fischer, 1803)

Tema tega diplomskega dela je bila morfometrična analiza variabilnosti leve čeljustnice pri treh vrstah podgan z različnih geografskih območij. Vir podatkov je predstavljalo 488 primerkov spodnjih čeljustnic, pridobljenih iz štirih muzejskih zbirk. Analiza je potekala na vrstah Rattus rattus (črna podgana), Rattus pyctoris (himalajska podgana) in Rattus tanezumi (orientalska podgana). Namen dela je bil s pomočjo geometrijske morfometrije analizirati geografsko variabilnost in sekundarni spolni dimorfizem znotraj vrste ter morfološko variabilnost med vrstami. Po določitvi 14 oslonilnih točk na čeljustnicah smo opravili uni- in multivariatne analize, pri čemer je analiza velikosti in oblike čeljustnic potekala ločeno. Ugotovili smo, da sekundarni spolni dimorfizem ni bil izražen pri nobeni od vrst. Vrste so se med seboj razlikovale v velikosti in obliki čeljustnic. Največje čeljustnice so imeli osebki vrste R. rattus, najmanjše pa R. pyctoris. Med vrstama R. pyctoris in R. tanezumi ter R. pyctoris in R. rattus so bile odkrite signifikantne razlike v velikosti čeljustnic, medtem ko je bila razlika med vrstama R. rattus in R. tanezumi statistično naključna. Analiza geografske variabilnosti vrst je pokazala, da so bile znotraj vrst R. rattus in R. tanezumi razlike v velikosti in obliki čeljustnic signifikantne, medtem ko znotraj vrste R. pyctoris ni bilo geografske variabilnosti v velikosti in obliki. Velikost čeljustnic pri R. rattus v bližini in južneje od ekvatorja je bila manjša v primerjavi s čeljustnicami severnejših regij. Pri R. tanezumi so bile najdene razlike v velikosti čeljustnic osebkov iz otoških in celinskih regij, pri čemer so bile čeljustnice osebkov otoških regij večje od čeljustnic osebkov iz celinskih regij.This thesis deals with the analysis of morphometric variability of the left mandible in rats, genus Rattus. 488 specimens, acquired from 4 different museum collections, were used as the data source. Three species were included in the research: Rattus rattus (Black rat), Rattus pyctoris (Himalayan rat) and Rattus tanezumi (Oriental house rat). The main objective of this work was to determine as to whether sexual dimorphism and geographic variability is present within a species and if morphological variability occurs between these three species. After defining 14 landmark points on each mandible, the uni- and multivariate statistical methods were used to perform the analysis, while the analysis of size and shape was carried out separately. The analysis confirmed the assumption that sexual dimorphism within a species was not present in any of analysed species. The analysis, however, confirmed the interspecific deviation of mandible size and shape. Specimens of the species R. rattus had the largest mandible, followed by R. tanezumi and R. pyctoris. Between R. pyctoris–R. tanezumi and R. pyctoris–R. rattus a significant difference in the size of the mandible was noted, whereas the difference between R. rattus–R. tanezumi was statistically insignificant. The analysis of intraspecific geographic variability noted a significant difference of mandible size and shape in two rat species, namely R. rattus and R. tanezumi. The mandibles of the species R. rattus collected around and south of the equator were smaller than those collected in northern regions. The differences were also pronounced in R. tanezumi. Moreover, the mandibles collected on island-regions were larger than those found on mainland. Geographic variability in R. pyctoris was not confirmed