Search

Additional file 3. Table S3 Procrustes ANOVAs of shape. % total—percentage of the total shape variation. Age categories: A1—first age category, A2—second age category, A3—third age category

Additional file 1. Table S1 Anatomical definitions of landmarks recorded on the labial view of the mandible and the ventral surface of the cranium of the yellow-necked field mouse (Apodemus flavicollis)

Additional file 2. Table S2 ANOVAs of centroid size (CS). % total—percentage of the total size variation. Age categories: A1—first age category, A2—second age category, A3—third age category

Additional file 4. Table S4 ANOVAs of centroid size (CS). % total—percentage of the total size variation. Categories regarding parasitism: P0—non-parasitized animals, P1—animals parasitized by one nematode species, P2—animals parasitized by two nematode species, P3—animals parasitized by three to five nematode species

We conducted a comparative (2D landmark-based geometric and traditional) morphometric analysis on tadpoles at early developmental stages. Two species of brown frog (Rana dalmatina and R. temporaria) and the common toad (Bufo bufo) were involved, all raised in the laboratory from fertilized eggs collected in their natural habitat. Taxonomic identification was confirmed by the DNA barcoding method with the 16S rRNA sequence as the gene marker. Interested to compare the methodologies for quantification and description of morphological differences among tadpoles of mentioned species, we aimed to: 1) calculate interspecies genetic distances as the most relevant measurement for species differentiation, 2) determine and describe size and shape variation, 3) identify relationships among the analyzed species at the morphological level and 4) assess their classification accuracy. Within the framework of the specified aims, both methodologies produced very similar results, i.e., the smallest divergence was between R. dalmatina and R. temporaria, while the most discriminative were B. bufo and R. temporaria. However, we observed subtle shape variation of the distal region of the tail that was detected only by the geometric morphometrics. Our findings support the following. Geometric morphometric method captures more subtle shape differences that were unable to be recovered from linear measurements. It performs slightly better in classification rate. Although it was not quantified, it stands to reason that there is no difference in time investment between the two approaches. Geometric morphometrics provides more information that can be leveraged to answer further questions and it has a clear advantage in visualizing.

Većina dosadašnjih istraživanja strukture i obrazaca varijabilnosti glavenog skeleta odnosila su se na grupe sa akinetičkom lobanjom. Istraživanje kinetizma u okviru glavenog skeleta zmija može doprineti boljem razumevanju odnosa razvojne i funkcijske integracije, uticaja alometrije na varijabilnost oblika i morfološku integraciju glavenog skeleta, promena oblika tokom ontogenije, kao i morfološke divergencije između polova. Pored toga, analizama varijabilnosti pileusa može se steći uvid u opštu sliku varijabilnosti glavenog regiona. Osnovni zadatak ove disertacije je utvrđivanje obrazaca morfološke varijabilnosti i faktora koji utiču na varijabilnost glavenog skeleta i pileusa kod dve sestrinske vrste zmija iz roda Natrix (belouške, N. natrix i ribarice, N. tessellata) primenom metoda kompjuterizovane tomografije i geometrijske morfometrije. Rezultati su pokazali da se belouška i ribarica razlikuju u veličini i obliku elemenata glavenog skeleta. Uočene razlike najverovatnije odslikavaju razlike u tipu i veličini plena, sredini u kojoj love, strategijama lova i sposobnostima držanja i gutanja plena. Polni dimorfizam u veličini i obliku elemenata glavenog skeleta veoma je izražen kod belouške i ribarice. Kod obe vrste moždana čaura i elementi trofičkog aparata su visoko integrisani, dok se kosti njuške ponašaju kao zasebni moduli. Funkcija najviše doprinosi integrisanosti elemenata glavenog skeleta. Utvrđeno je da se tek rođene belouške i ribarice razlikuju u obliku pileusa, dok se unutar vrsta polni dimorfizam u obliku pileusa ispoljava tek kod adulata. Između moždane čaure i pileusa ustanovljeni su visoki nivoi korelisanosti, kako za veličinu, tako i za oblik. Most of the previous investigations on the structure and patterns of cranial skeletons variability were done in groups with akinetic skull. Research of snake’s kinetic cranial skeleton can provide a better understanding of the relationship between developmental and functional integration, influence of allometry on shape variation and morphological integration of the cranial skeleton, shape changes during ontogeny, as well as morphological divergence between the sexes. In addition, analysis of pileus variability may provide insight into general pattern of head variability. The main aim of this thesis was to define the patterns of morphological variability and factors that affect the variability of head skeleton and pileus in two sister snakes species from the genus Natrix (Grass snake, N. natrix and Dice snake, N. tessellata) using the methods of computed tomography and geometric morphometrics. The results showed that N. natrix and N. tessellata differ in size and shape of cranial elements. Observed differences probably reflect differences in the type and size of the prey, hunting environment and strategies, handling abilities and prey swallowing. Sexual dimorphism in size and shape of cranial elements are pronounced among Grass and Dice snakes. In both species, braincase and elements of the trophic apparatus are highly integrated, while the bones of the snout can be considered as separate modules. The function is the main factor of morphological integration between cranial elements. Hatchlings of Grass and Dice snakes differed in pileus shape, while sexual dimorphism in pileus shape was detected in adults only. For both size and shape, high levels of correlation between braincase and pileus were estimated.