The existence of sexual dimorphism in the White Rasquera goat breed has long been known, with males being larger than females. However, no study so far has explored this dimorphism separately in its size and shape components. Here we analysed twenty-three skeletonized skulls from adult animals (11 males and 12 females) belonging to this breed by means of geometric morphometric (GM) methods using 7 landmarks on dorsal aspect. Differences observed between the sexes are size related, with males bigger than females. Shape is also an important component separating males from females. The difference in skull form between sexes may be interpreted in relation to extensive management styles of the animals: being under a low anthropogenic influence they tend to reinforce their natural sexual size dimorphism. This being the first known study to apply GM to a domestic goat breed, we advocate for further GM research in domestic breeds in order to have the possibility of comparing populations and easily exchanging information between research centres.
Developmental instability theory suggests that variation in some body parts in part can reflect the ability to buffer development from key environmental and genetic perturbations. Support for this approach comes mainly from assessment of fluctuating asymmetry, or deviations from symmetry of body features that are symmetric at the population level. In order to study dental asymmetry in domestic goats, we sampled 22 adult goat skulls. Bucco-palatine and mesio-distal distances (width and length) of the second molar on each side for each skull, on their occlusal aspect, were measured and compared using standard lineal methods. There was evidence of directional asymmetry, that is, unilateral mastication habits, being the left teeth of the arch slightly but systematically longer than the right. This directional change supported a right chewing side preference in the sample. It is important to highlight that the sample comes from non-pathological specimens. Therefore, it does depict the sample population of animals used in general. The observed asymmetries was not associated with any other cranio-facial abnormalities.
The size of body parts often co-vary through exponential scaling, this is known as allometry. Allometric changes are important to the generation of morphological diversity. To make inferences regarding the evolved responses in allometry to artificial selection in the genus Equus, we compared allometric parameters (slope and intercept) among 18 domestic breeds (11 for horses and 6 for donkeys) and 7 wild species, attempting to interpret the differences in allometric parameters (body length, withers height and head length). The allometric values were not different among domestic equids. Breeds of similar sizes have similar head lengths. The elongation of head length is related to overall body size, indicating that allometry was invariant and did not change under specific selection in the breed formation. Head elongation (dolicocephaly) is probably focused on the preorbital region (dolicoprosopial) rather than on basicranial region. A remarkably higher correlation among donkey breeds can be explained by its strong similar morphological evolution. These findings provide evidence that changes in the allometry pattern point to modifications of ontogenetic processes derived from breeds differentiation and evolution. Further analysis should focus on the relationship between ancestral ontogeny and adult morphology in equids.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.