Análise craniométrica comparada entre cães domésticos e canídeos sul-americanos
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Data
2023-07-17
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Universidade Estadual Paulista (Unesp)
Resumo
Os cães domésticos (Canis lupus familiaris) possuem tanta variação na morfologia do esqueleto craniano (EC) quanto toda a ordem Carnivora. Esta variação resulta da seleção artificial mediada por humanos, a qual favoreceu a seleção direcional de genes envolvidos no desenvolvimento de ossos e cartilagens. Em contraste, canídeos selvagens apresentam menor variação do EC devido a restrições impostas pela seleção natural. Portanto, o uso de cães domésticos como base para a análise craniométrica comparativa de espécies de canídeos selvagens é uma estratégia promissora no estudo da evolução craniana. Neste trabalho, um conjunto de 124 cães domésticos foi utilizado na análise comparativa entre duas espécies de canídeos sul-americanos: o lobo-guará (Chrysocyon brachyurus, n = 9) e o cachorro-do-mato (Cerdocyon thous, n = 8). Um total de 18 medições craniométricas foram feitas a partir desses espécimes, e 8 índices craniométricos foram calculados a partir dessas medições. Uma análise de correlação evidenciou que as 26 variáveis podem ser agrupadas em: (i) indicadores de comprimento rostro-caudal, (ii) altura ventro-dorsal e largura látero-lateral, (iii) índices cranianos e (iv) dimensões do forame magno. A exploração destas correlações em uma Análise de Componentes Principais (PCA) mostrou que o EC do cachorro-do-mato se assemelha a pequenos crânios dolicocéfalos de cães domésticos, enquanto o EC do lobo-guará é mais próximo dos cães dolicocéfalos maiores. Uma craniometria indireta realizada por meio de imagens radiográficas não diferiu significativamente da análise direta, sugerindo a viabilidade de futuras avaliações in vivo. Estes resultados mostram a utilidade da craniometria comparada no estudo da ecologia e evolução de canídeos selvagens.
Domestic dogs (Canis lupus familiaris) possess as much variation in cranial skeleton (CS) morphology alone as all carnivores do as an entire order. Most of that variation results from human-mediated selective breeding, which favored the directional selection of genes involved in bone and cartilage development. In contrast, wild canids present lower within-species variation in CS morphology owing to the fitness constrains imposed by stabilizing natural selection. Therefore, the use of domestic dogs as the basis for comparative craniometric analysis of wild canid species is a promising strategy in the study of CS evolution. Here, a set of 124 domestic dogs were used in a comparative analysis with two species of South American canids, namely maned wolf (Chrysocyon brachyurus, n = 9) and crab-eating fox (Cerdocyon thous, n = 8). A total of 18 craniometric measurements were taken from these specimens and 8 craniometric indices were further computed from those measurements. A correlation analysis showed that the 26 variables could be clustered into: (i) indicators of rostro-caudal length, (ii) ventro-dorsal height and latero-lateral width, (iii) cranial indices and (iv) dimensions of the foramen magnum. The exploration of these correlations in a Principal Component Analysis (PCA) showed that CS of crab-eating foxes resembled small dolichocephalic skulls of domestic dogs, whereas the CS of maned wolves were closer to that of larger dolichocephalic dogs. An indirect craniometry performed using radiographic images did not differ significantly from traditional craniometric analysis, suggesting the feasibility of future in vivo craniometric evaluations. These results show the utility of comparative craniometric analysis in the study of ecology and evolution of wild canids.
Domestic dogs (Canis lupus familiaris) possess as much variation in cranial skeleton (CS) morphology alone as all carnivores do as an entire order. Most of that variation results from human-mediated selective breeding, which favored the directional selection of genes involved in bone and cartilage development. In contrast, wild canids present lower within-species variation in CS morphology owing to the fitness constrains imposed by stabilizing natural selection. Therefore, the use of domestic dogs as the basis for comparative craniometric analysis of wild canid species is a promising strategy in the study of CS evolution. Here, a set of 124 domestic dogs were used in a comparative analysis with two species of South American canids, namely maned wolf (Chrysocyon brachyurus, n = 9) and crab-eating fox (Cerdocyon thous, n = 8). A total of 18 craniometric measurements were taken from these specimens and 8 craniometric indices were further computed from those measurements. A correlation analysis showed that the 26 variables could be clustered into: (i) indicators of rostro-caudal length, (ii) ventro-dorsal height and latero-lateral width, (iii) cranial indices and (iv) dimensions of the foramen magnum. The exploration of these correlations in a Principal Component Analysis (PCA) showed that CS of crab-eating foxes resembled small dolichocephalic skulls of domestic dogs, whereas the CS of maned wolves were closer to that of larger dolichocephalic dogs. An indirect craniometry performed using radiographic images did not differ significantly from traditional craniometric analysis, suggesting the feasibility of future in vivo craniometric evaluations. These results show the utility of comparative craniometric analysis in the study of ecology and evolution of wild canids.
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Crânio, Caninos, Domesticação, Cerdocyonina, Sistema esquelético, Cranium, Canines, Domestication, Skeletal system