Morphological and osteological characterization of indigenous domestic chickens (Gallus gallus domesticus): validation of Rensch’s, Bergmann’s and Allen’s rules

Frontiers in Ecology and Evolution

Ecology and Evolution

Gurja Belay¹  Tadelle Dessie²  Olivier Hanotte³  Mulalem Zenebe Kelkay⁴  Minister Birhanie Dagnhegn⁴  Gebreslassie Gebru⁵ 

[1] Department of Microbial, Cellular and Molecular Biology, College of Natural Resource, Addis Ababa University, Addis Ababa, Ethiopia;International Livestock Research Institute (ILRI), Addis Ababa, Ethiopia;International Livestock Research Institute (ILRI), Addis Ababa, Ethiopia;School of Life Sciences, University of Nottingham, Nottingham, United Kingdom;Centre for Tropical Livestock Genetics and Health (CTLGH), The Roslin Institute, The University of Edinburgh, Edinburgh, United Kingdom;Tigray Agricultural Research Institute, Mekelle, Ethiopia;Tigray Agricultural Research Institute, Mekelle, Ethiopia;Department of Microbial, Cellular and Molecular Biology, College of Natural Resource, Addis Ababa University, Addis Ababa, Ethiopia;International Livestock Research Institute (ILRI), Addis Ababa, Ethiopia;

关键词: adaptation;    appendage;    bone;    climate;    environment;    poultry;    shank length;    Tigray;   

DOI  :  10.3389/fevo.2023.1032082

 received in 2022-09-16, accepted in 2023-03-31,  发布年份 2023

来源: Frontiers

【 摘 要 】

Ecogeographical habitat heterogeneity in wild endotherm species results in morphological variability associated with physiological mechanisms for maintaining their body temperature at a thermoneutral state in different environments. This habitat-induced morphological variation has led to the proposal of three main ecogeographical and biological rules (Rensch, Bergmann, and Allen). Whether or not domesticated animal species, under the care and management of humans, follow the same rules has not yet been investigated in detail. In this study, we randomly sampled 333 adult indigenous chickens (Gallus gallus domesticus) from three habitats representing the highland, midland and lowland agro-ecologies in the Tigray Region (Ethiopia). We aimed to assess the importance of Rensch’s, Bergmann’s, and Allen’s rules in shaping their morphology and osteology. For Bergmann’s and Allen’s rules, we analyzed the morphological characteristics of 297 (208 female, 89 male) and the osteological characteristics of 36 (19 female, 17 male) indigenous chickens. For the morphological validation of Rensch’s rule, we used 89 male chickens and randomly selected 89 female chickens, while for the osteological validation, 17 male and female chickens were analyzed. Chickens from the lowland agro-ecology (warm climate) had a smaller body mass index (BMI) and larger appendages, while chickens from the highland agro-ecology (cold climate) had a larger BMI and smaller appendages (Bergmann’s and Allen’s rules). Morphological and osteological sexual dimorphism were observed, with the male chickens being larger than the female chickens and with size differences proportional to the body size (Rensch’s rule). In both sexes, regression analysis showed a relationship between BMI and altitude as well as temperature. Shank length, wingspan, and the length and surface area (earlobe, wattle, and beak) of the appendages were significantly associated with climatic variables. Moreover, our regression model revealed that wingspan and shank length could be predicted from the greatest length of the humerus and tarsometatarsus. Our findings support the idea that indigenous chickens’ adaptation mechanisms to environmental challenges largely agree with the expectation of Rensch’s, Bergmann’s, and Allen’s biogeographical rules across the different altitudinal habitats of the Tigray Region.

【 授权许可】

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Copyright © 2023 Gebru, Belay, Dessie, Zenebe Kelkay, Birhanie Dagnhegn and Hanotte.