| Tail length variation between Mezayen camel breeds. (a) Majaheem camels are characterized by long tails with a narrow tail-base. (b) Shaele, and (c) Waddah camels, which represent the Malaween breeds, display short-tails with wide tail-bases. The white disks on the tail are reference scales (five centimeters in diameter). Images were extracted from Cdrom Archive photos (collected by the authors).
Camels are livestock that exhibit unique morphological, biochemical, and behavioral traits, which arose by natural and artificial selection. Investigating the molecular basis of camel traits has been limited by: (1) the absence of a comprehensive record of morphological trait variation (e.g., diseases) and the associated mode of inheritance, (2) th...
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... separation of these two groups is in part based on coat color, but is also based on general features, such as body size, ear length and shape, and tail characteristics (Köhler-Rollefson, 1993;Abdallah and Faye, 2012). Majaheem camels are generally larger, and have long "speared" ears ( Figure 4A), and a long tail with a narrow tail-base (Figure 5a) (Al-Hazmi et al., 1994). On the other hand, all Malaween breeds exhibit comparatively smaller body sizes, have short and tilted ears (Figure 4B), and a short tail with a wide tail- base (Figures 5b-c) (see Supplementary Table S2 for naming details). ...
... camels are generally larger, and have long "speared" ears ( Figure 4A), and a long tail with a narrow tail-base (Figure 5a) (Al-Hazmi et al., 1994). On the other hand, all Malaween breeds exhibit comparatively smaller body sizes, have short and tilted ears (Figure 4B), and a short tail with a wide tail- base (Figures 5b-c) (see Supplementary Table S2 for naming details). Breeders often do not breed Majaheem camels with any of the Malaween breeds, and when such an event occurs, breeders can easily recognize the hybrid due to changes in body features; such hybrids are often disqualified from competing in beauty competitions (personal observation). ...
... The natural adaptations of the dromedaries were anthropologically exploited via (1) its domestication around 2000-3000 years B.C., (2) the expansion of their uses, and (3) the development of unique populations (i.e., camel-types) (Uerpmann and Uerpmann, 2002;Almathen et al., 2016;Orlando, 2016). However, unlike other domesticated animals (e.g., cattle, sheep, horses, dogs, and cats), dromedaries do not currently have breed definitions, standards, registries, or breeders' organizations (Arman, 2007;Lynghaug, 2009;Alhaddad and Alhajeri, 2019). Named dromedary populations are locally known and occasionally documented, but little is known about their breed status. ...
... Different dromedary camel-types have been named, yet little or no documentation can be found about their breed status (Arman, 2007;Lynghaug, 2009;Porter et al., 2016;Alhaddad and Alhajeri, 2019). Several camel-type naming systems were previously described such as those based on ecotype (e.g., hill and riverine), country (e.g., Omani and Sudani), region of origin (e.g., Raka and Turkana), tribal affiliation (e.g., Kenani and Borena), and phenotype (e.g., Waddah and Shaele) (Leese, 1927;Mburu et al., 2003;Mehta et al., 2006;Ishag et al., 2010;Mahrous et al., 2011;Porter et al., 2016;Saad et al., 2017). ...
... This is in accordance with previously reported measures of genetic variability reports (Mburu et al., 2003;Legesse et al., 2018). Dromedary camel-types named based on phenotype (e.g., Majaheem, Waddah, and Awadi) are usually selectively bred for distinctive phenotypes (e.g., coat color) (Almathen et al., 2016;Porter et al., 2016;Saad et al., 2017;Alhaddad and Alhajeri, 2019). These camels formed the most homogenous group based on haplotype; with B haplotypes being overrepresented in this group. ...
Dromedary camels are outstanding livestock that developed efficient abilities to tolerate desert conditions. Many dromedary camel-types (i.e., named populations) exist but lack defined specific breed standards, registries, and breeders’ governing organizations. The breed status of dromedary camel-types can partly be assessed by exploring mitochondrial DNA (mtDNA) variation. Accordingly, this study aimed to examine the breed status and the inter-population relationships of dromedary camel-types by analyzing sequence variation in the mtDNA control region and in three coding genes [ cytochrome b , threonine, and proline tRNA , and part of the displacement loop (D-loop)] (867 bp region). Tail hair samples ( n = 119) that represent six camel-types from Kuwait were collected, extracted, sequenced, and compared to other publicly available sequences ( n = 853). Within the sequenced mitochondrial region, 48 polymorphic sites were identified that contributed to 82 unique haplotypes across 37 camel-types. Haplotype names and identities were updated to avoid previous discrepancies. When all sequences were combined ( n = 972), a nucleotide diversity of 0.0026 and a haplotype diversity of 0.725 was observed across the dromedary-types. Two major haplogroups (A and B) were identified and the B1 haplotype was predominant and found in almost all dromedary-types whereas the A haplotypes were more abundant in African regions. Non-metric multidimensional scaling revealed an increased similarity among Arabian Peninsula “Mezayen” camel-types, despite their defining coat colors. The relationships among dromedary camel-types can partly be explained by mtDNA. Future work aimed at a deeper understanding of camel-type breed status should focus on a high number of nuclear markers.
Several FGF5 mutations are associated with hair length variation in many domestic animals, including New World camelids. The dromedary was investigated in the present study with breeds exhibiting marked variations in hair length. This study aimed to: (1) identify the molecular variation(s) in the three exons of FGF5 of a diverse group of breeds (Mejaheem, Shaele, Sofor, Waddah and Omani; n = 28); (2) examine the association of the identified variants with hair length; (3) validate the association via genotyping the polymorphism in a large population of diverse camels (n = 113); and (4) test the segregation of the identified variant with hair length in a pedigree. A non-synonymous mutation (c.779 C > T) was identified that changes the amino acid from proline to leucine and was found to be associated with different hair length in dromedaries. The variants at c.779 displayed a co-dominance mode of inheritance and three hair length phenotypes: short (C/C), intermediate (C/T) and long (T/T). Across the examined dromedary breeds, both alleles were present, which is probably due to the breeders’ preference for an intermediate hair length. When compared with other camelids, the identified variant was found exclusively in dromedaries with the ancestral allele at c.779 being ‘C’. This study constitutes the first thorough exploration of the FGF5 gene in dromedaries.
The dromedary camel is unique among livestock for being adapted to hot deserts. This livestock was domesticated for its beneficial uses to desert dwellers. Unlike other domesticated animals, camels lack breed standards, registries, or governing breeders' organizations. Nonetheless, over 200 camel populations worldwide are assigned local names, which are occasionally defined by general characteristics. These camel populations are generically considered separate breeds despite the lack of a thorough examination of their 'true' breed status. In this review, we document named camel populations that we refer to as "camel-types" and discuss the likelihood that they represent true breeds. We focus our discussion on seven categories of camel-types, which are based on each of: (1) ecotype, (2) phenotype, (3) rearing tribes, (4) region of existence, (5) country of origin, (6) general use, and (7) individual camels (i.e., a population named after a well-known camel). Based on this review, we favor careful examination of camel-types prior to the selection of specific populations for breeding/production programs or for genetic studies.
Camel populations can be found in large parts of the arid regions of Africa, Asia, and Australia. In this broad distribution, they exhibit large phenotypic variation, which so far has mostly been examined using traditional distance based morphometric approaches. The main pitfalls of previous studies include (1) the relatively few and ambiguously defined morphometric measurements, which often do not cover all functionally important traits, and (2) the narrow sampling of breeds and geographic regions. In this work, we provide some recommendations on how to standardize morphometric data collection, and also overview more advanced methods for capturing morphometric data in camels—this would greatly ease the process of data collection in these animals, which can sometimes be difficult to work with. As the morphometrics of camels can be studied for different purposes, we focus this review on its applicability to breed identification and delimitation, which is commonly studied on living camels. We also review methods commonly used in camel morphometrics, suggest a set of best practices, and outline novel methods. Finally, we suggest potential applied uses for these morphometric studies, particularly within the context of developing breeds specialized for different purposes, such as the production of meat, milk, and leather. While we focus this review on dromedaries, we anticipate that most recommendations will be widely applicable to other camelids, and livestock in general. The methods described in this review provide a detailed characterization of phenotype in an efficient manner, allowing for the compilation of large morphometric data banks that would improve the understanding of the phenotypic structure of camel populations.
The dromedary camel is a unique livestock for its adaptations to arid-hot environments and its ability to provide goods under extreme conditions. There are no registries or breed standards for camels. Thus, named camel populations (i.e. camel-types) were examined for genetic uniqueness and breed status. Camel populations are generally named based on: shared phenotype, country or region of origin, tribal ownership, or the ecology of their habitat. A dataset of 10 Short-Tandem Repeat markers genotyped for 701 individual camels from 27 camel-types was used to quantify genetic diversity within camel-types, compare genetic diversity across camel-types, determine the population genetic structure of camel-types, and identify camel-types that may represent true breeds. Summary statistics (genotyping call rate, heterozygosity, inbreeding coefficient FIS, and allelic frequencies) were calculated and population-specific analyses (pairwise FST, neighbor-joining tree, relatedness, Nei's genetic distance, PCoA, and STRUCTURE) were performed. The most notable findings were: (1) little variation in genetic diversity was found across the camel-types, (2) the highest genetic diversity measure was detected in Targui and the lowest was in Awarik, (3) camel-types from Asia (especially the Arabian Peninsula) exhibited higher genetic diversity than their counterparts in Africa, (4) the highest DeltaK value of population structure separated camel-types based on geography (Asia vs. Africa), (5) the most distinct camel-types were the Omani, Awarik, and the Gabbra, (6) camel-types originating from the same country did not necessarily share high genetic similarity (e.g. camel-types from Oman), and (7) camel-type names were not consistently indicative of breed status.
La conservación, mejora y uso racional de los recursos genéticos animales locales y su diversidad son propósitos prioritarios a nivel nacional e internacional de evidente carácter legítimo. Reconocida en situación de amenaza, la raza camellar canaria (Camelus dromedarius) se encuentra marginalmente reducida a las islas orientales del archipiélago. Su uso queda restringido fundamentalmente a la explotación turística y, de forma esporádica, a labores variadas en el ámbito agropecuario. La caracterización morfoestructural y zoométrica del camello canario es una tarea clave que permitirá la identificación de aquellos caracteres o rasgos fenotípicos implicados en la actividad productivo-económica de estos animales con el fin de recuperar posibles nuevos nichos funcionales. La presente propuesta metodológica se enmarca en un contexto de oportunidad y resurgimiento de una potencial industria de producción con el asentamiento de las bases para un programa de recuperación y cría selectiva de esta raza camellar a través de su sustentabilidad funcional.
Conservation and sustainable management of local animal genetic resources and their diversity are priority tasks within a national and international framework. Officially listed as a threatened native breed, Canarian camels (Camelus dromedarius) are marginally reduced to the eastern islands of the archipelago and mainly used in touristic activities; sporadically, these animals are used for production of food and other products. Morphostructural and zoometric characterization of Canarian camel will lead to the identification of those genetic-based characters or features involved in productive functional activities. The present methodological proposal is framed into a context of opportunity and resurgence of a potential production industry throughout the establishment of the baselines for a sustainable selective breeding program in this livestock species.
Old World camels have served humans in cross‐continental caravans, transporting people and goods, connecting different cultures and providing milk, meat, wool and draught since their domestication around 3000–6000 years ago. In a world of modern transport and fast connectivity, these beasts of burden seem to be out‐dated. However, a growing demand for sustainable milk and meat production, especially in countries affected by climate change and increasing desertification, brings dromedaries (Camelus dromedarius) and Bactrian camels (Camelus bactrianus) back onstage and into the focus of animal breeders and scientists. In this review on the molecular genetics of these economically important species we give an overview about the evolutionary history, domestication and dispersal of Old World camels, whereas highlighting the need for conservation of wild two‐humped camels (Camelus ferus) as an evolutionarily unique and highly endangered species. We provide cutting‐edge information on the current molecular resources and on‐going sequencing projects. We cannot emphasise enough the importance of balancing the need for improving camel production traits with maintaining the genetic diversity in two domestic species with specific physiological adaptation to a desert environment.