Mitochondrial Sequence Variation, Haplotype Diversity, and Relationships Among Dromedary Camel-Types

Abstract

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.

Genetic diversity among three camel populations reared in Egypt using mitochondrial COX-3 gene

“…The haplotype diversity (0.667) and nucleotide diversity (0.00254) of the polymorphisms suggested that there were low variations across the types of dromedary camels as evidenced by the moderate to high very low nucleotide diversity (0.00254) and haplotype diversity (0.667). These variety indicators may indicate a markedly reduced selection pressure on camels relative to other animals that are farmed more intensively for a particular purpose (Alaqeely et al, 2021).…”

“…It consists of 22 tRNA gene, two rRNAs genes, 13 protein-coding genes and non-coding control region. The 13 protein-coding genes are cytochrome c oxidases (COX) 1, 2 and 3; NADH dehydrogenases (ND) 1, 2, 3, 4, 4L, 5 and 6; ATP synthases (ATP) 6A and 8; and cytochrome b (CytB) (Alaqeely et al,2021). Little is known about COX-3 gene in camel, although it is an important component of the respiratory chain and is conserved among species.…”

Genetic similarity and diversity among three camel populations reared in Egypt

“…Present result has found little differences in dromedary camel populations, as evidenced by very low nucleotide diversity (0.00026) and moderate to high haplotype diversity (0.725). When compared to other animals that are more carefully bred for a specific function, these diversity indices may reflect a significantly lower selection pressure on camels [ 2 , 3 ]. Moreover, there were no genetic differences between Mongolian Bactrian camel groups according to Chuluunbat et al [ 7 ].…”

Exploiting morphobiometric and genomic variability of African indigenous camel populations-A review

“…Mitochondrial DNA (mtDNA) depicts maternal inheritance pattern which can be used to show genetic variation between species (Piro et al, 2020;Alaqeely et al, 2021). The evaluation of variation of the mtDNA cytochrome b (cyto b) gene in Nigerian dromedary camels with other populations defined 37 haplotypes, including nine novel sequences from Nigeria (H3, H5-H7, H9-H11 and H13-H14), seven from Ethiopia (H26-H32), two each from Kenya (H35-H36) and Saudi Arabia (H1, H37), one from Turkey (H25), and 10 from Iran (H15-H24); while the remaining six were shared (Xueqi et al, 2021).…”