Monophyletic origin of domestic bactrian camel (Camelus bactrianus) and its evolutionary relationship with the extant wild camel (Camelus bactrianus ferus)

Abstract

The evolutionary relationship between the domestic bactrian camel and the extant wild two-humped camel and the factual origin of the domestic bactrian camel remain elusive. We determined the sequence of mitochondrial cytb gene from 21 camel samples, including 18 domestic camels (three Camelus bactrianus xinjiang, three Camelus bactrianus sunite, three Camelus bactrianus alashan, three Camelus bactrianus red, three Camelus bactrianus brown and three Camelus bactrianus normal) and three wild camels (Camelus bactrianus ferus). Our phylogenetic analyses revealed that the extant wild two-humped camel may not share a common ancestor with the domestic bactrian camel and they are not the same subspecies at least in their maternal origins. Molecular clock analysis based on complete mitochondrial genome sequences indicated that the sub-speciation of the two lineages had begun in the early Pleistocene, about 0.7 million years ago. According to the archaeological dating of the earliest known two-humped camel domestication (5000–6000 years ago), we could conclude that the extant wild camel is a separate lineage but not the direct progenitor of the domestic bactrian camel. Further phylogenetic analysis suggested that the bactrian camel appeared monophyletic in evolutionary origin and that the domestic bactrian camel could originate from a single wild population. The data presented here show how conservation strategies should be implemented to protect the critically endangered wild camel, as it is the last extant form of the wild tribe Camelina.

Molecular phylogeny of the Bactrian camel based on mitochondrial Cytochrome b gene sequences

“…For example, haplotypes H2, H5, H10-13, H15, and H16 were only found in Chinese domestic Bactrian camels; haplotypes H6, H7, and H8 were only found in Mongolian domestic Bactrian camels; but there were no specific haplotypes in Russian domestic Bactrian camels. In this study, all wild Bactrian camels consisted of only one haplotype (H14), in contrast to three haplotypes reported by a previous study (Ji et al, 2009b). Our results also suggest an extremely small effective population size of wild Bactrian camels, which are considered critically endangered by the International Union for Conservation of Nature.…”

“…Archaeological research suggests that Bactrian camels migrated from North America through the Bering Strait, and then arrived in Asia about 3 million years ago (Harrison, 1985). Later, during the Pleistocene Epoch (1.8 million to 10 000 years ago), Bactrian camel populations may have again been subdivided geographically, leading to a split of the two lineages (wild and domestic lineages) (Ji et al, 2009b). In this study, we found that 16 different haplotypes were divided into a domestic haplogroup and a wild haplogroup, and the phylogeographic analysis showed two major groups (wild and domestic Bactrian camel groups).…”

“…In this study, we found that 16 different haplotypes were divided into a domestic haplogroup and a wild haplogroup, and the phylogeographic analysis showed two major groups (wild and domestic Bactrian camel groups). This finding provides evidence that the extant wild Bactrian camel and domestic Bactrian camel carry distinct, maternally inherited mitochondrial lineages (Ji et al, 2009b).…”

“…Molecular genetic analysis of mitochondrial (Jianlin et al, 2004;Ji et al, 2009b;Silbermmayr et al, 2010) and nuclear markers (Silbermmayr and Burger, 2012) provides estimates of the time of separation between wild and domestic Bactrian camels: 0.7-1.5 million years ago in the Pleistocene, which is much longer than the history of domestication. Archaeological research suggests that Bactrian camels migrated from North America through the Bering Strait, and then arrived in Asia about 3 million years ago (Harrison, 1985).…”

Ultrastructure Features of Coronary Artery Endothelium in Bactrian Camel (Camelus bactrianus)

“…Despite their valuable use as draft animals, they are also used for milk, meat and fur production (Ji et al, 2009;Chuluunbat et al, 2014). In recent years, the number of Bactrian camels is getting smaller due to environmental changes and disease.…”