The first whole genome sequence of the alpaca and the dromedary camel, and a whole genome and transcriptome sequence of the Bactrian camel, are reported this week in Nature Communications. The study provides insight into the genetic basis for the adaptations to the stresses associated with living in the desert in dromedary and Bactrian camels.
The dromedary and Bactrian camel are two domesticated camel species that live in the extreme desert environments of Africa and Asia. Their adaptations to arid conditions include a tolerance of temperatures exceeding 40°C and water losses greater than 25% of total body weight. In contrast, one of their nearest relatives, the alpaca, lives in the high altitudes of South America and does not exhibit similar adaptations to hot desert environments.
Huanmin Zhou and colleagues identify accelerated evolution in both camels in genes associated with stress response to heat, respiratory function and visual protection, when compared to the alpaca, which the authors believe are adaptations of camels to endure the desert environment.
Analysis of the transcriptome of the Bactrian camel provides insights into its unique strategy for water reabsorption, and other strategies relating to hydration, which protect against stress during long-term water restriction. The authors suggest that different numbers of humps in these camels may reflect their distinct fat metabolism abilities; however, more research is required to establish that this is the case.