On the ancient Silk Road, Bactrian camels served as messengers of trade and cultural exchange.
They thrive in the harshest desert and semi-desert regions, consuming large amounts of salt per meal, and ingesting ample fats, with blood sugar levels more than twice those of other ruminants.
However, they not only avoid metabolic diseases like diabetes or hypertension but also survive in deserts with extreme temperature variations, becoming the "ships of the desert." How do Bactrian camels adapt to such extreme environments?
Previous studies suggest that living in arid desert areas, camels have evolved many physiological traits not found in other animals. Camels possess strong thirst and heat resistance, exceptional adaptability to vegetation, and a unique immune system.
In recent years, researchers from institutions such as the National Biotechnology Center of King Abdullah University of Science and Technology in Saudi Arabia have successfully decoded the genomes of three species in the Camelidae family: Bactrian camels, dromedaries, and llamas.
This breakthrough has allowed scientists to analyze the desert adaptability mechanisms of the Camelidae family at the genetic level. The latest research findings have been published in the journal "Nature Communications."
In this study, scientists attempted to unravel the evolutionary history and desert adaptability mysteries of camels by conducting whole-genome sequencing analysis on a Bactrian camel, a dromedary, and a llama.
Researchers extracted blood DNA from a Bactrian camel, a dromedary, and a llama for high-depth whole-genome sequencing from scratch. Combined with transcriptome data from Bactrian camels, they studied camel desert adaptability and the evolutionary history of Camelidae species.
Population size analysis showed that the population size of these three species is closely related to geological changes over time. Comparative genomic studies revealed the characteristics of Camelidae species in aspects such as fat metabolism, water metabolism, heat stress, drought resistance, UV radiation resistance, and sandstorm resistance.
Transcriptome analysis revealed the camel's unique osmotic regulation and osmotic protection mechanisms, laying an important foundation for studying camel desert adaptability.
The researchers also constructed a phylogenetic tree of camels, studying the evolution of Camelidae species at the genomic level. The analysis results showed that the divergence of Bactrian camels and dromedaries occurred approximately 16.3 million years ago, while the divergence of dromedaries and llamas occurred approximately 4.4 million years ago.
Evolutionary analysis based on synonymous and nonsynonymous mutations showed that compared to other mammals, camels have a faster evolutionary rate.
In terms of camel desert adaptability mechanisms, researchers found rapid evolution in some camel entries related to heat stress, respiration, sodium, potassium ion transport, etc. Some genes related to respiration undergo positive selection in camels.
Researchers also found that osmotic pressure regulation is a major adaptive evolution of camels to cope with desert water scarcity. Camel kidney cells contain high levels of organic osmolytes, which help maintain high osmotic pressure in cells and retain water content in cells.
To counteract the adverse effects of high osmotic pressure, camels have evolved numerous antioxidant-related genes.
During the journey of crossing the desert, we witness the adaptation and evolution of organisms to the environment. With unwavering spirit and unique survival wisdom, they carve out paths of survival in the desert. This spirit and wisdom not only enable camels to survive in the desert but also provide profound insights for us humans.
