Everybody knows that vultures are nature’s garbage cleaners. They perform an essential function by efficiently locating and consuming carcasses and preventing the spread of diseases, without getting ill – vultures resist infection from such highly infective pathogens as anthrax and brucellosis.
Now a new study published recently in the journal Genome Biology (you can download it below) explains how they do it: they have a unique genetic make-up that allows them to digest carcasses and guard themselves against constant exposure to pathogens. A team from the Ulsan National Institute of Science and Technology (South Korea) sequenced the genome of a cinereous vulture and compared it to that of the North American bald eagle.
These researchers found that vultures have variations in the genes relating to the regulation of gastric acid secretion. This is consistent with the ability to eat rotting meat. They also have variations relating to immunity and defence against viral and microbial infections – including genes that allow cells to target pathogens of ingestion and elimination.
It was well known that vultures had strong immune systems and mechanisms to stop infection – what this paper shows are that these are underlined by genetic variations.
The researchers were also able to determine that the species is far more closely related to the North American bald eagle than had previously been thought, perhaps more closely related than to new world vultures. According to the study, Old World vulture species split from the New World 60 million years ago, but the cinereous vulture only diverged from the North American bald eagle around 18 million years ago.
“Old World” vultures from Eurasia and Africa and “New World” vultures and condors from the Americas might look the same and fill in the same ecological role, due to “convergent evolution”, but in fact they are evolutionary very separate - Old World vultures share a common ancestry with eagles while New World species are more closely related to storks.
They resist natural toxins – but not man-made ones
This unusual tolerance of natural toxins doesn’t protect vultures from man-made contaminants however – man-made toxins, poisons and veterinary drugs like diclofenac. As a result two thirds of the 23 vulture species in the world are listed as threatened or near-threatened.
In spite of their bad press, it’s time for us to appreciate and value what these unique and highly-specialised birds do for us – clean our environment in the most effective way. Help us save vultures!
Photo - a cinereous vulture scavenging in the middle of griffon vultures. Bruno Berthemy/VCF