Once domesticated thousands of years ago, dogs spread across the globe wherever humans migrated and settled. As ancient humans expanded from Eurasia, they developed genes to help them survive the harsh climates and diseases of their new homelands.
Now a study has shown that dogs taken to tropical regions adapted the same protective gene as our ancestors to help fight off deadly parasites like malaria.
This ‘convergent evolution’ helped these dogs survive as man’s closest companion for thousands of years despite migrating from a vastly different climate.
As ancient humans expanded from Eurasia, they developed genes to help them survive their new homelands. Now a study has shown that dogs taken to tropical countries adapted the same protective gene as our ancestors to help fight off deadly parasites (stock image)
THE STUDY
Researchers sequenced the full genomes of 19 African village dogs from Nigeria.
They identified a number of potential genes that must have developed through recent natural selection.
The team found that one of these genes, ‘ADGRE1’, protects the dogs from a type of infection closely linked to the malaria virus, known as a ‘plasmodium infection’.
The gene boosts the immune response in African dog cells infected with plasmodium parasites like malaria.
ADGRE1 is also found in humans in the region, suggesting the two species developed the resistance alongside one another.
In the new study, a team led by researchers at Yunnan University in Kunming, China, found genes in modern African village dogs leftover from these ancient adaptations.
‘Dogs have survived in tropical environments for thousands of years alongside humans,’ said study lead author Dr Ya-ping Zhang.
‘In this study, we have identified genes associated with insulin secretion and sensitivity, immunity, angiogenesis and ultraviolet protection that showed adaptive selection.’
The Yunnan team has previously shown that dogs that migrated with our ancestors to Tibet adapted human-like genes to help them survive high altitudes.
In their new study, the researchers sequenced the full genomes of 19 African village dogs from Nigeria.
They identified a number of potential genes that must have developed through recent natural selection.
The team found that one of these genes, ‘ADGRE1’, protects the dogs from a type of infection closely linked to the malaria virus, known as a ‘plasmodium infection’.
A gene found in African village dogs boosts the immune response in cells infected with plasmodium parasites like malaria. The same gene has previously been found in humans, suggesting the two species evolved it side-by-side after migrating to Africa (stock image)
WHAT IS CONVERGENT EVOLUTION?
In evolutionary biology, convergent evolution is the process in which organisms not closely related independently evolve similar traits as a result of having to adapt to similar environments or ecological niches.
It is the opposite of divergent evolution, where related species evolve different traits.
The gene boosts the immune response in African dog cells infected with plasmodium parasites like malaria.
‘Our study suggests ADGRE1 contributes to defence against Plasmodium infection in dogs, and thus, convergent evolution in this gene between humans and dogs,’ said study coauthor Dr Guo-Dong Wang.
‘This is a novel finding since in earlier studies the most apparent cases of convergent evolution between humans and dogs were in genes for digestion and metabolism, neurological process, and cancer.’
The team also investigated the Nigerian dogs’ evolutionary history compared to other dogs, including Eurasian grey wolves and African golden wolves.
They found that the Nigerian dog population diverged from Eurasian dog populations around 14,000 years ago.
After this divergence, the population fell on hard times, and experienced a severe genetic bottleneck caused by dwindling numbers.
This led to reduced genetic diversity within the Nigerian dog population, and increased gene flow to the species from African golden wolves after the divergence.
