A new milestone in shark conservation has been achieved after scientists have successfully sequenced the genomes of endangered shark species.
The scientists managed to sequence the genomes of shortfin Mako and Hammerhead sharks down to the chromosome level. This gives them an insight into the evolution of the species and what danger they may face in their genes.
For instance, DNA timelines have shown a dramatic decline in population over 250,000 years. Also, great hammerheads have lower genetic diversity and show signs of inbreeding. Both these make the species less resilient to environmental changes and can threaten its population’s survival.
The shortfin mako, on the other hand, showed much less inbreeding and greater genetic diversity. Hopefully, this offers a glimmer of hope in its ability to deal with environmental changes.
According to Mahmood Shivji, professor at Nova Southeastern University’s Halmos College of Arts and Sciences and director of the Save Our Seas Foundation Shark Research Center and NSU’s Guy Harvey Research Institute and one of the lead scientists behind the project:
“To understand why this might be undesirable, you can think about it in terms of disease. You need two copies of the gene to express certain recessive diseases: one from your mother and one from your father. If you are homozygous for a trait, you have inherited the same gene sequence from both your mother and father, and the trait will be expressed.”
“Genetics has advanced such that chromosomal level genomes are the expectation for a reference quality genome for species however, conservation research presents its own challenges to achieving this consistently and at the resolution expected in other fields. Obtaining tissue samples from endangered marine vertebrates is a major hurdle. You can assemble the genome with a single tissue sample from a single shark, but the ideal circumstance would be to sequence genomes from multiple individuals from different parts of their ocean range, an ethically difficult and costly endeavour.”
While Michael Stanhope from Cornell University’s College of Veterinary Medicine added:
“Technical advances in the study of genomes mean that DNA sequencing approaches are much more powerful and efficient now. We can apply these new technologies to gain insights about the organism, information that we hope can be leveraged to protect sharks and rays.”