Despite independent evolution for 400 million years, sharks and tunas still share common genetic traits. They include higher metabolism, body temperature and fast swimming skills.
In the lamnid group of sharks, great white sharks are a major presence. Some common genetics make them super predators with brisk swimming power and the ability to stay warm.
This was revealed in a new research by Imperial College London which asserted the commonality of genes in the two groups as key to their predatory edge.
Regarding the identical genes in both the groups, the team said they are mainly linked with metabolism and the ability to produce energy.
The study, published in Genome Biology and Evolution Journal, had Professor Vincent Savolainen from the Department of Life Sciences at Imperial as the Co-author.
"Lamnid sharks and tuna both have stiff bodies and tails that allow them to swim in bursts. They can also keep their temperature up in colder waters. Both of these things make them more effective predators, allowing them to snatch prey in usually inhospitable waters," Savolainen said.
Genetic analysis has affirmed convergent evolution and justified the awesome hunting nature of both the animals.
In tuna, the Atlantic Bluefin tuna is most famous for the swift hunting of mackerels and sardines. White sharks chase a range of food from seals to large fishes.
The study said these genes might be passed on as they bestow a critical survival advantage for the creatures.
Methodology Of Study
For the study, the team took muscle tissue from three species of lamnid sharks, six tuna species and mackerel species to examine their genes.
A phenotypic convergence was expressed in the commonalities of red muscle, distinctive swimming style and stiffened body that is coming from tail movements and retention of a higher body temperature known as endothermy.
The study has highlighted the elevated white muscle metabolic capacities that are further supporting their fast-swimming, pelagic and predatory behaviors.
In convergent evolution, a set of metabolic genes is in play. It was confirmed by the white muscle transcriptomes of tuna, mackerel, and sharks sequenced with previously published RNA-sequenced data.
The study constructed a phylogenetic tree, which was analysed for the likelihood of optimal gene selection. It found a common gene, glycogenin-1 that evolved under positive selection and hinting at convergent selective pressures at gene level over a shared physiology.