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New Genetic research Challenges long-Held Beliefs About Great White Shark Evolution – A recent study published in Current Biology reveals a surprising complexity in the genetic history of the great white shark (Carcharodon carcharias), questioning the widely accepted theory that female sharks consistently return to the same birthing grounds.
Researchers, lead by Dr. Yannis Papastamatiou at the University of Hawaii at Mānoa adn Dr. Colin Simpfendorfer at James Cook University, analyzed the complete genomes of 54 great white sharks from populations across the globe – including samples from South Africa, australia, and the United States – to uncover three distinct genetic lineages.This level of genetic differentiation was unexpected given the sharks’ capacity for long-distance migration.
The prevailing hypothesis, known as female philopatry, suggests that female sharks exhibit a strong tendency to return to their birthplaces to reproduce, leading to genetic isolation and the formation of distinct populations. However, the new genomic data contradicts this assumption. The team argues that “an alternative evolutionary mechanism must necessarily be operating”.
While natural selection acting on mitochondrial DNA (mtDNA) is another potential clarification, scientists find it improbable. The global great white shark population is estimated at fewer than 20,000 individuals, making it vulnerable. For a beneficial mtDNA mutation to become widespread, it would need to confer a significant survival advantage, protecting sharks from a “brutally lethal” threat, according to Dr. Gregory Naylor, a marine biologist involved in the research.
