Conservation for Homebody Tiger Sharks

 

Tiger sharks are undoubtedly one of the most recognizable megafauna that humans come into contact with in the ocean. Researchers recently discovered that tiger sharks have new formed at least two genetically distinct groups in both the Atlantic and Indo-Pacific basins. They found this by comparing the genomes of 242 tiger sharks from various locations around the world. The marine biologists focused on specific genetic markers on their genome and contrasted the differences. One of the authors expected that in the future, the differentiations in their genomes may lead to speciation. 

And while these sharks are generalist predators, their numbers are dwindling from the fin trade and commercial fishing. This is causing them to be listed as a Near Threatened species according to the IUCN. However, studying their genomes may help conservationists develop fishery policies to protect the sharks in each of the areas. Since these "homebody" sharks don't tend to migrate to reproduce as once thought, their habitats in each area can be protected and managed separately. The researchers hope to use these methods to investigate other species of sharks as well.

https://news.mongabay.com/2021/11/geneticists-have-identified-new-groups-of-tiger-sharks-to-protect/

Great White Sharks and Tuna Share Common Genes That Allow Them To Be Top Predators

Great White Sharks and Tuna have evolved independently from one another for 400 million years. Despite this, scientists from the Imperial College London looking at these two species have found evidence that suggests that these two fish have similarities in many of their genes that allow them to be dominant predators. Genes linked to traits such as quick swimming behavior, metabolism and the animals ability to produce energy were passed down in both groups and expressed in both. These common genes amongst species that evolved independently of each other could help researchers determine the relationship between genetics and physical traits.

Physical traits are difficult to link directly to specific genes as gene expression can be different in every individual. Tuna and Great White Sharks live completely separate lives but both are top predators with similarly expressed genes. Examining two different species with comparable gene expression is extremely valuable for scientists to find the link between the genes a physical traits on display. In order to do this, the team members on this project collected muscle tissue from sharks as well as tuna to see all the genes that were expressed. In doing this, it was able to be determined that genes could be seen in both species that were associated with different functions such as a higher metabolism being selected for in these sharks. This could spark more questions to be asked on genetic expression and its link to physical traits.

Will We Never Have To Worry About Losing Teeth Again?

A study from the University of Sheffield has identified a set of genes responsible for the continuous replacement of teeth seen in sharks.  These genes are responsible for the formation and operation of special cells called the dental lamina that from new teeth - the same cells that form baby teeth and adult teeth in humans.  Because the study showed that these genes have been conserved over hundreds of millions of years, they predict that these same genes made the first vertebrate teeth, and are also responsible for the production of human teeth.

A catshark

The study, which analyzed the teeth of catshark embryos, also found that these genes were activated when the shark's teeth first form, when they emerge, and when the shark needs new teeth.  They hope that the discovery of these genes will lead to new treatments for tooth loss in humans.
What it sounds like to me is that they hope to find a way to reactivate these genes so that lost teeth can be replaced.  If they can figure out how to do this, it would put a lot of dentists out of work, because who cares about toothcare when bad teeth can be automatically replaced?  Seriously though, that probably wouldn't happen, because the treatment would probably be really expensive, at least at first, and in all likelihood would need to be reapplied for every tooth lost.  Still, the idea of regaining good, strong, real teeth when some are lost is appealing.  Though denture-making companies will lose some business.

New Hybrid Sharks Found Off Coast of Australia

A very rare occurrence has been discovered off the coast off Australia recently. During a cataloging and tagging experiment done by lead researcher Jess Morgan, it was discovered that the Australian Black Tip shark had been mating and producing viable hybrid offspring with the Common Black Tip shark. This is extremely significant since the Australian Black tip can only survive in warm water near the coast of Australia, while the hybrid species was found over 1,000 miles off the coast in much cooler waters. The new species of black tip looks much like the smaller common black tip species, but has DNA more similar to the Australian relative. While tagging sharks and taking DNA samples, Morgan and her crew found that while tagging what they thought were common black tip and Australian black tip sharks, they found that about 20% of the sharks they tagged were actually the hybrid species

[caption id="attachment_4635" align="aligncenter" width="278" caption="The Newly Discovered Hybrid Black TIp Shark"][/caption]

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This was a shock to the science world but also could answer many questions we have about sharks. Sharks have been around for hundreds of millions of years however we seem to know very little about their habits and how they work. With this new discovery of hybrids allows for increased fitness and could be a reason sharks have been around for hundreds of millions of years. Morgan and her crew feel that a trigger to this phenomena could be global warming, and fishing, which are constantly harming the sharks and their habitats. They feel that this discovery could have been triggered by these factors and could be a way for species to expand their territory and enhance there chance of survival.