Shark DNA: an aid to tracking the origin of shark fins

As a follow up to yesterday's post on thresher shark research, another shark news item is making the rounds: tracing the source of shark fins through DNA. Thanks to research in identifying DNA components in various shark populations, scientists can now track down the origin of dried shark fins right back to the source - the location of the shark population from where the fin was taken. This will assist in enforcing shark conservation management regulations and hopefully stem the illegal taking of sharks which adds so much to the overall devastating annual toll.

Covering the subject, here is a re-cap post from Shark Divers' Underwater Thrills:

Sharks and DNA Zip Codes - Hope?

Thursday, April 28, 2011

An international team of scientists, led by the Institute for Ocean Conservation Science at Stony Brook University, has used DNA to determine that groups of dusky sharks (Carcharhinus obscurus) and copper sharks (Carcharhinus brachyurus) living in different coastal regions across the globe are separate populations of each species. Both are large apex predators that are heavily exploited for the shark fin trade, which claims tens of millions of animals every year to produce the Asian delicacy, shark fin soup.

Many of these species are declining as a result of this fishing pressure for their fins.

DNA research projects were conducted by a collaborative international team of scientists from the United States, Australia, South America, Asia, New Zealand and southern Africa. The scientists collectively analyzed part of the mitochondrial DNA in nearly 400 sharks sampled from all over the globe.

This research was funded by The Pew Charitable Trusts through a grant to the Institute for Ocean Conservation Science at Stony Brook University. Sequence data were collected in the Field Museum's Pritzker Laboratory for Molecular Systematics and Evolution, operated with support from the Pritzker Foundation. Additional sequence data were collected at the Guy Harvey Research Institute with operational funds and a grant from the Save Our Seas Foundation. Funding was also provided by the Turner Fellowship Program and the Tinker Foundation.

For more information on "Global phylogeography of the dusky shark, Carcharhinus obscurus: implications for fisheries management and monitoring the shark fin trade," visit here.

For more information on "Phylogeography of the copper shark (Carcharhinus brachyurus) in the southern hemisphere: implications for the conservation of a coastal apex predator," visit here.

Aspens and Chernobyl: nature's resiliency and ability to survive or not

Turning from the wet to the dryside for a moment, have you ever noticed how trees like Aspens seem to change into their fall colors simultaneously? Like the drop of a hat, one moment they're green and the next moment they are a striking brilliant yellow - almost as if they were one tree rather than individuals.

Well, in essence, they are one tree. Certain species, particularly aspens, have the ability to sprout new trees from an expanding root network without the need for reproduction or fertilization. Call it botanical cloning. In fact, some groves of aspens constitute some of the largest single living organisms on the planet (there are some fungus experts that might argue who has the title, as there are huge underground fungi that grow in a similar fashion).

However, a group of Canadian researchers from British Columbia have determined through groundbreaking (no pun intended) DNA studies, that this ability of the aspen to "clone" itself is not everlasting. Their studies show that this method of propagation, like with other biological species, can produce genetic mutations with each succeeding tree which impacts its fertility and its ultimate life span. At some point the tree (or trees) must reproduce by more "traditional" means.

According to Howard Falcon-Long of the BBC News, "Dr Ally's team found that genetic mutations gradually build up with each subsequent generation of clone, resulting in a decline in fertility. This means that the aspen cannot clone itself indefinitely, but eventually must reproduce sexually or die."

Here's a video I shot along California's eastern Sierras which contains scenes of aspen groves in the midst of changing to their fall colors. Imagine that many of the trees you see here are actually all part of the same tree.



On the other side of the globe, the effects of genetic mutation and biodiversity brought about by contamination have been the subject of a long study at Russia's Chernobyl nuclear facility. After four years of study in and around the plant's "exclusion zone," scientists from the U.S. and France have reported a decline in the number of mammals, insects, and reptiles. So, with environmental contamination events - like Chernobyl or, say, the Gulf oil spill - when left to its own devices, without human interference, nature does not necessarily heal itself or bring itself back to "normal."

According to a BBC News report, birds were heavily impacted by the contamination. "During their census work, [scientists Professor Timothy Mousseau] and Dr. [Anders] Moller have also examined the effects of radiation contamination on the animals. They say that these impacts are particularly obvious in birds. 'We think they may be more susceptible, after long migrations, to additional environmental stress.' explained Professor Mousseau."

The scientists are not without their critics. Though their motives or supporting data may be questionable, Ukrainian scientists have said the opposite is true: that without human influence, animals are thriving in Chernobyl. Professor Mousseau claims their evidence is totally anecdotal.

Nature has amazing ways to perpetuate life; backup systems, if you will, like the cloning and traditional reproduction methods of the aspens. But mankind's technology has been able to produce impacts that can overpower nature's ability to heal and come back strong. We must carefully monitor what happens in the wild, what happens in and around facilities like energy and oil drilling plants, and we must not drop the ball when it comes to following up on the effects of our mistakes.

Read about the aspens and Chernobyl in BBC News.