ScienceDaily (Oct. 11, 2008) -- Scientists have confirmed the second-ever case of a "virgin birth" in a shark, indicating once again that female sharks can reproduce without mating and raising the possibility that many female sharks have this incredible capacity. Lead author Dr. Demian Chapman, shark scientist with the Institute for Ocean Conservation Science at Stony Brook University, Beth Firchau, Curator of Fishes for the Virginia Aquarium & Marine Science Center, and Dr. Mahmood Shivji, Director of the Guy Harvey Research Institute and Professor at Nova Southeastern University in Florida, have proven through DNA testing that the offspring of a female blacktip shark named "Tidbit" contained no genetic material from a father. Tidbit had lived at the Virginia Aquarium in the Norfolk Canyon Aquarium for eight years since shortly after her birth in the wild. In May 2007, Chapman and Shivji were part of a team that made the groundbreaking scientific discovery confirming -- for the first time ever -- a virgin birth in a female shark. That shark was a hammerhead residing at an Omaha, Nebraska zoo and had not been in contact with male sharks for at least three years. That study was published in the journal Biology Letters and captured global media and scientific attention. The DNA-fingerprinting techniques used to prove both cases of virgin birth (scientifically known as "parthenogenesis") are identical to those used in human paternity testing. "It is now clear that parthenogenesis occurs in sharks other than just hammerheads," Chapman said. "The first case was no fluke. It is quite possible that this is something female sharks of many species can do on occasion." Sharks' ability to reproduce alone should not be viewed as an adequate replacement for normal sexual reproduction, Chapman cautioned. For one, the blacktip and hammerhead sharks that reproduced without mating both only produced one pup, rather than an entire litter. Shark litters can contain anywhere from a few to more than a hundred shark pups, depending upon the species. "The revelation that female sharks can reproduce alone shouldn't stop us from worrying about driving shark populations to very low levels through overfishing," said Chapman. "It is very unlikely that a small number of female survivors could build their numbers up very quickly by undergoing virgin birth."
ScienceDaily (Oct. 11, 2008) -- Scientists have confirmed the second-ever case of a "virgin birth" in a shark, indicating once again that female sharks can reproduce without mating and raising the possibility that many female sharks have this incredible capacity.
Lead author Dr. Demian Chapman, shark scientist with the Institute for Ocean Conservation Science at Stony Brook University, Beth Firchau, Curator of Fishes for the Virginia Aquarium & Marine Science Center, and Dr. Mahmood Shivji, Director of the Guy Harvey Research Institute and Professor at Nova Southeastern University in Florida, have proven through DNA testing that the offspring of a female blacktip shark named "Tidbit" contained no genetic material from a father. Tidbit had lived at the Virginia Aquarium in the Norfolk Canyon Aquarium for eight years since shortly after her birth in the wild.
In May 2007, Chapman and Shivji were part of a team that made the groundbreaking scientific discovery confirming -- for the first time ever -- a virgin birth in a female shark. That shark was a hammerhead residing at an Omaha, Nebraska zoo and had not been in contact with male sharks for at least three years. That study was published in the journal Biology Letters and captured global media and scientific attention. The DNA-fingerprinting techniques used to prove both cases of virgin birth (scientifically known as "parthenogenesis") are identical to those used in human paternity testing.
"It is now clear that parthenogenesis occurs in sharks other than just hammerheads," Chapman said. "The first case was no fluke. It is quite possible that this is something female sharks of many species can do on occasion."
Sharks' ability to reproduce alone should not be viewed as an adequate replacement for normal sexual reproduction, Chapman cautioned. For one, the blacktip and hammerhead sharks that reproduced without mating both only produced one pup, rather than an entire litter. Shark litters can contain anywhere from a few to more than a hundred shark pups, depending upon the species. "The revelation that female sharks can reproduce alone shouldn't stop us from worrying about driving shark populations to very low levels through overfishing," said Chapman. "It is very unlikely that a small number of female survivors could build their numbers up very quickly by undergoing virgin birth."
Volunteer mountain-rescue staff in Scotland are being asked to write to the UK regulator Ofcom to complain about increased spectrum prices that could drive them out of the life-saving business. The BBC reports that the Mountain Rescue Committee of Scotland has asked its members to write to the regulator in response to the current consultation on Maritime and Aeronautical radio use, which is open until the end of October, complaining that the "Administered Incentive Pricing" proposed will cost the charity thousands of pounds it doesn't have. The situation is similar for the Royal National Lifeboat Institute: which currently pays a discount rate of £38K for a licence around 156Mhz, but could end up with a bill knocking quarter of a million quid, annually. Even if they retain their 50 per cent discount, that's another £100K the charity is going to have to find if lifeboats are going to be able to talk to each other and the shore
Volunteer mountain-rescue staff in Scotland are being asked to write to the UK regulator Ofcom to complain about increased spectrum prices that could drive them out of the life-saving business.
The BBC reports that the Mountain Rescue Committee of Scotland has asked its members to write to the regulator in response to the current consultation on Maritime and Aeronautical radio use, which is open until the end of October, complaining that the "Administered Incentive Pricing" proposed will cost the charity thousands of pounds it doesn't have.
The situation is similar for the Royal National Lifeboat Institute: which currently pays a discount rate of £38K for a licence around 156Mhz, but could end up with a bill knocking quarter of a million quid, annually. Even if they retain their 50 per cent discount, that's another £100K the charity is going to have to find if lifeboats are going to be able to talk to each other and the shore
Please tell me that Emergency Services don't have to pay for their rights to radio spectrum.
My head will explode if someone doesn't write soon with a logic for this discord. [Even if it is someone other than someone.] AAAAGGGGHHHHH Never underestimate their intelligence, always underestimate their knowledge.
Frank Delaney ~ Ireland
Of course, as they are invovled in the saving of lives they exist in a grey area where the authorities would be obliged to take over if they didn't exist, but not necessarily with the same level of expertise. This would be expensive, so it is in the government's interest to sort this out.
Unfortunately it's a case of left hand/right hand and, as is usual in the UK, we end up with the worst of all possible worlds. A compromise will be agreed, but only as we get to the point of the organisations threatening to disband. keep to the Fen Causeway
