1 Name: ultispy !L9K4OkD6Mo : 2012-01-14 17:35 ID:v8vwWiz4 (Image: 537x403 png, 351 kb) [Del]
Scientists have identified the first-ever hybrid shark off the coast of Australia, a discovery that suggests some shark species may respond to changing ocean conditions by interbreeding with one another.
A team of 10 Australian researchers identified multiple generations of sharks that arose from mating between the common blacktip shark (Carcharhinus limbatus) and the Australian blacktip (Carcharhinus tilstoni), which is smaller and lives in warmer waters than its global counterpart.
“To find a wild hybrid animal is unusual,” the scientists wrote in the journal Conservation Genetics. “To find 57 hybrids along 2,000 km [1,240 miles] of coastline is unprecedented.”
James Cook University professor Colin Simpfendorfer, one of the paper’s co-authors, emphasized in an e-mail that he and his colleagues “don’t know what is causing these species to be mating together.” They are investigating factors including the two species’ close relationship, fishing pressure and climate change.
Australian blacktips confine themselves to tropical waters, which end around Brisbane, while the hybrid sharks swam more than 1,000 miles south to cooler areas around Sydney. Simpfendorfer, who directs the university’s Centre of Sustainable Tropical Fisheries and Aquaculture, said this may suggest the hybrid species has an evolutionary advantage as the climate changes.
Australian blacktips confine themselves to tropical waters, which end around Brisbane, while the hybrid sharks swam more than 1,000 miles south to cooler areas around Sydney. Simpfendorfer, who directs the university’s Centre of Sustainable Tropical Fisheries and Aquaculture, said this may suggest the hybrid species has an evolutionary advantage as the climate changes.
As a result, he wrote, “We are now seeing individuals carrying the more tropical species genes in more southerly areas. In a changing climate, this hybridization may therefore allow these species to better adapt to different conditions.”
The researchers — who had been working on a government-funded study of the structure of shark populations along Australia’s northeast coast — first realized something unusual was going on when they found fish whose genetic analysis showed they were one kind of blacktip but their physical characteristics, particularly the number of vertebrae they had, were those of another. Shark scientists often use vertebrae counts to distinguish among species.
The team also found that several sharks that genetically identified as Australian blacktips were longer than the maximum length typically found for the species. Australian blacktips reach 5.2 feet; common blacktips in that part of the world reach 6.6 feet.
Demian Chapman, assistant director of science of Stony Brook University’s Institute for Ocean Conservation Science, said the idea that sharks can interbreed is “something a lot of shark biologists thought could happen but now we have evidence, and it’s fantastic evidence.
He added, however, that the fact that these two species were so closely related made it easier for them to mate than wildly-divergent ones.
“It doesn’t mean we’re going to see great-white-tiger sharks anytime soon, or bull-Greenland sharks,” he said. “If any species was going to hybridize, it was going to be this pair.”
Chapman, who first documented in 2008 that some female sharks can reproduce without having intercourse, said this latest discovery suggests “there’s yet another path to reproduction that these species can do. It just reinforces that sharks can do it all when it comes to reproduction.”
tl;dr- Two different shark species have started mating with one another for unknown reason. Although they happen to be a closely related species, it's interesting to discover this is even possible.
It's very likely they're started to mate with each other because recent climate changes. "....this may suggest the hybrid species has an evolutionary advantage as the climate changes."
http://www.washingtonpost.com/national/health-science/first-ever-hybrid-shark-discovered-off-australia/2012/01/03/gIQAPy00YP_story.html - Link to the article.
Now, as darn fascinating as this is, isn't it bad the climate has changed so much such drastic measures had to be taken in the first place? However, it's possible things like this has happened before, whether it was during the Ice Age or recent.
2 Name: Bread!RTgBiSnMz2 : 2012-01-14 18:23 ID:Bo9oBaBy [Del]
This is like cheating the definition of 'hybrid'.
I've never really liked the idea of speciation. Especially when the differences aren't too large between the 2 species.
It's like people of different skin colors too, we live in different places but we're all one species :|
However, scientists are definitely more educated than I, so I won't argue with them about anything.
\Clap Clap/
I just hope 'closely related' doesn't pertain to us.
Just 'cause, evolution might still connect us to apes/ and O__O
It's a good thing I probably won't live to see most of these problems happening to the earth and the inhabitants adapting. I probably couldn't handle it all at once.
