Pretty much everyone who has seen this today shakes their head and wonders. I’m wondering too. First, the story which is being serially regurgitated without any thought in media outlets world wide:
Please read this excepted text from the story carefully:
In what is being hailed as the world’s first evidence of inter-species breeding among sharks, a team of marine researchers at the University of Queensland have identified 57 hybrid sharks in waters off Australia‘s east coast.
…
Ovenden speculated that the two species began mating in response to environmental change, as the hybrid blacktips are able to travel further south to cooler waters than the Australian blacktips. The team is looking into climate change and human fishing, among other potential triggers.
Pretty clear with the headline, right? There’s more examples of this, such as this one from the Business Insider which takes the cake:
Now, read the actual press release from the University of Queensland this story was based on:
World-first discovery of hybrid sharks off Australia’s east coast
A group of leading marine scientists has discovered that sharks on Australia’s east coast display a mysterious tendency to interbreed, challenging several accepted scientific theories regarding shark behaviour.
In a joint-UQ research project, scientists have discovered widespread hybridisation in the wild between two shark species commonly caught in Australia’s east coast shark fisheries.
The Australian black tip shark (Carcharhinus tilstoni) and the common black tip shark (C. limbatus) have overlapping distributions along the northern and eastern Australian coastline.
Using both genetic testing and body measurements, 57 hybrid animals were identified from five locations, spanning 2000km from northern NSW to far northern Queensland. Although closely related, the two species grow to different maximum sizes and are genetically distinct.
Dr Jennifer Ovenden, an expert in genetics of fisheries species and a member of the scientific team said this was the first discovery of sharks hybridising and it flagged a warning that other closely related shark and ray species around the world may be doing the same thing.
“Wild hybrids are usually hard to find, so detecting hybrids and their offspring is extraordinary,” Dr Ovenden said.
“To find 57 hybrids along 2000km of coastline is unprecedented.
“Hybridisation could enable the sharks to adapt to environmental change as the smaller Australian black tip currently favours tropical waters in the north.
“While the larger common black tip is more abundant in sub-tropical and temperate waters along the south-eastern Australian coastline.”
Scientists from The University of Queensland, James Cook University’s Fishing and Fisheries Research Centre, the Queensland Department of Employment, Economic Development and Innovation and the New South Wales Department of Primary Industries are now investigating the full extent of the hybrid zone and are attempting to measure hybrid fitness.
The research, co-funded by the Fisheries Research and Development Corporation, identified a mismatch between species identification using mitochondrial DNA sequence and species identification using morphological characters (length at sexual maturity, length at birth and number of vertebrae).
A nuclear DNA marker (inherited from both parents) was sequenced to confirm the hybrid status.
Dr Colin Simpfendorfer from James Cook University’s Fishing and Fisheries Research Centre said black tip sharks were one of the most studied species in tropical Australia.
“The results of this research show that we still have a lot to learn about these important ocean predators,” he said.
Media: Dr Jess Morgan on 0419 676 977.
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Important point: the press release DOES NOT contain the words “global warming” nor “climate change”.
I suspect this was the trigger for the reporter jumping the shark:
“Hybridisation could enable the sharks to adapt to environmental change as the smaller Australian black tip currently favours tropical waters in the north.
“While the larger common black tip is more abundant in sub-tropical and temperate waters along the south-eastern Australian coastline.”
So “environmental change” gets morphed into a “global warming” headline, when clearly, environmental change could be any number of things; pollution, changes in food supply, overfishing, competition, any of these (and others we don’t know about) could be factors…but “global warming” is automatically looked upon as the culprit. WUWT?
So, lets look at temperature. I asked Bob Tisdale to supply some sea temperature maps and graphs for the area. First the current available SST for Australia:
So much for the idea that the water is cooler to the southeast, and least in November. The waters of the south appear to be warming faster according to this anomaly map.
Here’s the last thirty years of sea surface temperatures from the area:
Less discerning reporters would immediately go A-Ha! The smoking gun, sea surface temperatures went up. Yes they did, and the trend is 0.135 °C/decade, and the trend line suggests Australian coastal sea temperature has increased by 0.45°C over thirty years.
But, in the last ten years (denoted by the span of the blue line) the temperatures have been pretty much flat.
Consider these points then:
1. Would you believe that one of the oldest creatures on Earth, which have managed to survive 500 million years over all sorts of temperature global temperature swings far greater, is sensitive to SST changes of 0.15 degree per decade enough to go on a panic breeding frenzy to save itself?
2. Since these “hybrid” sharks are a recent observation, it stands to reason they didn’t exist 20 years ago, maybe even 10 years ago. In this paper, the maximum lifespan of the Australian black tip shark (Carcharhinus tilstoni) is given:
The greatest recorded ages for C. tilstoni were 12 years for females and 8 years for males…
Davenport, S.; Stevens, J.D. (1988). “Age and growth of two commercially imported sharks (Carcharhinus tilstoni and C. sorrah) from Northern Australia”. Australian Journal of Marine and Freshwater Research 39 (4): 417–433.
So clearly, this new hybrid is a recent decadal scale development, and the last ten years of temperature in the area have been essentially flat. Connecting this with “global warming” doesn’t wash.
3. Ok, back to the “speculation” part of the headline:
Ovenden speculated that the two species began mating in response to environmental change, as the hybrid blacktips are able to travel further south to cooler waters than the Australian blacktips. The team is looking into climate change and human fishing, among other potential triggers.
It seems the Blacktip Shark isn’t confined in range at all, as this 2010 paper shows (bolding mine):
Genetic data show that Carcharhinus tilstoni is not confined to the tropics, highlighting the importance of a multifaceted approach to species identification
Boomer, J.J., Peddemors, V. and Stow, A.J., 2010. Genetic data show that Carcharhinus tilstoni is not confined to the tropics, highlighting the importance of a multifaceted approach to species identification. Journal of Fish Biology, 77:1165–1172.
Summary
Sharks are prone to human-induced impacts, including fishing, habitat destruction and pollution. Therefore, effective conservation and management requires knowledge of species distributions. Despite the size and notoriety of sharks, distributions of some species remain uncertain due to limited opportunities for observation or difficulties with species identification.
One of the most difficult groups of sharks to identify correctly is the ‘blacktip sharks’. This group of whaler sharks are harvested in substantial numbers along the Australian east coast, including NSW, yet little is known of their distribution and resultant potential portion of the commercial shark catch.
The NSW Shark Meshing Program (SMP) research has collected genetic samples from most sharks caught for many years. Analysis of these samples to determine proportions of each species caught in the shark nets yielded the surprising discovery that the tropical Australian blacktip shark (Carcharhinus tilstoni) was regularly represented. Approximately one-third of the ‘blacktip sharks’ previously assigned to the common blacktip (C. limbatus) were identified as Australian blacktip sharks. This discovery extends the range of this tropical species over 1000km southwards into temperate waters off Sydney.
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Wikipedia even has this helpful map of the range of Carcharhinus tilsoni
Quite comman with cetaceans
http://marinebio.org/oceans/dolphins.asp
“Three dolphins were found beached on the coast of Ireland in 1933 and were reportedly hybrids between Risso’s and bottlenose dolphins. This mating was apparently later repeated in captivity producing a hybrid calf. A bottlenose dolphin and a rough-toothed dolphin in captivity were also reported to have produced hybrid offspring.”
No good the sharks moving south if there food is not doing the same thing.
Sharks just follow the food.
Just like some who follow the money.
(Just had a big after shock here in Christchurch 8.30am)
It is the inter-species breeding between sharks and humans that I worry about. There are far too many “land sharks” preying on our fellow humans. It is these ravenous critters, that I warn my daughter about. Ocean shark’s sexual preference is not by choice, but by an appealing cut of the fin and a flash of belly. Nothing at all to do with remote climate change. Ocean sharks have limited choices, which both start with an “F”. Feed or F**K. GK
“Species,” definition:
If they are interbreeding they are NOT different species. They are subspecies varieties (what in human terms would be called “races”). So for all you “hybrids” out there, just know that the environmentalists find you very alarming. How did you get here anyway? Climate change? Bad. Very bad.
Specieization has been fading for a long time. Now with modern gentics we can determine
interbreeding and range. Now what used to be a color phase,is now a subspieces, or a separate
speices. Everything from squirrels to sharks…
@ur momisugly AndyG55; you are forcing me to respond. I read an article a few years back regarding the “red wolf”. It seems that after the reintroduction program for the “red wolf” began, a researcher began DNA testing and matching, and found that the “red wolf” is most likely a cross (I resist the term hybrid here because that implies the result is infertile, and the “red wolf” clearly is not) of the gray wolf and a coyote, and not a unique species at all! And the hysteria over the spotted owl is dying down as researchers have come to realize the barred and spotted owls are just different “races”, so to speak, of the same species. And after all, the crossing of the two owls seems to be insuring the spotted owls have descendents, isn’t that a good thing? So, back to the “hybrid” black-tipped sharks: are these “hybrids” fertile? Especially when bred to another “hybrid”? Then, as pointed out by other commenters, this is not a hybrid at all. I tend to agree with the other comment, they didn’t find these hybrids 20 years ago only because the technology was not available to identify them. When they are that plentiful, I suspect they may have always existed.
P.S. If liberals truly believed in evolution, they would allow endangered species to go extinct.
crosspatch says:
January 4, 2012 at 1:45 am
These sharks aren’t even different species, they are simply different varieties of the same species. Using their logic, should a European Caucasian man marry a Japanese Asian woman, we would have some environmental crisis induced inter-species … something … going on.
Give me a break.
Ah, Fred. Go back to the original article. They are same genus: Carcharhinus, but are classed as different species: “tilstoni” vs. “limbatus .” The problem with “species” is that the criteria that are used to delineate a difference at the species level very fuzzy. Ideally, a species is a population that is closed genetically – exchanges genes only among its members rather like climate scientists – but reality wasn’t organized according to ideals. There are examples among modern “species” where the only actual separation is behavioural, that is the difference is really “social” rather than biological or genetic.
Cyrus P. Stell, P.E., CEM
January 4, 2012 at 12:12 pm
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The red wolf story is far more complicated then what you imply. That you are still parroting 20 year old misinformation just goes to show how badly politics has muddied science. The red wolf is indeed a species and not a mix. The early DNA analysis problem was caused by the wolf DNA reference. The baseline included Timber Wolves. It turns out that Timber Wolves ( C. lycaon) and Red Wolves are varieties of the same US native species which is more closely related to the coyote (C latrans) then either is to the Grey Wolf (C. lupus) which is of Eurasian (Beringia) origin.
This is a normal part of the nature of any species. If a species is closely related of course they are going to interbreed it is all a part of nature’s evolution. Just like the Mule Deer and the White Tail deer have been interbreeding for a long time. Previous generations of hunters have noted that these deer chose to interbreed. So like the 2 species of Black tip, they chose to interbreed, it doesn’t mean global warming or anything like that. It just means that nature takes care of itself, and we have nothing to do with it! Man is so vain, it thinks it can control nature, by giving such a species a name and then noting that they never seen interbreeding of such sharks before? Which century do they live in? I thought that they were scientists, this should have been discovered a long time ago. If the main stream media is going to link it to global warming/climate change then there really is an agenda because why won’t they publish other stories that defy that man has been causing the changes when it is everything that nature is causing the changes. Nature is big on change, she changes all the time and we (MAN) CANNOT CONTROL those changes. We have to let nature take it’s course to see which way our temps will swing.
….hmmm, couldn’t we use this convergence of the two shark species as a proxy for approximating the climate at the original evolutionary divergence…and wouldn’t that climate be similar to the current climate…?
Talk about jumping the shark. More wild and indiscrimate fish sex coming:
“Met Office 2012 annual global temperature forecast
4 January 2012 – 2012 is expected to be around 0.48 °C warmer than the long-term (1961-1990) global average of 14.0 °C, with a predicted likely range of between 0.34 °C and 0.62 °C, according to the Met Office annual global temperature forecast.”
http://www.metoffice.gov.uk/news/releases/archive/2011/2012-global-temperature-forecast
DesertYote says:
January 4, 2012 at 12:38 pm
“It turns out that Timber Wolves ( C. lycaon) and Red Wolves are varieties of the same US native species which is more closely related to the coyote (C latrans) then either is to the Grey Wolf (C. lupus) which is of Eurasian (Beringia) origin.”
This is news to me and I keep up on this. Please provide a link or your source on this.
I hope you understand that some DNA analyses done by the eco-crisis industry is as reliable as Mike Mann’s work on climate history. So as this scenario you describe makes zero sense to me I need to see where it came from. Thanks.
Greater threat to shark populations?
Climate / environmental change
or
Human prediation
1 billion chinese want to know.
I think John Cook works for the same University.
Al Gored
January 4, 2012 at 1:01 pm
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The eco-nut have lately been trying to keep this quite. The reclassification of C. rufus would remove them from the endangered species list, which they do not want. Yet they are torn. The reclassification of C. lupus lycaon as C. lycaon would help justify using the Timber Wolf as a more formidable political weapon. Of course the genetics seems to indicate that the Red Wolf and all of the Timber Wolves are just inter grades, none of which are endangered.
I am at work, but when I get home, I will try to dig up a reference for you. I seem to remember that Meech wrote a paper a few years back that was pretty good science. I tend to judge him a bit harshly because of some of the nonsense that issues for from his mouth, but this paper looked very solid.
I cannot find any evidence that these two sharks are in any way separated by a temperature gradient. Both these sharks do well in both tropical and semitropical waters. They seem to perfectly overlap in their geographic range within Australian waters. They were considered the same species up until 1980.
All the Australian blacktips are a single population but not so with the more worldly common blacktip.
These two sharks are nearly identical except for some small genetics and form a closely related clade. The only visual difference is the larger size of the common blacktip (no help when dealing with subadults) and one having a propensity of more vertebrates before the tail. So these hybrids would and could only be seen by highly trained experts.
Fish have an amazing ability to selectively breed not only true to their own species ( whatever the definition) but also among their own sub-population. We can see this at work in some river lake systems with dozens of genetically isolated breeding populations of sockeye salmon co-existing within the same river system. The mate selection “barriers” that lead to isolated breeding include kin recognition by odor, and visual cues (size and other often small morphological cues)
The question is why are two distinct shark breeding populations -that normally overlap in geographic range- now interbreeding? The first and most obvious possibility is that they always have and that with the increased availability/cost of DNA testing we are just now noticing these “hybrids”. Given that these sharks have a maximum life of around twenty years and the pictures shown in the press of the hybrids are adults we start pressing back towards the date when no-one believed a hybrid was possible- seeing them all as a single specie!
Even so there is some question as to why we are seeing hybridization of isolated breeding populations as the Australian blacktips certainly seem to be. As I wrote earlier the alee effect seems to be the most likely explanation- IF the number of hybrids is outside of the normal anticipated range. And that I do not know.
My first thought if the number of hybrids is indeed anomalous then we are seeing an alee effect. Most likely the result of the crash in common blacktop numbers being targets as they are for the shark fin fishing fleet. The Common blacktop reduced in numbers has insufficient mates which then breaks down the visual and kairomone odor cues allowing breeding with Australians. It would be interesting to know which species were the females producing the hybrids.
I just cannot see how this is or could be in any way temperature related.
OK Yote. I’ll check back. But I must say, I don’t believe it – for many reasons – and I can see why the eco-crisis industry would want to tell that story.
That said, I don’t accept the idea of the ‘red wolf’ as a real species in any case – and I know one of the Chief Liars involved in this garbage, and more – so I get your point about it.
These people have been faking DNA stuff for a long time now, and it is very difficult to double check their results. Sometimes it is so obvious that it is laughable, like the so called ‘Sacramento Red Fox.’
I hear that bacteria contain human DNA. Does that mean they are human?
The WashPo carried this today but put it on the Politics page along side of “Far below, new species emerge” apparently recognizing both as more political than scientific although the second doesn’t appear to have an attached political statement.
Tom Davidson said @ur momisugly January 4, 2012 at 10:48 am
“The ability to produce fertile offspring is a satisfactory functional definition of ‘species’ for population biology.”
Herring gulls are spread from western Europe, across the whole width of Asia and across North America to the east coast. Each adjacent colony can breed with an adjacent colony, but the colonies of the American east coast and western Europe are mutually infertile and therefore by your definition different species.
Species are a “good faith guess” Quoting a Pompous Git:
There is, in fact, to use Sterelny and Griffiths’ words, a flock of species concepts:
* Phenetic species concepts define species by appealing to the intrinsic similarities between organisms. The idea is to purge species identification of theoretical commitments.
* Biological species concepts define species by appealing to reproductive isolation. One version of the biological species concept is the recognition concept, which defines species as systems of mate recognition.
* Cohesion species concepts generalise the biological species concept by recognising that gene flow is not the only factor that holds one population together and makes it recognisably different from others.
* Ecological species concepts define species by appealing to the fact that members of species are in competition with one another, since they need the same resources.
* Phylogenetic and evolutionary species concepts define species as segments of the tree of life. A species is a lineage of organisms, distinguished from other lineages by its distinctive evolutionary trajectory, and bounded in time by its origin in a speciation event and its disappearance by further speciation, or extinction.
[From Sterelny and Griffiths Sex and Death p 193]
It would be surprising indeed if all of these disparate ways that biologists view species produced agreement on which organisms were members of which species.
As others have noted, what constitutes a (separate) species is nothing like as clear as many think.
When there is interbreeding across part of the range of two apparently separate species, they are generally considered sub-species.
This may also be an example of a cline.
Clines consist of ecotypes or forms of species that exhibit gradual phenotypic and/or genetic differences over a geographical area, typically as a result of environmental heterogeneity. Genetically, clines result from the change of allele frequencies within the gene pool of the group of taxa in question.[2][3][4] Clines may manifest in time and/or space. (from wikipedia)
Greg Cavanagh said @ur momisugly January 4, 2012 at 1:33 pm
“I hear that bacteria contain human DNA. Does that mean they are human?”
It seems ever more likely that bacteria (prokaryotes) carry all of the DNA of all of the eukaryotes.
So if global warming causes evolution, why did most evolution happen before the industrial revolution?
WUWT: ‘I suspect this was the trigger for the reporter jumping the shark:
“Hybridisation could enable the sharks to adapt to environmental change…”‘
And since the Aus blacktip shark wasn’t even restricted to tropical waters but ranged into cooler southern waters without the need to “hybridize,” we now know that the scientists got it wrong on that count too. Nice catch.
In summary…sharks find eachother attractive and Aussies have PM Julia Gillard, and a carbon tax, all still inexplicable. Future study needed.
I agree with Philip Bradley @ur momisugly January 4, 2012 at 1:46 pm. This might be an example of a cline . A cline is one of the more interesting aspects of biology, and the most interesting example of a cline is the ring species.