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
Another thing I don’t know much about is HTML. There should have been “/sarc” after the “Horror!!!”
Curiousgeorge says:
“Do sharks practice safe sex? Is there a shark body shop some where in the area?”
or maybe a brothel ???
E.M.Smith says:
“Now if they had different numbers of chromosomes and were strongly isolated species, it would be much more interesting;”
You aren’t from New Zealand are you ?? (Aussie joke about sheep and New Zealanders)
Yet an other incident of media hyperbole! Unfortunately the ‘global warming’ angle will attract more attention and sell newspapers.
Great blog!
Jilly
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.
I disagree. This “new” hybrid is probably as ancient as the hills. Hybridization is actually not that uncommon among all sorts of animal species that are closely similar and that share a common range — the article exaggerates this, I fear, in implication but note well the real conclusion:
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.
Yes, lots of closely related species all over the planet may, and probably are, doing the same thing, and probably have been doing it far more commonly than we have long believed. Hybridization is one of the things that can possibly explain the extreme rapidity with which evolution can happen — variability within a species is clearly not as great as the variability accessible between species.
As for “hard to find” — if two species with common ancestors have mostly non-overlapping physical habitat — which is often the case, given that enough genetic drift has occurred for them to be considered different species, an observation that goes all the way back to Darwin and the finches of the Galapagos, then they simply lack the opportunity to interbreed. Sharks, however, experience no “barriers”, and there is no range of the Australian coastline where there are no blacktips. We can safely assume that their ranges have always overlapped by tens to hundreds of miles — there is no “magic temperature” in the ocean that repels sharks of one or the other species (and their territorial cues may not be temperature at all, it might be particular kinds of food. Who is really surprised by this? I’m not. It is evolution in action. Given enough hybrids that the hybrids themselves start to breed amongst themselves (perhaps driven by an “advantage” — hybrid vigor), and a bit of selection pressure, and a third species may emerge in between the two that are there now, and may expand into both of the older ranges. That’s what evolution does!
The “difficulty” at detecting wild hybrids is also very easy to explain. It was all but impossible to do at all until roughly 25-30 years ago. The extraordinary progress that has been made in genetics has been triggered by discoveries that are still remarkably recent — e.g. PCR, the ability to take genes out and amplify them — plus a remarkable array of physical equipment. We are still far, far from done mapping out the genotype of all of the world’s species — lots of genes, and lots of species. I wouldn’t doubt that this is the work this team is engaged in — mapping out the genotypes — so that they naturally enough would be the ones to observe and discover the hybridization.
Or, perhaps they discovered a new species, one in the process of emerging from hybridization. That would be really cool, because there is another debate I often participate in, and that is the debate between the numb-nuts who claim that the Earth is only ~6000 years old and that God hand-made all of the species. Evidence of evolution in action is marvelous stuff, although — in a way strangely like the debate over climate — simple evidence is never enough to convince a True Believer.
It is amazing how this original report was twisted into “proof” of global warming, though. An injudicious choice of words in the original report (there doesn’t have to be an environmental shift to cause two species with no physical barrier between them to have a common/overlapping range — it is expected that they will, this was something that didn’t need an explanation) is transformed by the alchemy of Faith into proof of global warming rather than proof of a dynamical ecosystem.
Really, they should look at birds. Birds, like fish, usually have ranges defined more by habit and competition than by climate. In the US, for example, there are similar species of songbirds with heavily overlapping ranges that hybridize, but really, this happens all of the time, all over the world, between all sorts of “neighboring” species. Hybrid offspring are often, but not at all always, sterile with both parent species (“mules”). The “not always” is well known to breeders of domesticated animals, who sometimes crossbreed a domestic species with a nearby wild one to try to fix some desired trait from the wild species in the domestic population. What humans do, nature does.
Anyone interested can read the wikipedia article on “Hybrid (biology)” — it is really quite interesting as it gives the lie to the idea that there is some sort of magic repellent that keeps similar species apart. While hybridization is usually between two animals in the same genus — the red wolf is believed to be a hybrid species produced by natural crossbreeding between wolves and coyotes, for example, sometimes, species that are very different manage to produce offspring. To quote from this article: “Where there are two closely related species living in the same area, less than 1 in 1000 individuals are likely to be hybrids because animals rarely choose a mate from a different species (otherwise species boundaries would completely break down). In some closely related species there are recognized “hybrid zones”.”
As I said, this happens all the time. It is not rare, it is commonplace. It is just the first observation of the phenomenon in sharks, and it is far more likely the case that it just hasn’t been observed because it hasn’t been looked for carefully enough than it is a “new” thing caused by humans.
The article clearly points out that humans are an important factor in hybridization. Indeed, we are probably the most important fact by an order of magnitude at this point, because we are constantly destroying or disrupting habitat or are simply actively moving species between different continents and then letting them go. See “killer bees”, kudzu, zebra mussels, and many more examples of our meddling and its sometimes profound effects on the environment. However, “climate change” a) happens all of the time without our help, and species either respond to it or fail the Darwinian test; b) is way, way down the list of things that threaten the purity or survival of species.
To put it bluntly, it is perhaps 10x more likely that if some anthropogenic rearrangement of the natural ranges of the sharks has occurred, it has occurred because of something other than climate change. For example, overfishing the waters so a key food species for one or the other becomes rare, driving the species further afield looking for food. Pollution causing blooms of toxic algae, ditto. Simple overfishing of the shark species themselves. Pressure on their breeding grounds. I teach every summer in one of the breeding ranges of blacktips (different species) I’m sure and several other (closely related but fairly “rare”) East Coast sharks — “spinner” sharks, for example. I fish for the same fish that they eat, and I not infrequently catch baby blacktips or baby spinners. I wouldn’t be at all surprised if hybridization is taking place right outside my summertime door, but there is so much that is not known about shark breeding and what its cues are and where/how it occurs that it might be a decade before anyone finds out and/or works out plausible reasons it is occurring.
rgb
@ur momisugly DesertYote
I refer you to the following: http://www.canids.org/PUBLICAT/CNDNEWS3/2conserv.htm Note that there is no mention whatsoever of a timber wolf species, all North American wolves are called gray wolves, other than the “red wolf”. And yes, I do notice that the date on the reference is from 1995, but that’s still less than the 20 years you claimed. (My brother got out of a speeding ticket with a similar argument: The ticket said he was doing 65 in a 55. The attorney asked my brother, “How fast were you going?” “I thought it was more like 75 myself.” Ticket dismissed, the officer failed to prove my brother was doing 65. So, specious (almost a bad pun, idn’t it?) as it may be, if I prove you wrong on one point…)
@ur momisugly DesertYote
http://genome.cshlp.org/content/21/8/1294 with a publication date of May 12, 2011. Recent. And reaffirms my original point. And in case you missed my original point, the fact that we develop a new technology that can observe something previously unobservable does not make it a new phenomenon. I suggest the shark species cross always existed, and probably always will, there’s nothing humans could or even should do about it.
Oops, sorry E. M. Smith — I missed your more or less identical remarks before posting. My bad. Truly a case (we agree) of “Move along, folks, nothing to see here”.
I almost brought up your observation about humans and chimps (and gorillas) because it is one of the most compelling pieces of evidence for evolution of both species from a common ancestor. Humans have 46 chromosomes; chimps have 48. Chromosome 2 (in humans) is clearly composed of a fusion of two chimp chromosomes. The evidence for this isn’t ambiguous — it is certain — you can see it for yourself here:
http://science.kqed.org/quest/2008/05/12/chromosome-fusion-chance-or-design/
Look at the near identity, slot by slot, for chromosome 2. Pretty amazing, actually. I sometimes wonder if “Yetis” and “Bigfoot” (if they exist) are human-whatever hybrids. Humans are well known for breeding well outside of their species lines (and sometimes halfway across the animal kingdom). There is a funny story in my family about how, in the early days of the Internet, my sister in law was trying to find the hours a nearby petting zoo was open by using (IIRC Alta Vista), a Google precursor. This was in the days of modem connection, quite slow, so she typed in “zoo farm” or some such and clicked the first link she got, with her (very small) kids looking over her shoulder.
Imagine, my friends, a picture, slowly emerging on the screen a few lines at a time. An elephant — good, it is a zoo! A woman’s face. Aw, look at that, she must be a zookeeper and the elephant likes her! The lines inexorably fill in, lower and lower and — yeep! That woman doesn’t have any clothes on! And what is that elephant doing with its trunk! Exeunt in haste, come on kids, nothing to see here, we’ll use the yellow pages, Rooobbbb (I was the resident “computer expert”) come in here and make that picture go away…
Human-chimp, human-gorilla, human-orangutan wouldn’t surprise me at all. Human-horse wouldn’t surprise me that much — I seem to recall some Russian Tsarina who was (shall we say) overly fond of horses. Give anything enough opportunities, some pretty unlikely surprises can occur in breeding…;-)
But we digress…
rgb
Cyrus P. Stell, P.E., CEM
January 5, 2012 at 6:54 am
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I was not disputing that hybridization happens naturally, and that new tools are revealing more cases for it. Your understanding of North American canids is quite incomplete. The Coyote x Grey Wolf theory for the Red wolf has been around for well over 20 year. The east coast wolves were originally considered a separate species ( C. lycaon (Linneus)) with the common name of Timber Wolf. That was revised to C. lupus lycaon, when naturalist started to encounter Grey Wolves (C. lupus), like they had in Europe. The Red wolf was different enough that they considered it a separate species (C. rufus). Early DNA testing included Timber Wolf and Grey wolf DNA as the Wolf reference. Of course the results would indicate that the Red Wolf shared DNA of Coyote ( C. latrans (say)). The Wolf DNA basis was invalid.
Your 1995 reference is way too old. Resent studies (e.g. Wilson 2002), on both morphology and DNA ( BTW, DNA analysis is no panacea) has shown that both C. lupus lycaon and C. rufus are the same species that ranged all across the eastern North America along the Appalachian range. This species is the sister of C. latrans and a North American native. That means that C. rufus is a coyote relative and only looks wolf-like because of adaption.
Personally I prefer to let the Marxist be the experts in perverting science to serve political ends. As Heinlein wrote “One can not use the weapons of the devil to defeat the devil”.
@Robert Brown..
“Imagine, my friends, a picture, slowly emerging on the screen a few lines at a time. An elephant — good, it is a zoo! A woman’s face. Aw, look at that, she must be a zookeeper and the elephant likes her! The lines inexorably fill in, lower and lower and — yeep! That woman doesn’t have any clothes on! And what is that elephant doing with its trunk!”
Man do you need some education re interbreeding ! 😉
Hint: The trunk ain’t gunna do nothing in that regard !!!!
Sharks adapting to extend their range to cooler waters when everyone knows that cooler waters are disappearing?
DesertYote says:
January 5, 2012 at 10:04 am
Thanks for those links. Due to time constraints I can’t spend much time on this until later but there are things that do not make any sense whatsoever, and things you are missing.
First, the original classifications of North American wolf subspecies by Merriam (like his classification of about 90 SPECIES of grizzly (brown) bears) was completely bogus.
Second, the original range of coyotes did not extend as far east as the so-called Red Wolf.
Third, what is a dog? When millions of Native North Americans living in eastern North America died of smallpox, what happened to all their ‘dogs’?
Finally, even if it was done with complete honesty, any recent DNA analysis is dubious at best because of historic population bottlenecks and the mixture of wolves and ‘dogs’ for the past two (plus) centuries, compounded more recently by the eastward expansion of coyotes .
The so called hybrization between wolves and ‘dogs’ – SAME species – is a very large and complex story which the green gang obviously would not want to think about. But I think it explains the so called ‘Red Wolf.’
On the subject of ‘wolf’ subspecies, it is worth noting that the same liars are promoting the absurd concept that the wolves on the BC coast – which no historic observer ever recorded, and which are not isolated from interior pops – are some unique subspecies to ‘save.’ No surprise. Each new ‘subspecies’ is like a franchise for the ‘species at risk’ listing industry if they can fool people into accepting them.
Al Gored
January 5, 2012 at 12:52 pm
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What is really funny is that many canid specialist are doubting the validity/utility of most subspecies designations for canids in general, and C. lupus in particular, yet the greenies are still trying to make every sub-population a subspecies. I am among those who think the whole idea of subspecies is flawed except in a very few cases (C. lupus baileyi, maybe). Merriam is guilty of crimes against taxonomy.
BTW, the Marxists definitely do not like the idea of invalidating C. rufus. If the red wolf ends up being C. lycaon, then the legal basis, under the ESA, for all of the control of private property that they currently enjoy, by evoking the endangered listing of C. rufus, goes out the window, even faster then if it is found that the population was formed from hybridization.
I am, like you, puzzled and dismayed by the lack of research on the North American dogs and the impact that they most surely have had. When I was a kid (I have always been a canid nut) I wanted to know about the dogs that the Indians had. No one knew anything. WOW how could that be?
Desert Yote
The topic of Indian ‘dogs’ is one that would be tooooo inconvenient for popular green mythology.
Tis a huge subject so, again due to time constraints, may as well leave it at that for the time being, except for one comment… that is, that ironically, both sides of the western wolf reintroduction issue have their heads in the sand on wolf ‘subspecies’ and all that. The people against those reintroductions like to argue that the reintroduced wolves, from Alberta, were the wrong subspecies. So for that argument they need to cling to the the old ‘splitter’ taxonomy.
So much fuzzy ‘science’ whenever political issues are involved.