About the “Hybrid Shark” found in Australia

About the “Hybrid Shark” found in Australia

The news that a new “Hybrid Shark” has been discovered recently in australian waters raised a lot if interest recently, after a publication by a pool of scientist from the prestigious James Cook University in the discover in the scientific journal Conservation Genetics. 

They suggested that this unusual discovery is important because it’s a indication that climate change is driving evolution towards new species of shark, more tolerant to this change. “Evolution in action” they said. These new hybrids, belonging to different generations, appar to be fitter than their parents and can better survive to the environmental changes that are occurring in these years.

Of course I’m not expert enough to judge this work coming from scientist belonging to a prestigious University, and for sure the paper has been submitted to other experts before the publication, but anyway I have a doubt related to the definition of different species and hybrid.

I commonly see many butterflyfish hybrids, all coming from the same genus (Chaetodon), from species relatively close each other. So why should not be possible for sharks as well?

As far as I can remember, the definition of species includes the fact that two different species cannot originate a fertile offspring (doesn’t matter which generation, can be directly on the 2nd but even after). If the species originate a fertile offspring, they are not a different species, but maybe just different subspecies. The definition of species anyway it’s one of the most controversial debate in biology (just see the Wikipedia page about Species Definition).

So, if these sharks are not different species but just subspecies, I don’t see any anomaly in that, and even other explanations rather than climate change can be found. It would be very nice if somebody can clarify this point: of course such a big change due to climate change is leading to a big impact to media, but sometimes news should be better explained! Just my humble opinion.

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6 Comments

  1. avatar

    Francesco, do you have the original paper? Did they assess somehow that the hybrid is fecund?

    • avatar

      Hello Massimo, unfortunately not, I have not longer access to scientific literature database.
      However, in the article linked there is this statement: “initial studies suggested the hybrid species was relatively robust, with a number of generations discovered across 57 specimens”. So I suppose they have checked in some ways this ‘number of generations’.
      Moreover, I don’t remember that hybridation is a known mechanism of species formation for animals, maybe for plants, but my Botany exam is too far away to remember exactly.
      And “Evolution in action” can only mean that these hybrids are able to reproduce.. or maybe there is another explanation I can’t see!

  2. avatar
    Andrea Bonisoli

    I just read the paper, which I find interesting, although I am no expert (to say the least). The authors cautiously state that they infer hybrid fertility from the likely presence of back-crossed individuals, which in turn they infer from nuclear and mitochondrial genetic markers. If this is true, it would be enough to say that evolution is in action. The adaptivity of all this is another pair of shoes. In fact, in the paper the authors limit themselves to stating that this hybridization “may not be threatening” as it may help the “long-term adaptation to environmental change”, which is cautious enough. It is well possible that the media emphasized the global warming-side of this, or that the authors did in communicating their discovery,but in the paper they are very cautious about it.

    I have the paper if you want it. Just email me or write me on FB!

    have a good Befana – for those who have vacation because of it!

    • avatar

      Hello Andrea, thanks for your comment!
      I hope that reading the paper will clear out my doubts.. Because a great confusion has been made in these days.
      About the evolution is in act, I think nobody with a minimum of scientific background can deny it.
      If these two species are really distinct (and as long I can understand, they are: different body size, different behavior, differences in the internal anatomy, even genetic markers different) they cannot generate a fertile offspring, F1, F2, F3 or whatever. How this hybridization can help in he “long-term adaptations” remains to me still very unclear.

      But anyway I think we (as “scientists”, or anyway scientific writers) we should be aware is that scientific communication is a serious thing, and we shouldn’t let it managed by people that is only looking for traffic in their website, or people buying their magazine. Probably many people now think that “genetic engineering” could produce a terrible killer mixing different shark species…

  3. avatar

    Andrea, if you can send me the paper, send it to massimo@kudalaut.com

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