One of the really cool things about having a robust scientific model of various parts of the universe is that we can use it to tell the future. This is not something you can do with any form of pseudoscience or religion. In this case, its the theory of evolution that provides us with a new prediction.
Recently we have heard about something really strange occurring. Now, if you are a theist, this would not be strange at all. It is only odd because evolution is such a well supported theory.
Here is what is weird: the picture to the right there is of an Antarctic sea anemone. This lil’ creature has a home that is remarkably large. These guys and 235 others are found at both the north and south pole, but not in the middle (as far as we know).
Many of these creatures that have obvious reasons to be at both poles, like whales and birds, like the Arctic Tern that migrates every single year from the arctic to the Antarctic and back. But it turns out that there are still many, many species, like the one above, that are anchored to the sea floor and have no known mode of transport. And yet, despite huge geographical separation, appear to be the exact same species at both poles. If this only happened rarely or once, with strong odds against it, we would have expected to see some speciation happen by now.
So this is a strange observation because we know evolutionary processes exist. So how can we explain this?
| 1 | The most probable idea is that there are strong continuous currents that regularly take spore or larvae from one pole to another. We know about ocean surface currents, but these mostly are in loops, called gyres, not generally from pole to pole. So the observation of “bipolar” species is that there are other currents that regularly take fauna from one pole to the other. So check this out, if true, then there are likely mechanics about the ocean that affect our climate, that we learned about from knowing evolution. |
| 2 | Another idea is that this happened recently. Some recent event could have happened that took some species from one pole to the other. for example, some one could have actually taken some species from one pole and set them free at the other. This is a very unlikely scenario, mostly because these creatures are far down in the water, and there are a number of bipolar species, not just one or two. |
| 3 | Another possibility is that something, like a whale is eating the spores and larvae at one pole and pooping (a recurring theme at this blog) them out at the other. We know that some seeds can stay in some birds for thousands of miles. However, in general, passage through the digestive tract is far faster than a trip from one pole to the other. |
| 4 | There is the possibility that the bipolar species were once ubiquitous throughout the ocean and got geographically isolated as the earth warmed. For them to have remained unchanged after isolation however, they would have to have remain unchanged not only through mutation and natural selection but also through all the evolutionary mechanisms that push evolution like genetic drift. A possible, but unlikely situation. |
| 5 | God liked these species as they are and decided to place them at both ends. |
Of these, ignoring the utter uselessness of the last one, the first is most probable and exciting. This observation may lead to some new information about our oceans and our planet. It would be yet another way evolution has helped us.
Sadly there are more observations that are needed before we can start truly verifying this hypothesis. Genetic testing must happen to be sure that these bipolar species are, in fact, the same species. But then, it would truly be great to know the mechanism by which these bipolar species can pull off these marathon expeditions! Not only would we have yet even more evidence of evolution by verification of a prediction, but we would have new information about our oceans that oculd lead to more information about our climate.
7 comments:
What about artic vessel ballast? There are a whole host of species that have colonised the world's ports (and now coastlines), thanks to ballast uptake & dumping.
Yes, excellent!
However, I'n my professional opinion (lol) I'm gonna still have to place this as less likely than #1. Reason being two fold, first off, you would need ships that regularly travel from one pole to another, or at minimum travel from one pole to a surface current that travels to the other pole. But secondly, the spore and larvae of these creatures are not the ones that bind to a surface (for the most part), its the adult plant that does this, and these guys live at very high pressures and low temperatures, a trip a the surface would probably be deadly to it.
Then again I only research 2 of these creatures, there are many many more, its a totally possible hypothesis.
It was aliens.
http://en.wikipedia.org/wiki/Ocean_conveyor
Did you perhaps not know about this? It's a super current that wraps around the world in a very twisty fashion and travels for great distances at both the lower and upper reaches of the ocean.
It's also important to know that Antartica has a loop of this current going around it which helps isolate most Antartic ocean life from the rest of the ocean.
...and just to be clear, these are gyres.
http://en.wikipedia.org/wiki/Oceanic_gyre
thanks Pheonix! I did know about that (it was mentioned in Gore's movie). I just forgot about it. And perhaps that is in fact the thing causing this weird behavior. I was under the impression that this current was rather slow and half of it was at the surface. Either way, if it is it, we may be able to have a great way to truly measure it now by measuring concentrations of larvae from polar creatures.
Slow is a relative term here, as it's estimated that the entire conveyor flow is a 2,000 year round trip or so. The specific part at work in this case would be the Atlantic flow which submerges around Greenland and goes straight south to Antartica(North Atlantic Deep Water). The flow then circles Antartica, all the while staying in the deep waters the entire trip.
Just looking at the map I would say from Greenland to Antartica is 10% of the conveyor or so, which all things equal means a 200 year trip. That should be enough to keep cross-breeding up and reduce speciation through isolation. Probably not that slow either, I'm just being conservative.
BBC Documentary "Earth: The Biography" has an episode on the ocean which covers the conveyor quite a bit, including past consequences of it altering or shutting down. It came as part of a package with my Planet Earth Blu-ray set =D
Looked on youtube and it's up there.
http://www.youtube.com/watch?v=i89HVeJhybk 4/6 Duckies @ 5mins, though that is surface currents of course.
http://www.youtube.com/watch?v=dtDdNRtquyg&feature=related 5/6 Ocean Conveyor @ 2min
This story of a claimed 235 bipolar species is not based on published science, but on a press release. In fact the anemone Stephanthus antarcticus in the picture is Antarctic only, described in 2003. Not bipolar. And there are no genbank records of it. It seems to be in the New Scientist story simply because they had a nice photo!
Biologists can be quite naive about how reliable species names are. Basically it is wise to distrust most old names of marine inverts. Polar species names published in the 19th Century under the much lower standards of that time can be quite a mystery today as to what they represented. If they lack type specimens from that era there is no way of knowing what the original animal was. Thus my guess is the explanation for the apparent bipolarity lies mostly in taxonomic uncertainty rather than in biology.