Adaptive Development
Consider Barbourula kalimantanensis, the frog that has no lungs. These small, elusive, lungless amphibians live in cold, fast rivers, deep in the rainforests of Borneo. Ten years ago David Bickford and his patient international team of biologists worked hard and long to find some specimens for their study.
Bickford and his colleagues had an idea of what they were looking for, but they had no idea, and no reason to suspect, that the two inch frog would be lungless. As Bickford recounted:
At first I did not believe that the frogs had no lungs, but then, we just kept on seeing the evidence pile up. I was flabbergasted.
It was all a lesson, once again, in biology’s only rule, and that exploration seems to always payoff:
The thing that struck me most then and now is that there are still major firsts — for example, first lungless frog! — to be found out in the field. All you have to do is go a little ways beyond what people have done before, and — voila! … There are so many difficulties in field work, and yet it remains my biggest joy. Having the undeniable privilege of going out to these remote sites, seeing some of the last and greatest treasures that exist in the wild, and then getting to study them — well, every day I feel lucky.
It was also a lesson once again that biology makes no sense on evolution. It turns out that some species can forego their lungs altogether in their embryonic development, given the right environmental conditions. This is another example of rapid, directed adaptation, in response to the environment.
If such a sophisticated development plasticity could have evolved—“and oh! what a big if!” *—it would provide no immediate fitness improvement, and so would not be selected for. It would be subject to harmful mutations, and be long forgotten in the annals of evolutionary history.
This is intelligent adaptation which makes no sense on evolution.
Religion drives science, and it matters.
"This is another example of rapid, directed adaptation, in response to the environment."
ReplyDeleteAnother one of your unsupported assertions. You might have a bit of a point if this frog were found in slow moving warm rivers. But they aren't.
Another one of your unsupported assertions.
DeleteIt is what the evidence indicates
You might have a bit of a point if this frog were found in slow moving warm rivers.
The water needs to have a high O2 concentration. The arapaima live in slow moving warm rivers and they have to breath air. That tells me those waters have a low O2 content.
You have it backwards.
Joke: "The water needs to have a high O2 concentration. The arapaima live in slow moving warm rivers and they have to breath air."
DeletePlease pay attention Joe. We are talking about a lungless frog that lives in cold fast flowing rivers. Not a fish. Oxygen demand decreases in cold water. And cold fast water carries more oxygen than slow warm water. Add the fact that all frogs obtain a large proportion of their oxygen through the skin (fish don't) and you will see that your argument is poorly thought out. But, being Joe, I am sure that you won't admit your mistake.
What? Nice of you to ignore my argument. Oh well-
DeleteThat cold water caries more O2 means these frogs are in an environment that allows them to breathe without lungs.
Strange that every thing you said supports my argument and yet you say mine is poorly thought out.
My point about the arapaima is that their environment- slow moving warm water- is that it is O2 poor which would not be a god environment for a lungless frog. The colder fast moving waters, rich in O2, are perfect for such frogs.
DeleteThe only reason I mentioned arapaima was to show they live in an O2 poor environment.
So if, as wee willie sed above:
You might have a bit of a point if this frog were found in slow moving warm rivers
is totally bogus as the frogs in question would never evolve in that environment. T\hey need an O2 rich environment like the one they were found in.
So either wee willie has a reading comprehension issue or a critical thinking issue.
Sorry Joe, but if you are too stupid to understand the point of my original comment, then you won't understand why your response to it was also stupid.
DeleteLoL! @ wee willie winkie! You didn't have a point in your original comment. Your original comment mangled the point Dr Hunter made in the OP.
DeleteDr Hunter said:
" It turns out that some species can forego their lungs altogether in their embryonic development, given the right environmental conditions. This is another example of rapid, directed adaptation, in response to the environment."
That follows from the evidence. Then you chimed in saying that would be true in a scenario the change would never happen. The frogs could never exist in "slow moving warm rivers" as you suggested.
So obviously you are too stupid to make a point.
It sounds as if the point being made by Spearshake is that any change that doesn't seem to have negative adaptational value is automatically not a problem for the Evolutionary Synthesis du jour.
DeleteI think Dr. Hunter is suggesting that the lunglessness of this species might be the result of a hard setting of something that began as a variable epigenetic setting. Modern theory doesn't help the investigators anticipate either the sophisticated plasticity or the result, however adaptational they might figure lunglessness to be a posteriori. Only a theoretical framework that takes both surprises and non-surprises as equally explained can inspire a biologist to think that his theories are as predictive as a physicist's. This puts one in mind of Gould and Eldridge's comments about Dr. Pangloss.
Good thread and points.
ReplyDeleteThere would be no intermediate ones. I wonder if experiments could be done to turn it back to having lungs or turn like lung ones to being lungless with selection working on mutations.?!
"It turns out that some species can forego their lungs altogether in their embryonic development, given the right environmental conditions. This is another example of rapid, directed adaptation, in response to the environment."
ReplyDeleteHow can one differentiate between mutations being _directed_towards_ an environment vs _constrained_by_ an environment?
In an environment with very rich oxygen environment, any mutation that prevents lungs formation is no longer necessarily deleterious even if not especially beneficial. In any other environment such mutations are going to be consistently removed before they are observed with any frequency.