Speedy Selection

The DpSU for last Tuesday was called Researchers See Fish Adapt in One Generation.

The source is a paper – you can see the full text here – that details an experiment investigating the speed at which fish adapted to breeding in hatcheries. They found that the fish managed to do so in a single generation, but that this came at a cost to their survivability in the wild. Mr Thomas, author of the DpSU, expresses his incredulity at this being the result of natural selection, as was credited.

Male freshwater phase Steelhead (Rainbow Trout)

To quote:

How do these observations compare with various ideas about how species change? The authors correctly identified how traditional ideas of natural selection over many generations could be verified: If the “rapid fitness decline” that the fish experienced after adapting to the hatchery was the result of either a very high mutation load or of “many generations in captivity,” then natural selection could presumably explain the changes.

But these fish only needed one generation to experience dramatic changes.

Moreover, the changes, which the study authors wrote were “possibly correlated,” occurred in multiple traits at once. And the evolutionary idea of random-based biological changes does not fit with such correlated changes.

I would like to register my incredulity that Brian Thomas knows what he is talking about at all: this is exactly how natural selection would operate.

What we have here is a population of fish that have a mix of traits, as is normal. Their environment changes: they are now reproducing in hatcheries. The fish are adapted to the wild, and not the hatchery, but after only a single generation of selection they will be better adapted for their new conditions. but this has a tradeoff: they are now less adapted for their old environment. And, because of the nature of the game, it is harder for them to adapt back – natural selection acts to weed out the traits that are helpful in the old setting but are harmful in the new.

With that in mind, changes in gene frequency can and will occur in “multiple traits at once.” The sentence after that is just plain nonsense. He is confusing mutations with natural selection. Natural selection is not random – and thus neither is evolution, as it happens.

So, since the salmon evidence refutes typical evolutionary explanations for such changes, then what does explain them best? The study authors said that the changes were enabled by the genetics already within the fish: “The wild population contained the requisite genetic variation for rapid adaptation to captivity.”

No, within the gene pool. Honestly, Mr Thomas was a biology teacher

This implies that the potential was not conferred on the organism by anything outside of it.


Confusingly, however, senior author and Oregon State University professor Michael Blouin told TheFishSite.com, “What this study shows is that intense evolutionary pressures in the hatchery rapidly select for fish that excel there, at the expense of their reproductive success in the wild.”

Confusing for Mr Thomas, maybe: it makes perfect sense.

But the study never identified or measured any specific “evolutionary pressures,” nor did it specify what entity did any selecting.

There’s no talking to some people. You’ll note another instance of the “you need a selector to select” meme.

Instead of evolution selecting “fish that excel,” perhaps biological mechanisms within the fish “selected” the best combination of genes for the next generation to most successfully survive and reproduce in its new hatchery environment. The resulting fish multiplied and filled the hatchery, but in the process lost some of the genetic information that enabled their forebears to better survive in the wild.

That’s called Lamarckism, and if Mr Thomas wants to propose it as a watertight theory he needs evidence, and not speculation. “Perhaps” indeed.

And, bar the typical ‘credit … belongs to the Creator’ conclusion, that’s it. Is Mr Thomas really completely ignorant of the process of natural selection, or is he just playing dumb? I still can’t tell you.



Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s