Slashdot Mirror
Reversing Undesirable Fish Evolution
TaeKwonDood writes "Your granddad's approach to fishing — throw the little 'uns back — may have hurt their evolution, but we can reverse that, says a group of researchers, with a change of policy.
Fish have been 'reprogramming' themselves to be smaller and live longer. Welcome to evolutionary dynamics, Lamarck. But, no, they are serious. And it can be fixed within 12 generations. What do the smart people out there think about this? Are they using the term 'evolution' the wrong way?"
Are they using the term 'evolution' the wrong way?
Nope. It seems correct to this biology teacher. This is a clear case of directional selection. Keep eliminating the larger fish and the median size of fish in the population will be smaller. So, by taking the large ones, we are selecting against them and for smaller fish and juveniles. If, over time the frequencies of the alleles for large and small change in the population, then we have, by definition, evolution.
What makes you think this wouldn't be an example of evolution?
"Empathise with stupidity, and you're halfway to thinking like an idiot." - Iain M. Banks
Are they using the term 'evolution' the wrong way?"
If being smaller enables the fish to survive long enough to breed, then no. Big fish die off, small fish breed.
William of Ockham had no beard. The most likely explanation is that it was chewed off by squirrels every morning.
What does Lamarck have to do with it? These fish haven't been passing down traits they've developed during their lifetimes - we've been killing all the big fish, so smaller fish are selectively left to breed. That's Darwinian evolution.
In normal situations, I'd imagine that bigger fish tend to reproduce more often. But when some external force (e.g., thousands of fishers in boats with GPS and big nets) changes things, you get a different outcome.
If we preferred to eat fish that were darker in colour, they'd be getting lighter instead.
Either TaeKwonDood misunderstands evolution, or rushed to post his article a little too quickly...
---sheath
Animal Husbandry has been doing it for years in one form or another.
See Wikipedia
Of course, if you leave the runts of the litter only, you end up with smaller critters. Its how many lap dogs were bred in the first place.
And like any breeder can tell you, of course it can be fixed in 12 animal generations!
... should read Beak of the Finch
Money is the root of all evil?
I don't know - once one of the selection pressures is an intelligent force that can predict the eventual path of evolution, I'd say words like, 'hurt' can start to apply.
What if the fish evolving to be smaller to avoid human mouths eventually leaves them set to be eliminated by some other force? In other words, what if we're forcing a short term evolutionary advantage that is long term fatal to the species?
I read, about twenty-five years ago, that traditional people in the Andes, when planting potatoes, only planted the biggest and most beautiful ones they had from previous harvest. The religious justification is that the "Pacha Mama", which is "Mother Earth", only deserves the best.
Natural selection works to increase the fitness of the average individual in a population sure, but Evolution also includes cases where the average fitness level can go down. Consider, for instance, the founder effect.
"Knowledge is the only instrument of production that is not subject to diminishing returns" -Journal of Political Econom
Bananas are a bad example. They might be a lot easier to eat these days, but they can't reproduce on their own anymore. They're also so limited genetically, because they don't reproduce like plantains do, that a banana-specific bacteria or mold or something could totally decimate a very large supply of the fruit.
Learn something new.