Talk:Fitness

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This Evolution related article has been awarded BRONZE status for quality. It's getting there, but could be better with improvement. See RationalWiki:Article rating for more information.

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Warning: Extreme Incoherency
At least one of the editors involved in this article/discussion was under the influence of:
  • power, absolute power!
  • the sheer joy of discovering that an article mentions dinosaurs
and has lapsed into incoherency. Mind this in bear.

Why does the section on hybrid vigour not talk about hybrid vigour at all? I'd prefer to delete or entirely rework that section, but I want some input from others first. Wazza (Not Wazzock, Wazza)Approach the Presence 22:54, 24 October 2008 (EDT)

To me, it does talk about hybrid vigour, ie. the idea that heterozygous individuals may have more fitness (though I will say that I am biased, as I know exactly what I meant when I wrote it). If that is not clear, then by all means, it should be rewritten. I will re-look at it when I am no longer under the influence of lack of sleep:)Until then, I invite anyone who has any background in the subject to weigh in...that's the beauty of a wiki. --Thinker 01:43, 25 October 2008 (EDT)

Hybrid vigour is what you get when you cross two lines that have been bred for a pure line for a few generations. The pure line tends to bring recessive genetic problems to the surface, so when you cross them there's a good chance the problems will be covered up resulting in much healthier offspring. I believe the example you have offered is an example of heterozygote advantage. No hybridism required; these traits are standard in the population. Wazza (Not Wazzock, Wazza)Approach the Presence 01:48, 25 October 2008 (EDT)

Ah I think I understand now. I admit that we are crossing into genetic evolution, which is slightly outside my field of ecological evolution. I will change the header to fit the example, and I invite you to add a section on actual hybrid vigour (which is still relevant to discussions of fitness, if I understant it correctly). Just goes to show you, you learn something new every day, so thanks for correcting me! --Thinker 02:16, 25 October 2008 (EDT)

Fitness tends to be extremely contingent and function at the level of an organism or group rather than a single gene. It's probably best to talk more in terms of different types of beak for different seeds in different weather patterns (the classic example, from Galapagos) Wazza (Not Wazzock, Wazza)Approach the Presence 02:27, 25 October 2008 (EDT)

Actually I disagree that fitness is best understood at the individual level. It may be more easily understood at the individual level, but it creates a false "gene versus individual dichotomy" (as per Dawkins in The Selfish Gene); ie. what benefits a gene may not benefit the individual. Huntington's is a great example, as it increases fecundity at the cost of individual survival (increased fecundity=more copies of the gene). Group selection is really troublesome unless we consider only kin selection, and then only if we factor in degrees of relatedness. Normally, I wouldn't be nit-picking over this, but I just completed a massive paper on Dawkins and gene selection, so that's pretty much all I think about, evolutionarily (The Selfish Gene is a great read, by the way).
But that's not completely relevant...just from our short discussion here, you seem to be more than well-versed in evolutionary theory, so have at the article, by all means. Social cognition theory holds that two competing viewpoints working in concert will create a work greater than either viewpoint individually could come up with;) --Thinker 03:00, 25 October 2008 (EDT)

No... what you have there is what we call a "revert war"... :P

Group selection can also work thus: by protecting a group of people with a similar impulse to protect the group, who are unrelated, you may be ensuring that the children you already have will be kept safe by the group. Social animals aren't always related, you see. They have to mix the genes to avoid inbreeding... basically you have the group coevolve as individual lineages to sacrifice themselves for the good of a group that may or may not contain their children. This can, if carried far enough, bind together an entire species. Moreover working together even with unrelated individuals increases one's own chance of survival; witness Argentine Ants.

Genes of course are a huge part of it, but you have to consider the animal as a whole. A gene to increase fecundity at the price of lifespan coupled with a gene to increase loyalty to a mate at the expense of spreading the genes around is less effective than a polygamous strategy with the same gene. Every level of biology comes into play at once.

And I'm not editing articles that matter: there's a reason that template's there.

Well I would say the revert war comes when the two viewpoints just sit there and refuse to play together rather than engage in debate.
I think I may have been unclear: group selection as I'm railing against it is the idea that natural selection operates on groups as a whole. In other words, group selection holds that natural selection favors the reproduction of the most successful groups, rather than (and yes, this is only barely different) individuals in the most successful groups. What you have described is really individual selection put into context of a group (which is, I admit, what you have to do in the long run). I.e. ecological evolution.
I also agree that you do have to consider the animal as a whole, but when we consider it, as your post implied, we consider it as the environment of the gene. Genes may have different successes in different environments (read: bodies). To quote Dakwins, "a carnivore gene will do well only in the context of carnivore genes." But the salient point is that natural selection operates at the gene level, selecting genes which are able to create better "survival machines," either individually or in concert with other genes.
I also think that I've argued myself into a state of profound confusion, so I'm going to leave this for a little while until I have regained coherence. --Thinker 10:56, 25 October 2008 (EDT)