Welcome to European Tribune. It's gone a bit quiet around here these days, but it's still going.
I am captivated to hear the technical terms "r-selected species" and "k-selected species". I make a point here sometimes that most living species are not optimally greedy. Primitive selfishness has obvious short-term benefits (and a certain necessity at critical times), but it has grave long time risks. There must be a kind of natural selection working on longer time scales, punishing species that are too greedy or aggressive. Provoking more frequent or deeper Malthusian crises is not to your survival benefit.  

R-selected species indeed keep on coming. But as they are exposed to a sequence of boom-and-bust cycles, they ought to "acquire" more "altruistic" traits, and become k-selected species. Of course, different scenarios are possible, and they occured numerous times throughout evolution, with various frequences.

What I may object is this assumption.

In stable or predictable environments K-selection predominates, as the ability to compete successfully for limited resources is crucial, and populations of K-selected organisms are typically very constant and close to the maximum that the environment can bear.

Ok, k-selection makes more sense in stable or predictable environments. (On longer times scales, many things are better predictable, by the way.) But then come the assumptions of "limited resources" and "crucial competition". I do not see that these aspects must be always overly important. How can we measure how close is the population to the maximal capacity? What law forbids species to ignore the possibility of most effective expansion and resource utilization?

I know, Dawkins would say that the idyllic picture of lively organisms taking "only what they need" is in principle unstable, since more greedy individuals will start "benefitting" most and forcing everyone to an exploitation race. But first of all, the "unstable" ignorant period may last much longer than the "rational" growth-bust phase. Secondly, it is assumed that you can do nothing at "crazy" times but join the bahanalia. Well, dealing with "foolish" species and bands is indeed problematic. But the things to do to overcome habitat's degradation does not have to be wholesome participation. Nothing may be guaranteed on individual level, but what may survive more easily are collective arrangements or symbiotic relations. The harsh times are the best times for altruism!

In general, the r-selection is "justifiable" when the resources are abound. That is perhaps the story of every "innovative" disturbance: a pack of r-selected species occur and a boom follows, with a "depression" (or worse) thereafter. But however dramatic this cycle may look for participating species, the booms and busts may perform a "pedestrian" function for more complex organisms, or ecosystems. In particular, the predictable sequences of ecological successions might be more orderly than it should be  expected from the determenistic chaos paradigm: the successions might be controled by a pool of genes distributed across participating organisms.

But even in times of plenty, it is not "stupid" to refrain from most effective growth, while that can last. K-selected species can be suboptimally greedy because of a genetic or habitual trait from critical times, and that can be useful on the long time scale. Of course, the art of long term survival must include dealing with "foolish" r-selected species. Living is a complicated problem - so the biological world is becoming more complicated while solving those problems. I think that cooperation and contribution to resilience pf environment must be important part of solutions against r-species. In this light, the Gaia hypothesis might become more interesting.

by das monde on Thu Apr 12th, 2007 at 02:26:34 AM EST
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