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> In that case, you have no idea what stable numbers means -- it means a species whose long-term average remains the same. Or do you think species are like dorm

by waps 13y ago

> In that case, you have no idea what stable numbers means -- it means a species whose long-term average remains the same. Or do you think species are like dormant bank accounts, with constant balances to the penny? Given the examples I've seen so far, I'd consider any species that stays within 50% of it's previous numbers over 2 generations stable. But intuitively I'd have a stricter standard, something like no more than 10% per generation. > Absolutely false. Do you really want to advertise your ignorance this way? Heh. Let me just go over your papers : http://www.neds-projekt.de/Sabine_Hoehler_-_Growth_Curve1.pdf http://www.neds-projekt.de/Sabine_Hoehler_-_Growth_Curve1.pd... Essentially makes the case for malthusianism, and proposes to re-introduce population control measures (laws, forced abortions, ...). It's at least 50% a political paper. Need I go on ? I'd really rather not read it in detail. It's also hosted on a site by the social sciences department of the university of Hamburg. Even so, the paper merely intends to "fuel the debate" on this issue, not actually carry out analysis. Allow me to copy a sentence from the paper's conclusion : "Although they [regulatory suggestions to overcome the "normal population cycle"] might seem strangely scandalous and even marginal today, the suggestions and effected regulatory measures to control population growth in the late 1960s and early 1970s merely followed a rigid and conservative accountancy logic still in effect" (I do know a bit of German, the last part is a way-to-literal translation from German. It means to say that while population control laws were repealed, the reasons for having them have become stronger. Now to put things bluntly, but when it comes to scientific credibility, the social sciences rank significantly below my local bookstore's "Fiction" section. I would note that the social sciences see it as their mission not to advance scientific knowledge, but rather to influence public debate and regulation. This obviously means that any social sciences related paper explicitly is NOT the facts, but an attempt to convince you, and should be read like a commercial advertisement. http://www.cs.xu.edu/math/math120/01f/logistic.pdf http://www.cs.xu.edu/math/math120/01f/logistic.pdf A set of exercises constructed to match the logistic function by the math department ... The one example of human population it has actually contradicts your thesis : human population growth starting in 1927, and ending in 2071 (because at that point there would be no more growth) somewhat matches the logistic function. Needless to say this is a prediction. Further analysis reveals that human population growth was calculated at the UN using the logistic function, with the same parameters. As to what this means, I'd have to say it's a very bad example of statistical fitting, nothing more. For example, they just assume they have the answer, and don't even bother to measure the error in their fitting. Please note that this is not criticism of the authors of the paper, who undoubtedly are achieving exactly what they set out to achieve : train students to correctly evaluate a non-trivial calculus function. This is criticism of your interpretation of this paper. http://monkeysuncle.stanford.edu/?p=933 http://monkeysuncle.stanford.edu/?p=933 Is a paper that I would say defends my side of the argument (I'd say it's a critique against the logistic model). Note the prominent line : "Why does the logistic model fail so spectacularly in this case (and many others)?", and look at the graph right above it, and the explanation below. A quote : "Specifically, the logistic model fails to consider mechanisms of population regulation. When density increases, what is affected? Birth rates? Death rates? The r parameter in the logistic model is simply the difference in the gross birth and death rates when there are no conspecifics present." I think it's probably best if I stop now.

lutusp 13y ago
You said you had no idea what the logistic equation had to do with natural selection, but you believed that human populations didn't show a correlation with the function. I provided the links only so you would have a way to find out how wrong that was, nothing else. But you're one of those posters who can't seem to stick to a single topic. As to that topic, I can't believe that you're still unable to see that a stable population supports classic natural selection. In such a population, who survives is determined by their fitness, just when the population's size is changing. The fact that a population's size is stable or changing is irrelevant to natural selection -- it is unaffected. On that basis, population rate of change, and natural selection, are orthogonal factors. The only way a stable population would interfere with natural selection is if there was no reproduction taking place, no births or deaths, and that is certainly not what a stable population means.
Retric 13y ago
"Given the examples I've seen so far, I'd consider any species that stays within 50% of it's previous numbers over 2 generations stable" Most plants are vary stable as in within 5% over time as they tend to be vary resource limited, so they kill off competitors. Infact most species's say within 5% outside of environmental changes dispite boom and bust times simply because the planet is large enough that area A may go though a boom, while area B, C, and D is in bust period. EX: Deer.

by waps 13y ago

lutusp 13y ago

You said you had no idea what the logistic equation had to do with natural selection, but you believed that human populations didn't show a correlation with the function. I provided the links only so you would have a way to find out how wrong that was, nothing else. But you're one of those posters who can't seem to stick to a single topic. As to that topic, I can't believe that you're still unable to see that a stable population supports classic natural selection. In such a population, who survives is determined by their fitness, just when the population's size is changing. The fact that a population's size is stable or changing is irrelevant to natural selection -- it is unaffected. On that basis, population rate of change, and natural selection, are orthogonal factors. The only way a stable population would interfere with natural selection is if there was no reproduction taking place, no births or deaths, and that is certainly not what a stable population means.

Retric 13y ago

"Given the examples I've seen so far, I'd consider any species that stays within 50% of it's previous numbers over 2 generations stable" Most plants are vary stable as in within 5% over time as they tend to be vary resource limited, so they kill off competitors. Infact most species's say within 5% outside of environmental changes dispite boom and bust times simply because the planet is large enough that area A may go though a boom, while area B, C, and D is in bust period. EX: Deer.