Foul Tasting Bugs

The most obvious explanation, and one that Fisher came up with in the 30s, is that it is propagated through a form of kin selection. While as you say the bug which gets eaten doesn't get any benefit from its being eaten the other bugs in the area do. If we assume that the other bugs in the area are likely to be closely related to the eaten bug, and therefore more likely to share the same genes for noxious taste, then the protection from its noxious taste enhances the survival of those related bugs relative to other unrelated bugs in different regions.So if you have a whole brood of dozens of foul tasting bugs in an area with a few predators and each predator learns to avoid them after 1 or 2 samplings then losing a moderate proportion of the brood could confer protection on the rest.As to the very inital development of the foul taste, it depends. We might assume that populations of bugs naturally vary in their tastiness and predation acts as a strong form of directional selection favouring less tasty bugs.Alternatively we might posit a novel exceptionally untasty mutation in an individual which would need to survive independent of its tastiness before it could mate and produce a brood in which tastiness could provide some group protection. Of course if we allow that predators sometimes taste noxious prey without killing them then the chances of a rare de novo noxious mutation propagating become much better.TTFN,WK

Sure and the whole concept of the evolution of noxious taste is usually bound up with the development of aposematic signals for letting predators know you are noxious. And from then of course onto various forms of inter and intraspecies mimicry and evolutionary cheating strategies.TTFN,WK

We had quite a few mimicry threads when MartinV was doing the rounds of the boards, see Mimicry and neodarwinism and Mimicry: Please help me understand how.TTFN,WK

The difference is in the honesty of the signal. If you are all signalling honestly it is better for everyone, if only some are signalling honestly then they are weakening the protection of the signal for everyone including the honest signallers.The basic effect is the same but the underlying evolutionary strategy, mutualism or parasitism, is what makes the difference.TTFN,WK

I'm not sure what you think is the difference between your answer and ours, you have just swapped 'sub-population' in to represent the population of more closely related organisms, but the chances are that the sub-populations where these traits are prevalent will be more closely related individuals since we know that many of them at least share the trait for unpalatability and individuals within the same area are also normally more likely to be related.The isssue is why does a trait prevail when it doesn't directly benefit the individual exhibiting that trait, the answer is kin selection. If you want to claim that none of the individuals exhibiting the same trait in the sub-population are related, or that they are generally no more related than with individuals of another sub population, then I think you will have a hard row to hoe.So I think you are making a distinction without a difference.TTFN,WK

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But RAZD, you have the answer with the "neutral mutation." Neutral mutations can be used to fill in a lot of blanks, I would guess-- kind of a get-out-of-jail-free card. It doesn't seem to me that the spread of neutral mutations, in this case, can be considered natural selection. It is chance.

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Actually RAZD's answer about the spread isn't really 'Neutral mutation' but rather 'Genetic Drift', which is indeed essentially the effect of chance on the spread of a mutation.Regardless of the fitness benefit or cost of a mutation stochastic processes will tend to change the frequency of the resulting allele in subsequent generations of a population. In some cases this will lead to even a strongly beneficial mutation being lost or deleterious mutations becoming fixed in a population, but it can also increase the rate at which a beneficial mutation runs to fixation.It may be that what we see with noxiousness is also a frequency dependent effect where the mutation only becomes beneficial when it is widespread enough in the population to confer protective benefit. In this case clearly drift is required to raise the allele frequency to the necessary level initially.TTFN,WK

Just to add to what Mr. Jack said, this is an understandable interpretation of Kin selection but Hamilton described in the 60s how altruism without kin recognition could evolve in 'viscous' populations, populations with low levels of dispersal, low levels of invasion by other populations and which therefore tend to stay in a restricted geographical location.Haldane famously explained Kin selection by saying, "I would lay down my life for two brothers or eight cousins", the development of noxious taste is just taking that principle to an extreme where it applies to hundreds or thousands of more distantly related individuals. When the only action involved is being eaten then kin recognition obviously doesn't play a part, but that doesn't mean it isn't an example of kin selection.The fact that you don't like it doesn't change the fact that this has been a recognised mechanism of Kin selection for almost 50 years.TTFN,WK

Frankly IGIT the fact that you are prepared to accept the explanations we have given you as sufficient to provide a naturalistic evolution of noxiousness makes you somewhat of an exception among the 'enemy'. If you look at the threads I referenced before about mimicry in Message 11 you will see the more common pattern where when MartinV is provided a naturalistic explanation for something evolving he simply ignores it and starts again with a new tack.Having anyone on the creation/ID side accept a naturalistic explanation for anything is something of a novelty, I exaggerate here but only a little bit.So bring on those other questions!TTFN,WK