While you've made several good points, I think you've neglected to address a sticking point: how does a sexual species mutate into a new species?
An example: let's say, by random chance, a bird hatches out of a lizard egg one day. If the bird represents a new species, then it will not be capable of reproducing, unless, by sheer coincidence, a compatible bird happens to hatch in the same generation. This is what makes macromutationism so implausible.
As I understand it, the punctuated equilibrium model is more complex to explain. An example of it might start with a population of a single species. Minor variations, which do not prevent interbreeding, occur in the population all the time, but mostly they are of no benefit and/or chance swallows them up again. However, if something happens to separate the smaller population away from the larger, then mutations in it stand a better chance of taking hold -- the "Southern" syndrome you refer to earlier. As long as the smaller population remains separate from the larger, chance may take it farther from its roots, until eventually enough variations have taken place that it can no longer interbreed with the original population. Thus, it becomes a new species.
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timeasmymeasure
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Date: 2002-11-19 05:48 am (UTC)An example: let's say, by random chance, a bird hatches out of a lizard egg one day. If the bird represents a new species, then it will not be capable of reproducing, unless, by sheer coincidence, a compatible bird happens to hatch in the same generation. This is what makes macromutationism so implausible.
As I understand it, the punctuated equilibrium model is more complex to explain. An example of it might start with a population of a single species. Minor variations, which do not prevent interbreeding, occur in the population all the time, but mostly they are of no benefit and/or chance swallows them up again. However, if something happens to separate the smaller population away from the larger, then mutations in it stand a better chance of taking hold -- the "Southern" syndrome you refer to earlier. As long as the smaller population remains separate from the larger, chance may take it farther from its roots, until eventually enough variations have taken place that it can no longer interbreed with the original population. Thus, it becomes a new species.