Originally posted by scottishinnzSure it has. But long periods of stasis are more common than gradual change. And there are certainly instances in the fossil record of mass extinctions and rapid evolutionary changes brought on by a change in external factors.
And the alternative? Saltationism perhaps? Gradual genetic change has been observed, saltation is exceptionally unlikely.
Originally posted by scottishinnzYou're not correcting "facts"; you are pretending that your beliefs are "facts" when they are, in fact, hotly disputed within the field and/or other fields with perhaps more expertise in the subject matter (ex human behavior in the other thread).
And if I got something factually wrong, you'd correct me, right?
Originally posted by no1marauderYou are going to have to define "gradual" and "rapid". Rapid, in the tense you are currently using it, may mean 50,000 years or more! In which case, what is gradual?
Sure it has. But long periods of stasis are more common than gradual change. And there are certainly instances in the fossil record of mass extinctions and rapid evolutionary changes brought on by a change in external factors.
Originally posted by scottishinnzWhy play semantic games? Do you deny that punctuated equilibrum relies on very long periods of stasis (I know, define "long"!)? I guess Dawkins, Dennett and Gould and others wasted a lot of time writing articles criticizing each others' position when according to you it's all the same.
You are going to have to define "gradual" and "rapid". Rapid, in the tense you are currently using it, may mean 50,000 years or more! In which case, what is gradual?
From your cited wiki article:
Recent work in developmental biology has identified dynamical and physical mechanisms of tissue morphogenesis that may underlie abrupt morphological transitions during evolution. Consequently, consideration of mechanisms of phylogenetic change that are actually (not just apparently) non-gradual is increasingly common in the field of evolutionary developmental biology, particularly in studies of the origin of morphological novelty. A description of such mechanisms can be found in the multi-authored volume Origination of Organismal Form
Originally posted by no1marauderWhy not just define the term? This is exactly what Dawkins does. It's his position. When I find my copy of Blind Watchmaker (in my car I think), I'll quote you the whole passage if you like.
Why play semantic games? Do you deny that punctuated equilibrum relies on very long periods of stasis (I know, define "long"!)? I guess Dawkins, Dennett and Gould and others wasted a lot of time writing articles criticizing each others' position when according to you it's all the same.
Originally posted by no1marauderSo, no leg to leg in one fell jump?
From your cited wiki article:
Recent work in developmental biology has identified dynamical and physical mechanisms of tissue morphogenesis that may underlie abrupt morphological transitions during evolution. Consequently, consideration of mechanisms of phylogenetic change that are actually (not just apparently) non-gradual is increasingly common in t ...[text shortened]... tion of such mechanisms can be found in the multi-authored volume Origination of Organismal Form
Found this to be rather interesting:
Among the more surprising and, perhaps, counterintuitive (from a neo-Darwinian viewpoint) results of recent research in evolutionary developmental biology is that the diversity of body plans and morphology in organisms across many phyla are not necessarily reflected in diversity at the level of the sequences of genes, including those of the developmental genetic toolkit and other genes involved in development. Indeed, as Gerhart and Kirschner have noted, there is an apparent paradox: "where we most expect to find variation, we find conservation, a lack of change".[8]
Even within a species, the occurrence of novel forms within a population does not generally correlate with levels of genetic variation sufficient to account for all morphological diversity. For example, there is significant variation in limb morphologies amongst salamanders and in differences in segment number in centipedes, even when the respective genetic variation is low.
A major question then, for evo-devo studies, is: If the morphological novelty we observe at the level of different clades is not always reflected in the genome, where does it come from? Apart from neo-Darwinian mechanisms such as mutation, translocation and duplication of genes, novelty may also arise by mutation-driven changes in gene regulation. The finding that much biodiversity is not due to differences in genes, but rather to alterations in gene regulation, has introduced an important new element into evolutionary theory.[9] Diverse organisms may have highly conserved developmental genes, but highly divergent regulatory mechanisms for these genes. Changes in gene regulation are "second-order" effects of genes, resulting from the interaction and timing of activity of gene networks, as distinct from the functioning of the individual genes in the network.
http://en.wikipedia.org/wiki/Evolutionary_developmental_biology
Apparently not every scientist buys into gene centered, neo-Darwinism. They must all be superstitious, ill-informed morons.
Originally posted by no1marauderSo both genes and the environment have an effect on development. Well, even a 5th form high school student could tell you that. Shame it's not part of this debate.
Found this to be rather interesting:
Among the more surprising and, perhaps, counterintuitive (from a neo-Darwinian viewpoint) results of recent research in evolutionary developmental biology is that the diversity of body plans and morphology in organisms across many phyla are not necessarily reflected in diversity at the level of the sequences of gen ...[text shortened]... buys into gene centered, neo-Darwinism. They must all be superstitious, ill-informed morons.