Genotype-Phenotype Correlations Confer 'Chaotic' Evolution
21/11/10 03:24 Filed in: GenomeWeb Daily Scan
Submitted by S. Pelech - Kinexus on Sun, 11/21/2010 - 03:24.
Right after Keith Bennett points out that "The overall picture is that the main response to major environmental changes is individualistic movement and changes in abundance, rather than extinction or speciation," he then stated, "In other words, the connection between environmental change and evolutionary change is weak, which is not what might have been expected from Darwin's hypothesis." I think that it would be unwise to under-estimate the impact of a rapidly changing environment on evolution. The rapid disappearance of dinosaurs is an obvious exception. The impact of human activity on the ecosystem on our planet is another obvious challenge to this notion.
On the one hand, it would seem logical that abrupt changes in environment, such as the Earth being hit by an asteroid or comet would produce rapid changes in the distribution and abundance levels of diverse species primarily on how adversely they may be affected and their ability to migrate. On the other hand, with careful breeding, it is evident that profound changes in phenotype can arise within a relatively small number of generations. Consider the huge variation in the sizes, shapes, colours, intelligence and other traits of dogs. It is not unreasonable that climate change, especially when it drastic enough to threaten survival, will favour those organisms with traits that enable them to cope and compete in that environment.
Such traits probably do not arise from single base pair changes but rather from multiple chance mutations in just the right combinations. Some advantageous genetic mutations may actually be deleterious in a different context. For example, a mutation of myosin in the human jaw so that we have a very poor bite relative to other simians has contributed to towards the development of our larger brains. Consequently, I agree with Dr. Bennet that macroevolutionary change is non-linear, very random and chaotic.
Some climatic changes may actually induce favorable conditions for induction of increased gene mutation rates and breeding to propagate advantageous mutations. For example, during periods with increase global warming and increased exposure to solar radiation, there might be conceivably higher rates of mutation, in parallel with a greater abundance and numbers of diverse organisms. In contrast, with global cooling, less expose to radiation and decreased reproduction from poorer access to nutrients, the expansion of organisms from cooler environments by migration probably plays an even greater role in ecosystem diversity.
In any event, the living world is the way it is because of a combination of incalculable freak events at the molecular, microscopic, macroscopic and cosmic scales.
Link to the original blog post.
Right after Keith Bennett points out that "The overall picture is that the main response to major environmental changes is individualistic movement and changes in abundance, rather than extinction or speciation," he then stated, "In other words, the connection between environmental change and evolutionary change is weak, which is not what might have been expected from Darwin's hypothesis." I think that it would be unwise to under-estimate the impact of a rapidly changing environment on evolution. The rapid disappearance of dinosaurs is an obvious exception. The impact of human activity on the ecosystem on our planet is another obvious challenge to this notion.
On the one hand, it would seem logical that abrupt changes in environment, such as the Earth being hit by an asteroid or comet would produce rapid changes in the distribution and abundance levels of diverse species primarily on how adversely they may be affected and their ability to migrate. On the other hand, with careful breeding, it is evident that profound changes in phenotype can arise within a relatively small number of generations. Consider the huge variation in the sizes, shapes, colours, intelligence and other traits of dogs. It is not unreasonable that climate change, especially when it drastic enough to threaten survival, will favour those organisms with traits that enable them to cope and compete in that environment.
Such traits probably do not arise from single base pair changes but rather from multiple chance mutations in just the right combinations. Some advantageous genetic mutations may actually be deleterious in a different context. For example, a mutation of myosin in the human jaw so that we have a very poor bite relative to other simians has contributed to towards the development of our larger brains. Consequently, I agree with Dr. Bennet that macroevolutionary change is non-linear, very random and chaotic.
Some climatic changes may actually induce favorable conditions for induction of increased gene mutation rates and breeding to propagate advantageous mutations. For example, during periods with increase global warming and increased exposure to solar radiation, there might be conceivably higher rates of mutation, in parallel with a greater abundance and numbers of diverse organisms. In contrast, with global cooling, less expose to radiation and decreased reproduction from poorer access to nutrients, the expansion of organisms from cooler environments by migration probably plays an even greater role in ecosystem diversity.
In any event, the living world is the way it is because of a combination of incalculable freak events at the molecular, microscopic, macroscopic and cosmic scales.
Link to the original blog post.