Wednesday, March 22, 2006
Creation, Ecological Diversification, and Symbiosis
Some Creationists have thought that the genome and traits are essentially unchanging, and that inheritance is almost entirely Mendellian in nature. However, this is usually a holdover from atelic assumptions about the nature of how genomic change can occur. However, there are a number of evidences that genomes can change in specific, adaptable ways, which I have touched on from time to time on this blog.
The great diversifications after the flood involved numerous speciation events. Here I am going to hypothesize one (of many) methods by which this speciation occurs, which I will call "Ecological Diversification". If anyone knows of an existing term which matches this, please post it in the comments.
Previously, I posted a review of a paper on ecological developmental biology. To recap, some of the ideas presented there included:
- During development, environmental factors can shape the developmental pathways an organism takes, and thus its resulting phenotype.
- Species can detect predators during development through kairomones and develop adaptively to help them against the predator.
- Many generations of exposure to an environmental influencer on developmental pathways can cause the change to be permanent, and continue on even in the absence of the environmental inducers. In other words, the inducers have become internalized. The term for this is genetic assimilation, though that does not necessarily mean it is a genetic change.
I would propose, therefore, that a major impetus for speciation is the organism detecting its environment, and then its offspring developing in specific ways to adapt to the environment. These adaptations are precoded for certain types of environmental inducers. Some of the inducers I would propose might be:
- Other organisms, both friend and enemy
- Available vegetation
- Landscape (there is nothing limitting the visual cortex of the parent from inducing change any more than any other organ)
So, let's say you have fours species, A, B, C, and D, and environments X, Y, and Z. My speculation is that if you were to put A, B, and C in environment X; B, C, and D in environment Y, and A and D in environment Z, all organisms would, in a relatively short amount of time become recognizably different species. And, accordingly, I would propose that if the same environment were reproduced for the same sets of species, the results would be the same. However, this would be difficult to determine because of the number of factors involved.
Taking this idea further, let's look at symbioses. Symbioses have always fascinated me. Some of the elaborate symbioses have long been used to demonstrated the wonderful beauty and integration of Creation. And yet, I am almost entirely certain that many if not most symbioses are recent, not permanent. This may sound like a contradictory view, but it is not. Some people mistakenly think that "irreducible complexity" and similar ideas mean that a given feature cannot have evolved. That is not entirely true. What it means is that it cannot have evolved purely by stochastic means (i.e. Darwinism). It means that the evolution of the feature must be guided by some other mechanism. In other words, the "evolution" of the feature must be pre-coded, or at least semi-pre-coded. In the same way, I think that organisms have the ability to evolve specific types of symbioses. Then, the types and morphologies of the other flora and fauna in their environment will trigger a change in the organisms, which will induce an appropriate symbiosis with one or more creatures in the area.
One class of such symbioses which have been studied are the Type III Secretory Systems of bacteria. These systems appear to be made to help bacteria develop symbiotic relationships with eukaryotic hosts. While reading the research, it was difficult to separate the fact from evolutionary speculation, so it would be interesting to see a Creationist look at this. It seems that at least some symbioses are apparently a one-way transformation. Here is an interesting paper on an endosymbiont that uses such a system to invade the cell.
[short rant] It would be much more interesting if these papers spent more time discussing functional aspects of the relationships than try to guess phylogenies [end short rant]
Also, Type III Secretory Systems are often the cause of pathogenicity of microbes. As we have noticed in previous entries, it seems logical that these pathogenic systems are due to a breakdown of symbiotic mechanisms that make them pathogenic. Unfortunately, most of the research seems to be on pathogens rather than symbiotes.
Anyway, this seems to be a very fertile area for Creationist research.
For those interested in reviews covering aspects of such secretory systems, you might see this genomic analysis of the systems and this description of the protein transport process.