28 December 2010
Towards An Updated Theory Of The Origin Of Species
In my previous blog, I posted a stream of consciousness on evolution that suggested that perhaps evolutionary theory as currently presented was too simplistic and not necessarily a complete mechanism for the origin of species. Therefore, I owe it to those who might happen upon that blog to propose an alternative idea.
There are at least two overarching competing forces ongoing to develop species on earth: one higher risk and one lower risk. The higher risk process is random mutation and speciation (macroevolution), while on the other hand there is adaptation, which includes several processes including microevolution and lateral gene transfer.
Against this backdrop, life on earth follows at least three basic principles: (i) preservation of life on earth; (ii) conservation of the status quo rather than favouring radical change; (iii) relative efficiency (or laziness) of life that will co-opt good ideas as they arise.
By overlaying these forces and principles, you have constant competition between the process of mutational speciation and that of adaptation with limited speciation, i.e. between the higher risk and lower risk strategies. However, as life and species become more interlocked and interdependent, the weight of the conservative and lazy principles of life becomes increasingly strong, which will work against mutational speciation, because it could destabilise the rest of life on earth, i.e. life normally selects naturally for the status quo and deselects for new species. Furthermore, it appears that this conservative principle kicks in pretty quickly as microorganisms appear to almost always prefer adaptation, including lateral gene transfer, over speciation. But why chose adaptation over speciation, because the status quo itself confers protective benefits to all current species on earth, whereas speciation results in the need to change the structure of a biological niche or life in general, which can be devastating for the rest if living species and resultsin a weak species without the protection conferred by the capability to adapt.
However, when new unoccupied niches become available, higher risk mutational speciation might become more attractive as opportunity outweighs inherent risks in generating new species and new ideas arising from genetic errors might prevail and can be tried out without the competitive pressure of life. Therefore, new species might arise relatively quickly in these circumstances, as there is no negative pressure from the rest of life. Such situations could occur at the start of life on earth, when life moved onto land or after mass extinctions, where opportunism reigns. However, as life becomes established in a niche or set of niches, embedded life will act like a dead hand tending to prevent new ideas being tried out and so life will favour change via adaptation. Generally completely new speciation is deselected as being normally negative for life.
However, a really radical new idea, like photosynthesis, can overcome this inherent conservatism and establish itself. However, it has to be a crackingly good idea and not just a reinvention of the wheel, which will be prevented from establishing itself. So in all these situations, life could be viewed to make a risk analysis, i.e. is it worth upsetting the status quo for this new idea? If not, then life works to squeeze it out, or if it is, then life will take the risk of potential extinctions for the future potential to increase the amount of DNA-RNA on earth. So even though there is a background level of new potential species being created all the time, it is unlikely that many (or any) of these will establish themselves.
What I like about this theory is that you can see how a chaotic change in species can happen all the time, with even the amount of permitted speciation and adaptation being capable of variation as the situation and needs move around. Also, it can explain why some species never disappear as it postulates that life only changes where and when changes are needed and better ideas arise, or when there is extinction in a niche, but for example no better solution to living in the hot springs at Rudeira has been found than stromatolites, so stromatolites it is then, but find a virgin untapped island like Galapagos then a finch can blossom out. It also explains why changes in range and composition of species is a more normal response than speciation as life prefers to use what it already has got than go for radical new ideas.
[This is a raw idea so needs to be worked on by those better than me to articulate more succinctly and perhaps even build a model that could even be run on a computer to simulate the origin of species. As for modelling, I envisage that whenever there is a change to the global environment (in its widest sense) species must consider whether it can adapt to these changes through behavioural changes, distribution changes, working together with other species, natural genetic variation, lateral gene transfer or finally speciation. Or perhaps interested people could analyse competition and speciation by looking at what happens in the business world when new businesses are formed and new ideas are invented, and watch how these survive and/or are transferred through the economic community and/or how they compete and work together to maintain existing relationships rather than nurture new businesses that might alter the status quo.]
