Evolution Principles

Organisms may or may not adapt by evolving through random genetic mutations more appropriate characteristics to meet the resources and constraints of the environment such that they thrive and reproduce better in that environment and are consequently said to be ‘fitter’. That is natural selection.

Populations have a myriad of different traits all evolving haphazardly as its component individuals mutate in different ways thus generating a continuum of generational changes that would make the species change over generations of evolution. Unless there has been geographical separation during this to create sub-populations there would be no speciation. It is geographical separation that separate sub-populations to speciate over time. My view is that speciation is determined as much by a willingness and ability of a male and female to mate naturally under optimal conditions of survival as also to need to demonstrate the successful reproduction of viable and fertile offsprings from this natural mating. Otherwise they are the different species regardless of other traits and morphology.

The term evolution is approprate to describe changes in a single generation resulting from the mating of a male and a female of a species as it appropriate for use to describe how these mutations spreads in the population over generations whether or not there has been geographical separation-induced speciation at the end of the chain of x number of generations. Bacterial evolution also means all mutational and swap genome changes whereas bacteria speciation is clearly not based on the above criterion of reproductive compatibility but determined through tests such as the one you mention concerning the resistance of a population to specific antibiotics or to antibiotics in general. They could of course be evolving in other ways that we have no means to detect.

New species may evolve due to geographical isolation but by what is being suggested as being sympatric speciation (http://en.wikipedia.org/wiki/Sympatry). However, the essential question is whether a single population of a species of animal occupying a clearly-defined ecological niche as its geographical environment separate into two viable sub-populations that would not interbreed thus leading to two distinct species of salmon still co-existing withn the same ecological niche? Concerning the relevance of reproduction in speciation, if sub-populations reproduce with each other no speciation can take place because genes will be exchanged and gathered as a common gene pool in the offsprings. Evolution is a process that is regulated by reproduction: speciation is the outcome of a lack of reproduction between sub-populations as far as I currently understand evolutionary biology.

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