This article contains much useful information. It gives insight in Evolution and its driving mechanisms, without going into undue details. I am not certain how easily it can be read by non-biologists, because I am a biologist myself. Basic terms (population, allele, genotype,...) are well defined in the glossary.
I think that a strange mix has been made in the driving (not 'deriving') mechanisms of evolution. There is a class of mechanisms that are true population genetic mechanisms: natural selection, genetic drift, non-random mating. Through these mechanisms a new generation in a population will have different allele frequencies than the preceding one. This can also be said for gene flow, at least when viewed from the point of view of a single semi-isolated population. The other mechanisms, however, are of a different nature. Mutation stands out as a mechanism leading to genetic variability (as well explained in the text) but not as a mechanism of evolution. Migration and competition are ecological processes that provide a basis for gene flow and natural selection respectively, but they should not be treated at the same level (in fact, they can probably just be dropped from this text). Speciation, finally, is more the product of evolution than a mechanism and thus should also not be treated on the same level as the mechanisms.
In the treatment of mutation, I do not understand what is meant by the sentence 'They cause changes in allele frequencies, smaller than those which the Hardy-Weinberg principle has predicted.' I do not understand why the figure on Hardy-Weinberg is introduced here. The figure is also not explained well enough. I can see reasons to introduce the Hardy-Weinberg principle, but this should be done at the beginning as a kind of 'neutral model': "if there are no mechanisms of selection, drift or non-random mating, then H-W says that everything will remain the same". In the treatment of genetic drift, it is not explained why the effect is much stronger in small populations. The figure is not explained well enough.
The section on biodiversity and evolution is short but interesting.