Hi,
The article revolves around the understanding of the evolution of HIV drug resistance.
http://www-cogsci.ucsd.edu/~rik/papers/hivPop-alifeX.pdf"HIV is obviously one of the most deadly diseases currently facing our species, but it also provides an extraordinary, well-documented example of a “successful” evolutionary system. We present a simple model that is capable of exploring interactions among several key features of this system that push the limits of traditional evolutionary theory."
This type of evolution conforms to macro- and not micro-evolution because:"Within these “refugia,” HIV is capable of evolving at a prodigious rate, producing on the order of 1010 virions daily. Worse, the reverse transcription process exploited by HIV as it introduces its DNA into host cells creates extremely
high mutation rates, affecting as many as one of every 2000 nucleotides. Once infected by a wild-type variant of the disease, drug-resistant mutants can be transmitted to newly infected individuals."
In short, the rate at which these viruses evolve is much faster, and so the time needed to pass from just micro- (a slightly better virus) to macro- (an entirly new virus, one that can deal with our drugs) evolution, is thus proportionaly shorter.