Diversity is crucial to the existence of life as it is. At the same time it
is fascinating that so much diversity is created in the biosphere. Diversity
is the key to survival of the larger organisms, the ones at the top of the
energy and biomass pyramids. The origin of biological diversity is a side
product of evolution, which is made of two parallel processes, one of
vertical change in the original population and one, dependent on the former,
of splitting of the original population (speciation). The origin of species
(which Darwin did not explain) is due to the evolution of structural
differences (hereditary isolating mechanisms)
that prevents the production of fertile hybrids between populations.
Such differences arise as traits that adapt species to the environment.
Two basic levels in biological diversity can be identifies: genetic
variation within species and differences among species.
By surveying adaptive radiation (the spread of species of common ancestry into different niches) and evolutionary convergence (the occupation of the same niche by outcomes of different adaptive radiations), Wilson proves that oportunity causes an explosion of species formation.
The book, written in colloquial english, is an excellent introduction to modern themes of evolutionary biology. Rather than offering a textbook view of firm theories, it continously shows the limits of our current knowledge. The last part deals with ethical issues.
TM, ®, Copyright © 2005 Piero Scaruffi