Principios de Taxonomia

XVIj Preface
all organisms to belong to a species whose genomes are similar in DNA sequence,
this view will soon be corrected by the awareness that there exist phylogenetically
young species that are genetically homogeneous as well as phylogenetically old
species that are genetically heterogeneous. There may be larger genetic differences
among the members of an evolutionary old species than among the members of
different species if the species are evolutionary young. Evolutionary distance cannot
be a reliable species criterion. At the end, all attempts to discriminate species from
each other are blurred by the fact that all criteria for these discriminations also may
apply to the individuals within a species. Intraspecific polymorphisms are a main
obstacle for taxonomic classification.
It appears that, in contrast to chemical objects, taxonomic objects cannot be
defined. What is it that makes this fundamental difference between chemical and
biological objects? It is very remarkable that taxonomists in most cases abandon the
species problem and are nevertheless quite able to work with species. How is it
possible to do scientific work and to obtain reproducible results with objects without
knowing what these objects are? Should it not be irritating or alarming to do
research with objects that are not defined?
Despite several promises, the species problem is not solved, and it cannot be
ignored. This book elucidates the inconsistencies and contradictions that stand
behind the conventional species concepts. In this book, it is emphasized repeatedly
that it is a doubtful, if not an unscientific, way to practice taxonomic classifications
while ignoring the foundations of the species problem. Furthermore, beyond these
theoretic considerations, uncertainties and ambiguities of the species problem have
considerable impact on the strategies of legislation in biodiversity conservation
politics.
Düsseldorf, April 2012 Werner Kunz