Principios de Taxonomia

2j Introduction
would be sufficient to identify the units of biodiversity without knowing what these
units are. Questions such as what is a tiger? or what makes a tiger a tiger? are
considered to be senseless questions that hamper science.
This type of reductionism, taxonomy is diagnosis or identification, generated the
recent technology of barcoding, a method that is evaluated as the future of
taxonomy for several reasons. Supported by substantial funding, assisted by very
successful public relations and preceded by the belief that this approach represents
genuine high-tech taxonomy, the barcoding-technology approach to taxonomy has
initiated a triumphal procession (Chapter 4).
However, it seems to be forgotten that identification cannot be the ultimate goal of
taxonomy. What result is ultimately obtained if groups of individuals are identified?
The use of diagnostic tools can allow the identification of a number of cat-like animals
as tigers or as lions. However, a number of individuals can also be identified as males
or as females. Furthermore, a number of individuals can be identified and distinguished
by differences in their blood groups. The results obtained by these three
approaches to identification are certainly very different, and the identification
procedures per se do not distinguish between intraspecific polymorphisms and
species differences.
The attempts to identify animal or plant groups do not achieve the final goal of
demonstrating that these groups are species. It does not suffice that the groups can
merely be distinguished from each other. Why are the different sexes not different
species? Neither the simplest conservative identification techniques nor the most
modern molecular techniques can determine whether two clearly distinguishable
groups are species. This consideration shows that the idea of species has additional
significance. It is the goal of this book to elucidate the true nature of species. Species
are not simply groups of individuals that can be distinguished. Species are something
else entirely.
Educated by a number of identification guides or field guides that are available for
most groups of animals or plants, we are misled to believe that individuals that clearly
differ in traits must belong to different species. If a goose in Eurasia has a uniformly
pink-to-orange beak and pink feet, it must be a Greylag Goose (Anser anser). However,
if it has an orange beak with black margins together with orange feet, then it must be a
Bean Goose (Anser fabalis). Nevertheless, these differences are not exhibited by each
individual Greylag Goose or Bean Goose because mutants occur. Hence, why are
those mutants still members of the species? Why are they not different species?
Indeed, of what help are identifying traits for the understanding of the species?
Linnaeus stated that certain traits are essential to the species. A particular member
of the species must possess these traits, or else it would not belong to the species.
However, Darwin stated that the particular traits found in the individuals of a species
change over time. This principle means that no single trait can be the essence of a
species. It is not possible that both authors can simultaneously be correct.
As a consequence of Darwin s theory of evolution, it was necessary to conduct a
thorough revision of Linnaeus s view of the species. This revision was achieved by
Poulton in 1903, and extended by Dobzhansky in 1937 and Mayr in 1942. These
authors replaced the Linnaean typological view of a species by the concept of a