Principios de Taxonomia

218j 8 Outlook
what leads to the discrepancies in each case. This lack of knowledge is surprising
because it concerns the major criteria determining why two organisms belong to
different species.
Distinguishing between two objects is not the same as knowing what those objects
are. It is easy to distinguish a piece of wood from a piece of iron, but distinguishing
these two objects does not provide information regarding what wood is or what iron
is. Wood is always a piece of a tree or a shrub and has a certain chemical composition.
Iron is a metal, consisting of atoms that have a specific atomic number. Why is the
question what is not asked more often in taxonomy? It is easy to distinguish a Tiger
from a Lion, but what is a Tiger and what is a Lion? Why are they considered to be
different species? This is certainly not because the Tiger has stripes, and the Lion
does not have stripes. Species identification is something different from the aim of
knowing why a group of organisms is a species. Two species are not two species
because they are different; rather, they become different because they are two
separate species. Speciation is separation, not the existence of diagnosable trait
differences. Taxonomy cannot be a science that runs out into diagnosis.
Species are individuals with a temporally and spatially transient existence. Species
can become extinct. Species are not classes because classes are universals that are not
restricted in time or space. Classes cannot become extinct. Species cannot be natural
kinds, as there are no essential traits that would necessarily and sufficiently
designate that a given individual organism has to belong to one particular species
rather than to another. Changes in traits during the course of evolution (anagenesis)
cannot be considered to be speciation because an individual remains the same
individual for its entire life, independent of whether it experiences changes in its
traits or not.
What Darwin meant with species in his work The Origin of Species were real,
biological entities, not classes. A problem arises because Linnaeus also talked about
species, although he had classes in mind. Herein lies the actual root reason that no
agreement has been able to be achieved regarding what a species is. Evolution does
not produce biological units of organization that are well-suited to satisfying
classification needs, but it was for this purpose that Linnaeus created taxa.
The biological species as an element of order and the biological species as a unit
that exists in reality and plays a role in evolution are two different entities that arise
from different scientific purposes. The more a species concept is used as an element
of order and the more it is suited for application in practicing taxonomy, the more it is
vulnerable due to lacking theoretical consistency. The reason that Linnaeus is still
important in biological science is not that his view of species would be valid today but,
instead, that his nomenclature retains some practical utility.