Principios de Taxonomia

76j 4 What are Traits in Taxonomy?
a bird s wing and a bat s wing are similar in appearance as well as function. However,
which component should be considered when talking about resemblance? It should
be disquieting that this cannot be expressed in numbers, that is, quantified. When is
the extent of similarities greater than the extent of dissimilarities? Could not a
perception of resemblance based on a spontaneous examination be examined with a
greater scientific foundation?
If two species are distinguished by their traits, this is only possible if the traits are
assessed. However, the fatal flaw is that there are neither quantitative nor qualitative
rules for such an assessment:
1) Quantitative: The number of trait differences approaches infinity, and trait
differences do not only distinguish two species but also distinguish two individuals
of the same species. There is no possibility for determining a limit; that is to
say, a given value of trait differences, whose exceedance would mean that the level
of species has been reached (Dupre, 1999). How similar do two organisms have to
be for them to be similar enough to belong to one and the same species (Hull,
1997)? Do there have to be ten or a hundred or more trait differences to justify the
status of species? If it has already been determined that there have to be ten traits,
what is then one of these traits? Is it body hair of a certain length and color, for
example or does the body hair already contain ten traits because the hair consists
of ten components or is controlled by ten genes?
2) Qualitative: There is also no possibility of defining categories of quality as
generally mandatory, which have to be complied with by particular traits to reach
taxonomic relevance, while those traits that do not reach these quality requirements
would then be taxonomically useless. Every attempt to assess traits can only
be based on a highly subjective decision. For example, a human and a rhesus
monkey can have exactly the same blood group. However, two humans in
comparison to each other or two Rhesus Monkeys in comparison to each other
might have markedly different blood groups. Why do all Rhesus Monkeys belong
to one and the same group, just because of a trait definition? Why do humans and
Rhesus Monkeys belong to different groups just because of a trait definition? The
underlying problem is that it concerns unerring intuition. It has often been said
that species can only be determined by the covariation of multiple traits and not by
traits being considered separately. Here, it is about the question of whether it is
possible to have a fundamental law in taxonomy from which it might be inferred
that blood group cannot be used as a taxonomic trait of delimitation. What law says
which traits are allowed to be used and which traits are forbidden?
4.6
Traits that are Used by the Species to Distinguish Themselves
If species live in the same region, they can only remain in existence for a long time if
their members can recognize and distinguish each other. If they cannot, they would
merge with each other and cease to be separate entities. Therefore, all biparental