Principios de Taxonomia

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3 Is the Biological Species a Class or is it an Individual? 3.1 Preliminary Note: Can a Species have Essential Traits? The question regarding whether the species unit is a matter of human sorting principles or a unit that really exists in nature is repeatedly asked in this book. This question relates to whether the species is viewed as a class or as an individual. To approach the problem more closely, one can ask, What is it that makes an organism belong to a species? An organism must certainly be characterized by something, the results of which designate it as a member of a species. Is an organism a member of a species because it has a particular descent, because it has sexual connections and therefore lateral gene flow to other organisms (Chapter 6) or because it has particular traits? It is surely not simply a Tiger s colored stripes that make it a Tiger because even a Tiger without stripes is a Tiger just the same. It is crucial to ask the question, why is a non-striped Tiger a Tiger? Accordingly, is there a particular feature that makes a Tiger a Tiger? This would be the Tiger s essence. If such an essence was to exist, then the following would be true: (1) If one particular organism did not have the Tiger s essence, then it would not be a Tiger. (2) Every organism that possessed the Tiger s essence would have to be a Tiger. The essence of a species would therefore be something that is necessary and sufficient for an organism to belong to a species (Sober, 1994); does such an essence exist in the case of species? Beginning with Aristotle on to Linnaeus, Putnam (1975) and Kripke (1980), there was no doubt that species essences existed, and all of these philosophers and scientists believed that these essences were intrinsic traits of the members of a species. The conviction that there are essential intrinsic species traits resulted in biological species being considered universal, similar to an element in chemistry. Furthermore, just as an element possesses an essence, which is the number of protons it has, the biological species was also believed to possess an essence, namely, its species-specific traits. Gold has 79 protons. If a particular element does not have this number of protons, then it cannot be gold, and every element that has 79 protons must necessarily be gold. The number of protons an element possesses is something that is necessary and Do Species Exist? Principles of Taxonomic Classification, First Edition. Werner Kunz. Ó 2012 Wiley-VCH Verlag GmbH & Co. KGaA. Published 2012 by Wiley-VCH Verlag GmbH & Co. KGaA. j45
46j 3 Is the Biological Species a Class or is it an Individual? sufficient for the element to belong to the class of this element. This type of logic applies to chemical elements. However, is there a trait in an animal species that every organism must necessarily possess to belong to the species? Would every organism on the planet need to belong to this animal species if it had the trait? The answer is no (Wilkins, 2010). Biological organisms have no traits that are necessary and sufficient for taxonomic membership. Every trait that characterizes the species membership of an organism can be absent from each individual organism, and if such a trait that characterizes the species membership of an organism is absent, this organism nevertheless does not lose its species membership. A non-striped Tiger is still a Tiger. This is very surprising; the fact that the absence of a species-specific trait does not preclude membership of the organism to a species clearly shows that traits cannot be the essence of species membership. Why is the number of protons in a chemical element a trait that does not tolerate exceptions, in contrast to the traits of living beings that do tolerate exceptions? The essence of species membership must be something other than traits (see Section below: The relational properties of the members of a species are the essence of the species ). Darwin s theory of evolution explains the fundamental differences between the essences of chemical elements and living beings. Darwin put an end to the idea that animals or plants have essential traits. The intrinsic traits of biological organisms cannot be essential for these organisms affiliations with a species because all of the biological organisms intrinsic traits are subject to mutative change thus evolution. Neither morphological, physiological, ethological, chromosomal nor genomic traits are essential for the members of a species and neither are certain DNA sequences. This is because all intrinsic traits can change permanently, including the DNA sequences in the genome. In this respect, there is no difference between a DNA sequence and a phenotypic trait. Both are diagnostic of the species, but neither is essential. If a species-specific DNA sequence mutates and thus changes, the affected organism does not lose its species membership. If one were to assume that a species is only that which has a very particular set of traits, then a species could, in principle, only exist for a single moment because some traits may already have minimally changed by the next moment. Therefore, a species cannot be defined by its intrinsic traits. Species are subject to reproduction and continuing mutative changes. In chemistry, the elements do not multiply but remain constant. No gold atom divides into two daughter gold atoms and then dies; this means that the objects of chemistry are present as rigid classes. The chemical elements have always possessed this quality, and they are likely to continue to express this quality in the far distant future. The elements have properties on Earth that are identical to their properties on distant planets. The elements are universals in the philosophical sense (see below), at least in the frame of our currently existing, spatiotemporally restricted universe. The objects of biology are an entirely different matter; they change constantly, and it is impossible for even one of our animal or plant species to exist simultaneously on a distant planet. If there are animal or plant species on distant planets, they must be completely different species or they must have migrated there from Earth.
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Werner Kunz Do Species Exist?
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Werner Kunz Do Species Exist? Princ
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Contents Foreword XI Preface XV Col
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5.5 Are Carrion Crow and Hooded Cro
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7.8 Gene Trees are not Species Tree
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XIIj Foreword formed out in various
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Preface What is water? You would no
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Color Plates Do Species Exist? Prin
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Color PlatesjXIX
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Color PlatesjXXI
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Color PlatesjXXVII
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Color PlatesjXXXI
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Color PlatesjXXXIII
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230j Scientific Terms Autapomorphy
Page 36 and 37: 232j Scientific Terms Gene-flow com
Page 38 and 39: 234j Scientific Terms Monophylum A
Page 40 and 41: 236j Scientific Terms barriers prev
Page 42 and 43: 238j Scientific Terms Universal Uni
Page 44 and 45: 2j Introduction would be sufficient
Page 46 and 47: 4j Introduction A number of the col
Page 48 and 49: 6j 1 Are Species Constructs of the
Page 50 and 51: 2 Why is there a Species Problem? 2
Page 52 and 53: 2.2 Can Species be Defined and Deli
Page 54 and 55: 2.3 What Makes Biological Species s
Page 56 and 57: These conclusions indeed sound para
Page 58 and 59: 2.4 Species: To Exist, or not to Ex
Page 60 and 61: If the species concept is, or even
Page 62 and 63: 2.6 The Constant Change in Evolutio
Page 64 and 65: 2.7 Can a Scientist Work with a Spe
Page 66 and 67: 2.8 The Species as an Intuitive Con
Page 68 and 69: Contrary to this, it is always auto
Page 70 and 71: 2.9 Taxonomy s Status as a Soft or
Page 72 and 73: 2.11 Sociological Consequences of a
Page 74 and 75: Races are not populations of indivi
Page 76 and 77: 2.12 Species Pluralism: How Many Sp
Page 78 and 79: 2.12 Species Pluralism: How Many Sp
Page 80 and 81: 2.13 It is One Thing to Identify a
Page 82 and 83: 2.14 The Dualism of the Species Con
Page 84 and 85: 2.14 The Dualism of the Species Con
Page 88 and 89: 3.2 Class Formation and Relational
Page 90 and 91: 3.3 Is the Biological Species a Uni
Page 92 and 93: 3.4 The Difference Between a Group
Page 94 and 95: 3.4 The Difference Between a Group
Page 96 and 97: 3.5 Artificial Classes and Natural
Page 98 and 99: 3.6 The Biological Species Cannot b
Page 100 and 101: 3.7 The Biological Species as a Hom
Page 102 and 103: 3.9 The Linnaean System is Based on
Page 104 and 105: 3.10 Comparison of the System of Or
Page 106 and 107: 3.11 The Relational Properties of t
Page 108 and 109: 68j 4 What are Traits in Taxonomy?
Page 134 and 135: 94j 5 Diversity within the Species:
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96j 5 Diversity within the Species:
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98j 5 Diversity within the Species:
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100j 5 Diversity within the Species
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128j 6 Biological Species as a Gene
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7 The Cohesion of Organisms Through
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7.2 The Problem of Displaying the P
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level of organisms with the next-hi
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Figure 7.4 Classification of organi
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7.4 How is a Cladistic Bifurcation
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7.5 Descent is not the Same Thing a
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Figure 7.7 Paraphyletic classificat
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7.6 Why are Paraphyla used Despite
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Figure 7.8 Phylogenetic trees at di
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Figure 7.10 Gene trees are not spec
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7.9 The Concepts of Monophyly and P
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7.10 Paraphyly and Anagenesis are M
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7.11 The Cladistic Bifurcation of a
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7.12 The Phylocode j213 Thus, if th
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7.12 The Phylocode j215 Figure 7.13
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8 Outlook What is a species? The an
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Index a aberration 96 Acinonyx juba
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essence 45, 46, 56, 58, 64, 65 esse
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Old World Ruddy Duck 150 Old World
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v vague boundaries 21, 184 vaguenes
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Principios de Taxonomia

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