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Date: Fri, 23 Jul 2004 17:28:06 -0400 (EDT)
From: StephanPickering@cs.com
To: paleo_bio_dinosaur_ontology@yahoogroups.com
Cc: birds-and-landscapes@yahoogroups.com, darkraptorsdinosaurclub@yahoogroups.com, DinosaurEvolution@yahoogroups.com, jurassicdavesdinoclub@yahoogroups.com, phylocode@ouvaxa.cats.ohiou.edu, thedinosaurabyss@yahoogroups.com, theraptorsrealm@yahoogroups.com
Subject: Walter Bock on the term "species" (concept, category, & taxon)
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W.J. Bock, 2004. Species: the concept, category, and taxon. Jour. Zoological
Systematics & Evolutionary Research 42(3):178-190. ABSTRACT. The term species
by itself is vague because it refers to the species concept, the species
category and the species taxon, all of which are distinct although related to one
another. The species concept is not primarily a part of systematics, but has
always been an integral part of basic biological theory, It is based on
evolutionary theory and applies only to sexually reproducing organisms. The species
concept and the phyletic lineage concept are quite distinct although they are
related to one another. The important aspect of the species concept is lack of
gene flow between different species, and hence the defining criterion of the
species is genetic isolation. The species concept is often considered as
non-dimensional, both in time and space. Species possess three different major
properties, namely genetic isolation, reproductive isolation and ecological
isolation; these properties evolve at different times and under the effect of
different causes during the speciation process. Speciation requires an external
isolating barrier during the initial allopatric phase in which genetic isolation
evolves and must reach 100% efficiency. The subsequent sympatric phase of
speciation occurs after the disappearance of the external isolating barrier when
members of the two newly evolved species can interact with one another and exert
mutual selective demands on one another. Much of the reproductive and
ecological isolation evolves during this secondary sympatric phase. The species
category is a rank in the taxonomic hierarchy and serves as the basis on which the
diversity of organisms is described; it is not the same as the species concept.
The species category applied to all organisms, sexually and asexually
reproducing. The species taxon is the practical application of the species category in
systematics with the recognition of species taxa requiring many arbitrary
decisions. No single set of rules exist by which the species category can be
applied to all organisms. Recognition of species taxa in asexually reproducing
organisms is based on amount of variation and gaps in the variation of phenotypic
features associated with ecological attributes of these organisms as compared
with similar attributes in sympatric species taxa of sexually reproducing
organisms. Species taxa are multidimensional in that they exist over space-time
and often have fuzzy borders. Because recognition of species taxa, including
those in sexually reproducing organisms, depends on many arbitrary decisions
especially when dealing with broad geographical and temporal ranges, species taxa
cannot be used as the foundation for developing and testing theoretical
concepts in evolutionary theory which can only be done with the non-dimensional
species concept.
*******************************************
STEPHAN PICKERING / Chofetz Chayim ben-Avraham
The Dinosaur Fractals Project
2333 Portola Drive # 4
Santa Cruz, California 95062-4250 USA
stephanpickering@cs.com
website: http://groups.yahoo.com/group/paleo_bio_dinosaur_ontology
theropod research summarized: <www.dinodata.net> see under PICKERING at their
Reference Base
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<HTML><FONT FACE=3Darial,helvetica><FONT SIZE=3D2 PTSIZE=3D10 FAMILY=3D"SAN=
SSERIF" FACE=3D"Arial" LANG=3D"0">W.J. Bock, 2004. Species: the concept, cat=
egory, and taxon. <I>Jour. Zoological Systematics & Evolutionary Researc=
h </I>42(3):178-190. ABSTRACT. The term species by itself is vague because i=
t refers to the species concept, the species category and the species taxon,=
all of which are distinct although related to one another. The species conc=
ept is not primarily a part of systematics, but has always been an integral=20=
part of basic biological theory, It is based on evolutionary theory and appl=
ies only to sexually reproducing organisms. The species concept and the phyl=
etic lineage concept are quite distinct although they are related to one ano=
ther. The important aspect of the species concept is lack of gene flow betwe=
en different species, and hence the defining criterion of the species is gen=
etic isolation. The species concept is often considered as non-dimensional,=20=
both in time and space. Species possess three different major properties, na=
mely genetic isolation, reproductive isolation and ecological isolation; the=
se properties evolve at different times and under the effect of different ca=
uses during the speciation process. Speciation requires an external isolatin=
g barrier during the initial allopatric phase in which genetic isolation evo=
lves and must reach 100% efficiency. The subsequent sympatric phase of speci=
ation occurs after the disappearance of the external isolating barrier when=20=
members of the two newly evolved species can interact with one another and e=
xert mutual selective demands on one another. Much of the reproductive and e=
cological isolation evolves during this secondary sympatric phase. The speci=
es category is a rank in the taxonomic hierarchy and serves as the basis on=20=
which the diversity of organisms is described; it is not the same as the spe=
cies concept. The species category applied to all organisms, sexually and as=
exually reproducing. The species taxon is the practical application of the s=
pecies category in systematics with the recognition of species taxa requirin=
g many arbitrary decisions. No single set of rules exist by which the specie=
s category can be applied to all organisms. Recognition of species taxa in a=
sexually reproducing organisms is based on amount of variation and gaps in t=
he variation of phenotypic features associated with ecological attributes of=
these organisms as compared with similar attributes in sympatric species ta=
xa of sexually reproducing organisms. Species taxa are multidimensional in t=
hat they exist over space-time and often have fuzzy borders. Because recogni=
tion of species taxa, including those in sexually reproducing organisms, dep=
ends on many arbitrary decisions especially when dealing with broad geograph=
ical and temporal ranges, species taxa cannot be used as the foundation for=20=
developing and testing theoretical concepts in evolutionary theory which can=
only be done with the non-dimensional species concept. =20
<BR> =20
<BR></FONT><FONT COLOR=3D"#000000" BACK=3D"#ffffff" style=3D"BACKGROUND-COL=
OR: #ffffff" SIZE=3D6 PTSIZE=3D24 FAMILY=3D"SANSSERIF" FACE=3D"Arial" LANG=
=3D"0">*******************************************</FONT><FONT COLOR=3D"#00=
0000" BACK=3D"#ffffff" style=3D"BACKGROUND-COLOR: #ffffff" SIZE=3D2 PTSIZE=
=3D10 FAMILY=3D"SANSSERIF" FACE=3D"Arial" LANG=3D"0">
<BR>
<BR></FONT><FONT COLOR=3D"#000000" BACK=3D"#ffffff" style=3D"BACKGROUND-COL=
OR: #ffffff" SIZE=3D1 PTSIZE=3D8 FAMILY=3D"SERIF" FACE=3D"Georgia" LANG=3D"0=
"><B>STEPHAN PICKERING / Chofetz Chayim ben-Avraham
<BR>The Dinosaur Fractals Project
<BR>2333 Portola Drive # 4
<BR>Santa Cruz, California 95062-4250 USA
<BR>stephanpickering@cs.com
<BR>website: http://groups.yahoo.com/group/paleo_bio_dinosaur_ontology
<BR>theropod research summarized: <www.dinodata.net> see under PICKERI=
NG at their Reference Base
<BR></B></FONT></HTML>
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