martes, 27 de julio de 2010

Pluralism of concepts: the PCS

D.F.Silva

There are three basic concepts phylospecies. one of them, initially defined by Hennig, is the Henniano species concept (Meier & Willmann 2000). Henniana convention: if new species arise from division from a parent species, then I would say the parental species is not monophyletic (now paraphyletic), has been lost and now there are two new species. The second concept is called phylospecie Concept synapomorphic. A species is one in which no beyond there taxonomic division or subdivision is the phylogenetic analysis unit. The version of Mishler adds it on this concept, the vision of that species should be monophyletic. The phylospecie third concept of the so-called Autopomorphyic concept, according to one version of Wilkins. The concept is called diagnosis. this concept is derived from the work tends to Rosen.este rely on the diagnosis of taxa or is a completely epistemological notion of species. All concepts that rely on autapomorficos species is the terminal taxon in a cladogram.

Hennig is often read as: species cease to exist when they are divided bone when relationships end hologenetics be a simple set. hennig but assumes that species are reproductive communities genes harmonic butler, as he had said Dobzhansky, and that species are reproductive groups as Mayr said, however hennig assumes that species are reproductive lineages. but the most important aspect of the definition lies in the dimencion hennig time where the note that species have to be bounded by speciation event "The limits of the species in a longitudinal section through time could therefore be determined by two processes of speciation: one which rise as an independent reproductive community and one which travez the descendants of these initial populations ceased to exist as one homogeneous reproductive community. When some of the relationships between individuals tokogenetics of a species no longer exist, that breaks into two species and ceases to exist.

The criticisms have not been expected and appeared to be a delineation somewhat arbitrary to species taxa. this has come to call Hennig convention. the Hennig the concept of the species has been expanded by Meier & Willmann. hennnig proposed a modified concept: species are natural populations reproductively isolated groups of wild populations. they originate by way of the dissolution of the stem species of speciation events and cease to exist travez of speciation or extinction. hennig basically the concept of species is a concept of biomolecules as has hennig accepted that reproductively isolated species were exposed and that the criteria used identifying relevant edges of the clades are phylogenetic simply those of biospecies or BCS. The extinction is a taxonomic extinction.

Synapomorphic species

The Concept is special because although Brent Mishler has defined Cracraft the species taxon as the smallest diagnosable cluster organisms within which there is a pattern of ancestry or descent. Mishler and monophyletic version: a species is the most inclusive taxon recognized in a classification into which organisms are grouped together because evidence of monophyly (usually, but not restricted to the presence of synapomorphies) such that it is positioned as a species because it is the smallest lineage important. and redefine monophyly: A monophyletic taxon is a group that contains all and only descended from a common ancestor originandoce in the same event.

Synapomorphic species are usually based on historical lines ancestry current offspring that are represented in a cladogram. as a phylogenetic taxon species is a synapomorphy shared by agupada for individuals that show monophyly .The definition of Mishler and Theriot: a species is the most inclusive taxon recognized in a formal phylogenetic classification. As with all levels levels of taxa in such classifications grouped organisms within species because of evidence of monophyly. taxa are classified as species because they are the groups phylogenetic smaller. monophyletic conception here is explicit. dual nature of the epistemic and the ontological aspects are expressed notably marked and the range of species lineages is restricted to biologically important. De Queiroz and Donoghue [1988, 1990] do not think that species have to be monophyletic because the monophyly of the populations does not provide a way to specify which is the basis of the range.

Autapomorphyc Species or diagnostic.

Diagnosis of the species has been embroiled in a debate. species have diagnostic autapomorphies whereas higher taxa are synapomorphies Rosen noticed that the subspecies are by definition unobservable and indefinable. since they have no apomorphies. Nelson and Platnick tratarona species as shows just the smallest of organisms detected own perpetuation that have unique set of character . (Wheeler & Platnick 2000; 56) Almost contemporaneously Eldredge & cracaraft defined a species as a diagnosable cluster of individuals who within which there is a pattern of ancestry and descent.