martes, 20 de julio de 2010

Phylogenetic Species Concept

Gualdrón-Diaz J. C.

Several Phylogenetic Species Concept have been proposed. The first in applied cladistic methods to the species problem was Rosen (1978), who defined species as "a geographically constrained group of individuals with some unique apomorphous characters, is the unique evolutionary significance", after de Queiroz and Donogue (1988) argued that species should be based on monophyly and the grouping of populations supported on sinapomorphies.
Although an ancestor must have existed ans must have been a species in its own time, an ancestral species according to phylogenetic theory has no autapomorphies in relation to their own descendant species (Wheeler 1999). According to this concept of the species are defined from the point of view phenotype, the level of state support monophyletic, nevertheless sometimes there is no evidence on monophyletic status of a group.

Also, Eldredge and Cracraft (1980) and Nelson and Platnick (1981) proposed similar species definitions, later amplified by Nixon and Wheeler (1990) and Wheeler and Platnick (2000);
All based on defining species a unique combination of diagnosable characters; moreover, some of these concepts have in mind a pattern in the ancestor-descendant. Nevertheless this approach does emphasis in the capacity that is had to distinguish to a species of other one, which is a problem of the taxonomist and of the systematic one, which does not concern the existing organism in the nature (Haro 1999).

In spite of the different concepts proposed with relation to the phylogeny, the goal for developing a phylogenetic species concepts is to support the aims of phylogenetics systematics as the elements for reconstruction of phylogenetic history, distinguish among kinds of organisms, describe and predictively classify the diversity biological, and permit the study of evolution and comparison of clades (Wheeler and Platnick 2000).

References

Eldredge, N., and J. Cracraft. 1980. Phylogenetic patterns and the evolutionary process. New York: Columbia University Press.

Haro, J.J. 1999. ¿Qué es una especie?.Bol. S.E.A. 26:105-112

Nelson, G., and N. I. Platnick. 1981. Systematics and biogeography: Cladistics and vicariance. New York: Columbia University Press.

Nixon, K. C., and Q. D. Wheeler. 1990. An amplification of the phylogenetic species concept. Cladistics 6:211±223.

Rosen, D. E. 1978. Vicariant patterns and historical explanation in biogeography. Systematic Zoology 27: 159±188.

Wheeler, Q. D. 1999. Why the phylogenetic species concept? -elementary. Journal of Nematology 31:13–141.

Wheeler, Q. D., and Platnick, N. I. 2000. A critique from the Wheeler and Platnick Phylogenetic Species Concept Perspective: Problems with Alternative Concepts of Species. In: Species Concepts and Phylogenetic Theory (Ed. Q. D. Wheeler and R. Meier), pp. 133-145, Columbia University Press, New York.

de Queiroz, K., and M. J. Donogue. 1988. Phylogenetic systematics and the species problem. Cladistics 4:317-338.