Does the phylogenetic Species Category exist in virus?

Jiménez- Silva C. L.
Universidad Industrial de Santander.
Laboratorio de Sistematica y Biogeografia

Introduction

Phylogenetic specie is the smallest diagnosable group identified as an ancestor-descendant populations evolving separately from others (Cacraft, 1983). The species can be considered a species level, among all those available in the hierarhy Phylogenetic. Only monophyletic groups can be recognized and formally named taxa. This principle is based on the groups which include all the descendants of a single common ancestor are the only groups with real and natural existence in relation to the evolutionary process (De Luna and Mishler, 1996). The real existence of the species gives genealogical relationships with other group of organisms, their historical behavior, so it is considered that the species are different because they have diverged evolutionarily. Wiley (1978) supports this assertion by suggesting that the species is a single lineage of ancestral-descendant populations, they retain their identity from other lineages and have their own evolutionary tendencies and historical fate.

According to the above and the ontological status of phylogenetic species suggests that instead of viewing species as natural kinds we should think of them as individuals (Ghiselin, 1974 and Hull, 1978). Given the class/individual distinction, Ghiselin and Hull argue that species are individuals, not classes. Their argument assumes that the term ‘species’ is a theoretical term in evolutionary theory, so their argument focuses on the role of ‘species’ in that theory. Here is Hull's version of the argument, which can be dubbed the ‘evolutionary unit argument.’ Since Darwin, species have been considered units of evolution. The "individuals" can you discover connectors or space - time, ie, the status of "individual" at a time and place particle is linked to another state at another time and space site for historical connections (Dupré 2001, Reydon de 2003, y Crane 2004). From this concept and its ontological status is to intend whether the phylogenetic Species exist in virus Category.

The idea that species are individuals has a number of implications. For one, the relationship between an organism and its species is not a member/class relation but a part/whole relation. An organism belongs to a particular species only if it is appropriately causally connected to the other organisms in that species. The organisms of a species must be parts of a single evolving lineage (Hull, 1978). If belonging to a species turns on an organism's insertion in a lineage, then qualitative similarity can be misleading. Two organisms may be very similar morphologically, genetically, and behaviorally, but unless they belong to the same spatiotemporally continuous lineage they cannot belong to the same species.

Virus Species

The international Committee on taxonomy of viruses (ICTV) endorsed the following definition of virus species: a virus species is a polythetic class of viruses that constitutes a lineage of replication and occupies a particular ecological niche (Van Regenmortel & Mahy, 2004). This definition applies for viruses like units called "classes", in a biological classification scheme, an individual organism or a virus can be a member of several abstract classes like a species or a genus. Class membership must be distinguished from the so-called ‘‘part-whole’’ relationship which exists only between two concrete objects, one being a part of the other in the way, for instance, that cells and organs are parts of an organism. It is not possible for a concrete object like a virus to be ‘‘part’’ of an abstract entity like a species (similarly a thought cannot be part of an object). The mixing of logical categories has led to much debate in viral taxonomy (Bos, 2003; Van Regenmortel, 2003).

A class is defined by properties that are constant and immutable. This allows members of such a class to be recognized with absolute certainty since one or more property is necessarily present in every member of the class. Virus families, for instance, are universal classes because they consist of members, all of which share a number of defining properties that are both necessary and sufficient for class membership. Allocating a virus to a family is thus an easy task since a few structural or chemical attributes will suffice to allocate the virus to a particular family. (Van Regenmortel, 2006).

Classifying viruses consists in inventing taxonomic classes like particular families or species and allocating individual viruses to these classes in order to achieve some order whereby similar viral agents are grouped together. The failure to distinguish between real objects such as organisms and viruses and the mental constructions and abstractions needed to build up any classification system has been a fertile source of confusion in taxonomy (Van Regenmortel, 2003) Distinguishing between real, tangible objects like viruses (i.e. concrete individuals) and mental constructs like virus species and genera (i.e. classes) that exist only in the mind is a basic requirement for clear thinking. Although a taxonomic class is defined by properties possessed by concrete objects, it is an abstract, conceptualized collection, i.e. a mental construct.

Returning to the phylogenetic species concept, this raises the real Existence of the species Conceived as discrete units, ie, restricted in space and time. Inconsistent with the vision Referred to by (ICTV), Which Takes the virus species as a class being these, units exist independent and unrestricted that teporales or spatial boundaries. If we encuena that "classes" are abstractions, ie, a mental construct, missing reality. The concept proposed by De Luna and Mishler (1996), on the phylogenetic concept where raise the species as a group with real existence in relation to the natural evolutionary process. The virus species is not wonderful to hang phylogenetic species category and be closer to a nominalist concept (real missing) or phenetic.

References

Bos, L., 2003. Virus nomenclature; continuing topicality. Arch. Virol. 148, 1235–1246.

Crane, J. 2004, “On the Metaphysics of Species”, Philosophy of Science, 71: 156–173

Cracraft, J. 1983. Species concepts and speciation analysis. Current Ornithology, 1, 159–187.

Dupré, J., 2001, “In Defense of Classification”, Studies in the History and Philosophy of Biology and the Biomedical Sciences, 32: 203–219.

Ghiselin, M., 1974, “A Radical Solution to the Species Problem”, Systematic Zoology, 23: 536–544

Hull, D., 1978, “A Matter of Individuality”, Philosophy of Science, 45: 335–360
Reydon, T., 2003, “Species Are Individuals Or Are They?” Philosophy of Science, 70: 49–56.

Van Regenmortel, M.H.V. and Mahy, B.W.J., 2004. Emerging issues in virus taxonomy. Emerg. Infect. Dis. 10, 8–13.

Van Regenmortel, M.H.V., 2003. Viruses are real, virus species are man-made taxonomic constructions. Arch. Virol. 148, 2481–2488.

Van Regenmortel, M.H.V., 2006. Virologists, taxonomy and the demands of logic. Arch. Virol. 151, in press.

Wiley, E. O.,1978. The evolutionary species concept reconsideres. Syst. Zool., 27: 17-26.

Evaluation of genetic recombination on phylogenetics relationships in Dengue virus

A. Susana Ortiz Bae

Laboratorio de Sistematica y Biogeografia

Introduction

Genetic recombination in RNA viruses is an evolutionary process defined as the exchange of genetic information from two or more nucleotide sequences into recombinant progeny virus (Mahy, 2009). This mechanism apparently plays a significant role in the generation of genetic diversity especially important under adverse conditions (Worobey et al. 1999). Despite above, the process is a rare event in natural populations of Dengue virus in which through a copy-choice mechanism, the polymerase switches between parental viral molecules during replication (Lai, 1992). However, the approximate inference of recombination can be based regarding their effect on genealogy as events that can change or not the final topology or branch lengths and therefore can disrupt the pattern of phylogenetic relationships between viral sequences (Wiuf et al. 2000). Given that many recombinant sequences are mosaics comprising regions with quite different phylogenetic histories, this study evaluated the effect of genetic recombination on phylogenetics relationships in Dengue virus type 1 sequence, based on the detection of conflicting phylogenic signals under parsimony criterion.

Methods

Viral recombinants , parental and no recombinants sequences from dengue strains used in this study were provide from the analysis reported by Chen et al. (2008) and Worobey et al. (1999). Prior to the analysis of these sequences was constructed a data set and recombination events were simulated between regions of the serotypes with the aim to detect sensitivity to genetic recombination in the inter-serotype level. The sequences from literature, was partitioned in specific coding regions corresponding to recombination breakpoints and were aligned, then the the phylogenetic relationships were reconstructed under phylogenetic inference criteria such as parsimony implementing heuristic method and finally the pattern of relationships were summarized on a strict consensus. Representative sequences from Denv-2, Denv-3 and Denv4 were used as outgroups to root the tree.

Results and Discussion

Based on phylogenies inferred from the structural and non-structural regions, the results pointed differential levels of resolution and rearrangement of the parental sequences as recombinant sequences were eliminated depending on the analyzed partition. This was clearly seen given the pattern of phylogenetic relationships between Philippines84 with Nauru74 and ARG992 strains which are closely related in the region encoding the capside. On the other hand, from the region encoding the membrane (prM/M) protein the Philippines84 strain diverges to associate with Thailand80 strain while the region coding for envelope (E) protein and at the junction with the membrane protein (preM/E), Phylippines84 is reassociated with both viral sequences Nauru74 and Thailand80 which indicates these sequences as parental of Philippines84 in a higher or lower component depending on the partition analyzed and corroborates Philippines84 as descendant of one ancestor that derived independently.

Moreover, despite the reassociations between Thailand80 strains with Philippines84, this was never dissociated from its parental sequence Jamaica77 which indicates an important contribution of this sequence to the genetic diversity of Thailand80. Concerning the strain BR 90, although suggested by Woorobey et al. (1999) no clearly evidenced the pattern of relationships with its parental sequences Jamaica77 and Singapore90 when new sequences are incorporated into the analysis, however seems that Jamaica77 classified as genotype VI represent a significant component in the C and preM regions while Singapore90 classified as genotype I, contributes most notably to E and junction preM/E regions. Such discordant relationships and different topologies between regions within the same sequence may suggest the existence of intra-serotype mosaic genomes produced by recombination between divergent parent lineages (Worebey and Holmes, 1999).

Similarly for GD23_95 strain, phylogenetic trees based on recombinants and non-recombinants regions showed that the variation in the sequence on the topology generated under Parsimony criterion is nor a strong indication of its recombinant condition, opposite to that found by Chen et al. (2008) by the neighbor-joining method, then such a definition could be an artifact. Additionally, given the elimination of the putative recombinant sequences on the topology, we often observe an improvement in the resolution of phylogenetic relationships, except in the preM region where three sequences were localizated in the same clade. Nonetheless this response was nor evident on topologies where the GD23_95 strain was eliminated, which could promote a false positive. Finally, it is important to note that although not recover a general pattern of phylogenetic relationships, each partition reflects a hypothesis that despite being different between these may be clouded by the presence of recombinant sequences which may contain regions with very different evolutionary histories within individual strains present.

Conclusions

Phylogenetic approaches can provide a method for detecting and characterizing recombination events among conflicting phylogenetic signals in gene sequence data with different patterns of relationship for different sequence regions in Dengue viruses, however, is necessary be careful in the some affirmations about recombinant events given that different regions pointed different patterns of phylogenetic relationships and regions non-recombinants don’t imply resolution on this relationships.

References

Lai, M.M.C., 1992. RNA recombination in animal and plant viruses. Microbiol. Rev. 56, 61–79.
Mahy, B., 2009. The Dictionary of virology. Elsevier, 4ed. 518p.
Wiuf, C. & Hein, J., 2000. Genetics 155, 451–462.
Worobey, M., Rambaut, A., Holmes, E.C., 1999. Widespread intraserotype recombination in natural populations of dengue virus. Proc. Natl. Acad. Sci. U.S.A. 96, 7352–7357.
Worobey, M., Holmes, E.C., 1999. Evolutionary aspects of recombination in RNA viruses. Mol. Journal of General Virology , 80, 2535±2543

Delimitation biological species in genus
Acanthoxyla (Phasmidae) using
mitochondrial and nuclear DNA

Gualdrón-Diaz J. C.

1. Introduction

From the broader perspective of evolutionary theory, delimiting species is im-
portant in the context of understanding many evolutionary mechanism and pro-
cesses(Sites & Marshall, 2003). The species boundary will define the limist
within or across which evolutionary processes operate (Barton & Gale , 1993).
Species are also routinely used as fundamental units of analysis in biogeogra-
phy, ecology, macroevolution and conservation biology (Brown et al., 1996) and
a better understanding of these larger scale processes requires that systema-
tists employ methods to delimit objectively and rigorously what species are in

nature.

There have been many proposals for the conceptual and practical handling of
species and among these, the biological species concept (Mayr, 1942) has been
the most thoroughly promoted and most widely accepted. One of the more
frequently stated deficiencies of the BSC is its inapplicability to uniparental
organisms (Foottit, 1997). The parthenogenesis is a common phenomenon in
the Animal Kingdom. It has been estimated that there are over 1000 obligately
parthenogenetic species situated over a broad range of taxa and over 15000
species which reproduce by cyclic parthenogenesis (White, 1978; Bell, 1982).
In stick insects(phasmids) the hybrid speciation and parthenogenesis both
appear to be unusually common phenomena (Bullini, 1994). In New Zealand
thera are parthenogenetic populations of otherwise sexual species of Clitarchus
and Argosarchus (Salmon, 1991). However, genus Acanthoxyla is entirely parthenogenetic. It comprises eight species without males and no closely related bisexual species (Jewell & Brock, 2002). This eight Acanthoxyla species exhibit a degree of morphological diversity not evident in any other New Zealand stick insects genus (Morgan & Trewick, 2005). The aim of this work is to make a nested clade analysis and phylogeography of haplotypes using nuclear and mitochondrial DNA to delineate species Acanthoxyla (Phasmatidae).

2. Materials and Methods

Five different genes of the genera Acanthoxyla and Clitarchus were used. 21
localities of New Zealand and 171 sequences in total of both genera were ana-
lyzed (fig. 1). Three were sequences nuclear genes, elongation factor 1x (EF1x),
phosphoglucose isomerase(PGI) and the large ribosomal subunit (28S) and two
were mitochondrial, cytochrome oxidase subunits I and II (COI-II) listed in
Buckley et al. (2008). The sequences have been deposited in GenBank under
accession EU492930-EU493090; Two operational criteria to delimit specie were
used, nested clade analysis (NCA)and phylogeographic analysis sensu Avise.
The nucleotide sequences were aligned using multiple alignment with Mus-
cle 3.6 software package. The nested clade analysis conducted using the ANECA software, which implements programs TCSv2.1 and GEODIS for analysis(Panchal, 2007). Haplotype networks were reconstructed in TCS v2.1. Then examined the relationship between haplotype/clades and geography through a statistical analysis of permutations, using the program GEODIS. For the phylogeographic analysis sensu Avise (Avise et al, 1987): ML bootstrap analysis (1000 permutations) were realized using the softwate Phyml 3.0 (Guindon & Gascuel, 2003).


3 Results and Discussion

3.1 Nested clade analysis

The cladistic analysis of haplotypes for mitochondrial genes shows 10 clades for
both COI and COII, in terms of nuclear genes, 28S, PGI and EF1x, there are
9, 11 and 7 respectively clades, but none of them considers the fragmentation
allopatric pattern as inferred from the clades formed. Therefore can not assign
the species status of these genera using this method since only fragmentation
allopatric is the important biological implication of the NCA to infer species
status (Templeton 2001).
Patterns inferred from the clades formed were restricted gene flow with iso-
lation by distance, contiguous range expansion and restricted gene flow with
isolation by distance (restricted dispersal by distance in non-sexual species) for
COII genes, EF1x and PGI, respectively. The 28S and COI gene showed Incon-
clusive outcome.

3.2 Phylogeographic analysis sensu Avise

The phylogeographic analysis, with mitochondrial genes (COI-COII) reveals the
presence of two different groups, which have a high value of confidence limits
(fig. 2-3), according to Avise (1995) assert that to infer species status requires a
confidence limit ( 95%) therefore they deserve the status of species. By contrast
with the results obtained using nuclear DNA cladograms show low resolution
and with diverging results obtained with mitochondrial DNA, in the analysis
with the 28S gene, showed levels very low limits of confidence, the evidence
suggests an clagograma unresolved with this type of gene. Similar results were
obtained through EF1x and PGI genes, however these if you showed higher
values of confidence limit (fig. 4-6).

Given the resutlados obtained, it appears that for the nested clade analsis
neither nuclear nor mitochondrial DNA showed species status. As for the re-
sults obtained with the phylogeographic analysis, differences in the phylogenetic relationships of the genus Acanthoxyla haplotypes generated with mitochondrial DNA with respect to nuclear. The mitochondrial DNA results show that only A. inermis and A. geisovii deserve species status.

4. References

Avise, J. C., Arnold, J., Ball, R. M., Bermingham, E., Lamb, T., Neigel, L. E., Reeb, C. A. & Saunders, N. C., 1987. Intraspecific phylogeography: The mitocondrial DNA bridge between population ge­netics and systematics. Annual Review in Ecology and Systematics, 18: 489–522.

Bell, G. 1982. The Masterpiece of Nature. The Evolution and Genetics of Sexuality, University of California Press, Berkeley and Los Angeles

Buckley T.R., Attanayake D., Park D., Ravidran S., Jewell T.R., Normark B.B. 2008. Investigating hybridization in the parthenogenetic New Zealand stick insects Acanthoxyla (Phasmatodea) using single-copy nuclear loci. Molecular Phylogenetics and Evolution 48: 335-349.

Bullini L. 1994. Origin and evolution of animal hybrid species. Trends Ecol. Evol. 9:422-426.

Guindon S. & Gascuel O. 2003. A simple, fast, and accurate algorithm to estimate large phylogenies by maximum likelihood. Systematic Biology, 52(5):696-704, 2003.

Jewell T., Brock, P.D. 2002. A review of the New Zealand stick insects: new genera synonymy, keys and a catalogue. J. Orthopteran Res. 11, 189-197.

Mayr, E. 1942. Systematics and the Origin of Species from the Viewpoint of a Zoologist. Columbia University Press: New York.

Panchal, M. (2007), 'The automation of Nested Clade Phylogeographic Analysis', bioinformatics 23, 509-510.

Salmon, J.T., 1991. The Stick Insects of New Zealand. Redd, Auckland, New Zealand.

Sites J. W. Jr., Marshall J. C. 2003. Delimiting species: A Renaissance issue in systematic biology. Trends Ecol. Evol. ;18:462-470.

Templeton AR (2001) Using phylogeographic analyses of gene trees to test species status and processes. Molecular Ecology, 10, 779–791.

White, M.J.D. 1978. Modes of Speciation, W.H, Freeman and Company, San Francisco.

5. Figures



Figure 1. Map of New Zealand showing sampling localities


Figura 2. Maximun likelihood gene trees for the mtDNA data (COII). Numbers above branches are bootstrap value.


Figura 3. Maximun likelihood gene trees for the mtDNA data (COI). Numbers above branches are bootstrap value.


Figura 4. Maximun likelihood gene trees for the 28S data. Numbers above branches are bootstrap value


Figura 5. Maximun likelihood gene trees for the PGI data. Numbers above branches are bootstrap value.


Figura 6. Maximun likelihood gene trees for the EF1 data. Numbers above branches are bootstrap value.

SPECIES CONCEPT.

Jiménez- Silva C. L.


A specie is the smallest diagnosable group identified as an ancestor-descendant populations evolving separately from others (Cacraft, 1983).The species is diagnosable by a unique combination of characters to compare individuals who achieve this identity is owned by the agency and not the investigator.

The actual existence of the species gives genealogical relationships with other group of organisms, their historical behavior, so it is considered that the species are different because they have diverged evolutionarily. Wiley (1978) supports this assertion by suggesting that the species is a single lineage of ancestral-descendant populations, they retain their identity from other lineages and have their own evolutionary tendencies and historical fate. A realistic notion of species derived from its interactions with the environment and other species (Mayr, 1942).

The species is monophyletic given that can be considered as a species level, among all that exist in the phylogenetic hierarchy. Only monophyletic groups can be recognized and formally named taxa.This principle is based on the groups which include all the descendants of a single common ancestor are the only groups with real and natural existence in relation to the evolutionary process (De Luna & Mishler, 1996).The phylogeny, or search for parsimonious cladograms is the only formal and robust procedure to discover monophyletic groups and build a classification according to Mishler.

The species concept of Rosen (1978.1979) states that the basis for grouping the cladistic system is synapomorphies. A monophyletic group consists of a cross section of a race and only includes members coexisting at the time (Sober, 1998). Empirically synapomorphies are known for, as these are the only evidence of recent common ancestry.Taxa at the species level, must also be distinguished by discrete apomorphic states rather than by total or plesiomorphic similarity (Theriot, 1992).According to Mishler and Donoghue (1982) separated two operational aspects of species recognition. First, agencies may be grouped into species on the basis of evidence monofilesis (autopomorphies), as is the case in other taxonomic levels. The criteria for crossover in particular should not be used for purposes of grouping. Second, the criteria to assign species status to certain monophyletic groups should be pluralistic, they vary in different organisms.

In the biological species concept, according to Mayr (1963) states: "Species are groups of interbreeding natural populations that are reproductively isolated themselves from other groups", I don´t consider it appropriate because it does not provide mechanisms for the recognition of species( Sneath & Sokal, 1973),applies only to individuals with sexual reproduction, it doesn´t solve the problems of parthenogenetic forms groups or developmental stages of a simple line.(Coyne et al., 2004); Furthermore, the similarity does not indicate reproductive membership in the same lineage or monophyletic group, since the ability to interbreed is a plesiomorphic often.( Bremer y Wanntorp, 1979; Donoghe, 1985; Rosen, 1979).

Over the genealogical history, phylogenetic species concept Biological has no clear meaning, for example: itself a kind A, extinct, resulting in two species: B and C by cladogenesis, then you can apply the biological species concept to the stem species to extinction of A makes it meaningless words "that are reproductively isolated from other groups".

In conclusion the concept of species must be based on a real group, Diagnosable, ancestor-descendant populations evolving separately from others, is monophyletic are recognized by discrete synapomorphies and apomorphic states instead of all or plesiomorphic similarity.

References

Bremer, K. & Wanntorp, H.-E. 1979. Hierarchy and reticulation in systematics. Systematic Zoology 28: 624—627.

Cracraft, J. 1983. Species concepts and speciation analysis. Current Ornithology, 1, 159–187.

Coyne, J.A. & Orr, H.A. 2004. Speciation. Sinauer Associates, Inc. Sunderland, Massachussets.

de Queiroz, K., and M. J. Donogue. 1988. Phylogenetic systematics and the species problem. Cladistics 4:317±338.
Haro, J.J. 1999. ¿Qué es una especie?.Bol. S.E.A. 26:105-112

Mayr, E. 1942. Systematics and the Origin of Species from the Viewpoint of a Zoologist. Columbia University Press: New York.

Mayr, E. 1963. Animal species and evolution. Cambridge: Belknap Press of Harvard University Press.

Mishler, B. D., and E. de luna. 1997 Sistemática Filogenética y el concepto de especie.Bol. Soc. Bot. México 60: 45-57

Mishler, B.D. & M.J. Donoghue. 1982. Species concepts: a case for pluralism. Systematic Zoology 31: 491-503.

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.
Sokal, R.R. & Rohlf, F.J. 1966. Random scanning of taxonomic characters. Nature 210: 461-462
Theriot, E. 1992. Clusters, species concepts and morphological evolution of diatoms. Systematic Biology 41:141-157.
Wiley, E. O.,1978. The evolutionary species concept reconsideres. Syst. Zool., 27: 17-26.

Phylogenetic Species Concepts: Diagnosable Version

Gualdrón-Diaz J. C.

Since of need individual for different researchers, have been development at least 22 concepts of species to characterize diversity, some of these researchers have been motivated by operational or empirical definitions, others by theoretical necessity, while some encouraged by peculiarities of organisms studied (Mayden 1997). However, all the concepts to present problems and disadvantage, some more than others, many of these are notably incompatible in the accounts the diversity and not all concepts have been equally well characterized or explicitly defined (Mayden 1997). Despite this, all attempts to define species depending on the needs and interests of each.

Of all the concepts raised, I agree with the definition of phylogenetic species. The phylogenetic species concept (PSC) has its origin in the writing of Willi Hennig (1966) and subsequent transformations of phylogenetic theory. Hennig recognized that the Biological Species Concept (Mayr, 1942-1963) was problematic with relative to the chronological history of species and proposed modifications designed to fix this species concept.

Several positive aspects of the PSC make them particurly attractive as operations in discovering biodiversity, and resolving some of the perceived problems with other concepts (Mayden and Wood, 1995). Currently at least three different concepts of species are identified as phylogenetic.The different PSCs form three general classes; one emphasizing monophyly, one emphasizing diagnosable, and one emphasizing both (Mayden 1997).

I concur with the diagnosable version of phylogenetic species concept, which have been proposed by several authors who defined the species as: “...a diagnosable cluster of individuals within which there is a parental pattern of ancestry and descent, beyond which there is not, and which exhibits a pattern of phylogenetic ancestry and descent among units of like kind” (Eldredge and Cracraft, 1980); ...”the smallest diagnosable cluster of individual organisms within which there is a parental pattern of ancestry and descent”(Cracraft, 1983); “...simply the smallest detected samples of self perpetuating organisms that have sets of characters” (Nelson and Platnick, 1981); “...the smallest aggregation of populations (sexual) or lineages (asexual) diagnosable by a unique combination of character states in comparable individuals (semaphoronts)” (Nixon and Wheeler, 1990; Wheeler and Platnick, 2000).

This definition emphasizes that a priori species are diagnosable regardless of a criterion of monophyly. Although the correspondence between characters, homologs, and apomorphies is of critical importance to cladistics (Patterson 1985), such distinctions are irrelevant to species recognition. In this sense, this concept differs from other proposed phylogenetic concepts, which require identification apomorphies to diagnose species; According to this, those not possesing autapomorphic attributes do no constitute a species.The monophyly, for proponents of this concept, apply only at a level of organization above species. Species are delimited by the distributions of fixed, diagnostic characters across populations (Mayden 1997) and there is no inherently arbitrary divergence or distinction between species or subspecies in a polytypic species (Cracraft, 1983, Warren, 1992). subspecies have no ontological status.

The positive aspects to this concept over others are: First, process is not invoked before patters is observed, to initially distinguish species, this do so in preparation for and prior to a cladistic analysis (Wheeler and Platnick, 2000). Second, phylogenetic methodologies are argued to be applicable only to genealogical relationships of species and supraspecific taxa, not below the level of integration of species wherein tokogenetic relationships of infraspecific entities are the norm (Wheeler and Nixon, 1990; Nixon and Wheeler, 1990).

Finally, this concept also have the ability to recognize both biparental and uniparental species, and possess no implied modes of selection nor speciation, besides it is more compatible with phylogenetic theory because speciation events are marked by character transformations (Mayden 1997, Wheeler and Platnick, 2000).

References

Cracraft, J. 1983. Species concepts and speciation analysis. Current Ornithology, 1, 159–187.

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

Hennig, W. 1966. Phylogenetic systematics. Urbana, IL: University of Illinois Press.

Mayden, R. L., and R. M. Wood. 1995. Systematics, Species Concepts, and the Evolutionarily Signficant Unit in Biodiversity and Conservation Biology. Special Publication, American Fisheries Society, Bethesda, Maryland. (No. 17: 58-113).

Mayden, R. L. 1997. A hierarchy of species concepts: the denouement in the saga of the species problem. In Species:The units of biodiversity. Edited by M. F. Claridge, H. A. Dawah, and M. R. Wilson. London: Chapman & Hall. pp. 381-424.

Mayr, E. 1942. Systematics and the Origin of Species from the Viewpoint of a Zoologist. Columbia University Press: New York.

Mayr, E. 1963. Animal species and evolution. Cambridge: Belknap Press of Harvard University Press.

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

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

Paterson, H. 1985. The recognition concept of species. Pp. 21-29 in E. Vrba, ed. Species and speciation. Transvaal Museum, Pretoria.

Warren, M. L., 1992. Variation of the spotted sunfish, Lepomis punctatus complex (Centrarchidae): meristics, morphometrics, pigmentation and species limits. Bull. Ala. Mus. Nat. Hist. 12:1-47.

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.

Who is Right?

Susana Ortiz B.

Although it is true the species concept has been controversial and approached from multiple perspectives throughout history, its applicability and acceptance depends on how well to recognize, identify and understand the species in nature hence its relevance in areas like conservation, ecology, evolution, taxonomy and of course systematic. The Biological Species Concept (BSC) is perhaps the most widely accepted species concept in biology, it defines species in terms of interbreeding and reproductive isolation (Mayr, 1963). This lats feature based on barriers to gene flow between populations includes not only geographic isolation but also prezygotic factors such mate choice, and fertilization incompatibilities and postzygotic factors i.e., hybrid inviability and sterility caused by genomic incompatibilities (Dobzhansky, 1937). However, in practice this concept involves some difficulties mainly in relation to hybridization, asexual populations, adimensionality and not distinction between reproductive isolation and the speciation´s process (Mallet, 2007; Fernandez et al., 1994; Templeton, 1989).

In view of this scenario, emerges the Phylogenetic Species Concept (PSC), which stablishes the recognition as criterion for species delimitation through characters; despite the multiple versions, the PSC proposed by Eldredge and Cracaft (1980) and later rephrased by Cracraft (1983) conceives the specie as “…the smallest diagnosable cluster of individual organisms within which there is a parental pattern of ancestry and descent”, the above entails some operational advantages, such as its applicability to fossils and all evolving systems of living things whether sexual and asexual populations and you do not need to know or understand the process driving speciation in order to recognize species (Claridge et al. 1997; Nelson and Placnick, 1981) . Under this concept the pattern of characters distribution in nature provides testable evidence of the existence of species in nature (Wheeler, 1999), additionally it seems to return to typological species concept given its confinement to diagnostic characters, nonetheless, the PSC emphasizes the relationship between unique combination of inherited characters either molecular or morphological and an ancestral–descendant sequence.

According to Cracraft (1989), species defined under this diagnostic criterion are real taxa suitable for phylogenetic analysis and evolutionary studies, being so is necessary to take special care of strict application rather in small groups and polymorphic species if unknown genetics aspects, geographic distribution and demography of the group, this in order to avoid underestimating the intraspecific variation and therefore the wrong multiplication of species (Mallet, 2007; Fernadez et al., 1995); However, to counteract such diagnosable groups have no authentic parental pattern of ancestry and descent (Cracraft, 1989). Another relevant aspect of the diagnostic species concept is the fundament of this diagnosticability that is the characters as synapomorphies or autapomorphies or simply characters as descriptors indistinctly of their historical background. This latest maybe is the most permissive given that it has not conflict in to recognize cladogenesis or anagenesis indistinctly and can be monophyletic or non-monophyletic. On this basis, also the concept is ambiguous because it could behave like synapomorphy, autapomorphy or simplesiomorphy in the same branch, also the major practical difficulties include determining whether shared traits have attained fixation in the population (Wiens and Servedio, 2000) and the inapplicability of this approach to most continuously varying quantitative traits (Willmann and Meier, 2000).

The monophyly criterion of species is an important component in synapomorphic and autapomorphic versions of the PSC, thus, they do not recognize the phyletic change or anagenesis, just the cladogenesis as evolutionary process. Following the above, in cladogenesis from a stem species, subspecies may first appear and then a new species with acquisition of apomorphies, nevertheless, the autapomorphic concept could recognize subspecies as species before the consolidation of the cladogenesis (De Haro, 2005); other problem is that it excludes the existence of stem-species by definition, since these can neither be monophyletic, nor can they possess autapomorphies, relative to its own descendant species since they inherit their "autapomorphies", so that the former autapomorphies of the stem-species become the autapomorphies of the resulting monophylum and thus become symplesiomorphies of the stem-species (Wheeler, 1999; Wheeler and Meier, 2000). On the other hand, the PSC based on synapomorphy, addresses the species problem from a perspective different, perhaps this is synapomorphy and monophyly in terms of relations among species and their characters (Hennig, 1966), but at this level should reflect the branching, or cladistic, relationships among species (Goldstein and De Salle, 2000), ie, the synapomoraphies may show the phylogenetic relationships of two or more species belong to a monophyletic group, then take this group as a single species is inadequate and even more when the historical status may be unresolved. Maybe, monophyly is an ambiguous concept whose problem lies a fundamental distinction between species and monophyletic taxa, where species form mutually exclusive reticulated systems, while higher taxa form inclusive hierarchical systems (Rieppel, 2009).

Finally, although in many contexts the PSC emphasizes a diversity of mechanisms that can give rise to real species in nature and that are not all recognized by the BSC (Claridge et al. 1997), operational difficulties exist for the identification of distinct historical entities in nature regardless of the phylogenetic species concept applied (Frost and Kluge, 1995), however, seems that the most adequate species concept is perhaps the autapomorphic concept in despite of its difficulties, without this meaning that it is the right or the universal criteria by which species may be delimited, it is just a good approximation to define and recognize the diversity of life.

References

Claridge, M. F., H.A. Dawah, and M. R.Wilson. 1997a. Practical approaches to species concepts for living organisms. Pp. 1–15 in Species: The units of biodiversity. Edited by M. F. Claridge, H. A. Dawah, and M. R. Wilson. London: Chapman & Hall.

Cracraft, J. 1983. Species concepts and speciation analysis. Current Ornithology, 1, 159–187.

Cracraft, J. (1989). Speciation and its ontology: The empirical consequences of alternative species concepts for understanding patterns and processes of differentiation. In Speciation and its Consequences (D. Otte and J. A. Endler, Eds.), pp. 28–59. Sinauer Associates, Sunderland, MA

Dobzhansky, T. 1937. “Genetics and the Origin of Species.” Columbia Carpenter, J. M. (1992). Random cladistics. Cladistics 8, 147–153.

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

Fernández, F., Hoyos J. M. and D. R. Miranda. 1994. Biodiversidad, Extinciones y el Problema de la la Especie. Colombia: Ciencia y Tecnología. 12 (4).

Fernández, F., Hoyos J. M. and D. R. Miranda. 1995. Especie. Innovacion y Ciencia. 32-37.

Frost D. R. and A. G. Kluge. 1995. A consideration of epistemology in systematic biology, with special reference to species. Cladistics 10:259-294.

Goldstein, P. Z., DeSalle, R., Amato, G., and Vogler, A. P. 2000. Phylogenetic Species, Nested Hierarchies, and Character Fixation. Cladistics 16, 364–384.

Hennig, W. 1966. Phylogenetic systematics. Urbana, IL: University of Illinois Press.

Mallet, J. 2007. Species Concepts Of. University College London Trans. Encyclopedia of Biodiversity. 10, 294–299

Mayr, E. 1963. Animal species and evolution. Cambridge: Belknap Press of Harvard University Press.

Murphy, F. A., C. M. Fauquet, D. H. L. Bishop, S. A. Ghabrial, A. W. Jarvis, G. P. Martelli, M. A. Mayo, and M. D. Summers (ed.). 1995. Virus taxonomy: classification and nomenclature of virus, p. 415±421. Spring-Verlag, New York, N.Y.

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

Rieppel, O. 2009. Species monophyly. Journal of Zoological Systematics and Evolutionary Research. 48 (1), 1-8.

Templeton, A. R. 1989. The meaning of species and speciation: A genetic perspective. In “Speciation and Its Consequences” (D. Otte and J. A. Endler, Eds.), pp. 3–27. Sinauer Associates, Sunderland, MA.

Van Regenmortel, M. H. V. 1990. Virus species, a much overlooked but essential concept in virus classification. Intervirology 31:241±254.

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

Wheeler, Q. D., and R. Meier, eds. 2000. Species concepts and phylogenetic theory: A debate. New York: Columbia University Press.

Willmann, R., and R. Meier. 2000. A critique from the Hennigian Species Concept Perspective. In: Species Concepts and Phylogenetic Theory (Ed. Q. D. Wheeler and R. Meier), pp. 101-108, Columbia University Press, New York.

Wiens, J. J., and M. R. Servedio. 2000. Species delimitation in systematics: inferring diagnostic differences between species. Proc. R. Soc. London, Ser. B 267:631-636.

Species Concept: position

D.F.Silva

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.

PHYLOGENETIC SPECIES CONCEPT

Jiménez- Silva C. L.

The ratings are the historical framework for interpreting the patterns of similarities between taxa, ecological interactions and their geographic distribution (Brooks, 1981; Cracraft, 1983; Eldredge and Cracraft, 1980; Farris, 1979) The species has been considered the foundation in construction of classifications of the trees evolutivos.Las different versions of the phylogenetic species concept is characterized by accepting the evolutionary and biological conception and to delimit the species in one way or another. Hennig defined the species as "groups of individuals who are interconnected by tocogèneticas relations are called species (Hennig 1996). Then Hennig believed that: "The species should then be defined as a complex of spatially distributed reproductive communities, or if we call this relationship in the" vicariance "as a vicariant complex communities of reproduction" (Hennig 1966)

The species can be considered a species level, among all those available in the hierarhy filogenética. Only monophyletic groups can be recognized and formally named taxa. This principle is based on the groups which include all the descendants of a single common ancestor are the only groups with real and natural existence in relation to the evolutionary process (De Luna and Mishler, 1996). The phylogeny or the search for parsimonious cladograms formal and robust only to discover monophyletic groups and build a classification according to Mishler. Mishler and Donoghue (1982) also split two operational aspects of species recognition. First, agencies may be grouped into species based over monofilesis evidence (autopomorphies), as is the case in the other taxonomic levels. The criteria for crossover in particular should not be used for purposes of grouping. Second, the criteria to assign species status to certain monophyletic groups should be pluralistic, ie, they vary in different organisms. Theriot is, agree to the taxa at the species level should be distinguished by discrete apomorphic states rather than by total or plesiomorphic similarity (Theriot, 1992).

Other authors such as Wiley says, "An evolutionary species is a single lineage of ancestral-descendant populations which maintains its identity from other lineages and have their own evolutionary tendencies and historical fate" (Wiley 1978). In this case the species is formed by organsmos evolve independently, while maintaining the identity to other lineages, which is maintained through relations that are generated lattice throught mating among similar organizations. From this it follows that the species is well defined independent biological units to be guided by evolution and that holds it together through reproduction (De Haro 1999)

Cacraft states that a species diagnosable smaller group of individual organisms in which there is a pattern of parental ancestor descendant (Cacraft 1983). To this author is an indispensable part of the definition to diagnose the species in question. For some like De Haro (1999) this is beyond the interest of the dynamics of the process since we are not able to diagnose the species exist and our limitations do not affect the process.



The phylogenetic species concept as Nixon and Wheeler: "the smallest aggregation of populations (sexual) or lineages, (asexual) diagnosable by a unique combination of character states in comparable individuals (semaforontes)" (Nixon and Wheller 1990). This definition of species differs little from the Cacraft in depth, but it is operationally more precise phylogenetic studies, which are those that may eventually shed light on these patterns of segregation and on the basis of which should be the separation of the species and is the grouping of these terminals evolving information which may eventually define a more precise and natural supraspecific categories. This definition creates a working tool for the detection of minimal terminals for phylogenetic analysis (Davis and Nixon 1992). Species are groups of organisms that evolve together and are able to maintain its own identity distinct from grups. These other species are different because they have diverged evolutionarily and not because they are different according to the human eye.


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

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

Cracraft, J. 1983. Species concepts and speciation analysis. Current Ornithology 1:159±187.

Hennig, W. 1966. Phylogenetic systematics. Urbana, IL: University of Illinois Press.

Wiley, E. O.,1978. The evolutionary species concept reconsideres. Syst. Zool., 27: 17-26.

Mishler, B. D., and E. de luna. 1997 Sistemática Filogenética y el concepto de especie.Bol. Soc. Bot. México 60: 45-57

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.

An approach from phylogenetic species concept

Susan@ Ortiz B.

Even though the species concept is an important topic in the recognition and conservation of biological diversity, presently there are no a universal concept and choosing one in particular is controversial in all cases. Perhaps, just like Wheeler (1999) mentioned, there are more species concepts in use today than any other time; however, the Phylogenetics Species Concept (PSC) could be considered a good approach. According to cladistic principles, the PSC suggested by Rosen (1978), is focused to population or group of populations geographically constrained defined by one on more unique apomorphous features. After a decade, a modified version was proposed by Queiroz and Donoghue (1988), as the smallest unit determined cladistically at least one specific character. Evidently, this concept is based on autapomorphic background and therefore the species are defined under monophyly criterion. However, some practical difficulties arise about recognition of ancestral species based on autapomorphies, since, the character becomes a synapomorphy and the ancestral taxon actually differs from its descendant due to lack of the evolutionary novelty. Additionally the PSC point out against BSC the absence of reproductive isolation as a plesiomorphic character inappropriate in the delimitation of species (Wheeler and Meier, 2000) and the absence of reproductive boundaries between ancestral and descendant populations (Hennig, 1966).

On the other hand, Eldredge and Cracraft (1980) and Cracraft (1983) addressed the PSC towards diagnosable characters, establishing the specie as a diagnosable cluster or the smallest diagnosable cluster of individuals within which there is a parental pattern of ancestry and descent. Afterwards Nelson and Wheeler (1990) redefine it as the smallest aggregation of populations or lineages diagnosable by a unique combination of character states. As well this concept also is based on the relationships between species and its characters, although not necessarily imply monophyly, being that the autapomorphic characters are diagnosable, but no all diagnosable characters can be autapomorphies. This approach seems to evoke the Typological Species Concept with regard to constant diagnostic differences to identify species (Mayr, 1991); nonetheless the measure is less arbitrary because it follows a parental pattern of ancestry and descent. A critique against this concept indicates that the species exist in nature independently of the systematic’s ability to diagnose them (Haro, 1999). Obviously, diagnosable apomorphies must be sought, but this is a systematic’s problem that does not affect the organism as real entity. Another difficulty is to define the boundaries of diagnostic in polytypic species with a wide variety, which could lead to false increases in diversity and underestimation of intraspecific variation (Fernandez et al., 1995).

Despite the above, the PSC is an operational concept compatible with phylogenetic theory designed to recognize and define the groups for any characteristic, from morphological to molecular. Some fundamental components of the PSC are the weighting of the recognition against reproductive isolation and lack of a temporal dimension under BSC (Willmann and Meier, 2000), its applicability to all evolving systems, whether sexual or asexual (Balakrishnan, 2005) and the recognition that species based on observable, testable characters simply avoid the confusion imparted by considerations of modes of speciation (Wheeler, 1999). Likewise, according to Balakrishnan (2005) the major practical troubles include determining whether shared traits have attained fixation in the population (Wiens and Servedio, 2000), determining how many diagnostic traits to consider and the inapplicability of this approach to most continuously varying quantitative traits (Willmann and Meier, 2000). Finally, although PSC has not completely solved the conflict between the real species existing in nature and the criteria and tool to recognize, it constitutes an attractive approach and a step in this direction. Also emphasize the diversity of mechanisms that can give rise to real species in nature and that are not all recognized by the BSC.

References

Balakrishnan, R. 2005. Species Concepts, Species Boundaries and Species Identification: A View from the Tropics. Syst Biol.2005; 54: 689 -693.

Cracraft, J. 1983. Species concepts and speciation analysis. Current Ornithology 1:159±187.

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

Fernández, F., Hoyos J. M. and D. R. Miranda. 1995. Especie. Innovacion y Ciencia. 32-37.

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

Hennig, W. 1966. Phylogenetic systematics. Urbana, IL: University of Illinois Press.

Mayr , E. 1991. One long, argument, Charles Darwin and the genesis of modern evolutionary thought. Harvard University Press, Cambridge, Mass.

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 R. Meier. 2000. Species Concepts and Phylogenetic Theory. Columbia University Press, New York. pp. 133-145.

Willmann, R., and R. Meier. 2000. A critique from the Hennigian Species Concept Perspective. In: Species Concepts and Phylogenetic Theory (Ed. Q. D. Wheeler and R. Meier), pp. 101-108, Columbia University Press, New York.

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