Species Concept

Contemporary species concepts are diverse. Nonetheless, all share the fundamental idea that species are segments of lineages at the population level of biological organization. They differ in the secondary properties (e.g., intrinsic reproductive isolation, monophyly, diagnosability) that are treated as necessary for considering lineages to be species. A unified species concept can be achieved by interpreting the common fundamental idea of being a separately evolving lineage segment as the only necessary property of species and viewing the various secondary properties either as lines of evidence relevant to assessing lineage separation or as properties that define different subcategories of the species category (e.g., reproductively isolated species, monophyletic species, diagnosable species). This unified species concept has a number of consequences for taxonomy, including the need to acknowledge that undifferentiated and undiagnosable lineages are species, that species can fuse, t...

Cyclidium glaucoma is the best-characterized member of the genus Cyclidium. This ciliated Protist feeds on Bacteria, and therefore plays an important role in the environment, and it is very common in sewage treatment plants.
Different Cyclidium species have been described within the genus Cyclidium, but the validity of these descriptions are problematic because of the lack of morphological and in particular molecular diagnostic data. Additionally, what constitutes a species is not well defined for many Protists.
However, the accurate identification of Protist species is important for having reliable data about their biodiversity, geographic distribution and ecology.
To accurately identify a species, it is necessary to corroborate all available information, especially the morphological data and the molecular data.
Our morphological study deals with silver nitrate and protargol impregnated specimens, and also with DAPI-stained nuclei.
Furthermore, three sequences which are important in molecular systematic have been obtained: the ribosomal RNA 18 S, the Internal Transcribed Spacer (ITS), and the Cytochrome Oxidase (COX). The primers designed for the amplification of the COX produce a 610 bp sequence of the “barcode” region.

Armillaria root and butt rot disease is a common problem in peach orchards, tea and pine plantations in the Eastern Highlands of Zimbabwe. The species of Armillaria causing this disease have not been fully identified but it is believed that at least three species are involved. These included A. fuscipes (previously referred to as RFLP Group I) and two unnamed species known as RFLP Group II and RFLP Group III. The aim of the study was to use PCR-RFLP, sequences of the IGS-1 region of the rDNA operon and AFLP fingerprinting to characterize 27 Zimbabwean Armillaria isolates. PCR-RFLP tests showed that the isolates resided in five groups. Analysis of sequence data elucidated four groups, which were also supported by AFLP data. Thirteen isolates belonged to RFLP Group I, which is considered to represent A. fuscipes, four isolates were most similar to those previously referred to as Zimbabwean RFLP Group II and two isolates clustered most closely with RFLP Group III. The remaining isolate...

The formal definition of species as explanatory hypotheses presented by Fitzhugh (Marine Biol 26:155–165, 2005a, b) is emended. A species is an explanatory account of the occurrences of the same character(s) among gonochoristic or cross-fertilizing hermaphroditic individuals by way of character origin and subsequent fixation during tokogeny. In addition to species, biological systematics also employs hypotheses that are ontogenetic, tokogenetic,

The study of biodiversity of prokaryotes in transitional waters is hampered by the fact that we do not posses any comprehensive inventories of prokaryotic species. Microbial biodiversity is thus often estimated indirectly by extraction of nucleic acids from the natural environment and by using 16S ribosomal RNA gene sequences as phylogenetic and taxonomic markers. Experimental microbial ecology has contributed over the years to developing niche-assembly theories of community assemblage and I review some of their major findings. Finally, the aim of establishing a link between biodiversity and ecosystem functioning is quite recent and has prompted a novel experimental approach that can be applied in microbial ecology. The following observations have been forwarded. 2 - The species richness for prokaryotes is difficult to assess in transitional waters, because of an unclearly defined species concept and because the Bacteriological Code requires living cultures as type strains for taxon...

Tortoises of the Testudo graeca complex inhabit a patchy range that covers part of three continents (Africa, Europe, Asia). It extends approximately 6500 km in an east-west direction from eastern Iran to the Moroccan Atlantic coast and about 1600 km in a north-south direction from the Danube Delta to the Libyan Cyrenaica Peninsula. Recent years have seen a rapid increase of recognized taxa. Based on morphological investigations, it was suggested that this group consists of as many as 20 distinct species and is paraphyletic with respect to T. kleinmanni sensu lato and T. marginata. Based on samples from representative localities of the entire range, we sequenced the mitochondrial cytochrome b gene and conducted nuclear genomic fingerprinting with ISSR PCR. The T. graeca complex is monophyletic and sister to a taxon consisting of T. kleinmanni sensu lato and T. marginata. The T. graeca complex comprises six well-supported mtDNA clades (A-F). Highest diversity is found in the Caucasian...

Recent proposed taxonomic changes in the Certhiidae are reviewed within the geographic scope of this series and their reliability is discussed in terms of the Biological Species Concept, with respect to secondary contacts, bioacoustics, and molecular genetics. Certain hitherto unpublished data, useful for the understanding of taxonomic decisions, are included. In accordance with Article 24.2.3 of the Code one of us acts as First Reviser in selecting the correct spelling of the name of the recently described Chinese species.

Under the biological species concept, the intraspecific variability and true species richness of Palearctic mammals has often been overlooked, and therefore the need to conserve it. Recovery projects of endangered European mammals in Western Europe rely mainly upon translocation of conspecifics from viable populations in Central or Eastern Europe. From a wildlife management and restoration ecology point of view, many

... Catherine Girard a , Corresponding Author Contact Information , E-mail The Corresponding Author and Sabrina Renaud b. ... of genetic studies evidences that hybridization significantly contributed to the evolution of many species ([Green et al., 2010] and [Mallet, 2005]), showing ...

Immunofluorescence assays using polyclonal and preadsorbed antibodies as well as FITC-labelled lectins were employed to characterize two morphospecies of the cyanophytes Pseudanabaena catenata and P. planctonica from laboratory cultures isolated from two reservoirs in Spain and one in Denmark. Binding of both antibodies and lectins was unaffected by phase of the cell division cycle, growth phase and environmental factors such

The issue of species delimitation has long been confused with that of species conceptualization, leading to a half century of controversy concerning both the definition of the species category and methods for inferring the boundaries and numbers of species. Alternative species concepts agree in treating existence as a separately evolving metapopulation lineage as the primary defining property of the species category, but they disagree in adopting different properties acquired by lineages during the course of divergence (e.g., intrinsic reproductive isolation, diagnosability, monophyly) as secondary defining properties (secondary species criteria). A unified species concept can be achieved by treating existence as a separately evolving metapopulation lineage as the only necessary property of species and the former secondary species criteria as different lines of evidence (operational criteria) relevant to assessing lineage separation. This unified concept of species has several conse...

Contemporary species concepts are diverse. Nonetheless, all share the fundamental idea that species are segments of lineages at the population level of biological organization. They differ in the secondary properties (e.g., intrinsic reproductive isolation, monophyly, diagnosability) that are treated as necessary for considering lineages to be species. A unified species concept can be achieved by interpreting the common fundamental idea of being a separately evolving lineage segment as the only necessary property of species and viewing the various secondary properties either as lines of evidence relevant to assessing lineage separation or as properties that define different subcategories of the species category (e.g., reproductively isolated species, monophyletic species, diagnosable species). This unified species concept has a number of consequences for taxonomy, including the need to acknowledge that undifferentiated and undiagnosable lineages are species, that species can fuse, t...

A molecular phylogeny of the Spizaetus cirrhatus complex is presented in this study, based on two sections of the mitochondrial genome: partial sequences of the cytochrome b gene and of the control region (CR). The topologies derived from the two sequences are in agreement. Within S. cirrhatus distances are rather low (0–1.5% in cytochrome b). Among the cirrhatus subspecies the island taxa floris, vanheurni and andamanensis form distinct haplogroups in the CR trees, conforming to the earlier subspecific divisions which were based on morphological characters. On the other hand, the most widespread subspecies, limnaeetus, does not represent a monophyletic group in the gene trees and its haplogroups do not cluster according to geographic affinities. An unambiguous resolution of relationships among haplotypes and haplogroups, respectively, was not achieved, suggesting a more recent radiation of this group of hawk-eagles in the course of the last ice ages. Concerning the outgroup taxa Sp...

New genetic information on the taxonomic status of an endangered species may have strong implications for its continued protection and that of other listed taxa with questionable species status. While analyzing a more comprehensive project on the molecular phylogeny of North American Spiranthes (Orchidaceae), lack of genetic differentiation between endangered S. parksii, endemic only to Texas, and a common local congener,