Phylogenetic Nomenclature

Phylogenetic nomenclature is formulated in terms of evolution and common descent rather than the type specimens, categorical ranks, and morphological characters. The latter is used most commonly in cladistic analysis. Taxon names are strictly connected to phylogenetic tree topology and evolutionary history. In taxonomy, each name is attached to a clade taxonomic group containing a common ancestor and all its descendants. Phylogenetic nomenclature discards categorical ranks. The problem with ranks are evident when one considers biodiversity lineages and clades. Questions like "how many lineages are there?" or "how many clades are there?" become pointless, since there are no answers. These are relative concepts, illustrating the fractal nature of the tree of life and the need to let a phylogenetic hypothesis be the focus, rather than the categories, when biodiversity is quantified. Phylogenetic nomenclature helps to put focus on phylogenetic trees by offering an explicit link between names and parts of species history, that is, clades.

PHYLOGENETIC

In biology, phylogenetics (Greek: phyle = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e.g., species, populations). Also known as phylogenetic systematics or cladistics, phylogenetics treats each species as a group of lineage-connected individuals. Taxonomy, the classification of organisms according to similarity, has been richly informed by phylogenetics but remains methodologically and logically distinct.
Evolution is regarded as a branching process, whereby populations are altered over time and may speciate into separate branches, hybridize together, or terminate by extinction. This may be visualized as a multidimensional character-space that a population moves through over time. The problem posed by phylogenetics is that genetic data are only available for the present, and fossil records (osteometric data) are sporadic and less reliable. Our knowledge of how evolution operates is used to reconstruct the full tree.
Cladistics provides a simplified method of understanding phylogenetic trees. There are some terms that describe the nature of a grouping. For instance, all birds and reptiles are believed to have descended from a single common ancestor, so this taxonomic grouping (yellow in the diagram) is called monophyletic. "Modern reptile" (cyan in the diagram) is a grouping that contains a common ancestor, but does not contain all descendents of that ancestor (birds are excluded). This is an example of a paraphyletic group. A grouping such as warm-blooded animals would include only mammals and birds (red/orange in the diagram) and is called polyphyletic because the members of this grouping do not include the most recent common ancestor.

Diagnosis

Diagnosing mesothelioma is often difficult, because the symptoms are similar to those of a number of other conditions. Diagnosis begins with a review of the patient's medical history. A history of exposure to asbestos may increase clinical suspicion for mesothelioma. A physical examination is performed, followed by chest X-ray and often lung function tests. The X-ray may reveal pleural thickening commonly seen after asbestos exposure and increases suspicion of mesothelioma. A CT (or CAT) scan or an MRI is usually performed. If a large amount of fluid is present, abnormal cells may be detected by cytology if this fluid is aspirated with a syringe. For pleural fluid this is done by a pleural tap or chest drain, in ascites with an paracentesis or ascitic drain and in a pericardial effusion with pericardiocentesis. While absence of malignant cells on cytology does not completely exclude mesothelioma, it makes it much more unlikely, especially if an alternative diagnosis can be made (e.g. tuberculosis, heart failure).