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Bangweulu Tsessebe
The Bangweulu tsessebe (''Damaliscus lunatus superstes'') is a population and possible taxon of ''Damaliscus lunatus'' (topi or sassaby), which are large African antelopes of the grasslands. This population is presently restricted to northern Zambia in the wild, although it was recorded as occurring in neighbouring southernmost Democratic Republic of the Congo in the 1940s. Also seen as the northernmost population belonging to the nominate southern sassaby subspecies, in 2003 it was described as a new species, only to be downgraded to a subspecies a few years later. Its taxonomic status is unclear as of 2021. As an individual sassaby of this taxon cannot be clearly distinguished from populations to the south, the taxon was defined using an experimental suite of statistical techniques applied to a sample set, based on multivariate analysis, and recognised under an experimental new taxonomy. Nominate sassaby antelopes become progressively darker on average in the northern populations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taxon
In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and given a particular ranking, especially if and when it is accepted or becomes established. It is very common, however, for taxonomists to remain at odds over what belongs to a taxon and the criteria used for inclusion. If a taxon is given a formal scientific name, its use is then governed by one of the nomenclature codes specifying which scientific name is correct for a particular grouping. Initial attempts at classifying and ordering organisms (plants and animals) were set forth in Carl Linnaeus's Linnaean taxonomy, system in ''Systema Naturae'', 10th edition (1758), as well as an unpublished work by Bernard de Jussieu, Bernard and Antoine Laurent de Jussieu. The idea of a unit-based system of biological classification was first mad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biological Species Concept
The species problem is the set of questions that arises when biologists attempt to define what a species is. Such a definition is called a species concept; there are at least 26 recognized species concepts. A species concept that works well for sexually reproducing organisms such as birds may be useless for species that reproduce asexually, such as bacteria. The scientific study of the species problem has been called microtaxonomy. One common, but sometimes difficult, question is how best to decide which species an organism belongs to, because reproductively isolated groups may not be readily recognizable, and cryptic species may be present. There is a continuum from ''reproductive isolation'' with no interbreeding, to ''panmixis'', unlimited interbreeding. Populations can move forward or backwards along this continuum, at any point meeting the criteria for one or another species concept, and failing others. Many of the debates on species touch on philosophical issues, such as no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptic Species
In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each other, further blurring any distinctions. Terms that are sometimes used synonymously but have more precise meanings are cryptic species for two or more species hidden under one species name, sibling species for two (or more) species that are each other's closest relative, and species flock for a group of closely related species that live in the same habitat. As informal taxonomic ranks, species group, species aggregate, macrospecies, and superspecies are also in use. Two or more taxa that were once considered conspecific (of the same species) may later be subdivided into infraspecific taxa (taxa within a species, such as bacterial strains or plant varieties), that is complex but it is not a species complex. A species complex is in most cas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rumen
The rumen, also known as a paunch, is the largest stomach compartment in ruminants and the larger part of the reticulorumen, which is the first chamber in the alimentary canal of ruminant animals. The rumen's microbial favoring environment allows it to serve as the primary site for microbial fermentation of ingested feed. The smaller part of the reticulorumen is the reticulum, which is fully continuous with the rumen, but differs from it with regard to the texture of its lining. Brief anatomy The rumen is composed of several muscular sacs, the cranial sac, ventral sac, ventral blindsac, and reticulum. The lining of the rumen wall is covered in small fingerlike projections called papillae, which are flattened, approximately 5mm in length and 3mm wide in cattle. The reticulum is lined with ridges that form a hexagonal honeycomb pattern. The ridges are approximately 0.1–0.2mm wide and are raised 5mm above the reticulum wall. The hexagons in the reticulum are approximately 2â ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gut Microbiota
Gut microbiota, gut microbiome, or gut flora, are the microorganisms, including bacteria, archaea, fungi, and viruses that live in the digestive tracts of animals. The gastrointestinal metagenome is the aggregate of all the genomes of the gut microbiota. The gut is the main location of the human microbiome. The gut microbiota has broad impacts, including effects on colonization, resistance to pathogens, maintaining the intestinal epithelium, metabolizing dietary and pharmaceutical compounds, controlling immune function, and even behavior through the gut–brain axis. The microbial composition of the gut microbiota varies across regions of the digestive tract. The colon contains the highest microbial density recorded in any habitat on Earth, representing between 300 and 1000 different species. Bacteria are the largest and to date, best studied component and 99% of gut bacteria come from about 30 or 40 species. Up to 60% of the dry mass of feces is bacteria. Over 99% of the b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maxillary Teeth
A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tearing food, for defensive purposes, to intimidate other animals often including their own, or to carry prey or their young. The roots of teeth are covered by gums. Teeth are not made of bone, but rather of multiple tissues of varying density and hardness that originate from the embryonic germ layer, the ectoderm. The general structure of teeth is similar across the vertebrates, although there is considerable variation in their form and position. The teeth of mammals have deep roots, and this pattern is also found in some fish, and in crocodilians. In most teleost fish, however, the teeth are attached to the outer surface of the bone, while in lizards they are attached to the inner surface of the jaw by one side. In cartilaginous fish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zygoma
The term zygoma generally refers to the zygomatic bone, a bone of the human skull commonly referred to as the cheekbone or malar bone, but it may also refer to: * The zygomatic arch, a structure in the human skull formed primarily by parts of the zygomatic bone and the temporal bone * The zygomatic process, a bony protrusion of the human skull, mostly composed of the zygomatic bone but also contributed to by the frontal bone, temporal bone, and maxilla See also *Zygoma reduction plasty Zygoma reduction, also known as cheekbone reduction surgery, is a surgery used to reduce the facial width by excising part of the zygomatic bone and arch. Wide cheekbones are a characteristic facial trait of Asians, whose skull shapes tend to be m ... {{set index article Anatomy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pelage
Fur is a thick growth of hair that covers the skin of mammals. It consists of a combination of oily #Guard hair, guard hair on top and thick #Down hair, underfur beneath. The guard hair keeps moisture from reaching the skin; the underfur acts as an thermal insulation, insulating blanket that keeps the animal warm. The fur of mammals has many uses: protection, sensory purposes, waterproofing, and camouflaging, with the primary usage being thermoregulation. The types of hair include * ''definitive'', which may be moulting, shed after reaching a certain length; * ''vibrissae'', which are sensory hairs and are most commonly whiskers; * ''pelage'', which consists of guard hairs, under-fur, and awn hair; * ''spine (zoology), spines'', which are a type of stiff guard hair used for defense in, for example, porcupines; * ''bristles'', which are long hairs usually used in visual signals, such as the mane (lion), mane of a lion; * ''velli'', often called "down fur", which insulates new ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morphology (anatomy)
Morphology is a branch of biology dealing with the study of the form and structure of organisms and their specific structural features. This includes aspects of the outward appearance (shape, structure, colour, pattern, size), i.e. external morphology (or eidonomy), as well as the form and structure of the internal parts like bones and organs, i.e. internal morphology (or anatomy). This is in contrast to physiology, which deals primarily with function. Morphology is a branch of life science dealing with the study of gross structure of an organism or taxon and its component parts. History The etymology of the word "morphology" is from the Ancient Greek (), meaning "form", and (), meaning "word, study, research". While the concept of form in biology, opposed to function, dates back to Aristotle (see Aristotle's biology), the field of morphology was developed by Johann Wolfgang von Goethe (1790) and independently by the German anatomist and physiologist Karl Friedrich Burdach ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Southern Africa
Southern Africa is the southernmost subregion of the African continent, south of the Congo and Tanzania. The physical location is the large part of Africa to the south of the extensive Congo River basin. Southern Africa is home to a number of river systems; the Zambezi River being the most prominent. The Zambezi flows from the northwest corner of Zambia and western Angola to the Indian Ocean on the coast of Mozambique. Along the way, the Zambezi River flows over the mighty Victoria Falls on the border between Zambia and Zimbabwe. Victoria Falls is one of the largest waterfalls in the world and a major tourist attraction for the region. Southern Africa includes both subtropical and temperate climates, with the Tropic of Capricorn running through the middle of the region, dividing it into its subtropical and temperate halves. Countries commonly included in Southern Africa include Angola, Botswana, the Comoros, Eswatini, Lesotho, Madagascar, Malawi, Mauritius, Mozambique, Namib ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
