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Milnesium Alpigenum
''Milnesium alpigenum'' is a species of tardigrade that falls under the Tardigrada phylum. Like its taxonomic relatives it is an omnivorous predator that feeds on other small organisms, such as algae, rotifers, and nematodes. M. alpigenum was discovered by Christian Gottfried Ehrenberg in 1853. It is very closely related to '' Milnesium tardigradum'' along with many other species from the '' Milnesium'' genus. History and taxonomy ''M. alpigenum'' was first suggested to be an independent species by Christian Gottfried Ehrenberg in 1853. However immediately it was turned down to be a valid species due to its extreme morphological similarity to Milnesium tardigradum ( Doyère, 1840). This was also because Intraspecific phenotypic variation was thought to be very large between species of tardigrade, and that each species was vastly physiologically different from one another. However, in the early 20th century more research was conducted in relation to the morphological d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Christian Gottfried Ehrenberg
Christian Gottfried Ehrenberg (19 April 1795 – 27 June 1876) was a German naturalist, zoologist, comparative anatomist, geologist, and microscopist. Ehrenberg was an evangelist and was considered to be of the most famous and productive scientists of his time. Early collections The son of a judge, Christian Gottfried Ehrenberg was born in Delitzsch, near Leipzig. He first studied theology at the University of Leipzig, then medicine and natural sciences in Berlin and became a friend of the famous explorer Alexander von Humboldt. In 1818, he completed his doctoral dissertation on fungi, ''Sylvae mycologicae Berolinenses.'' In 1820–1825, on a scientific expedition to the Middle East with his friend Wilhelm Hemprich, he collected thousands of specimens of plants and animals. He investigated parts of Egypt, the Libyan Desert, the Nile valley and the northern coasts of the Red Sea, where he made a special study of the corals. Subsequently, parts of Syria, Ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ernst Marcus (zoologist)
Ernst Gustav Gotthelf Marcus (8 June 1893 – 30 June 1968) was a German zoologist, former occupant of the chair of zoology at the University of São Paulo from 1936 to 1963, and co-founder of the Oceanographic Institute of the University of São Paulo. Life Marcus was born in Berlin in a Jewish family, the son of Georg Marcus, a jurist, and Regina Schwartz. As a child, he lived near the Berlin Zoo, where he observed all kinds of animals, and collected beetles. He studied at the Kaiser Friedrich Gymnasium and later entered the Friedrich Wilhelm University to study zoology. He began his doctoral studies in the Entomology Department at the Berlin Museum and, in 1914, he published his first zoological work. However, his studies were later delayed due to World War I, where he fought as a soldier, and his second work, a thesis on Coleoptera, was published only in 1919, when he received his doctorate. After graduation, he continued to work at the museum and was assigned to the Bryozoa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symmetry
Symmetry (from grc, συμμετρία "agreement in dimensions, due proportion, arrangement") in everyday language refers to a sense of harmonious and beautiful proportion and balance. In mathematics, "symmetry" has a more precise definition, and is usually used to refer to an object that is invariant under some transformations; including translation, reflection, rotation or scaling. Although these two meanings of "symmetry" can sometimes be told apart, they are intricately related, and hence are discussed together in this article. Mathematical symmetry may be observed with respect to the passage of time; as a spatial relationship; through geometric transformations; through other kinds of functional transformations; and as an aspect of abstract objects, including theoretic models, language, and music. This article describes symmetry from three perspectives: in mathematics, including geometry, the most familiar type of symmetry for many people; in science and n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echiniscus
''Echiniscus'' is a genus of tardigrades in the family Echiniscidae. The genus was named and described by Karl August Sigismund Schultze in 1840. Species The genus includes the following species: * ''Echiniscus africanus'' Murray, 1907 * ''Echiniscus aliquantillus'' Grigarick, Schuster & Nelson, 1983 * ''Echiniscus angolensis'' da Cunha & do Nascimento Ribeiro, 1964 * '' Echiniscus apuanus'' Bertolani, 1946 * '' Echiniscus arcangelii'' Maucci, 1973–74 * ''Echiniscus arctomys'' Ehrenberg, 1853 * '' Echiniscus arthuri'' Pilato, Binda & Lisi, 2005 * '' Echiniscus azoricus'' Fontoura, Pilato & Lisi, 2008 * ''Echiniscus baius'' Marcus, 1928 * ''Echiniscus baloghi'' Iharos, 1973 * '' Echiniscus barbarae'' Kaczmarek & Michalczyk, 2002 * '' Echiniscus batramiae'' Iharos, 1936 * '' Echiniscus becki'' Schuster & Grigarick, 1966 * ''Echiniscus bigranulatus'' Richters, 1907 * '' Echiniscus bisculptus'' Maucci, 1983 * '' Echiniscus blumi'' Richters, 1903 * '' Echiniscus calcaratus'' Ri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echiniscidae
The Echiniscidae are a family of tardigrades, a phylum of water-dwelling, eight-legged, segmented micro-animals. It is one of the four families in the order Echiniscoidea.Echiniscidae The family was named by Gustav Thulin in 1928.Thulin, ''Über die Phylogenie und das System der Tardigraden'' (''On the Phylogeny and the System of Tardigrade''). Hereditas (1928) vol. 11, no. 2/3, p. 207-266 Genera The family Echiniscidae consists of the following genera: * ''[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylogenetics
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups of organisms. These relationships are determined by Computational phylogenetics, phylogenetic inference methods that focus on observed heritable traits, such as DNA sequences, protein amino acid sequences, or morphology. The result of such an analysis is a phylogenetic tree—a diagram containing a hypothesis of relationships that reflects the evolutionary history of a group of organisms. The tips of a phylogenetic tree can be living taxa or fossils, and represent the "end" or the present time in an evolutionary lineage. A phylogenetic diagram can be rooted or unrooted. A rooted tree diagram indicates the hypothetical common ancestor of the tree. An unrooted tree diagram (a network) makes no assumption about the ancestral line, and doe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Post-zygotic Isolation
The mechanisms of reproductive isolation are a collection of evolutionary mechanisms, behaviors and physiological processes critical for speciation. They prevent members of different species from producing offspring, or ensure that any offspring are sterile. These barriers maintain the integrity of a species by reducing gene flow between related species.Strickberger, M. 1978. ''Genética''. Omega, Barcelona, España, p.: 874-879. .Futuyma, D. 1998. ''Evolutionary biology'' (3ª edición). Sinauer, Sunderland. The mechanisms of reproductive isolation have been classified in a number of ways. Zoologist Ernst Mayr classified the mechanisms of reproductive isolation in two broad categories: pre-zygotic for those that act before fertilization (or before mating in the case of animals) and post-zygotic for those that act after it.Mayr, E. 1963. ''Animal species and evolution''. Harvard University Press, Cambridge. The mechanisms are genetically controlled and can appear in species whose ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pre-zygotic Isolation
The mechanisms of reproductive isolation are a collection of evolutionary mechanisms, behaviors and physiological processes critical for speciation. They prevent members of different species from producing offspring, or ensure that any offspring are sterile. These barriers maintain the integrity of a species by reducing gene flow between related species.Strickberger, M. 1978. ''Genética''. Omega, Barcelona, España, p.: 874-879. .Futuyma, D. 1998. ''Evolutionary biology'' (3ª edición). Sinauer, Sunderland. The mechanisms of reproductive isolation have been classified in a number of ways. Zoologist Ernst Mayr classified the mechanisms of reproductive isolation in two broad categories: pre-zygotic for those that act before fertilization (or before mating in the case of animals) and post-zygotic for those that act after it.Mayr, E. 1963. ''Animal species and evolution''. Harvard University Press, Cambridge. The mechanisms are genetically controlled and can appear in speci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. '' Panthera leo'' (lion) and '' Panthera onca'' (jaguar) are two species within the genus ''Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants of an ancestral taxon are grouped together (i.e. phylogenetic analysis should c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Speciation
Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within lineages. Charles Darwin was the first to describe the role of natural selection in speciation in his 1859 book ''On the Origin of Species''. He also identified sexual selection as a likely mechanism, but found it problematic. There are four geographic modes of speciation in nature, based on the extent to which speciating populations are isolated from one another: allopatric, peripatric, parapatric, and sympatric. Speciation may also be induced artificially, through animal husbandry, agriculture, or laboratory experiments. Whether genetic drift is a minor or major contributor to speciation is the subject of much ongoing discussion. Rapid sympatric speciation can take place through polyploidy, such as by doubling of chromosome numb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sympatry
In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. An initially interbreeding population that splits into two or more distinct species sharing a common range exemplifies sympatric speciation. Such speciation may be a product of reproductive isolation – which prevents hybrid offspring from being viable or able to reproduce, thereby reducing gene flow – that results in genetic divergence. Sympatric speciation may, but need not, arise through secondary contact, which refers to speciation or divergence in allopatry followed by range expansions leading to an area of sympatry. Sympatric species or taxa in secondary contact may or may not interbreed. Types of populations Four main types of population pairs exist in nature. Sympatric populations (or species) contrast with parapatric populations, which contact one another in adjacent but not shared ranges and do n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Sequencing
DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, guanine, cytosine, and thymine. The advent of rapid DNA sequencing methods has greatly accelerated biological and medical research and discovery. Knowledge of DNA sequences has become indispensable for basic biological research, DNA Genographic Projects and in numerous applied fields such as medical diagnosis, biotechnology, forensic biology, virology and biological systematics. Comparing healthy and mutated DNA sequences can diagnose different diseases including various cancers, characterize antibody repertoire, and can be used to guide patient treatment. Having a quick way to sequence DNA allows for faster and more individualized medical care to be administered, and for more organisms to be identified and cataloged. The rapid speed of sequencing attained with m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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