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Heterokairy
In evolutionary developmental biology, heterochrony is any genetically controlled difference in the timing, rate, or duration of a Developmental biology, developmental process in an organism compared to its ancestors or other organisms. This leads to changes in the size, shape, characteristics and even presence of certain Organ (biology), organs and features. It is contrasted with heterotopy, a change in spatial positioning of some process in the embryo, which can also create Morphology (biology), morphological innovation. Heterochrony can be divided into intraspecific heterochrony, variation within a species, and interspecific heterochrony, phylogenetic variation, i.e. variation of a descendant species with respect to an ancestral species. These changes all affect the start, end, rate or time span of a particular developmental process. The concept of heterochrony was introduced by Ernst Haeckel in 1875 and given its modern sense by Gavin de Beer in 1930. History The conc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Walter Garstang
Walter Garstang FLS FZS (9 February 1868 – 23 February 1949), a Fellow of Lincoln College, Oxford and Professor of Zoology at the University of Leeds, was one of the first to study the functional biology of marine invertebrate larvae. His best known works on marine larvae were his poems published as ''Larval Forms and Other Zoological Verses'', especially ''The Ballad of the Veliger''. They describe the form and function of several marine larvae as well as illustrating some controversies in evolutionary biology of the time. Garstang was known for his vehement opposition to Ernst Haeckel's Biogenetic Law, now discredited. He is also noted for his hypothesis on chordate evolution, known as Garstang's theory, which suggests an alternative route for chordate evolution from echinoderms. Early life Walter Garstang was born on 9 February 1868 as the eldest son of Dr Walter Garstang of Blackburn and his wife Matilda Mary Wardley, and older brother of the archaeologist John Gars ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ambystoma Talpoideum
''Ambystoma talpoideum'', the mole salamander, is a species of salamander found in much of the eastern and central United States, from Florida to Texas, north to Illinois, east to Kentucky, with isolated populations in Virginia and Indiana. Older sources often refer to this species as the tadpole salamander because some individuals remain in a neotenic state. This salamander lives among the leaf litter on the forest floor, migrating to ponds to breed. Description Mole salamanders are stocky, with short bodies and large heads. They can grow to 10 cm (4 in) in length. They are normally gray or dark brown in color, with darker mottling and lighter gray undersides. Males can be distinguished by the presence of a swollen cloaca. Larvae and paedomorphic adults are aquatic and have large feathery gills. ''A. talpoideum'' can be distinguished from other salamander larvae by the presence of two light stripes on their underside Distribution and habitat Mole salamanders are fou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterochrony
In evolutionary developmental biology, heterochrony is any genetically controlled difference in the timing, rate, or duration of a developmental process in an organism compared to its ancestors or other organisms. This leads to changes in the size, shape, characteristics and even presence of certain organs and features. It is contrasted with heterotopy, a change in spatial positioning of some process in the embryo, which can also create morphological innovation. Heterochrony can be divided into intraspecific heterochrony, variation within a species, and interspecific heterochrony, phylogenetic variation, i.e. variation of a descendant species with respect to an ancestral species. These changes all affect the start, end, rate or time span of a particular developmental process. The concept of heterochrony was introduced by Ernst Haeckel in 1875 and given its modern sense by Gavin de Beer in 1930. History The concept of heterochrony was introduced by the German zoologist E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of Experimental Zoology
''Journal of Experimental Zoology'' is a peer-reviewed scientific journal of zoology established in 1904. In 2003, the journal was split into the ''Journal of Experimental Zoology Part A: Ecological Genetics and Physiology,'' currently edited by David Crews and Randy Nelson and the ''Journal of Experimental Zoology Part B: Molecular and Developmental Evolution'', currently edited by Ehab Abouheif. Both parts are currently published by Wiley-Blackwell Wiley-Blackwell is an international scientific, technical, medical, and scholarly publishing business of John Wiley & Sons. It was formed by the merger of John Wiley & Sons Global Scientific, Technical, and Medical business with Blackwell Publish .... Originally, part A was called Comparative Experimental Biology until 2007 when it changed to Ecological Genetics and Physiology, but it is now titled Ecological and Integrative Physiology. Part B has kept the name it took during the split, Molecular and Developmental Evolution. Referen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil Record
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the absolu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambridge University Press
Cambridge University Press is the university press of the University of Cambridge. Granted letters patent by Henry VIII of England, King Henry VIII in 1534, it is the oldest university press A university press is an academic publishing house specializing in monographs and scholarly journals. Most are nonprofit organizations and an integral component of a large research university. They publish work that has been reviewed by schola ... in the world. It is also the King's Printer. Cambridge University Press is a department of the University of Cambridge and is both an academic and educational publisher. It became part of Cambridge University Press & Assessment, following a merger with Cambridge Assessment in 2021. With a global sales presence, publishing hubs, and offices in more than 40 Country, countries, it publishes over 50,000 titles by authors from over 100 countries. Its publishing includes more than 380 academic journals, monographs, reference works, school and uni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embryos And Ancestors
Sir Gavin Rylands de Beer (1 November 1899 – 21 June 1972) was a British evolutionary embryologist, known for his work on heterochrony as recorded in his 1930 book ''Embryos and Ancestors''. He was director of the Natural History Museum, London, president of the Linnean Society of London, and a winner of the Royal Society's Darwin Medal for his studies on evolution. Biography Born on 1 November 1899 in Malden, Surrey (now part of London), de Beer spent most of his childhood in France, where he was educated at the Parisian École Pascal. During this time, he also visited Switzerland, a country with which he remained fascinated for the rest of his life. His education continued at Harrow and Magdalen College, Oxford, where he graduated with a degree in zoology in 1921, after a pause to serve in the First World War in the Grenadier Guards and the Army Education Corps. In 1923 he was made a fellow of Merton College, Oxford, and began to teach at the university's zoology departme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene Expression
Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product that enables it to produce end products, protein or non-coding RNA, and ultimately affect a phenotype, as the final effect. These products are often proteins, but in non-protein-coding genes such as transfer RNA (tRNA) and small nuclear RNA (snRNA), the product is a functional non-coding RNA. Gene expression is summarized in the central dogma of molecular biology first formulated by Francis Crick in 1958, further developed in his 1970 article, and expanded by the subsequent discoveries of reverse transcription and RNA replication. The process of gene expression is used by all known life—eukaryotes (including multicellular organisms), prokaryotes (bacteria and archaea), and utilized by viruses—to generate the macromolecular machinery for life. In genetics, gene expression is the most fundamental level at which the genotype gives rise to the phenotype, '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zygote
A zygote (, ) is a eukaryotic cell formed by a fertilization event between two gametes. The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information of a new individual organism. In multicellular organisms, the zygote is the earliest developmental stage. In humans and most other anisogamous organisms, a zygote is formed when an egg cell and sperm cell come together to create a new unique organism. In single-celled organisms, the zygote can divide asexually by mitosis to produce identical offspring. German zoologists Oscar and Richard Hertwig made some of the first discoveries on animal zygote formation in the late 19th century. Humans In human fertilization, a released ovum (a haploid secondary oocyte with replicate chromosome copies) and a haploid sperm cell (male gamete) combine to form a single diploid cell called the zygote. Once the single sperm fuses with the oocyte, the latter completes the division of the second ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Genetics
Molecular genetics is a sub-field of biology that addresses how differences in the structures or expression of DNA molecules manifests as variation among organisms. Molecular genetics often applies an "investigative approach" to determine the structure and/or function of genes in an organism's genome using genetic screens. The field of study is based on the merging of several sub-fields in biology: classical Mendelian inheritance, Cell biology, cellular biology, molecular biology, biochemistry, and biotechnology. Researchers search for mutations in a gene or induce mutations in a gene to link a gene sequence to a specific phenotype. Molecular genetics is a powerful methodology for linking mutations to genetic conditions that may aid the search for treatments/cures for various genetics diseases. History For molecular genetics to develop as a discipline, several scientific discoveries were necessary. The discovery of DNA as a means to transfer the genetic code of life f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neoteny
Neoteny (), also called juvenilization,Montagu, A. (1989). Growing Young. Bergin & Garvey: CT. is the delaying or slowing of the physiological, or somatic, development of an organism, typically an animal. Neoteny is found in modern humans compared to other primates. In progenesis or paedogenesis, sexual development is accelerated. Both neoteny and progenesis result in paedomorphism (as having the form typical of children) or paedomorphosis (changing towards forms typical of children), a type of heterochrony. It is the retention in adults of traits previously seen only in the young. Such retention is important in evolutionary biology, domestication and evolutionary developmental biology. Some authors define paedomorphism as the retention of larval traits, as seen in salamanders.Schell, S. C. ''Handbook of Trematodes of North America North of Mexico'', 1985, pg. 22 History and etymology The origins of the concept of neoteny have been traced to the Bible (as argued by Ashley Monta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
