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Taxonomy (biology)
In biology, taxonomy (from Ancient Greek τάξις (taxis), meaning 'arrangement', and -νομία (-nomia), meaning 'method') is the science of defining and naming groups of biological organisms on the basis of shared characteristics. Organisms are grouped together into taxa (singular: taxon) and these groups are given a taxonomic rank; groups of a given rank can be aggregated to form a super-group of higher rank, thus creating a taxonomic hierarchy. The principal ranks in modern use are domain, kingdom, phylum (division is sometimes used in botany in place of phylum), class, order, family, genus, and species
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Human Evolution
Human
Human
evolution is the evolutionary process that led to the emergence of anatomically modern humans, beginning with the evolutionary history of primates—in particular genus Homo—and leading to the emergence of Homo sapiens
Homo sapiens
as a distinct species of the hominid family, the great apes
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Gene Flow
In population genetics, gene flow (also known as gene migration or allele flow) is the transfer of genetic variation from one population to another. If the rate of gene flow is high enough, then two populations are considered to have equivalent allele frequencies and therefore effectively be a single population. It has been shown that it takes only "One migrant per generation" to prevent populations from diverging due to drift.[1] Gene
Gene
flow is an important mechanism for transferring genetic diversity among populations. Migrants change the distribution of genetic diversity within the populations, by modifying the allele frequencies (the proportion of members carrying a particular variant of a gene). High rates of gene flow can reduce the genetic differentiation between the two groups, increasing homogeneity
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Scientific Classification (other)
Scientific classification may refer to:Chemical classification Mathematical classification, construction of subsets into a set Statistical classification, the mathematical problem of assigning a label to an object based on a set of its attributes or features Taxonomy, the practice and science of categorization .mw-parser-output .tocright float:right;clear:right;width:auto;background:none;padding:.5em 0 .8em 1.4em;margin-bottom:.5em .mw-parser-output .tocright-clear-left clear:left .mw-parser-output .tocright-clear-both clear:both .mw-parser-output .tocright-clear-none clear:none Contents1 Biology 2 Astronomy 3 See alsoBiology[edit] Alpha taxonomy, the science of finding, describing and naming organisms Biological classification Cladistics, a newer way of classifying organisms, based solely on phylogeny Linnaean taxonomy, the classic scientific classification system Virus classification, naming and sorting viruses Astronomy[edit] Galaxy morphological classification
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Parallel Evolution
Parallel evolution is the similar development of a trait in distinct species that are not closely related, but share a similar original trait in response to similar evolutionary pressure.[1][2]Contents1 Parallel vs. convergent evolution1.1 Examples1.1.1 Parallel evolution between marsupials and placentals2 ReferencesParallel vs. convergent evolution[edit] Evolution at an amino acid position. In each case, the left-hand species changes from incorporating alanine (A) at a specific position within a protein in a hypothetical common ancestor deduced from comparison of sequences of several species, and now incorporates serine (S) in its present-day form
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Genetic Divergence
Genetic divergence is the process in which two or more populations of an ancestral species accumulate independent genetic changes (mutations) through time, often after the populations have become reproductively isolated for some period of time. In some cases, subpopulations living in ecologically distinct peripheral environments can exhibit genetic divergence from the remainder of a population, especially where the range of a population is very large (see parapatric speciation). The genetic differences among divergent populations can involve silent mutations (that have no effect on the phenotype) or give rise to significant morphological and/or physiological changes
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Divergent Evolution
Divergent evolution
Divergent evolution
or divergent selection is the accumulation of differences between closely related populations within a species, leading to speciation. Divergent evolution
Divergent evolution
is typically exhibited when two populations become separated by a geographic barrier (such as in allopatric or peripatric speciation) and experience different selective pressures that drive adaptations to their new environment. After many generations and continual evolution, the populations become unable to interbreed with one another.[1] The American naturalist J. T. Gulick
J. T. Gulick
(1832-1923) was the first to use the term "divergent evolution",[2] with its use becoming widespread in modern evolutionary literature
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Timeline Of Paleontology
Timeline of paleontology6th century B.C. — The pre-Socratic Greek philosopher Xenophanes
Xenophanes
of Colophon argues that fossils of marine organisms show that dry land was once under water.[1] 1027 — The Persian naturalist, Avicenna, explains the stoniness of fossils in The Book of Healing
The Book of Healing
by proposing the theory of petrifying fluids (succus lapidificatus).[2] 1031-1095 — The Chinese naturalist, Shen Kuo, uses evidence of marine fossils found in the Taihang Mountains
Taihang Mountains
to infer geological processes caused shifting of seashores over time,[3] and uses petrified bamboos found underground in Yan'an, to argue for gradual climate change.[4] 1320-1390 — Avicenna's theory of petrifying fluids (succus lapidificatus) was elaborated on by Albert of Saxony.[2] c
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History Of Paleontology
The history of paleontology traces the history of the effort to understand the history of life on Earth by studying the fossil record left behind by living organisms. Since it is concerned with understanding living organisms of the past, paleontology can be considered to be a field of biology, but its historical development has been closely tied to geology and the effort to understand the history of Earth itself. In ancient times, Xenophanes
Xenophanes
(570–480 BC), Herodotus
Herodotus
(484–425 BC), Eratosthenes
Eratosthenes
(276–194 BC), and Strabo
Strabo
(64 BC-24 AD) wrote about fossils of marine organisms, indicating that land was once under water
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Evolutionary Developmental Biology
Evolutionary developmental biology
Evolutionary developmental biology
(informally, evo-devo) is a field of biological research that compares the developmental processes of different organisms to infer the ancestral relationships between them and how developmental processes evolved. The field grew from 19th-century beginnings, where embryology faced a mystery: zoologists did not know how embryonic development was controlled at the molecular level. Charles Darwin
Charles Darwin
noted that having similar embryos implied common ancestry, but little progress was made until the 1970s. Then, recombinant DNA technology at last brought embryology together with molecular genetics. A key early discovery was of homeotic genes that regulate development in a wide range of eukaryotes. The field is characterised by some key concepts, which took evolutionary biologists by surprise
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Timeline Of Evolutionary History Of Life
This timeline of the evolutionary history of life represents the current scientific theory outlining the major events during the development of life on planet Earth. In biology, evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organization, from kingdoms to species, and individual organisms and molecules, such as DNA
DNA
and proteins. The similarities between all present day organisms indicate the presence of a common ancestor from which all known species, living and extinct, have diverged through the process of evolution
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Charles Darwin
Professional institution:Geological Society of London Academic advisors John Stevens Henslow Adam Sedgwick Influences Charles Lyell Alexander von Humboldt John Herschel Thomas Malthus InfluencedHooker, Huxley, Romanes, Haeckel, Lubbock Signature Charles Robert Darwin, FRS FRGS FLS FZS[2] (/ˈdɑːrwɪn/;[5] 12 February 1809 – 19 April 1882) was an English naturalist, geologist and biologist,[6] best known for his contributions to the science of evolution.[I] His proposition that all species of life have descended over time from common ancestors is now widely accepted, and considered a foundational concept in science.[7] In a joint publication with Alfred Russel Wallace, he introduced his scientific theory that this branching pattern of evolution resulted from a process that he called natural selection, in which the struggle for existence has a similar effect to the artificial selection involved in selective breeding.[8]
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Extinction Event
An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. It occurs when the rate of extinction increases with respect to the rate of speciation. Estimates of the number of major mass extinctions in the last 540 million years range from as few as five to more than twenty. These differences stem from the threshold chosen for describing an extinction event as "major", and the data chosen to measure past diversity. Because most diversity and biomass on Earth
Earth
is microbial, and thus difficult to measure, recorded extinction events affect the easily observed, biologically complex component of the biosphere rather than the total diversity and abundance of life.[1] Extinction occurs at an uneven rate
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Biodiversity
Biodiversity
Biodiversity
is the variety and variability of life on Earth. Biodiversity
Biodiversity
is typically a measure of variation at the genetic, species, and ecosystem level.[1] Terrestrial biodiversity is usually greater near the equator,[2] which is the result of the warm climate and high primary productivity.[3] Biodiversity
Biodiversity
is not distributed evenly on Earth, and is richest in the tropics. These tropical forest ecosystems cover less than 10 percent of earth's surface, and contain about 90 percent of the world's species.[4] Marine biodiversity is usually highest along coasts in the Western Pacific, where sea surface temperature is highest, and in the mid-latitudinal band in all oceans
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Evolutionary Taxonomy
Evolutionary
Evolutionary
taxonomy, evolutionary systematics or Darwinian classification is a branch of biological classification that seeks to classify organisms using a combination of phylogenetic relationship (shared descent), progenitor-descendant relationship (serial descent), and degree of evolutionary change. This type of taxonomy may consider whole taxa rather than single species, so that groups of species can be inferred as giving rise to new groups.[1] The concept found its most well-known form in the modern evolutionary synthesis of the early 1940s. Evolutionary
Evolutionary
taxonomy differs from strict pre-Darwinian Linnaean taxonomy (producing orderly lists only), in that it builds evolutionary trees. While in phylogenetic nomenclature each taxon must consist of a single ancestral node and all its descendants, evolutionary taxonomy allows for groups to be excluded from their parent taxa (e.g
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Transitional Fossil
A transitional fossil is any fossilized remains of a life form that exhibits traits common to both an ancestral group and its derived descendant group.[1] This is especially important where the descendant group is sharply differentiated by gross anatomy and mode of living from the ancestral group. These fossils serve as a reminder that taxonomic divisions are human constructs that have been imposed in hindsight on a continuum of variation. Because of the incompleteness of the fossil record, there is usually no way to know exactly how close a transitional fossil is to the point of divergence. Therefore, it cannot be assumed that transitional fossils are direct ancestors of more recent groups, though they are frequently used as models for such ancestors.[2] In 1859, when Charles Darwin's On the Origin of Species
On the Origin of Species
was first published, the fossil record was poorly known
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