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Evolutionarily Significant Unit
An evolutionarily significant unit (ESU) is a population of organisms that is considered distinct for purposes of conservation. Delineating ESUs is important when considering conservation action. An ESU is not always equivalent to a biological species but can be also a subspecies, variety, geographic race, or population. In marine animals the term "stock" is often used as well. Definition Definitions of an ESU generally include at least one of the following criteria:Jeffrey Conner, Daniel Hartl. ''A Primer of Ecological Genetics''. 2004, # Current geographic separation, # Genetic differentiation at neutral markers among related ESUs caused by past restriction of gene flow, or # Locally adapted phenotypic traits caused by differences in selection. Criterion 2 considers the gene flow between populations, measured by FST. A high degree of differentiation between two populations among genes that provide no adaptive advantage to either population (known as ''neutral markers'') i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organism
An organism is any life, living thing that functions as an individual. Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have been proposed to define what an organism is. Among the most common is that an organism has autonomous reproduction, Cell growth, growth, and metabolism. This would exclude viruses, despite the fact that they evolution, evolve like organisms. Other problematic cases include colonial organisms; a colony of eusocial insects is organised adaptively, and has Germ-Soma Differentiation, germ-soma specialisation, with some insects reproducing, others not, like cells in an animal's body. The body of a siphonophore, a jelly-like marine animal, is composed of organism-like zooids, but the whole structure looks and functions much like an animal such as a jellyfish, the parts collaborating to provide the functions of the colonial organism. The evolutiona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fixation Index
The fixation index (FST) is a measure of population differentiation due to genetic structure. It is frequently estimated from Polymorphism (biology), genetic polymorphism data, such as single-nucleotide polymorphisms (SNP) or Microsatellite (genetics), microsatellites. Developed as a special case of Sewall WWright's F-statistics, it is one of the most commonly used statistics in population genetics. Its values range from 0 to 1, with 0 being no differentiation and 1 being complete differentiation. Interpretation This comparison of genetic variability within and between populations is frequently used in applied population genetics. The values range from 0 to 1. A zero value implies complete panmixia; that is, that the two populations are interbreeding freely. A value of one implies that all genetic variation is explained by the population structure, and that the two populations do not share any genetic diversity. For idealized models such as Isolation_by_distance#Sewall_Wright-_Ec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. Other ways of defining species include their karyotype, DNA sequence, morphology (biology), morphology, behaviour, or ecological niche. In addition, palaeontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. About 14% of these had been described by 2011. All species (except viruses) are given a binomial nomenclature, two-part name, a "binomen". The first part of a binomen is the name of a genus to which the species belongs. The second part is called the specific name (zoology), specific name or the specific ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Committee On The Status Of Endangered Wildlife In Canada
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC, French: Comité sur la situation des espèces en péril au Canada, COSEPAC) is an independent committee of wildlife experts and scientists whose "raison d'être is to identify species at risk" in Canada. It designates the conservation status of wild species. It was established in 1977 to provide a single, scientifically sound classification of wildlife species at risk of extinction. In the 2002 Species at Risk Act, COSEWIC was appointed as the body to identify and assess a species status. Although the status assigned by COSEWIC is not legally binding, it does report its results to the government and the public. The report is influential toward the addition of species to the List of Wildlife Species at Risk by the Minister of the Environment. Risk categories By December 2013 there were "686 wildlife species in various COSEWIC risk categories, including 196 Special Concern (SC), 166 Threatened (T), 302 Endan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distinct Population Segment
{{no footnotes, date=February 2018 A distinct population segment (DPS) is the smallest division of a taxonomic species permitted to be protected under the U.S. Endangered Species Act. ''Species'', as defined in the Act for listing purposes, is a taxonomic species or subspecies of plant or animal, or in the case of vertebrate species, a distinct population segment. Criteria for designation The criteria for designation of a population or group of populations as a DPS was most recently articulated in a 1996 joint USFWS-NMFS The National Marine Fisheries Service (NMFS), informally known as NOAA Fisheries, is a United States federal agency within the U.S. Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) that is responsible for the ste ... policy (61 FR 4722: February 7, 1996): Three elements are considered in a decision regarding the status of a possible DPS as endangered or threatened under the Act. These are applied similarly for addition to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endangered Species Act
The Endangered Species Act of 1973 (ESA; 16 U.S.C. § 1531 et seq.) is the primary law in the United States for protecting and conserving imperiled species. Designed to protect critically imperiled species from extinction as a "consequence of economic growth and development untempered by adequate concern and conservation", the ESA was signed into law by President Presidency of Richard Nixon#Environmental policy, Richard Nixon on December 28, 1973. The Supreme Court of the United States described it as "the most comprehensive legislation for the preservation of endangered species enacted by any nation"."Tennessee Valley Authority v. Hill" 437 U.S. 153 (1978) Retrieved 24 November 2015. The purposes of the ESA are two-fold: to prevent extinction and to recover species to the point wher ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Host Adaptation
When considering pathogens, host adaptation can have varying descriptions. For example, in the case of ''Salmonella'', host adaptation is used to describe the "ability of a pathogen to circulate and cause disease in a particular host population." Another usage of host adaptation, still considering the case of ''Salmonella'', refers to the evolution of a pathogen such that it can infect, cause disease, and circulate in another host species. Description While there might be pathogens that can infect other hosts and cause disease, the inability to pervade, or spread, throughout the infected host species indicates that the pathogen is not adapted to that host species. In this case, the ability or lack thereof of a pathogen to adapt to its host environment is an indicator of the pathogen's fitness or virulence. If a pathogen has high fitness in the host environment, or is virulent, it will be able to grow and spread quickly within its host. Conversely, if the pathogen is not well adapte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Menyanthes Trifoliata
''Menyanthes'' is a monotypic genus of flowering plants in the family Menyanthaceae containing the single species ''Menyanthes trifoliata''. The North American form is often referred to as ''M. trifoliata'' var. ''minor'' Michx. It is known in English by the common names bogbean, marsh trefoil and buckbean. Description ''Menyanthes trifoliata'' has a horizontal rhizome with alternate, trifoliate leaves. The inflorescence is an erect raceme of white flowers. The buds are rose-pink in color. The flowers when fully open look like "white stars" and the petals are fringed with white whiskers. The species occurs in fens and bogs in Asia, Europe, and North America. In eastern North America, it is considered to be a diagnostic fen species. It sometimes creates big quagmires with its thick roots. Taxonomy The name ''Menyanthes'' comes from Greek ''menyein'' 'disclosing' and ''anthos'' 'flower' in reference to the sequential opening of flowers on the inflorescence. Fossil record ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hemileuca Maia
The buck moth (''Hemileuca maia'') is a common insect found in oak forests, stretching in the United States from peninsular Florida to New England, and as far west as Texas and Kansas. It was first described by Dru Drury in 1773. The larvae typically emerge in a single generation in the spring. The larvae are covered in hollow spines that are attached to a poison sac. The poison can cause symptoms ranging from stinging, itching and burning sensations to nausea. Subspecies ''Hemileuca maia maia'' is listed as endangered in the US state of Connecticut. Subspecies ''Hemileuca maia menyanthevora'', the bog buck moth, is federally endangered, and also protected by Canada and the state of New York. There were five populations known historically but only three still survive, one in the US and two in Canada. The larvae feed on various oaks including scrub oak (''Quercus ilicifolia''), live oak (''Quercus virginiana''), blackjack oak (''Quercus marilandica''), white oak (''Quercus alba''), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endangered Species
An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, invasive species, and climate change. The International Union for Conservation of Nature (IUCN) Red List lists the global conservation status of many species, and various other agencies assess the status of species within particular areas. Many nations have laws that protect conservation-reliant species which, for example, forbid hunting, restrict land development, or create protected areas. Some endangered species are the target of extensive conservation efforts such as captive breeding and habitat restoration. Human activity is a significant cause in causing some species to become endangered. Conservation status The conservation status of a species indicates the likelihood that it will become extinct. Multiple factors are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Drift
Genetic drift, also known as random genetic drift, allelic drift or the Wright effect, is the change in the Allele frequency, frequency of an existing gene variant (allele) in a population due to random chance. Genetic drift may cause gene variants to disappear completely and thereby reduce genetic variation. It can also cause initially rare alleles to become much more frequent and even fixed. When few copies of an allele exist, the effect of genetic drift is more notable, and when many copies exist, the effect is less notable (due to the law of large numbers). In the middle of the 20th century, vigorous debates occurred over the relative importance of natural selection versus neutral processes, including genetic drift. Ronald Fisher, who explained natural selection using Mendelian inheritance, Mendelian genetics, held the view that genetic drift plays at most a minor role in evolution, and this remained the dominant view for several decades. In 1968, population geneticist Mot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Selection
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the Heredity, heritable traits characteristic of a population over generations. Charles Darwin popularised the term "natural selection", contrasting it with selective breeding, artificial selection, which is intentional, whereas natural selection is not. Genetic diversity, Variation of traits, both Genotype, genotypic and phenotypic, exists within all populations of organisms. However, some traits are more likely to facilitate survival and reproductive success. Thus, these traits are passed the next generation. These traits can also become more Allele frequency, common within a population if the environment that favours these traits remains fixed. If new traits become more favoured due to changes in a specific Ecological niche, niche, microevolution occurs. If new traits become more favoured due to changes in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
