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Evolutionary 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. This term can apply to any species, subspecies, geographic race, or population. Often the term "species" is used rather than ESU, even when an ESU is more technically considered a subspecies or variety rather than a biological species proper. 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 t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organism
In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and fungi; or unicellular microorganisms such as protists, bacteria, and archaea. All types of organisms are capable of reproduction, growth and development, maintenance, and some degree of response to stimuli. Beetles, squids, tetrapods, mushrooms, and vascular plants are examples of multicellular organisms that differentiate specialized tissues and organs during development. A unicellular organism may be either a prokaryote or a eukaryote. Prokaryotes are represented by two separate domains – bacteria and archaea. Eukaryotic organisms are characterized by the presence of a membrane-bound cell nucleus and contain additional membrane-bound compartments called organelles (such as mitochondria in animals and plants ... [...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 genetic polymorphism data, such as single-nucleotide polymorphisms (SNP) or microsatellites. Developed as a special case of Wright's F-statistics, it is one of the most commonly used statistics in population genetics. Definition Two of the most commonly used definitions for FST at a given locus are based on 1) the variance of allele frequencies between populations, and on 2) the probability of Identity by descent. If \bar is the average frequency of an allele in the total population, \sigma^2_S is the variance in the frequency of the allele between different subpopulations, weighted by the sizes of the subpopulations, and \sigma^2_T is the variance of the allelic state in the total population, FST is defined as : F_ = \frac = \frac Wright's definition illustrates that FST measures the amount of genetic variance that can be explained by population stru ... [...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 Endang ... [...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 l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endangered Species Act
The Endangered Species Act of 1973 (ESA or "The Act"; 16 U.S.C. § 1531 et seq.) is the primary law in the United States for protecting 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 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 where the law's protections are not needed. It therefo ... [...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 adapted ... [...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 and buckbean. Description ''Menyanthes trifoliata'' has a horizontal rhizome with alternate, trifoliate leaves. The inflorescence is an erect raceme of white flowers. 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 the Greek words ''menyein'', meaning "disclosing", and ''anthos'', meaning "flower", in reference to the sequential opening of flowers on the inflorescence. Fossil record One fossil seed of ''Menyanthes trifoliata'' has been extracted from borehole samples of the Middle Miocene fresh wate ... [...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. The larvae feed on various oaks including scrub oak (''Quercus ilicifolia''), live oak (''Quercus virginiana''), blackjack oak (''Quercus marilandica''), white oak (''Quercus alba''), and dwarf chinquapin oak (''Quercus prinoides''). Eggs are typically laid in spiral clusters on oak twigs. Mature larvae enter the soil or leaf litter to pupate in late July and emerge between October and the following February as moths to mate and lay e ... [...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 and invasive species. 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 considered when assessing the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Drift
Genetic drift, also known as allelic drift or the Wright effect, is the change in the 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. 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 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 Motoo Kimura rekindled the debate with his neutral theory of molecular evolution, which claims that ... [...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 heritable traits characteristic of a population over generations. Charles Darwin popularised the term "natural selection", contrasting it with selective breeding, artificial selection, which in his view is intentional, whereas natural selection is not. Genetic diversity, Variation exists within all populations of organisms. This occurs partly because random mutations arise in the genome of an individual organism, and their offspring can inherit such mutations. Throughout the lives of the individuals, their genomes interact with their environments to cause variations in traits. The environment of a genome includes the molecular biology in the Cell (biology), cell, other cells, other individuals, populations, species, as well as the abiotic environment. Because individuals with certain variants of the trait tend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conservation Ethic
Nature conservation is the moral philosophy and conservation movement focused on protecting species from extinction, maintaining and restoring habitats, enhancing ecosystem services, and protecting biological diversity. A range of values underlie conservation, which can be guided by biocentrism, anthropocentrism, ecocentrism, and sentientism, environmental ideologies that inform ecocultural practices and identities. There has recently been a movement towards evidence-based conservation which calls for greater use of scientific evidence to improve the effectiveness of conservation efforts. As of 2018 15% of land and 7.3% of the oceans were protected. Many environmentalists set a target of protecting 30% of land and marine territory by 2030. In 2021, 16.64% of land and 7.9% of the oceans were protected. The 2022 IPCC report on climate impacts and adaptation, underlines the need to conserve 30% to 50% of the Earth's land, freshwater and ocean areas – echoing the 30% goal of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
