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Biology LibreTexts

Glossary

  • Page ID
    39881
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    (Eg. "Genetic, Hereditary, DNA ...") (Eg. "Relating to genes or heredity") The infamous double helix bio.libretexts.org/ CC-BY-SA; Delmar Larsen
    Glossary Entries

    Word(s)

    Definition

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    allopatric speciation speciation achieved between populations that are completely geographically separated (their ranges do not overlap or are not contiguous).        
    alpha diversity the diversity within a particular area or ecosystem; usually expressed by the number of species (i.e., species richness) in that ecosystem        
    area of endemism an areas which has a high proportion of endemic species (i.e., species with distributions that are naturally restricted to that region)        
    bequest value the value of knowing something will be there for future generations        
    beta diversity a comparison of of diversity between ecosystems, usually measured as the amount of species change between the ecosystems        
    biodiversity the variety of life on Earth at all its levels, from genes to ecosystems, and the ecological and evolutionary processes that sustain it        
    biodiversity coldspots areas that have relatively low biological diversity but are also experiencing a high rate of habitat loss        
    biodiversity hotspots in general terms these are areas that have high levels of endemism (and hence diversity) but which are also experiencing a high rate of loss of habitat. This concept was originally developed for terrestrial ecosystems. A terrestrial biodiversity hotspot is an area that has at least 0.5%, or 1,500 of the worlds ca. 300,000 species of green plants (Viridiplantae), and that has lost at least 70% of its primary vegetation (Myers et al., 2000). Marine biodiversity hotspots have been defined for coral reefs, based on measurements of relative endemism of multiple taxa (species of corals, snails, lobsters, fishes) within a region and the relative level of threat to that region (Roberts et al., 2002)        
    biogeography the study of the distribution of organisms in space and through time        
    Biological species concept a species is a group of interbreeding natural populations unable to successfully mate or reproduce with other such groups, and which occupies a specific niche in nature (Mayr, 1982; Bisby and Coddington, 1995).        
    Community the populations of different species that naturally occur and interact in a particular environment.        
    Demography the statistical characteristics of the population such as size, density, birth and death rates, distribution, and movement or migration.        
    direct use value refers to products or goods which are consumed directly such as food or timber        
    dominant species species that are important due to their sheer numbers in an ecosystem        
    Ecological biogeography the study of the dispersal of organisms (usually individuals or populations) and the mechanisms that influence this dispersal, and the use of this information to explain spatial distribution patterns        
    ecological value the values that each species has as part of an ecosystem
     
           
    Ecoregion, Ecoregions a relatively large unit of land or water containing a geographically distinct assemblage of species, natural communities, and environmental conditions. The ecosystems within an ecoregion have certain distinct characters in common (Bailey, 1998a).        
    ecosystem a community plus the physical environment that it occupies at a given time.        
    Ecosystem a community plus the physical environment that it occupies at a given time.        
    Endemic species those species whose distributions are naturally restricted to a defined region        
    Evolutionary significant unit a group of organisms that has undergone significant genetic divergence from other groups of the same species. Identification of ESUs is based on natural history information, range and distribution data, and results from analyses of morphometrics, cytogenetics, allozymes and nuclear and mitochondrial DNA. Concordance of those data, and the indication of significant genetic distance between sympatric groups of organisms, are critical for establishing an ESU.        
    existence value the value of knowing something exists even if you will never use it or see it        
    Extinct a species is assumed to be extinct when there is no reasonable doubt that the last individual has died (IUCN, 2002)        
    Extinction the complete disappearance of a species from Earth        
    Gamma diversity a measure of the overall diversity within a large region. Geographic-scale species diversity according to Hunter (2002: 448)        
    Genetic Diversity refers to any variation in the nucleotides, genes, chromosomes, or whole genomes of organisms.        
    Historical biogeography the study of events in the geological history of the Earth and their use to explain patterns in the spatial and temporal distributions of organisms (usually species or higher taxonomic ranks)        
    indirect use value refers to the services that support the products that are consumed, this includes ecosystems functions like nutrient cycling        
    keystone species species that have important ecological roles that are greater than one would expect based on their abundance        
    Landscapes a mosaic of heterogeneous land forms, vegetation types, and land uses         
    Mass extinction
     
    a period when there is a sudden increase in the rate of extinction, such that the rate at least doubles, and the extinctions include representatives from many different taxonomic groups of plants and animals        
    Metapopulation a group of different but interlinked populations, with each different population located in its own, discrete patch of habitat        
    Morphological species concept species are the smallest natural populations permanently separated from each other by a distinct discontinuity in the series of biotype (Du Rietz, 1930; Bisby and Coddington, 1995).        
    non use or passive value refers to the value for things that we don't use but would feel a loss if they were to disappear        
    Orobiome a mountainous environment or landscape with its constituent ecosystems        
    Orogenesis the process of mountain building.
     
           
    Parapatric occupying contiguous but not overlapping ranges.        
    Photosynthesis the formation of carbohydrates from carbon dioxide and water, through the action of light energy on a light-sensitive pigment, such as chlorophyll, and usually resulting in the production of oxygen        
    Phylogenetic diversity the evolutionary relatedness of the species present in an area.        
    Phylogenetic species concept a species is the smallest group of organisms that is diagnosably [that is, identifiably] distinct from other such clusters and within which there is a parental pattern of ancestry and descent (Cracraft, 1983; Bisby and Coddington, 1995).        
    Plate Tectonics the forces acting on the large, mobile pieces (or "plates") of the Earth's lithosphere (the upper part of the mantle and crust of the Earth where the rocks are rigid compared to those deeper below the Earth's surface) and the movement of those "plates".        
    Population a group of individuals of the same species that share aspects of their demography or genetics more closely with each other than with other groups of individuals of that species
    A population may also be defined as a group of individuals of the same species occupying a defined area at the same time (Hunter, 2002: 144)
           
    potential or option value refers to the use that something may have in the future        
    Sink a population patch, in a metpopulation that does not have a high degree of emigration outside its boundaries but, instead, requires net immigration in order to sustain itself        
    Source a population patch, in a metapopulation, from which individuals disperse to other population patches or create new ones        
    Species diversity the number of different species in a particular area (i.e., species richness) weighted by some measure of abundance such as number of individuals or biomass        
    Species evenness the relative abundance with which each species are represented in an area.        
    Species richness the number of different species in a particular area        
    Sympatric occupying the same geographic area.        
    Terrestrial Biodiversity hotspots          
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