page_title: Dark diversity
section_title: Overview
hierarchical_section_title: Dark diversity / Overview
caption_attribution_description: English: Common cowslip (Primula veris) is frequent plant species in temperate European grasslands.
context_page_description: Dark diversity is the set of species that are absent from a study site but present in the surrounding region and potentially able to inhabit particular ecological conditions.
context_section_description: Dark diversity is part of the species pool concept. A species pool is defined as set of all species that are able to inhabit particular site and that are present in the surrounding region or landscape. Dark diversity comprises species that belong to a particular species pool but that are not currently present at a site. Dark diversity is related to "habitat-specific" or "filtered" species pool which only includes species that can both disperse to and potentially inhabit the study site. For example, if fish diversity in a coral reef site has been sampled, dark diversity includes all fish species from the surrounding region that are currently absent but can potentially disperse to and colonize the study site.  Because all sampling will also miss some species actually present at a site, we also have the related idea of 'phantom species' -- those species present at a site but not detected within the sampling units used to sample the community at that site.Beck, J.B.; Larget, B.; Waller, D.M. (2018). "Phantom species: Adjusting estimates of colonization and extinction for pseudo-turnover". Oikos. 127 (11): 1605–1618. doi:10.1111/oik.05114.</ref> The existence of these phantom species means that routine measures of colonization and extinction at a site will always overestimate true rates because of "pseudo-turnover."
  Dark diversity name is borrowed from dark matter:  matter which cannot be seen and directly measured, but its existence and properties are inferred from its gravitational effects on visible matter. Similarly, dark diversity cannot be seen directly when only the sample is observed, but it is present if broader scale is considered, and its existence and properties can be estimated when proper data is available. With dark matter we can better understand distribution and dynamics of galaxies, with dark diversity we can understand composition and dynamics of ecological communities.
caption: Common cowslip (Primula veris) is a frequent plant species in European grasslands. If the environmental conditions are suitable, but the cowslip is missing from studied grassland patch, it belongs to the dark diversity for given grassland.
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