{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.tr.effective-population-size","code":"thing-q1295959","url":"https://ver.cy/models/thing/q1295959/","name":"effective population size","alternateNames":[],"kind":"thing","status":"published","version":"0.2.0-wave.3","language":"en","classifiers":{"family":"Thing Registry","category":"Cross-cutting context","entryKind":"thing","plane":"XCT","domain":["XCT.QTY"],"industry":[],"navPath":"","tags":[],"facets":{}},"whatItIs":"In population genetics, the size of an idealised population that would lose genetic diversity through drift at the same rate as the real population; usually much smaller than the census size because of unequal sex ratios, variation in family size and fluctuations over time, and used in conservation to judge the genetic risk to small populations.","purpose":"Let an agent define effective population size, explain why it differs from census size and how it is estimated, relay conservation rules of thumb with attribution, and separate it from census counts and from minimum viable population.","scope":{"in":[],"out":[],"boundaries":[]},"distinguishingFeatures":["Genetic rather than demographic measure","Depends on sex ratio, family size variance and fluctuation","Variance and inbreeding effective sizes as variants","Estimated from pedigrees or genetic markers"],"structure":{"bundles":[{"id":"concept","name":"Concept","description":"What effective size is.","layers":[{"id":"definition","name":"Definition","description":"Definition.","findings":[{"id":"definition-finding","name":"Definition","description":"Definition.","questions":[{"text":"What is effective population size, and why does it differ from census size?","kind":"definition"},{"text":"Is the question about effective size, census size or minimum viable population?","kind":"boundary"}]}]},{"id":"variants","name":"Variants","description":"Variants.","findings":[{"id":"variants-finding","name":"Variants","description":"Variants.","questions":[{"text":"How do variance, inbreeding and other effective sizes differ?","kind":"definition"},{"text":"Which entry fits genetic drift?","kind":"action"}]}]}]},{"id":"estimate","name":"Estimate","description":"Estimation.","layers":[{"id":"demographic","name":"Demographic","description":"Demographic methods.","findings":[{"id":"demographic-finding","name":"Demographic","description":"Demographic.","questions":[{"text":"How is effective size estimated from sex ratio, family size and fluctuations?","kind":"measurement"},{"text":"Which formulas apply?","kind":"provenance"}]}]},{"id":"genetic","name":"Genetic","description":"Genetic methods.","findings":[{"id":"genetic-finding","name":"Genetic","description":"Genetic.","questions":[{"text":"How is it estimated from genetic markers, and with what uncertainty?","kind":"measurement"},{"text":"Which software and references are standard?","kind":"provenance"}]}]}]},{"id":"apply","name":"Apply","description":"Conservation use.","layers":[{"id":"thresholds","name":"Thresholds","description":"Rules of thumb.","findings":[{"id":"thresholds-finding","name":"Thresholds","description":"Thresholds.","questions":[{"text":"What thresholds such as the 50/500 rule are used, and how are they debated, with attribution?","kind":"provenance"},{"text":"Is the presentation neutral on the debate?","kind":"boundary"}]}]},{"id":"management","name":"Management","description":"Management.","findings":[{"id":"management-finding","name":"Management","description":"Management.","questions":[{"text":"How do managers raise effective size in captive and wild populations?","kind":"provenance"},{"text":"Which entry fits conservation genetics?","kind":"action"}]}]}]},{"id":"learn","name":"Learn","description":"History and teaching.","layers":[{"id":"history","name":"History","description":"History.","findings":[{"id":"history-finding","name":"History","description":"History.","questions":[{"text":"How did Wright and later geneticists develop the concept?","kind":"provenance"},{"text":"Which entry fits population genetics?","kind":"action"}]}]},{"id":"teach","name":"Teach","description":"Teaching.","findings":[{"id":"teach-finding","name":"Teach","description":"Teaching.","questions":[{"text":"How is effective size taught, and which misconceptions arise?","kind":"provenance"},{"text":"Which references are standard?","kind":"provenance"}]}]}]}]},"agentConduct":{"may":["Explain how effective population size differs from census size.","Report published estimates with their method, sample and uncertainty."],"mustNot":["Use census counts in place of effective size when judging genetic risk.","Present thresholds such as the 50 and 500 rules of thumb as fixed laws.","Report estimates from small or unrepresentative samples without saying so.","Misstate a species' genetic status to support or oppose a conservation decision."],"requiresHuman":["Using an estimate to decide on listing, culling or translocating a population."]},"ethics":{"considerations":["Conservation decisions on whole species can rest on this number.","Small effective size means lost diversity that cannot be recovered."],"affectedParties":["Threatened species and populations","Conservation managers","Breeders of domestic animals"]},"owners":{"steward":"Nobody owns the concept; researchers answer for each published estimate.","roles":[],"masterSystems":[]},"relations":[{"target":"Q1613416","type":"parent","note":"registry parent class"},{"target":"population size","type":"related","note":"a genetic measure of size"},{"target":"genetic drift","type":"related","note":"the rate of drift"},{"target":"conservation genetics","type":"related","note":"risk assessment"},{"target":"census population size","type":"related","note":"the head count"}],"interaction":{"identity":{"applicability":"required","items":["Vercy registry: vr.tr.effective-population-size","Wikidata: Q1295959 (https://www.wikidata.org/wiki/Q1295959)"]},"properties":{"applicability":"not-applicable","items":["typical ratio to census size: about 0.1-0.5 ratio - varies widely by species","conservation rule of thumb: 50 and 500 individuals - the 50/500 rule, debated"]},"recognition":{"applicability":"optional","items":["Idealised size matching the drift rate","Smaller than the census population in almost all cases","Census size counts individuals; minimum viable population is a different threshold","Not visible; a number derived from demographic or genetic data."]},"capabilities":{"applicability":"required","items":["explain the concept and its variants","explain why it is smaller than census size","relay estimation methods","relay conservation thresholds with attribution"]},"hazards":{"applicability":"required","items":["Using census size in place of effective size","Applying rules of thumb as fixed laws","Poor estimates from small samples"]},"interfaces":{"applicability":"required","items":["IUCN Red List criteria that use population size","Conservation genetics guidelines"]},"context":{"applicability":"required","items":["Judging the rate of genetic drift and inbreeding in a population.","variance effective size","inbreeding effective size","eigenvalue effective size","contemporary and historical estimates","effective size in conservation assessments"]}},"sources":[{"title":"Wikidata item Q1295959: effective population size","url":"https://www.wikidata.org/wiki/Q1295959","note":"identity and sense of the item"},{"title":"Wikipedia: Effective population size","url":"https://en.wikipedia.org/wiki/Effective_population_size","note":"general description of the item"}],"openQuestions":["Should the variants be separate entries?","How should estimation software be linked?","How should the 50/500 debate be recorded?"],"resources":{"spec":"/models/things/publications/thing-q1295959/spec.json"},"provenance":{"origin":"thing registry research (pass 2)","builtFrom":["models/things/publications/thing-q1295959/spec.json"],"providers":["Claude"],"researchStatus":"unreviewed","generatedAt":"2026-09-12T20:28:17Z","builder":"tools/build_cards.py@1.0.0"},"completeness":{"sections":{"classifiers":"filled","whatItIs":"filled","purpose":"filled","distinguishingFeatures":"filled","structure":"filled","agentConduct":"filled","ethics":"filled","owners":"filled","relations":"filled","interaction.identity":"filled","interaction.properties":"not-applicable","interaction.recognition":"filled","interaction.capabilities":"filled","interaction.hazards":"filled","interaction.interfaces":"filled","interaction.context":"filled","sources":"filled"},"notes":{"_gate":"Published through the thing publication gate 1.0 on 2026-10-06T19:51:54+00:00: completeness 1.00; sense: Wikidata description; 2 live sources; review by codex: pass","interaction.properties":"Plane XCT: no invented physical properties."},"score":1.0}}