Editing Minimum viable population (section)

==Estimation==
There is no unique definition of what constitutes a sufficient population for the continuation of a species, because whether a species survives will depend to some extent on random events. Thus, any calculation of a minimum viable population (MVP) will depend on the population projection model used.<ref name=Shaffer>{{Cite journal|last=Shaffer|first=Mark L.|date=Feb 1981|title=Minimum Population Sizes for Species Conservation|journal=BioScience|language=en|volume=31|issue=2|pages=131–134|doi=10.2307/1308256|issn=0006-3568|jstor=1308256|doi-access=}}</ref> A set of random (stochastic) projections might be used to estimate the initial population size needed (based on the assumptions in the model) for there to be, (for example) a 95% or 99% probability of survival 1,000 years into the future.<ref name=":0">{{Cite journal|last=Frankham|first=Richard|last2=Bradshaw|first2=Corey J. A.|last3=Brook|first3=Barry W.|date=2014-02-01|title=Genetics in conservation management: Revised recommendations for the 50/500 rules, Red List criteria and population viability analyses|journal=Biological Conservation|volume=170|pages=56–63|doi=10.1016/j.biocon.2013.12.036|issn=0006-3207}}</ref> Some models use generations as a unit of time rather than years in order to maintain consistency between [[taxon|taxa]].<ref>{{Cite journal|last=O’Grady|first=Julian J.|last2=Brook|first2=Barry W.|last3=Reed|first3=David H.|last4=Ballou|first4=Jonathan D.|last5=Tonkyn|first5=David W.|last6=Frankham|first6=Richard|date=2006-11-01|title=Realistic levels of inbreeding depression strongly affect extinction risk in wild populations|journal=Biological Conservation|volume=133|issue=1|pages=42–51|doi=10.1016/j.biocon.2006.05.016|issn=0006-3207}}</ref> These projections ([[population viability analysis|population viability analyses]], or PVA) use [[computer simulation]]s to model populations using demographic and environmental information to project future [[population dynamics]]. The probability assigned to a PVA is arrived at after [[Monte Carlo method|repeating the environmental simulation thousands of times]].