Classics: Minimum Viable Population size

21 08 2008

‘Classics’ is a category of posts highlighting research that has made a real difference to biodiversity conservation. All posts in this category will be permanently displayed on the Classics page of

Too-Few-CaloriesShaffer, M.L. (1981). Minimum population sizes for species conservation. BioScience 31, 131–134

Small and isolated populations are particularly vulnerable to extinction through random variation in birth and death rates, variation in resource or habitat availability, predation, competitive interactions and single-event catastrophes, and inbreeding. Enter the concept of the Minimum Viable Population (MVP) size, which was originally defined as the smallest number of individuals required for an isolated population to persist (at some predefined ‘high’ probability) for some ‘long’ time into the future. In other words, the MVP size is the number of individuals in the population that is needed to withstand normal (expected) variation in all the things that affect individual persistence through time. Drop below your MVP size, and suddenly your population’s risk of extinction sky-rockets. In some ways, MVP size can be considered the threshold dividing the ‘small’ and ‘declining’ population paradigms (see Caughley 1994), so that different management strategies can be applied to populations depending on their relative distance to (population-specific) MVP size.

This wonderfully simply, yet fundamental concept of extinction dynamics provides the target for species recovery, minimum reserve size and sustainable harvest if calculated correctly. Indeed, it is a concept underlying threatened species lists worldwide, including the most well-known (IUCN Red List of Threatened Species). While there are a host of methods issues, genetic considerations and policy implementation problems, Shaffer’s original paper spawned an entire generation of research and mathematical techniques in conservation biology, and set the stage for tangible, mathematically based conservation targets.

Want more information? We have published some papers and articles on the subject that elaborate more on the methods, expected ranges, subtleties and implications of the MVP concept that you can access below.

CJA Bradshaw

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14 responses

27 09 2017
Four decades of fragmentation |

[…] events or other stochastic phenomena, thus increasing the probability of populations dipping below minimum viable sizes and becoming locally […]


18 09 2017
Basic Concepts: Biology – Evolving Thoughts

[…] Minimum Viable Population size by CJA Bradshaw at ConservationBytes.Com […]


26 06 2015
Classics: Fishing down the web |

[…] that highly reduced populations are now much more extinction-prone if they fall below their minimum viable population size. The corollary is that marine species we wouldn’t consider palatable for a dog 50 years ago […]


28 01 2014
We’re sorry, but 50/500 is still too few |

[…] are familiar with my colleagues’ and my work will know that we have been investigating the minimum viable population size concept for years (see references at the end of this post). Little did I know when I started this […]


27 09 2013
Too small to avoid catastrophic biodiversity meltdown |

[…] abundance and patch size. We’ve certainly written about the former on many occasions (see here, here, here and here for our work on minimum viable population size), with the associated […]


25 06 2012
Dimensions of Sustainability « Bottom Up Thinking

[…] the area of habitat shrinking below a given carrying capacity or a population declining below the Minimum Viable Population. Thus a red line is drawn. Everything else must fit around that line, and the further away from the […]


18 10 2011
Not magic, but necessary «

[…] vocal adversary of some of the applications of population viability analysis and its child, MVP size, for many years. While there was some interesting points raised in their review, their arguments […]


27 04 2011

Thanks for writing about this (albeit it took me almost 3 years to find it). We are trying to determine the population size of a CR freshwater turtle in Malaysia, and I would appreciate it if you would share with us any papers that you might have published between 2007 and now :D


27 04 2011

Check out the publications page – PDFs are available to download.


27 04 2011

Aww.. Thank you so much! :D


16 03 2011
Classics: demography versus genetics «

[…] may usually be of more immediate importance than population genetics in determining the minimum viable size of wild […]


27 03 2009
Classics: Ecological Triage «

[…] have unique ecosystem roles or that face almost certain extinction given they fall well below their minimum viable population size (Walker 1992). Financial resources such as investment in recovery programmes, purchase of remaining […]


5 02 2009
Cloning for conservation - stupid and wasteful «

[…] on how serious Allee effects are in determining extinction risk. Populations need to number in the 1000s of genetically distinct individuals to have any chance of persisting. To postulate, even for a moment, that cloning can artificially recreate genetic diversity […]


22 08 2008
Science Blogs » Blog Archive » Basic Concepts in Science: A list [Evolving Thoughts]

[…] to this post for updates, use the RSS feed in the address bar of this post. Recent additions: Minimum Viable Population size by CJA Bradshaw at ConservationBytes.Com in Biology Anyone can add to this series, even if you […]


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