‘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 ConservationBytes.com
–
- © CEES, Oslo
Shaffer, 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.
- Traill, LW, CJA Bradshaw, BW Brook. 2007. Minimum viable population size. In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment)
- Traill, LW, CJA Bradshaw, BW Brook. 2007. Minimum viable population size: a meta-analysis of 30 years of published estimates. Biological Conservation 139: 159-166
- Brook, BW, LW Traill, CJA Bradshaw. 2006. Minimum viable population size and global extinction risk are unrelated. Ecology Letters 9: 375-382
[...] 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 [...]
[...] 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 [...]
[...] 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 [...]
[...] may usually be of more immediate importance than population genetics in determining the minimum viable size of wild [...]
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
Check out the publications page – PDFs are available to download.
Aww.. Thank you so much! :D
[...] 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 [...]
[...] 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 [...]