Navigation Links
Metapopulation


A metapopulation consists of a group of spatially separated populations of the same species which interact at some level. The term metapopulation was coined by Richard Levins in 1969 to describe a model of population dynamics of insect pests in agricultural fields, but the idea has been most broadly applied to species in naturally or artificially fragmented habitats.

A metapopulation is generally considered to consist to several distinct populations together with areas of suitable habitat which are currently unoccupied. Each population cycles in relative independence of the other populations and eventually goes extinct as a consequence of demographic stochasticity (fluctuations in population size due to random demographic events); the smaller the population, the more prone it is to extinction.

Although individual populations have finite life-spans, the population as a whole is often stable because immigrants from one population (which may, for example, be experiencing a population boom) are likely to re-colonize habitat which has been left open by the extinction of another population. They may also immigrate into another small population and so rescue it from extinction (called the rescue effect).

The development of metapopulation theory, in conjunction with the development of source-sink dynamics emphasis the importance of connectivity between seemingly isolated populations. Although no one population may be able to guarantee the long-term survival of a given species, the combined effect of many populations may be able to do this.

The most important contributer to metapopulation theory is the Finnish biologist Ilkka Hanski of the University of Helsinki.

The Levins Model

Levins' original model applied to a metapopulation distributed over many patches of suitable habitat with significantly less interaction between patches than within a patch. Population dynamics within a patch were simplified to the point where only presence and absence were considered. Each patch in his model is either populated or not.

Let N be the fraction of patches occupied at a given time. During a time step, each occupied patch can become unoccupied with an extinction probability e. Additionally, 1-N of the patches are unoccupied. Each of these may become populated by colonization. Let c be a constant rate of propagule generation for each of the N occupied patches. This give a probability of cN for each unoccupied patch to be colonized. So for each time step, the change in the proportion of occupied patches, dN, is

dN = (1 - N)cN - eN.

This takes on a sigmoid shape similar to the logistic model. The equilibrium value of N can be calculated by setting dN to be equal to zero. Solving for N gives either N = 0 or

N = 1 - e / c

This result, that N is always less than one, implies that some fraction of a species habitat will always be unoccupied.

See also

References

  • Levins, R. (1969) "Some demographic and genetic consequences of environmental heterogeneity for biological control." Bulletin of the Entomology Society of America, 71, 237-240
  • Hanski, I. Metapopulation Ecology Oxford University Press. 1999. ISBN 0198540655

'"/>


(Date:4/2/2015)... BETHESDA, Md. , April 2, 2015 ... Salt Lake City , the American ... election of five new directors to its Board.  Members ... for the ACMG and for forming and advancing its ... the medical genetics profession. "It,s an eventful ...
(Date:4/1/2015)...   Medisafe ™, the leading global medication management ... and Android smartphones and tablets, announces ... platform to allow patients to track and correlate their ... patients will be able to visualize in real-time how ... such as glucose levels and blood pressure. ...
(Date:3/26/2015)... -- The Granite Club, Canada,s ... today announced it has implemented a state-of-the-art access and ... members and staff, while restricting access to authorized users ... FST,s IMID Access system because it has the perfect ... staff, in addition to unparalleled security," said James ...
Breaking Biology News(10 mins):American College of Medical Genetics and Genomics Announces New Board Members: Dr. Louanne Hudgins is ACMG President-Elect 2American College of Medical Genetics and Genomics Announces New Board Members: Dr. Louanne Hudgins is ACMG President-Elect 3American College of Medical Genetics and Genomics Announces New Board Members: Dr. Louanne Hudgins is ACMG President-Elect 4American College of Medical Genetics and Genomics Announces New Board Members: Dr. Louanne Hudgins is ACMG President-Elect 5American College of Medical Genetics and Genomics Announces New Board Members: Dr. Louanne Hudgins is ACMG President-Elect 6American College of Medical Genetics and Genomics Announces New Board Members: Dr. Louanne Hudgins is ACMG President-Elect 7American College of Medical Genetics and Genomics Announces New Board Members: Dr. Louanne Hudgins is ACMG President-Elect 8Medisafe Announces Launch of Biometric Integration, Enabling Patients to Stay Adherent to Their Meds and See Tangible Health Results 2Granite Club First Private Club in North America to Implement FST Biometrics Secure Access Solution, as Part of Multi-million Dollar Expansion 2
... that increase the risk of developing endometriosis, a common ... of this often very painful condition, which has a ... Details of the research, carried out at ... Nuffield Department of Obstetrics & Gynaecology, University of Oxford; ...
... Men with type 1 diabetes may be able ... tissue, say Georgetown University Medical Center (GUMC) researchers who ... Cell Biology 50th annual meeting in Philadelphia. Their laboratory ... human spermatogonial stem cells (SSCs) extracted from testicular tissue ...
... treatment of breast cancer just because a woman is pregnant, ... Breast Group. This suggestion is based on study results ... Loibl presented this data at the 33rd Annual CTRC-AACR San ... the time we started the study in 2003, there was ...
Cached Biology News:Genetic variants linked to increased risk of common gynecological disease 2'Grow your own transplant' may be possible for men with type 1 diabetes 2Unique needs and outcomes of pregnant women with breast cancer identified 2
Other biology definitionOther Tags