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meta

meta. From Greek among, with, after Current: occurring later than or in succession to change : transformation used with the name of a discipline to designate a new but related discipline designed to deal critically with the original one. Metapopulations.

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  1. meta • From Greek • among, with, after • Current: • occurring later than or in succession to • change : transformation • used with the name of a discipline to designate a new but related discipline designed to deal critically with the original one

  2. Metapopulations • Metapopulation: Group of populations linked by migration in which each population has a significant risk of extinction. • Persistence of a metapopulation is possible even where extinction of any population within the metapopulation is guaranteed!

  3. Metapopulation Dynamics • Balance of extinction and colonization • % occupied patches (P) = 1 - e/c • e = extinction rate per occupied patch • c = colonization rate per unoccupied patch per occupied patch • Extinction if e > c

  4. VORTEX and Metapopulations • Model a population within the metapopulation as a single closed population (c “low”). • Model the metapopulation as a single closed population (c “high”). • Many current conservation plans are based on metapopulation approaches.

  5. Natural Metapopulations

  6. Metapopulations & Fragmentation

  7. Glanville Fritillary • Habitat occurs in discrete patches • All populations have a substantial risk of extinction • Dispersal occurs among all patches • Patch dynamics are asynchronous • Ignore population dynamics within a patch

  8. Distribution of Glanville Fritillary metapopulation “network” From: Hanski, I. A., and M. E. Gilpin. 1996. Metapopulation Biology. Academic Press

  9. Conservation Implications:Glanville Fritillary From: Hanski, I. A., and M. E. Gilpin. 1996. Metapopulation Biology. Academic Press

  10. Minimum Viable Metapopulation % occupied patches = 1- e/c e = .5, c= .75 Probability that all three patches go extinct? e# patches Rule of thumb: At least 10-15 well connected, patches are required for long term persistence of metapopulation, UNDER A CLASSIC METAPOPULATION MODEL

  11. Modifications of Metapopulation Models SOURCE vs. SINK

  12. Sources vs. Sinks dispersal r < 0 λ, R0 < 1 r > 0 λ, R0> 1 SINK (low quality habitat) SOURCE (high quality habitat) Because sink populations will decline to extinction in the absence of dispersal, immigration from source populations has been termed the RESCUE EFFECT.

  13. SOURCE SINK Sources vs. Sinks DEFINED BY DEMOGRAPHY, NOT DENSITY! N = 50 r = 2.4 N = 200 r = -0.04

  14. Conservation Implications:Peregrine Falcon N = 60 0.71 fledglings /  / yr. “SOURCE” N = 29 0.53 fledglings /  / yr. “SINK” From: Wooton, T. J., and D. A. Bell. 1992. Ecological Applications 2: 307-321.

  15. Conservation Implications:Peregrine Falcon • In order to manage these populations, you have instituted a captive breeding program that produces ~ 50 fledglings per year. • Do you supplement the N or S population or ½ in each?

  16. Conservation Implications: Peregrine Falcon + 50 fledgling to N pop. + 25 fledglings to N pop. + 25 fledglings to S pop. + 50 fledgling to S pop. CONCLUSION: Management of this population is best accomplished by focusing efforts on the northern population From: Wooton, T. J., and D. A. Bell. 1992. Ecological Applications 2: 307-321.

  17. Source-Sink Caveats • Data are difficult to generate. • Sink one year could be a source the next! • Nevertheless, many species seem to be characterized by source and sink populations. • Remains a useful concept, especially where we consider the source-sink concept as a continuum

  18. Food Web VORTEX

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