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 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!

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

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.

Natural Metapopulations

Metapopulations & Fragmentation

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

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

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

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 well connected, patches are required for long term persistence of metapopulation, UNDER A CLASSIC METAPOPULATION MODEL

Modifications of Metapopulation Models SOURCE vs. SINK

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

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

Conservation Implications: Peregrine Falcon N = fledglings /  / yr. N = fledglings /  / yr. “SOURCE” “SINK” From: Wooton, T. J., and D. A. Bell Ecological Applications 2:

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?

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

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

VORTEX Food Web