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Lecture

BIOC50H3 Lecture Notes - Northern Spotted Owl, Patch Dynamics, Metapopulation


Department
Biological Sciences
Course Code
BIOC50H3
Professor
Marc Cadotte

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BIOB50 LECTURE 19: Metapopulations and Metacommunities
Metapopulations
Isolated populations do affect one another’s pop dynamics because individuals/gametes
occasionally disperse from one pop to another such a group of interacting populations=
metapopulation=population of populations
Many species have a metapopulation structure in which sets of spatially isolated pops are linked
by dispersal for many species areas of suitable habitat exist as a series of favorable sites that
are spatially isolated from one another
Meta= Greek for about itself in science it it translated as something of something i.e. meta-
analyses= analysis of analyses
Hufaker: can see through time where and when prey/predators are over time and how they
occupy different locations at different times
Metapopulations: spatially isolated pops that are linked by the dispersal of individuals or
gametes
Metapopulations are characterized by repeated extinctions and colonizations
Patches are prone to extinction for two reasons
o 1) if small, they have small pop sizes= more likely to go extinct= demographic
stochasticity
o 2) environmental conditions often change in a rapid and unpredictable manner =
environmental stochasticity
Metapopulations aid persistence of populations although the individual pops may be prone to
extinction, the collection of pops, the metapopulation persists since it includes pops that are
going extinct and new pops established by colonization
Proportion (p) of patches occupied can be predicted in terms of extinction and colonization of
habitat patches
o dp/dt= immigration rate-extinction rate
o extinction and colonization of habitat patches can be described by this equation
dp/dt=cp(1-p)-ep
o p=proportion of habitat patches that are occupied at time t
o c=patch colonization rate
o e=patch extinction rate
o for a metapopulation to persist for a long time, the ratio e/c must be less than 1
o this equation has several assumptions
1)there is an infinite number of identical habitat patches=unrealistic
2) all patches have an equal chance of receiving colonists (i.e.
distance)=unrealistic
3) All patches have an equal chance of extinction (i.e. size)
4) once a patch is colonized, its pop increases to its carrying capacity more
rapidly than the rates of colonization and extinction (allows pop dynamics
within patches to be ignored)
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