Lecture 19 – Metapopulations & Metacommunities
Many species have a metapopulation structure in which sets of spatially isolated populations 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 is a greek word for about its self. In science it is translated as something of something.
Literally means a population of a population, but it is usually defind in a more particular sense as a
set of spatially isotlated populations linked to one another by disepersal
Figure 10.17 – Seven patches of suitable habitat for a species are diagrammed, four of which are
currently occupied and three of which are not. Members of the species occasionally disperse from
one patch of suitable habitat to another.
Figure 12.21 – from first half of semester– C.B Huffaker constructed a simple lab environment to
test for conditions under which predators and prey would coexsis and produce population cycles.
He placed oranges in a few positions in an experiment tray to provide food for the herbivourous
sixspotted mite; the remainder of the position contained inedible rubber balls. (B) When
predatory mite was introduced into this simple environment, it drove the prey to extinction causing
its own population to go extinct as well
Metaanalysis means analysis of analyses.
Figure 12.22 – seen before – modified the above experiment to create a more complex
environment that aided the dispersal of the prey species, but hindered the dispersal of the predator.
Under these conditions, predator and prey populations coexisted, and their abundances cycled over
time. They illustrated a form of “hideandseek” dynamics that produced population cycles.
Metapopulations – spatially isolated populations that are linked by the dispersal of individuals or
Metapopulations are characterized by repeated extinctions and colonization’s.
Patches are prone to extinction for two reasons
o If small, they have small population sizes, more likely to go extinct. (Demographic
o Environmental conditions often change in a rapid unpredictable manner (Environmental
Levins model – represented metapopulation dynamics in terms of the extinction and colonization
of habitat patches
o Proportion (p) of patches occupied can be predicted
o Dp/dt = immigration rate – extinction rate
o Extinction and colonization of habitat patches can be described by the following equation
C = patch colonization rate
E= patch extinction rate
o The equation has several assumptions:
There is an infinite number of identical habitat patches
All patches have an equal chance of receiving colonists (distance) All patches have an equal chance of extinction (size)
Once a patch is colonized, its population icreases to its carrying capacity more
rapidly than the rates of colonization and extinction (allows population
dynamics within patches to be ignored)
Although some of the assumptions of the equation are not realistic, it leads to a
simple but fundamental insight: for a metapopulation to persist for a long time
ratio e/c must be less than 1.
• Some patches will be occupied as long as the colonization rate is
greater than the extinction rate; otherwise metapopulation will collapse
and all populations in it will become extinct.
o It led to research on key issues:
How to estimate factors that influence pat