BIO120H1 Lecture Notes - Lecture 25: Insular Biogeography, Patch Dynamics, Metapopulation

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4 Dec 2018
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BIO120 LECTURE 22: Mutualism and Symbiosis
November 28, 2018 (Relevant Reading Excerpt from I Contain Multitudes, Ed Young)
Dispersal, Metapopulations, and Island Biogeography
- Dispersal, advantages and adaptations
- Metapopulations and patch dynamics, sources and sinks, Levin’s patch occupancy model
- How metapopulations enable species coexistence
- Scaling up from metapopulations to metacommunities
- Theory of island biogeography; influence of area
- Island or patch like habitats
Immigration and Emigration
- Real populations are not closed systems
- Individuals can move from one populations to another; they can disperse
- Dispersal allows organisms to:
o Colonize new areas
o Escape competition
o Avoid inbreeding depression
Many Taxa Have Evolved Traits That Aid in Dispersal
- Sweet, fleshy fruit is an adaptation that attracts animal seed dispersers
- Other seeds are dispersed by wind or water
Dispersal is Important for Colonization of New Habitats
- Postglacial colonization depends on plant and animal dispersal
o Most of Canada was under ice ~ 12 000 years ago
- Range shifts in response to climate change
- Islands
- Etc.
Metapopulations: Populations of Populations”
- Dispersal connects populations
- A metapopulation is a collection of spatially distinct populations that are connected via dispersal
- We call each spatially distinct population a patch
Metapopulation Structure Allows Population Persistence when Individual Populations are Doomed
- Local populations can be reestablished by colonists from other populations after going extinct
- Source sink dynamics:
o ‘sinks’ are populations in small habitat patches that would go extinct, except…
o Migrants from ‘source’ populations ‘rescue’ these populations
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From Population Dynamics to Metapopulation Dynamics
- Imagine an oceanic island
(Powerpoint, Slide 7)
1. Some prey colonize empty island
(Powerpoint, Slide 8)
2. Prey quickly grow toward carrying capacity
(Powerpoint, Slide 9)
3. Some predators arrive and reproduce rapidly
(Powerpoint, Slide 10)
4. Predators drive prey to extinction
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