Lecture 29: Metapopulations , Keystone Species , Succession, & Species Richness

1. Lecture 29: Metapopulations, Keystone Species, Succession, & Species Richness

2. Metapopulations • a group of spatially distinct populations that are connected by occasional movements of individuals between them via “corridors.”

3. Keystone Species • A species that exerts profound influence on a community • More important to the community than what would be expected based on abundance • The dependence of other species on the keystone species is apparent when the keystone species is removed • Protecting keystone species is a goal to conservation biologists

4. Keystone Species • Keystone species- a species that plays a role in its community that is far more important than its relative abundance might suggest.

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8. Succession • The process where a community develops slowly through a series of species • Earlier species alter the environment in some way to make it more habitable by other species • As more species arrive, the earlier species are outcompeted and replaced • Two types of succession • Primary succession • Secondary succession

9. Primary Succession • Succession that begins in a previously uninhabited environment • No soil is present! • Ex: bare rocks, cooled lava fields, etc. • General Succession Pattern • Lichen secrete acids that crumble the rock (soil begins to form) Lichen mosses grasses shrubs forests

10. Primary Succession • Primary succession- occurs on surfaces that are initially devoid of soil.

11. 1 2 • Primary Succession • Bare rock with lichen • Grasses and shrubs • Forest community 3

12. Secondary Succession • Succession that begins in an environment following destruction of all or part of the earlier community • Ex: abandoned farmland, open area after fire • Does NOT follow primary succession! • Even though name may imply this • Generally occurs more rapidly than primary succession

13. Secondary Succession of an abandoned farm field in North Carolina

14. Secondary Succession • Secondary succession- occurs in areas that have been disturbed but have not lost their soil.

15. What Type of Succession

17. Aquatic Succession

18. Factors that determine species richness: • Latitude • Time • Habitat size & Distance

19. Species Richnesslattitude • Go North/South Poles, the number of species DECLINES

20. Species RichnessTime • Longer time greater • Colonization • Speciation • Extiction • Lake Baikal –v- the Great Slave Lake

21. Species Richness: Habitat Size & Distance • Theory of Island Biogeography • Island Biogeography Simulator • Species find larger habitats first • Larger habitats can support more species • Larger habitats have a wider range of environmental conditions, therefore a greater abundance of niche • Size & distance

22. Island Geography & Conservation • Consider the SIZE of the protected area AND, • the DISTANCE between the protected area and other areas that could provide colonists!

23. Theory of Island Biogeography • Theory of island biogeography- the theory that explains that both habitat size and distance determine species richness.