1. Habitat & Niches
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Habitat2108.ppt

2. Habitat
Totality of environment factors in which a population or species regularly lives.
Space and time
Physical and biotic environment
Vegetation
Forest, meadow, pasture, coniferous forest, etc.
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Habitat2108.ppt

3. Habitat Habitats may be subdivided into layers or zones Microhabitats
Forest canopy: leaves, branches
Shrub layer: leaves, branches, trunks
Herb layer: leaves, stems, mosses, ferns
Litter: dead fallen leaves, logs,
Varies in depth, quality
Soil: topsoil, subsoil
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Habitat2108.ppt

4. Niche Species’/population’s role in its community
Dimensions of a niche:
Habitat & microhabitat (Space occupied)
Food “spectrum,” essential nutrients
Reproductive requirements
Nutrition, nest/den sites
Seasonality: When are resources required, used.
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Habitat2108.ppt

5. Niche Fundamental niche
All resources that could be used in absence of competition.
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Habitat2108.ppt

6. Niche
Realized niche
Resources actually used in presence of competitor.
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Habitat2108.ppt

7. Niches Competitive exclusion
When forced to compete, one species eliminates other(s)
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Habitat2108.ppt

8. Niches Resource partitioning avoids competition;
Realized niches divide resources (caterpillars) among several species of warblers.
Each species evolved & adapted to specialized diet.
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Habitat2108.ppt

9. Niches Character displacement Species evolve to minimize competition
Niche and morphologic overlap when allopatric
Difference and specialization when sympatric
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Habitat2108.ppt

10. Keystone Species
Species in a community with vital role in community organization.
Analogy to arch
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Habitat2108.ppt

11. Keystone Species
Species in a community with vital role in community organization.
Sea otter on North America’s Pacific Coast
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Habitat2108.ppt

12. Keystone Species More examples:
Sea stars on rocky shores
Dominant plant species
Lupines in mountain meadows
“Top” carnivores
Wolves in Yellowstone National park
Sharks on coral reefs
Invasive species may prey on or parasitize keystone
Human removal of sea otters, wolves, sharks
Out-compete keystone for space or resources
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Habitat2108.ppt

13. Niches Invasive species may prey on or parasitize keystone
Sea lamprey parasitizes large predatory fishes in Great Lakes.
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Habitat2108.ppt

14. Niches Out-compete keystone for space or resources Imported fire ant
Kudzu
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Habitat2108.ppt

15. Niches Out-compete keystone for space or resources Purple loosestrife
Zebra mussel
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Habitat2108.ppt

16. Invasive species: Kudzu Fire ant Zebra mussel Purple loosestrife
Leafy spurge
Asian long-horned beetle
Emerald ash borer
Japanese beetle
African honeybee
Tiger mosquito
Brown snake
Guam
European starling
House sparrow
More, & more, & …
24 June 2009
Habitat2108.ppt