habitat 2108 habitats, niches, and community interactions

7/27/2019 Habitat 2108 Habitats, Niches, and Community Interactions

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24 June 2009 Habitat2108.ppt 1

Habitat & Niches


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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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Habitat

Habitats may be subdivided into layers orzones

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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Niche

Species/populations 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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Niche

Fundamental niche

All resources that could be used in absence of

competition.


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Niche

Realized niche

Resources actually used in presence of competitor.


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Niches

Competitive exclusion

When forced to

compete, one specieseliminates other(s)


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Niches

Resource partitioning

avoids competition;

Realized niches divideresources (caterpillars)

among several species

of warblers.

Each species evolved& adapted to

specialized diet.


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Niches

Character displacement

Species evolve to

minimize competition

Niche and morphologicoverlap when allopatric

Difference and

specialization when

sympatric


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Keystone Species

Species in a community with vital role in

community organization.

Analogy to arch



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Keystone Species

Species in a

community with vital

role in community

organization. Sea otter on North

Americas Pacific

Coast



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Keystone Species

More examples:

Sea stars on rocky

shores

Dominant plant species Lupines in mountain

meadows

Top carnivores

Wolves in YellowstoneNational 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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Niches

Invasive species

may prey on or

parasitize

keystone

Sea lamprey

parasitizes large

predatory fishes

in Great Lakes.


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Niches

Out-compete

keystone for space

or resources

Imported fire ant

Kudzu
http://upload.wikimedia.org/wikipedia/commons/4/4c/Kudzu_on_trees_in_Atlanta%2C_Georgia.jpg


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Niches

Out-compete

keystone for space

or resources

Purple loosestrife

Zebra mussel


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Invasive species:

Kudzu

Fire ant

Zebra mussel

Purple loosestrife

Leafy spurge

Asian long-horned

beetleEmerald ash borer

Japanese beetle

African honeybee

Tiger mosquito

Brown snake

Guam

European starling

House sparrow

More, & more, &

24 June 2009 16Habitat2108.ppt

habitat 2108 habitats, niches, and community interactions

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