Ch. 20 Community Ecology - PowerPoint Presentation

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Ch. 20

Community Ecology

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What is predation?

Predator eats prey

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What are three adaptations of predators?

What makes them good at finding, capturing, and consuming prey?

acute smell

heat sensing pits

venom

sticky webs

teeth/mouthparts

camouflage

speed

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List three adaptations of prey?

What makes them good at escaping, avoiding, or warding off predators?

fleeing

hiding

warning coloration

resembling something inedible

deceptive markings

chemical defenses

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What is mimicry?

One species resembles another

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What are the two types of mimicry?

Batesian – harmless species resembles a harmful one

Mullerian – 2 or more dangerous or distasteful species look similar

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What are some plant prey adaptations?

Thorns, spines, sticky hairs, tough leaves, chemical defenses

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Define interspecific competition

Two or more species using the same limited resource

Intraspecific

– same species competing

Interspecific

– different species competing

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Competitive Exclusion

A species is eliminated from a community because of competition

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What is symbiosis?

Close long-term relationship between two organisms.

3 types:

Parasitism (-/+)

Mutualism (+/+)

Commensalism (+/0)

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Parasitism : one benefits (parasite), one is harmed (host)

Exp. fleas, ticks, tapeworms

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Mutualism: both benefit

Exp. ants and acacia trees

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Commensalism: one benefits, other is neither helped nor harmed

Exp. cattle egrets and cape buffalos, sharks and remoras

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Patterns in Communities

Succession

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What is succession?

Gradual sequential re-growth of a community.

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Ecological succession

Gradual, sequential regrowth of a community

years or decades

usually after a disturbance

Mt. St. Helens

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What’s the difference between primary and secondary succession?

Primary – no soil previously; area previously did not support life

Secondary – soil already intact; follows disruption of a pre-existing community

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Primary succession

Begins with virtually lifeless area without soil, then…

bacteria

lichens & mosses

Once there’s soil, other plants can grow:

g

rasses

shrubs

trees

make

soil

{

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When is primary succession likely to occur?

On bare rock

Sand dunes

After volcanic eruption

On concrete (like an abandoned parking lot)

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What is a pioneer species?

First species in an area

Predominate early succession

Characteristics: small, grow quickly, reproduce quickly, disperse seed easily

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What organisms are typically found in the early stages of primary succession?

Lichens – form soil

→

Grasses/weeds

→

Mosses

→

Eventually larger plants and finally trees

Large conifers may be found in the end stage of primary succession in northern latitudes (pines, balsams, spruces)

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Secondary succession

Existing community cleared,

but base soil is still intact

burning releases nutrients formerly locked up in the tissues of tree

the disturbance starts the process of succession over again

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When is secondary succession likely to occur?

After forest fires, strong storms, farming, logging, mining

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Organisms found in early stages of secondary succession?

Weeds

→

Perennial grasses and shrubs

→

Hardwood trees eventually (deciduous forest)

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Climax Community

Plant community dominated by trees

Representing final stage of natural succession for specific location

stable plant community

remains essentially unchanged in species composition as long as site remains undisturbed

birch, beech, maple,

hemlock

oak, hickory, pine