1 How does an animal choose where to live?. 2 5/29/08: Habitat Selection Lecture objectives: 1.Understand the adaptive value of: habitat selection, dispersal.

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How does an animal choose where to live?

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5/29/08: Habitat Selection

Lecture objectives:

1. Understand the adaptive value of: habitat selection, dispersal & migration, and territoriality

2. Be able to distinguish between multiple adaptive hypotheses for a given behavior

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Where an animal chooses to live can greatly affect its fitness

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Where an animal chooses to live can greatly affect its fitness

Least tern&

Habitat restoration

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Since habitat selection is important, animals should have evolved the ability to evaluate habitat quality

30-60 L

Smallentrance

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So, where should an animal choose to live?

But what happens to an animal’s fitness if all individuals choose the same spot?

Animals must somehow distribute themselvesbetween patches that vary in resources

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Animals must somehow distribute themselvesbetween patches that vary in resource # or quality

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Example: distribution of female aphids

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Dispersal: moving to a new home area

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Why disperse?

Costs Benefits

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Migration is a special form of dispersal

Migration – the regular (seasonal) movement back and forth between two relatively distant locations by animals

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Why do animals migrate?

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Animals have evolved behaviors that lower the costs of migration

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Some birds can adjust their migratory strategy

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To defend or not to defend?

Home Range Territory

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Why be territorial?

Costs Benefits

Bitterling (w/ mussel)

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How does an animal establish/maintain territorial boundaries?

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Example: Animals adjust territory size in relation to resource abundance

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Example: Animals adjust territory size in relation to resource abundance

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Example: well-defined boundaries reduce costs of territoriality

“Good fences make good

neighbors!!”

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In territorial disputes, the territory owner often wins

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Why does the owner often win?

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Example: Resource-holding power in damselflies

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Example: Benefits of a dear neighbor

Fiddler crab, Uca mjoebergi

Crab + neighbor Crab (alone)

Success in driving away intruder

88% 71%