Seasonal Breeding 2 Flashcards

1
Q

What are the two effects of long days on the reproductive system?

A
  1. Stimulate gonadal growth

2. Induce the gradual development of an inhibitory process that eventually causes the reproductive system to shut down

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2
Q

What is photorefractoriness?

A

A physiological state in which the animal is unable to respond to a day length that previously induced a change in the activity of the reproductive axis

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3
Q

What is breeding timed to coincide with in British starlings?

A

The maximum availability of insect larvae in soil

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4
Q

In lab studies what was found to remove the inhibitory effects of photorefractoriness?

A

Exposure to short days

Allows the bird to become stimulated by long days again

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5
Q

What is the degree of refractoriness related to?

A

The length of breeding season

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6
Q

Give an example of a supplementary cue that may be required to enter full breeding season?

A

Rainfall

Without rainfall there is no food available

E.g. rufous- winged sparrow in Arizona

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7
Q

What are breeding seasons like in birds that live near the equator?

A

Day length is a weaker predictor of when to breed

Usually breed during rainy season

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