Seasonal breeding

Question 1

what are short day breeders?

Answer 1

bcome fertile when daylight is short (autumn) and are anestrus in spring and summer.

Question 2

what are long day breeders?

Answer 2

fertile when daylight is long (spring) and are anestrus in autumn and winter.

Question 3

what is photoperiod?

Answer 3

the number of hours of light and darkness in the day of different periods. this determines seasonal changes in physiology. one of these changes may be reproductive function.

Question 4

what do pineal glands do?

Answer 4

activated by noradrenaline from adrenergic fibres to increase melatonin synthesis and release.

Question 5

what determines how much melatonin is secreted by pineal glands?

Answer 5

high levels synthesized during the night. melatonin levels fall dramatically from dawn, so in daytime levels very low.

Question 6

how is melatonin responsible for seasonal changes in physiology for long day breeders?

Answer 6

short melatonin duration in the summer (long days) stimulates kisspeptin which increases GnRH. long duration in winter (short days) inhibits kisspeptin.

Question 7

how is melatonin responsible for seasonal changes in physiology for short day breeders?

Answer 7

short melatonin duration in the summer (long days) inhibits kisspeptin. long duration in winter (short days) increases kisspeptin which increases GnRH.

Question 8

GnIH effect?

Answer 8

only effect short day breeders? high levels in long days to inhibit GnRH

Question 9

how does opportunistic breeding occur in golden spiny mouse?

Answer 9

regulated by amount of water in enviroment. less water=more AVP (vasopressin)=less reproductive function.