Lecture 1 Introduction. Sexual selection vs Natural selection

Question 1

Describe polygynous vs monogamous.

Answer 1

Polygynous:
Intense male: male competition for females.

Evolution of weapons.

Dimorphic behaviour driven by sex steroids.

Abandonment of parental care by male.

Monogamous:

Males and females share resources.

No weapons for intrasexual conflict.

Dimorphic behaviour minimal.

Both sexes share in parental care or defence of a common family territory.

Question 2

birds are weird why

Answer 2

The majority of bird species are monogamous

And have different sex-determining mechanisms to mammals

Question 3

what led to different reproductive strategies?

Answer 3

difference in reproductive costs - ie heavily female orientated - pregnancy and lactation.

Males have less opportunity to share in the energy costs of rearing offspring, which has opened up selective forces for polygynous behaviour.

Question 4

what has led to dimorphism in behaviour, growth and physiology?

Answer 4

Intense male-male competition for access to females (the limiting resource) has led to dimorphism in behaviour, growth and physiology

Question 5

what drives sexual dimorphism?

Answer 5

sexual selection.

Question 6

where is the hypothalamus located/function?

Answer 6

just above the brainstem.

homeostasis of hormones via control of the pituitary gland (which sits just below)

Question 7

Describe the functions of the posterior pituitary gland.

Answer 7

oxytocin

vasopressin

both made in the hypothalamus and sent to the pituitary gland (via?)

Question 8

Describe the functions of the anterior pituitary gland.

Answer 8

growth hormones.

FSH

LH

adrenocorticoptropic hormone

thyroid stimulating hormone

prolactin

hypothalamus connected to anteroir pituitary gland via the hypothalamic portal blood system.

Question 9

what is FSH?

Answer 9

follicle stimulting hormone

Question 10

what is LH?

Answer 10

luteinizing hormone

Question 11

how is the hypothalamus connected to anteroir pituitary gland?

Answer 11

Hypothalamic portal blood system.

Question 12

how is action on the gonads achieved frmo the hypothalamus?

steroidgenesis later lecture
??????????????

Answer 12

Specialised neurones
producing “releasing”
peptides.

Release into
Portal system
of anterior pituitary.

Large complex
glycoprotein hormones
(LH FSH) secreted to
main blood supply.

Action on gonads.

Question 13

GnRH and LH FSH?

Answer 13

GnRH causes release of FSH and LH in pulses.

Question 14

location of GnRH neurons?

Answer 14

Scattered through the basal forebrain (hypothalamus)

Question 15

Why are GnRH neurons not active until puberty?

Answer 15

GnRH are connected to a variety of interneurons which are regulated by the environment.

The interneurons are not active until puberty.

secrete GnRH into portal system and reaches pituitary target cell, driving downstream LH

Gonadotrophin axis?

Question 16

how is the posterior pituitary area regulated?

Answer 16

cluster of neurons in the pre optic area, very long and extend into the posterior pituitary and directly secrete there.

oxytocin and vasopressin

Question 17

colours of anterior/posterior?

Answer 17

anterior - red, vascular

posterior - white, neural

Question 18

gonad functions?

Answer 18

Produces sex steroids:

Act locally to regulate gonadal function

Act on body to differentiate development and physiology

Act on brain to regulate behaviour

Question 19

secretion of oxytocin and vasopressin?

Answer 19

direct action on brain behaviour.

peripheral organs like breast, uterus, kidney.

Question 20

principles of neuroendocrine system?

Answer 20

neurons in hypothalamus project directly to pituitary to drive larger glycoprotein hormones.

and others project to other structures with same signal, act as a NT there.