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REPRODUCTIVE AND DEVELOPMENTAL BIO > week 2 - sperm comp. testes etc > Flashcards

week 2 - sperm comp. testes etc Flashcards

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1
Q

What 2 things influence the probability of offspring surviving to sexual maturity?

A

rate of development and survival (starvation predation)

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2
Q

what are the 3 main things that maximise a species reproductive success? as in a diagram

A

parenting
reproduction
development

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3
Q

what is the balancing investment? and which taxa are at the 2 ends of the spectrum?

A

producing gametes to parental care

aquatic invertebrates to mammals

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4
Q

what are the 2 modes of reproduction species can be?

A

r selected and k selected

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5
Q

how can males maximise their lifetime reproductive success?

A

maximise LRO
maximise number of mates
strong drive to polygyny
(there must be incentive for a male to be monogamous and stay and contribute to parental care rather than finding a new mate)

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6
Q

how can females maximise their life time reproductive success?

A

maximise survival of offspringg to sexual maturity - parenting
invest in egg and yolk nutrition
select fittest partner - sexual selection
maximise number of mates
strong drive to polyandry
sperm competition

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7
Q

what are the 2 main parental priorities?

A

maximise the number of offspring (as dictated by resources, trade off against parental role even K selected sp. want to do this)
keep offspring alive

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8
Q

what are the 5 ways parents can help to keep offspring alive?

A 
ensure infants avoud starvation
avoid predation
ensure infants arent born into an overly competitive envirnoment (k selected at carrying capacity\)
ensure infants dont die by misadventure
ensure infants arent killed!
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9
Q

How can parents ensure infants avoid starvation?

A

ensure that there is sufficient food in the immediate environment:
before laying eggs / giving birth
before conceiving
food sufficiently renders animals sub/infertile and can terminate pregnancies

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10
Q

How can parents ensure infants avoid predation?

A

ensure offspring are cryptic
put offspring in a creche
guard offspring
dont produce offspring in the vicinity of predators

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11
Q

How can parents ensure infants avoid competition?

A

dont produce offspring in an over crowded / competitive environment
natural selection against runts - not enough teets deliberately produce too many kids so pick genetically weakest e.g. piglets

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12
Q

how can parents ensure infants avoid misadventure?

A

supervised play and training

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13
Q

how can parents ensure infants avoid being killed?

A

ensure infants are cryptic and guarded

social bonding with group members that might pose a threat - in baboons the biggest threat are other babboons

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14
Q

How long are parents useful to their offspring? (2)

A

until offspring achieve sexual maturity and can give rise to the F2 generation
until parents achieve reproductive senescence

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15
Q

what is the concept of extended family in matriarchal species?

A

aunt behaviour

extended family help look after

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16
Q

what 2 parental roles cannot be assumed by males?

A

nourish the embryo

lactate (mammals only)

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17
Q

which 3 parental roles can be assumed by males?

A

carry the embryo (“pregnant males”)
guard the embryo (eggs)
carry and guard neonate

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18
Q

example of pregnant males?

A

Sygnathidae fish see paper

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19
Q

example of incubating males

A

penguin

male guarding embryo mum goes off to feed

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20
Q

example of male carrying neonates

A

marmosets

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21
Q

when is sperm competition likely to occur?

A

if a female is inseminated by 2 or more males it creates the opportunity for sperm competition within the female

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22
Q

what 5 ways can a male win the sperm competition?

A

faster sperm - longer
high sperm number
repeated insemination of same female (drive towards monogamy)
optimise timing of insemination
exclude other sperm - break of penis or biochemical plug

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23
Q

give an example of how the sperm number varies in mammals? and evidence for high sperm number

A

sperm density million/ml

highest in ram at 3000 lowest in humans

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24
Q

what is a harem?

A

single reproductively active male, all offspring are sired by the harem holder it is an extreme case of mate guarding

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25
Q

example of a harem

A

hamadryas baboon

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26
Q

what are the 2 types of harem

A

patriarchal - male holds it together

matriarchal female chooses harem

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27
Q

what is infanticide?

A

killing of all offspring that arent your own when an alpha male dominates a new pack e.g. lions

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28
Q

what is the benefit of infanticide?

A

ensure that a male isnt wasting resources on offspring that he didnt sire

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29
Q

what is a lioness response to infanticide?

A

comes back into oestrous quicker and mates with new harem

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30
Q

what are the two mechanisms of mate guarding?

A

pre copulatory and post copulatory

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31
Q

what are mating plugs?

A

used to ensure paternity

block reproductive tract of female

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32
Q

what is the compex composition of mating plugs?

A

fatty acids
seminal proteins
anti reproductive molecules - supress her mating drive and kill any other sperm before new male deposits

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33
Q

paper example for copulatory plugs?

A

the orb weaver spider one

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34
Q

describe aquatic invertebrates male strategy

A

predomniantly external fertilisation
cephalopod molluscs e.g. octopus hectocotylus delivers the spermatophore into female mantle - more efficient / less sperm if internal fertilisation

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35
Q

describe aquatic vertebrates male strategy

A

fish and amphibians
predominantly external fertilisation
elasmobranchs - claspers deliver spermatophore into female cloaca

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36
Q

Terrestrial animals invertebrates practice _____ internal fertilisation as seen in arachnids or ____ internal fertilisationa s seen in insects

A

indirect

direct

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37
Q

terrestrial vertebrates always have direct internal fertilisation known as _____

A

insemination

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38
Q

indirect fertilisation must be fast why?

A

because reproduction needs fluid so the sperm doesnt dessicate

39
Q

Explain a bit about scorpion fertilisation

A

indirect internal fertilisation
male paraxial organs deliver the spermatophore
complete a promenade a deux - dance
female cloaca is dragged over spermatophore, she resists as he pulls and this rocking motion takes up the sperm

40
Q

explain a bit about spider fertilisation

A

indirect internal fertilisation
spermatophore deposited and then picked up by pedipalp
pedipalp delivers spermatophore into female cloaca
pedipalp is produced at the back of the male
a copulatory plug is formed from breaking off of pedipalp, of which there are only 2 so the male dies after 2 matings

41
Q

explain a bit about insect fertilisation and the bed bug

A

direct internal fertilisation
several specialised structures for insemination e.g. aedeagus and juxta
traumatic insemination in cimicidae where the male punctures female abdomen and sperm enters anywhere into paragenital system

42
Q

explain about terrestrial vertebrate fertilisation

A

direct fertilisation via penis

43
Q

explain about terrestrial vertebrates as in birds

A

97% of birds and the tuatara lack penis
direct fertilisation via cloacal kiss
tuatara is a very old primitive vertebrate and penises are a relatively new feature

44
Q

which birds do have penises?

A

ostrich ratites and some ducks. but run on lymphatics not blood PAPER

45
Q

the mammalian testis are ___ ___ in size and exhibit allometric scaling which is??

A

highly variable

testis as a proportion of body mass decreases with increasing size ((kenagy and trombulak 1986

46
Q

which order has the largest proportionately testis?

A

rodents specifically gerbil

47
Q

some animals have internal testes or ____ e.g. ____

A

testicondids

mole seal elephant

48
Q

Where do the mammalian testes originate?

A

in the abdomen

49
Q

what is it called when the testes move into the scrotum and what is it caused by?

A

anterio-rostral migration

contraction of gubernuculum caused by androgens

50
Q

why do the testes descend in scrotal mammals?

A

keep them cooler at a temperature that can produce the most sperm
suggested ancestor had lots of sperm competition and had larger testes to produce more sperm but needed to be outside of the body

51
Q

the size of testes is based on what?

A

whether there is sperm competition. more comp = big balls!

52
Q

What is the main testis structure?

A

comprised primarily of seminiferous tubules

53
Q

what two things do seminiferous tubules contain?

A

sertoli cells

maturing sperm

54
Q

packed inbetween the seminiferous tubules are ___ ___ ___

A

interstitial leydig cells

55
Q

what are the two functions of the testis?

A

testosterone synthesis

spermatogenesis

56
Q

which cells synthesise testosterone?

A

leydig cells also produce paracrine growth factors

57
Q

what do sertoli cells do?

A

synthesise and secrete inhibin and androgen-binding protein (ABP) and produce paracrine growth factors

58
Q

the structures of the male pelvic anatomy are _____ in most eutheria

A

similar

59
Q

testis are a collection of tubules, however it is not as many as you first think when you first cut them open, why?

A

supercoiling

60
Q

in what other part of the testes is there super coiling?

A

the epididymus, it looks to be a simple tube but under the covering it is convoluted

61
Q

what is vas deferens?

A

a simple tube that runs out of the epididymus to the penil uretha and on its way passes the seminal vesicles

62
Q

the epididymis itself is a collection of tubules until it runs out into the vas deferens and becomes a simple tubule, how many regions does it have?

A

3 regions:
caput epididymus - head
corpus epididymus - body
cauda epididymus - tail

63
Q

why is the epididymus called head, body and tail?

A

this is the way sperm moves through them, from the head, body to the tail. in humans it is also orientated this way to the earth but in other mammals it is not.

64
Q

where does spermeogenesis finish off?

A

in the epididymus

65
Q

When the spermatazoan is mature it contains what?

A

the head has a nucleus and a bag of enzymes called the acrosome these sit over the nucleus
spiral mitochondrion wraps around the flagellum
tail - flagellum - for propulsion

66
Q

When sperm leave the testis they are ______ and in the ______ the sperm need to acquire ____. this is essential for their function

A

immotile
epididymus
motility

67
Q

As the sperm passes through the caput and the cauda we get ____ and the ability to _____

A

motility

fertilise

68
Q

You dont want sperm to be hyperactive in the epididymus why?

A

waste all their energy

69
Q

to prevent the sperm from being hyperactive it needs to be ____

A

decapacitated

70
Q

what ever gets put on the sperm to decapacitate it needs to be removed when it enters the female tract, what causes this to happen?

A

the pH of the female tract

alkaline

71
Q

what does it appear to be is the decapacitation factor covering the sperm in the epididymus?

A

extra cholesterol

72
Q

As the sperm pass through the epididiymus other secretions are added to the sperm, including what? (2)

A

a sugar inositol - major source of preserving osmolarity

glycerophospherocoline

73
Q

What are the accessory sex glands? (3)

A

seminal vesicle
prostate gland
cowpers gland - bulbo urethral

74
Q

there are huge differences in mammals with the size of these accessory sex glands, why?

A

see table in lecture

because of different strategies to maximise fertilisation in different animals have evolved different structures

75
Q

What does the prostate gland produce?

A

citric acid

76
Q

what is the function of the substance produced by the prostate gland?

A

citric acid. this prevents coagulation.

77
Q

what happens to citric acid when it enters the female tract?

A

it will be neutralised when entering the alkaline female tract, this measn the semen will coagulate and form a mating plug

78
Q

acid phosphatase comes from the prostate gland which will break down what?

A

gylcerolphosphorylcholine

79
Q

the class of molecules that are produced by the prostate gland are known as what?

A

prostoglandines

80
Q

what 3 things can the seminal vesicles produce?

A

secrete fructose - sperm propulsion
secrete inositol - convergent evolution in bull and boar, preservation of cell osmolarity
OR
citric acid in other species to stop semen coagulate

81
Q

what does the bulbo-urethral produce?

A

the pre ejacuate that lubricates the penis

82
Q

why is the pre ejaculate produced by the bulbo-urethral really important?

A

produces alkaline secretions, if too acid then the sperm will die, the biggest acid we have to worry about it the uric acid from urine in the urethra. in mammals sperm move down the same tract as urine, so the bulbo urethral gland has to produce an alkaline secretion because it needs to keep the sperm alive.

83
Q

why does the bull have such large ejaculate?

A

the bull can produce 1.5litres of ejaculate a large portion will be gel fraction which stops the ejaculate falling out, this is made in the bulbo-urethral hence why the bulbo-urethral is huge in boars

84
Q

What sort of cells are in the anterior pituitary gland?

A

gonadotroph

85
Q

what do the gonadotroph cells in the anterior pituitary gland synthesise and secrete?

A

gonadotrophins

  • –LH - luteinizing hormone
  • –FSH - follicle-stimulating hormone
86
Q

LH stimulates ____ cells to synthesise testosterone

A

leydig

87
Q

FSH stimulates -____ cells to mature sperm

A

sertoli

88
Q

FSH also stimulates sertoli cells to synthesise and secrete ___

A

inhibin

89
Q

meiosis in the testis initiates at puberty (_____) and continuous throughout adult life

A

spermarche

90
Q

what is the process of spermatogenesis? (12)

A 
spermatogonium A
spermatogonium B
Primary spermatocyte( leptotene, zygotene, pachytene, diplotene, diakinesis)
secondary spermatocyte
round spermatid
elongate spermatid
spermatozoan
91
Q

complete spermatogenesis and spermiogenesis are dependent on ?

A

FSH and testosterone/DHT

92
Q

FSh is more important in ___ stages of meiosis

A

early

93
Q

___ more important in latter stages pus spermiogenesis

A

androgens

REPRODUCTIVE AND DEVELOPMENTAL BIO (13 decks)

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