Fish endocrinology - Part 2 Flashcards Preview

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Flashcards in Fish endocrinology - Part 2 Deck (52)
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1

What is a feedback loop, relating to the hypothalamus?

A feedback loop helps to regulate hypothalamic and pituitary activity.

Based on circulating hormones, prevents from making too much.

2

Where do 17B estradiol and testosterone both feedback to?

Anterior pituitary and hypothalamus, decrease how much is made.

3

What are the other feedback loops related to?

NTs in the brain.
These 3 can regulate the hypothalamus, up or down regulate.
Mostly behavioural component.

4

Reproductive physiology is controlled by lots of factors such as: _______ factors/disruptors, _______, _____, ______

endocrine
temperature
light
pheromones

5

Why does reproductive physiology matter?

Matters for aquaculture, ecotoxicology and ties into growth, osmoregulation, nutritional state and can be used for genetic rescue of endangered populations.

6

Male reproductive anatomy:
Testis hold ______ which exits through the ________ duct (kidney) or through a ________ duct

sperm
mesonephric
separate

7

Female reproductive anatomy:
______ in ovary.
______ goes either directly through ______ to exit or goes into ______ cavity first.

Eggs
Egg
oviduct
body

8

For the most part, sperm and urine exit through a common opening. True or false?

True

9

What are the 4 basic spawning types?

1 - Group broadcast spawning
2 - Paired broadcast spawning
3 - Adhesive eggs in nest
4 - Internal fertilization

10

What is group broadcast spawning?

Fish get together in a group and release sperm and eggs in a large cloud.

11

What is paired broadcast spawning?

Male and female choose each other but still release eggs and sperm.

12

What are adhesive eggs in nest?

External fertilization, still have pair
instead of broadcasting, put eggs directly into a nest

13

What is internal fertilization?

Generally, male adds sperm to female.
Fertilized eggs can be released or stay inside for a period of time.

14

What are the benefits and costs of group broadcast spawning.

Benefits:
- Less cost for care
- Good chance of fertilization at the group level
- Good chance there was enough fertilization going on so that the species as a whole can continue
- No selection (benefit for less fit fish)
- safe from predators since in group

Cost:
- No guarantee that genes are passed on - individual
- No guarantee that a fish didn't get outcompeted at the sperm level
- Eggs float away - no idea if they survive
-- predation is a big issue
- No mate choice (bad if fit fish)
- odds of survival of each individual egg is low

15

What is the compatible gene idea?

Ties in with group-broadcast spawning since there is arguably no selection going on.
So, even though you aren't choosing your mates, sperm and eggs with the most compatible genes are more likely to fertilize.

16

What are the benefits and costs of paired broadcast spawning?

Benefits:
- More specific - mate choice
-- can lead to enhanced survival
- Low reproductive investment

Costs:
- offspring still float away - don't know if survive
-- predation is a big issue
- male competition - sneaker males (fertilization rate might be lower)
- less efficient since fewer fish
- eggs are still small since no parental care

17

What is pelagic larval duration?

Means that as eggs float away, eggs and larvae are pelagic, the longer that they are in the pelagic phase, the lower their survival.
This is because they are floating around, open to predation.
Survival for broadcast spawning can be as low as 1%.

18

What are the benefits and costs of Adhesive eggs in nest?

Benefits:
- More protection/less predation*
- Mother is spending time investing so get large eggs/embryos (good at the individual level)
- offspring more likely to reach maturity (tend to grow faster)
- Sexual selection*

Costs:
- Sexual selection*
- More parental care (cost to parent)
- Predation is more devastating*
- Possible sneak fertilization
- all your eggs are in one basket

19

What are the benefits and costs of internal fertilization?

Benefits:
- Fish will be bigger, hatch our larger and more developed (benefit for offspring)
- offspring may be more fit due to sexual selection
- increased fertilization (sperm and egg not diluted; better chance of meeting)
-Environmental protection (mother can swim to better habitat)
- No sneakers (highest degree of sexual selection
- Mother can choose where to lay eggs

Costs:
- fewer offspring at a time
- Costs more energy to keep eggs inside
- Space limitation in mother (and possibly dad)
- If mother gets eaten, rip reproductive investment
- male and female have to physically connect - vulnerable to predation during the deed

20

What is iteroparous?

Multiple spawning events (iterations)

21

What is semelparous?

Only spawn once

22

What is oviparous?

Lay external eggs

23

What is ovoviparous?

Live young but no maternal nourishment

24

What is viviparous?

Live young with maternal nourishment.

25

What are the benefits of iteroparous?
Costs?

Benefits:
- lots of chances to pass on genes
- if conditions werent good the first time, can have another go

Costs:
- limit on reproductive effort - still need energy to live so, fewer gametes at a time

26

What are the benefits and costs of semelparous?

Benefits:
- can put all your energy into one spawning event
-- can have more eggs, bigger eggs and lots of gametes

Costs:
- only one shot
-- if conditions are bad or can't find a mate, no ability to pass on genes

27

How do semelparous fish quite literally give it all they've got?

Digest muscles and GI tract and send energy to reproductive organs.

28

When is semelparous a better strategy? When is iteroparous a better strategy?

Semelparous is better when the environment is stable.
Iteroparous is better when the environment is not stable.

29

Between semelparous and iteroparous, which is more common?

Iteroparous

30

Mammals are ______. (Spawning mode)

viviparous

31

What are the two ways to be viviparous?

Either placental-like connection - direct connection between baby and mother which provides nourishment and removes wastes or;
baby lays fin on ovary wall allowing nutrient exchange

32

What are the benefits of vivparous? What are the costs?

Benefits:
- most chance of individual embryo surviving and developing

Cost:
- most cost per embryo
- fewer embryo

33

What is monogamy?

One male and one female.

34

What is polyandry?

1 female with multiple males

35

What is polgyny?

1 male with multiple females

36

Describe monogamy in fishes?

Can be for just one season - like when nest building in anemonefish.
In some cases, share nest for life until one partner dies.
Can be continued mate choice, breeding season after breeding season

37

Which is rarer? Polyandry or polygyny?

Polyandry

38

When would polyandry be more likely to occur.
Provide an example.

When the female is much larger than the males and when it is difficult to find mates.
This is the case with the deep sea angler fish.
Also occurs with seahorses.
- high cost for male (parental care) but low cost for female

39

Describe polygyny.

One male with multiple females.
Often, male will guard a number of females and restrict access from other males.
Often, male will guard a nest site and only allow access to females.

40

How can a female cheat in polygyny?

Can go from nest to nest.

41

What fish will have satellite males?

Blue gill

42

What fish will have sneaker males?

Salmon

43

Describe satellite males.

Life stage choice in blue gills.
Larger adult males will entice the females so, the younger ones have no chance.
The younger ones might be reproductively mature but cannot compete.
Younger, satellite fish will perform extra-pair copulations.
Younger however, eventually becomes dominant male and will defend a nest.
Life stage choice:
- younger is sneaker, older is not

44

Describe sneaker males in salmon.

Jack vs hooknose in salmon.
Choice between the two occurs relatively early on in life.
Jacks do not have hooks, hooknoses do. (i.e. jacks lack secondary sexual character)
Jacks do not become hooknoses and hooknoses do not become jacks,
When spawning time comes, hooknose defends nest and attracts females, jacks will hide along the edges and will try to fertilize eggs at the same time.
Jacks for the most part tend to die off after spawning but, some evidence they can come back.

45

What are the two types of sequential hermaphrodites?

Protrandrous
Protagynous

46

What is protrandrous?

Male to female

47

What is protagynous?

Female to male

48

Describe how social controls can work for a sequential hermaphrodite species.

One large female fish with other small male fish.
Presence of female keeps the other fish male, peeing out pheromones = social control, keeps the other fish male.

When she dies, lose social control.
Largest male fish, generally, will become female and reestablish the social control.

This only works when 1 fish is dominant with 4/5 subordinates.
More often found in reefs.

49

What is parthenogenesis?

Giving birth without fertilization. (No fish actually does this)

50

What is gynogenesis?

Triploid female fish, lays triploid egg, no normal meiosis.
Sperm from male needed to activate egg, causing it to divide.
All offspring will be triploid females identical to the mother.
No genetic contribution from sperm

51

What is hybridogenesis?

Diploid female lays haploid egg with equal contribution from male and female (thus far).
Egg hatches into a female.
When this female lays an egg, all female, only passes on maternal genome and rejects male genome - segregation during meiosis, throwing away male genome.

52

How can hybridogenesis and gynogenesis persist

Male from a different, related species will mate with the female of that species.
When this occurs, this impresses the female from his own species, leading him to have higher reproductive success while allowing these parthenogenic methods of reproduction to persist.