Lecture 14 - Reproduction Flashcards

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1
Q

What is iteroparity?

A

Breeding several times during a life cycle.

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2
Q

What is semelparity?

A

Breeding once and then dying.

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3
Q

Describe semelparity in ragworms.

A
  • Lose all muscle, digest body tissue, stop feeding (put all of energy into reproductive event)
  • Swim out of burrows and burst, releasing sperm and eggs into the water.
  • Pick the time they reproduce depending on the risk level of the environment that they are living in.
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4
Q

What is semelparity favoured by?

A
  • High population growth rate
  • Low adult survivorship
  • Longer intervals between reproductive episodes
  • Early senescence
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5
Q

What is epitzoky?

A

Partial or complete transformation in order to swim into the water column for reproduction.

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6
Q

Give an organism where epitoky is a semelparous strategy.

A

In Nereidae, where the whole worm becomes the epitoke.

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7
Q

Describe the reproduction strategies of the palolo worm (Palola viridis).

A

Semelparous.
Use cues from moon, temperature and daylight hours to tell them exactly when to reproduce, via swarming in vast numbers, for reproductive success.

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8
Q

What is broadcast spawning?

A

Throwing eggs and sperm into the environment.

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9
Q

What is the ancestral reproduction strategy?

A

Broadcast spawning

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10
Q

What is predator satiation?

A

Mass spawning of multiple species in synchronisation; too many eggs are produced for the fish to eat in one day, avoids predation/ensures some reproductive success.

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11
Q

How do fertilisation rates vary over distance from males in broadcast spawners?

A

Decline, due to sperm dilution.

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12
Q

How is fertilisation success altered by turbulence that is

a) Mild or moderate?
b) Extreme?

A

a) Mild or moderate turbulence enhances fertilisation success by gamete mixing.
b) Gametes are diluted in extreme turbulence, and egg-sperm interaction is disrupted, reducing fertilisation success.

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13
Q

Describe the work of Campbell et all (2016).

A

Studying sperm competition under future conditions of ocean acidification.
OA always reduced sperm fitness.
Sperm switch in genotypes in what makes them best in different environments.

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14
Q

What does it mean if a cleavage is

a) Holoblastic?
b) Meroblastic?

A

a) Holoblastic = the whole embryo

b) Meroblastic = partial cleavage.

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15
Q

What is cleavage under control of?

A

Proteins and mRNAs stored in the oocyte by the mother (before the sperm arrives).

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16
Q

What percentage of bony fish broadcast spawn?

A

90%

17
Q

Describe the reproduction of nudibranchs.

A

Simultaneous hermaphrodites.
Maximises the chances of mating when you reach the same species; can mate with any individual you come into contact with.
Pass sperm to one another in sperm packets, and fertilise each other’s eggs.

18
Q

Describe reproduction in seahares.

A

All are monoecious - both male and female.

Form large mating chains; front is female only, back is male only.

19
Q

Describe reproduction in barnacles.

A

Uncoils long tubular penis (largest in animal kingdom in comparison to body size - 40x its body), extends it out through operculum to search for a nearby receptive predator.

20
Q

Describe the reproduction of spend polychaetes.

A

Invest in parental care, coiling round an e.g. mass in encapsulation.

21
Q

What is encapsulation?

A

Formation of an egg mass; eggs wrapped in a jelly coat, protecting them from filter feeders.
Mother wraps around egg mass to protect offspring.

22
Q

Describe the juveniles of spinoid polychaetes.

A

Hatch from egg mass as crawling individuals; protected from ‘drifting’ into unfavourable conditions.

23
Q

What is brooding?

A

Fertilised eggs are retained for varying periods of development by the female.

24
Q

Give a group of organisms in which brooding is seen.

A

Arthropods.

Fertilised eggs retained in carapace (fecundity therefore limited by female’s size).

25
Q

What percentage of invertebrates engage in broadcast spawning / biphasic life histories?

A

80%

26
Q

Give the names of the larvae from the following groups:

a) Molluscs
b) Polychaetes
c) Crabs/lobster
d) Copepod

A

a) Molluscs = veliger
b) Polychaete = trochophore
c) Crab/lobster = zoea
d) Copepod = Nauplius

27
Q

How many species of invertebrate produce planktonic larvae?

A

90,000

28
Q

What is the advantage of a larval stage?

A

Dispersal.
Wider genetic exchange and decreased likelihood of inbreeding.
Reduced competition between adults and juveniles.

29
Q

What are some disadvantages of having a larval stage?

A
  • Greater loss of freely spawned eggs between fertilisation and settlement
  • High predation rates on larvae
  • Advection away from favourable settlement sites
  • Physiological stress (e.g. starvation, offshore transport).
30
Q

What was the daily mortality rate of marine larvae measured by Rumrill (1990)?

A

2-100%

31
Q

What is planktotrophic development?

A

Broadcast spawning with very small eggs.

Have a feeding larval form, long pelagic development, higher dispersal potential.

32
Q

What is lecithototrophic development?

A

Broadcast spawning with slightly bigger eggs.

Have non-feeding larval form, short pelagic duration, planktonic stage limited by energy reserves.

33
Q

What is direct development?

A

Emerge from the egg in adult form, has no pelagic duration, low dispersal potential.

34
Q

Which development mode is common in gastropods?

A

Direct development.

35
Q

How do planktonic larvae feed?

A
  • Using ciliary bands (also used for swimming)
  • These direct food from the water column to the mouth
  • Plutei can produce longer larval arms and smaller stomachs when food is scarce.
36
Q

In how many species of echinoderms is viviparity and direct development described in?

A

14

37
Q

What are nurse cells?

A

Small eggs found inside egg capsules that can be eaten by pre-hatch juveniles

38
Q

What is development time influenced by?

A
  • Temperature
  • Food availability
  • Size at metamorphosis
39
Q

Describe the reproduction and development of Phestilla sibogae.

A
  • Hatch after 6-8 days
  • Becomes competent after 3 days (ready to settle), but can remain as a swimming larvae for up to 7 weeks.
  • Inducer chemical cue released by coral prey acts upon larvae, causing them to stop swimming and sink.
  • Transformation to bottom-living, coral-eating sea slug takes less than 20 hours.