Lecture 14 - Reproduction Flashcards
What is iteroparity?
Breeding several times during a life cycle.
What is semelparity?
Breeding once and then dying.
Describe semelparity in ragworms.
- 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.
What is semelparity favoured by?
- High population growth rate
- Low adult survivorship
- Longer intervals between reproductive episodes
- Early senescence
What is epitzoky?
Partial or complete transformation in order to swim into the water column for reproduction.
Give an organism where epitoky is a semelparous strategy.
In Nereidae, where the whole worm becomes the epitoke.
Describe the reproduction strategies of the palolo worm (Palola viridis).
Semelparous.
Use cues from moon, temperature and daylight hours to tell them exactly when to reproduce, via swarming in vast numbers, for reproductive success.
What is broadcast spawning?
Throwing eggs and sperm into the environment.
What is the ancestral reproduction strategy?
Broadcast spawning
What is predator satiation?
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.
How do fertilisation rates vary over distance from males in broadcast spawners?
Decline, due to sperm dilution.
How is fertilisation success altered by turbulence that is
a) Mild or moderate?
b) Extreme?
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.
Describe the work of Campbell et all (2016).
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.
What does it mean if a cleavage is
a) Holoblastic?
b) Meroblastic?
a) Holoblastic = the whole embryo
b) Meroblastic = partial cleavage.
What is cleavage under control of?
Proteins and mRNAs stored in the oocyte by the mother (before the sperm arrives).
What percentage of bony fish broadcast spawn?
90%
Describe the reproduction of nudibranchs.
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.
Describe reproduction in seahares.
All are monoecious - both male and female.
Form large mating chains; front is female only, back is male only.
Describe reproduction in barnacles.
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.
Describe the reproduction of spend polychaetes.
Invest in parental care, coiling round an e.g. mass in encapsulation.
What is encapsulation?
Formation of an egg mass; eggs wrapped in a jelly coat, protecting them from filter feeders.
Mother wraps around egg mass to protect offspring.
Describe the juveniles of spinoid polychaetes.
Hatch from egg mass as crawling individuals; protected from ‘drifting’ into unfavourable conditions.
What is brooding?
Fertilised eggs are retained for varying periods of development by the female.
Give a group of organisms in which brooding is seen.
Arthropods.
Fertilised eggs retained in carapace (fecundity therefore limited by female’s size).
