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224 > Reproduction > Flashcards

Reproduction Flashcards

Simons 1

1
Q

what is reproduction?

A

The production of gametes to from new offspring either sexually or asexually.

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2
Q

What is asexual reproduction?

A

Budding or fission. (plathelminthes)
Fragmentation - splitting of individuals into more than one. (Hydrozoans)
Parthenogenesis - parent produces diploid eggs with no meiosis involved. (Daphnia)

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3
Q

What is sexual reproduction?

A

Gonochorisom or dimorphic - separate male and female.
Hermaphroditic - male and female organs in one individual.

Produces male and female gametes that fuse and develop into embryos.

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4
Q

How does reproduction in the sea occur?

A

A-dense and viscous = larvae won’t sink
A-high humidity = gametes won’t dry out
A-high [dissolved nutrients] = larvae can feed passively
D-low [dissolved O2] = eggs or larvae risk suffocation.

sedentary adults and sessile juveniles. = small broods.

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5
Q

What are the marine invertebrates life cycles?

A

Broadcast spawning - fertilization occurs in the water column and develops into free-swimming larvae ( feeding = planktotrophic, non-feeding = lecithotrophic) that eventually settle and metamorphose.

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6
Q

What are the advantages of broadcast spawning?

A
  • no parental care
  • larvea can take advantage of short term food sources.
  • dispersing larvae = increases the # habitats where the larvae can settle and increases the # of populations and species.
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7
Q

What are the disadvantages of broadcast spawning?

A
  • high mortality
  • lots of energy input into reproduction
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8
Q

What is sperm casting and brood protection?

A

females lay eggs in tubes and males cast sperm into the water column.

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9
Q

What are the advantages of sperm casting?

A
  • population does not need to be synchronized.
  • when laying eggs the individual has stored sperm to use for eggs.
  • increase fertilisation success (each egg is fertilised as it is laid)
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10
Q

WHat is the disadvantage sof sperm casting?

A
  • sperm dilution (if not close to a female), decreased fertilization.
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11
Q

What is mixed development?

A

sexually dimorphic, feamle lays capsules within a tube, males release sperm to the female.
Eggs are fertilised as she lays them, eggs develop in capsules and hatch then settle enand metamorphose into juveniles.

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12
Q

Advantages of mixed development?

A
  • protection from dessication
  • protection form predators
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13
Q

What is internal fertilisation and direct development?

A

insemination occurs when males transfer sperm into the female. then internal fertilization occurs in the female. and a small version of the adult is born.

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14
Q

Advantages of internal fertilisation?

A
  • direct transfer of sperm to the egg
  • increased change of survival of the embryo
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15
Q

Disadvantages of internal fertilisation?

A
  • high parental care
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16
Q

Which species employ which strategies and where?

A
  • No clear phylogenetic constraints.
  • Body size
    – Need enough space in body to produce enough eggs to compensate for high mortality of larvae.
  • Environment
    – Conditions that delay larval development are expected to be selected against planktonic/planktotrophic larval phases.
    – Latitude (~temperature)
  • food and temperature
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17
Q

What are the main advantages and disadvantages to reproducing on land and in freshwater?

A
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18
Q

How could/did terrestrial and freshwater taxa overcame the limitations of reproducing under these conditions?

A
19
Q

What do you think the predominant fertilisation strategy is?

A
20
Q

Which phylum is/phyla are most represented in these environments? (fresh and terrestrial)

A
21
Q

How have their life history strategies pre-adapted them to
these alternative/stressful environments?

A
22
Q

What are the consequences of internal fertilization?

A
  1. Complex copulatory behavior leading to sexual selection
    - Adults rarely hermaphroditic
  2. Embryos all lecithotrophic
    - Eggs must include enough nutrients to enable
    development
23
Q

Non-marine, non-arthropod
invertebrates reproduction:

A
  • Eggs are not freely discharged
  • sperm storgae
  • internal, intracapsular fertilisation, complex mating behaviors
  • large egg yolk concentration
  • Absent care of young, guarding/brooding, food provisioning
  • often hermaphoroditic
  • multiple reproductive events
24
Q

Small marine invertebrate reproduction:

A
  • eggs not freely discharged
  • sperm storage
  • internal/intratubular fertilisation
  • large egg yolk concentration
  • usually brooded care of young
  • hermaphoroditic or gonochoristic
  • multiple breeding events.
25
Q

LHS for freshwater & terrestrial invertebrates that are
NOT arthropods

A

Selection pressures differ:
Environment vs small body size

26
Q

arthropod reproduction

A
  • Why are Arachnida (spiders, scorpions, ticks & mites), Myriapoda (millipedes & centipedes) & Insecta (insects) so successful?
    – Adults AND eggs have waterproof external covering
    – Development may be internal
  • Very strong phylogenetic signal – closely related taxa reproduce in similar/the same way.
27
Q

Development and metamorphosis in terrestrial arthropods?

A
  • Arachnida & Myriapoda
    – Live birth (scorpions)
    – Eggs - hatchlings that look like small adults (spiders)
    – Eggs - hatchlings look like adults, but
  • fewer pairs of legs (mites and ticks) or legs and segments (millipedes and centipedes)
  • Hexapoda/Insecta
    – Various levels of metamorphosis.
28
Q

Development in crustaceans:

A

one taxa is fully terrestrial - woodlice [isopod]

Incomplete metamorphosis

29
Q

insect development

A

Ametabolous - no metamorphosis, just gets bigger
Hemimetabolous - incomplete metamorphosis
Holometabolous - complete metamorphosis

30
Q

Insect life history strategies:

A
  • 3 modes of parental care
    – Non-carers (e.g., Ephemeroptera, locusts)
    – Guarders look after eggs but don’t provide extra food
  • Protect against predators, keep eggs clean of fungi etc.
    – Provisioners provide offspring with food (e.g., certain
    wasps, dung beetles)
  • Life history traits expected to differ among these
    groups towards optimising reproductive success
    – Egg size, life-time fecundity
31
Q

Parental care trade-offs in insects:

A
  • No trade-off between egg size and number
  • Mean egg size ALWAYS increases with body size regardless of degree of parental care.
  • Within adult size classes, egg size does not increase with increased levels of parental care.
32
Q

parental care trade-offs in marine and fresh water insects:

A
  • In marine and freshwater invertebrates, egg size (usually) increases with
    – increased parental care, and
    – decreased adult size
  • Why insects showing parental care may lay large eggs (guarders AND provisioners)
    – Increased developmental time increases the period of protection
    – Decreased mortality of eggs
    – Fewer larger eggs decrease sibling conflict after hatching.
33
Q

parental care trade-offs in non-cares/guarders/provisioners

A
  • For non-carers and guarders
    – There was no significant trade-off between lifetime fecundity (clutch size) and egg size.
    – Lifetime fecundity increases slightly with adult body size
  • Guarders find it equally easy to look after big and small broods
  • For provisioners
    – Lifetime fecundity (clutch size) decrease with an increase in adult body size and egg size
  • Larger provisioners laid fewer eggs
  • Limit to how much it can increase foraging rate as adults get bigger,
    – If clutch size increases too much, she won’t be able to collect enough food to feed whole brood.
    – Better to keep clutches smaller.
34
Q

Why do animals reproduce when they
do?

A
  • Reproduction can only happen when multiple coordinated sequences of cellular activity have been completed
  • Timing of reproduction is coordinated by
    – Ultimate forces
  • Evolutionary forces that control timing of reproduction
    – Reason for coordination
    – Proximate forces
  • Environmental events that regulate the progression of gamete production & therefore timing of reproduction
    – Process of coordination
35
Q

Control of reproduction in marine
invertebrates

A

Temperature effects in reproduction in marine invertebrates
- Timing of spawning
- only when all sequences are synchronized, specific ques
- when it is dark there are less predators

36
Q

Synchronous reproduction in marine invertebrates

A

Multispecies spawning on the Great Barrier Reef
- hard and soft coral mass spawning in Panama.

These spawning events usually occur in early summer, after a specific period of darkness, and at low tide after the full or new moon. - when there are less predators.

These are the proximate forces. What are the ultimate forces? That is, WHY would spawning occur at these times?

37
Q

Endocrine control of reproduction in
marine invertebrates

A

Hormones that stimulate gonad function & development

38
Q

Reproduction in Nereidid polychaetes

A
  • Female (summary)
    – High brain hormone → growth of body tissue, mitotic division of oogonia (cells that develop into oocytes)
    – Low Brain Hormone, low temperature, short days → vitellogenesis
    – Lower Brain Hormone, warm temperature, longer days → oocyte maturation
  • Male:
    – High Brain Hormone → mitotic division of spermatogonia (i.e., cells that develop into sperm)
    – Low Brain Hormone → meiosis and spermatogenesis (development of sperm) continues
  • Lunar cue→ spawning
39
Q

Semi-continuous breeder Cirratulus cirratus

A

Environmental conditions don’t exert
control over oogenesis

40
Q

Control of reproduction in terrestrial
and freshwater invertebrates

A

Environmental conditions that may influence reproductive cycles in terrestrial & freshwater invertebrates:
Very high seasonal variability
– Food availability
– Temperature

Reproductive activity
vs.
Reproductive inactivity

41
Q

Environmental cues:
Photoperiod - perception

A

Photoperiod info
Endocrine system
Reproduction (long days)
Reproductive inactivity (short days)

42
Q

Reproductive inactivity?

A
  • Quiescence - adult stages of molluscs, earthworms, some insects
  • Diapause
    – Physiological resting phase
    – Facultative - adult stages of molluscs, earthworms, some insects
    – Obligatory - early stages: eggs, larvea, pupae

Survive drought/ polar winter:
* Cold winters
* Extreme heat
* Low / no food

43
Q

Insect larval or pupal diapause

A

Shut down of brain – Prothoracic Gland axis
– Most common system

44
Q

Adult insect diapause

A

Shut down of JH (Juvenile Hormone) synthesis by corpora allata in the brain

224 (13 decks)

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