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IB 362 lecture 6. Reproduction, Dispersal and Migration in Marine Organisms. Reproduction. Behavior Regulation/effect of hormones Allocation of resources i.e. somatic vs. non-somatic tissue growth Method/frequency of fertilization Parental Care.

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ib 362 lecture 6

IB 362 lecture 6

Reproduction, Dispersal and Migration in Marine Organisms

reproduction

Reproduction

Behavior

Regulation/effect of hormones

Allocation of resources i.e. somatic vs. non-somatic tissue growth

Method/frequency of fertilization

Parental Care

reproduction1

dominant/large males select best shelters

  • females select dominate male’s shelter and moves in
  • female will molt and then mate
  • after mating, female waits for shell to harden then moves out
  • other females in waiting move into shelter with olfactory cues

Reproduction

Behavior

North Atlantic Lobster – Homarus americanus

reproduction2

Reproduction

  • no active searching for mates or pre-spawning behavior
  • females secrete pheromone after molting and any nearby male is attracted

Behavior

Opossum Shrimp

reproduction3

Reproduction

Behavior

Regulation/effect of hormones

Allocation of resources i.e. somatic vs. non-somatic tissue growth

Method/frequency of fertilization

Parental Care

lifetime reproduction two basic strategies
Lifetime Reproduction-two basic strategies
  • Iteroparous:
    • spawning possible more than once
    • most fishes and invertebrates
  • Semelparous:
    • spawning only once, followed by death
    • pacific salmon, some eels, lampreys
lifetime reproduction two basic strategies1
Lifetime Reproduction-two basic strategies
  • Iteroparous:
    • spawning possible more than once
    • most fishes and invertebrates
  • Semelparous:
    • spawning only once, followed by death
    • pacific salmon, some eels, lampreys
lifetime reproduction
Lifetime Reproduction

What are benefits and potential risks of each strategy?

  • Iteroparous
  • Semelparous
advantages disadvantages
Advantages / Disadvantages
  • Iteroparous:

+several opportunities

+ environment unpredictable

- longevity expected

  • Semelparous:

+ maximum investment

- unfavorable conditions

mating systems
Mating Systems

number of mating partners an individual has during a breeding season

  • Promiscuous: little or no mate choice
  • Polygamous: one sex has multiple partners
    • Polyandry: one female, several males - rare
    • Polygyny: one male, several females - common
  • Monogamous: mates stay together, exclusively
mating systems1
Mating Systems
  • Promiscuous
    • organisms that live in large groups
    • organisms with high fecundity
    • sedentary organisms
mating systems2
Mating Systems
  • Polygamous – Polyandry / Polygyny
    • none to some parental care
    • nest guarding
    • relatively rare in marine organisms, especially beyond egg stage
mating systems3
Mating Systems
  • Monogamous
    • defense of territory / resource
    • parental care by both parents
    • relatively rare in marine organisms
extreme atypical mating systems
Extreme/Atypical Mating Systems
  • Monogamous

Males rely on females for nutrition - internal organs degenerate with

exception of testes

gender roles
Gender Roles
  • Gonochoristic:gender fixed, determined early
  • Hermaphrodites:either both, or sex change
    • Simultaneous: eggs & sperm at same time

Hamlets

gender roles1
Gender Roles
  • Gonochoristic:gender fixed, determined early
  • Hermaphrodites:either both, or sex change
    • Simultaneous: eggs & sperm at same time
    • Sequential : sex change during life
sequential common in several marine fishes most common in wrasse family labridae
Sequential – common in several marine fishes (most common in wrasse family – Labridae)

Lyretail Coralfish:

  • Large aggregations
  • Sex-ratio 36F:1M
    • If x M removed, x F change sex
sex change
Sex Change

Clownfish – 30 species

  • Two large and several small fish
  • largest = female
  • 2nd largest = male
  • rest = immature(even if same age as mature fish) but hiearchal by size
  • Body size maintained until change
parental care
Parental Care

very diverse across fishes

Trade-off in resource allocation:

  • few, but high-quality
  • many, but low-quality

?

7

300,000,000

fertilization
Fertilization

InternalExternal

Transfer of sperm in many invertebrates is via a spermatophore

  • Can be stored internally or attached externally
  • May provide nutrients to female
  • May prevent subsequent matings by other males
  • Decreased surface area
fertilization1
Fertilization

Transfer of sperm in many invertebrates is via a spermatophore

  • Successful system, why not more common?
fertilization2
Fertilization

Transfer of sperm in many invertebrates is via a spermatophore

  • Successful system, why not more common?

Metamerism – serial repetition of body regions

= more opportunity for appendage specialization

fertilization3
Fertilization
  • Rare in invertebrates
  • Becomes more common in “higher” vertebrates

Internal (in body cavity)External

slide24

Open spawners

Brooders

External

pelagic

benthic

  • More common in marine fishes
  • Also known as broadcast spawners
  • Some benthic fishes will do it
  • high fecundity
slide25

Open spawners

Brooders

External

benthic

pelagic

  • gametes released into current
  • settle to substrate after fert.
slide26

Open spawners

Brooders

  • gametes can be stored internally
  • fertilization is external
  • fert. eggs carried (usually by females)
  • until hatching
  • more common in invertebrates

External

slide27

Open spawners

Brooders

External

  • parental care of juveniles after hatching
  • does occur but is rare, mostly in fishes

Cardinal Fish

slide28

Occurs via splitting, budding or fragmentation

  • Generally rare, but more common in colonial organism at
  • the cellular level of organization

Asexual Reproduction

dispersal
Dispersal

egg >> larvae >> juveniles >> adults

  • Most marine organisms have a larval stage
dispersal1
Dispersal

egg >> larvae >> juveniles >> adults

  • Most marine organisms have a larval stage
  • Most freshwater organisms do not
  • Why the difference?
hatch egg to larvae
Hatch – egg to larvae
  • not tied to specific developmental stage
  • water temp and oxygen content
  • tide conditions, time of day, seasonal current changes

Hatching occurs at sunset of night of

strongest ebb tide

Coral Reef Flat Damselfish

larval stage
Larval stage

Duration of larval stage dependant on resource needs in relation to currents

  • Food, habitat
  • 1 week to 18 months
larval stage1

Two main types

  • Lecithotrophic –with yolk sac, no digestion
  • Planktotrophic – feed while larvae, digestion
Larval stage
  • Name different across taxonomic groups

Zoea – Crustaceans

Amphiblastula - sponges

Veliger – some molluscs

Leptocephalus – some fishes

Hard corals - planula