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IB 362 lecture 6 Reproduction, Dispersal and Migration in Marine Organisms

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Text of IB 362 lecture 6 Reproduction, Dispersal and Migration in Marine Organisms

  • IB 362 lecture 6Reproduction, 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

  • Reproduction Behavior

    North Atlantic Lobster Homarus americanus dominant/large males select best shelters females select dominate males 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

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

  • Reproduction

  • Lifetime Reproduction-two basic strategiesIteroparous: spawning possible more than oncemost fishes and invertebrates

    Semelparous:spawning only once, followed by deathpacific salmon, some eels, lampreys

  • Lifetime Reproduction-two basic strategiesIteroparous: spawning possible more than oncemost fishes and invertebrates

    Semelparous:spawning only once, followed by deathpacific salmon, some eels, lampreys

  • Lifetime ReproductionIteroparous SemelparousWhat are benefits and potential risks of each strategy?

  • Advantages / DisadvantagesIteroparous: + several opportunities+ environment unpredictable- longevity expected

    Semelparous:+ maximum investment- unfavorable conditions

  • Mating Systemsnumber of mating partners an individual has during abreeding seasonPromiscuous: little or no mate choicePolygamous: one sex has multiple partnersPolyandry: one female, several males - rarePolygyny: one male, several females - commonMonogamous: mates stay together, exclusively

  • Mating SystemsPromiscuousorganisms that live in large groupsorganisms with high fecunditysedentary organisms

  • Mating SystemsPolygamous Polyandry / Polygynynone to some parental carenest guardingrelatively rare in marine organisms, especially beyond egg stage

  • Mating SystemsMonogamousdefense of territory / resourceparental care by both parentsrelatively rare in marine organisms

  • Extreme/Atypical Mating SystemsMonogamousMales rely on females for nutrition - internal organs degenerate with exception of testes

  • Gender RolesGonochoristic: gender fixed, determined early

    Hermaphrodites: either both, or sex changeSimultaneous: eggs & sperm at same time

    Hamlets

  • Gender RolesGonochoristic: gender fixed, determined early

    Hermaphrodites: either both, or sex changeSimultaneous: eggs & sperm at same timeSequential : sex change during life

  • Sequential common in several marine fishes (most common in wrasse family Labridae) Lyretail Coralfish: Large aggregationsSex-ratio 36F:1MIf x M removed, x F change sex

  • Sex ChangeClownfish 30 speciesTwo large and several small fishlargest = female2nd largest = malerest = immature(even if same age as mature fish) but hiearchal by size

    Body size maintained until change

  • Parental Care very diverse across fishes

    Trade-off in resource allocation:few, but high-qualitymany, but low-quality?300,000,0007

  • FertilizationInternal External 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

  • FertilizationTransfer of sperm in many invertebrates is via a spermatophore

    Successful system, why not more common?

  • FertilizationTransfer 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

  • Fertilization Rare in invertebrates

    Becomes more common in higher vertebrates

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

  • External Open spawners pelagic benthic gametes released into current settle to substrate after fert.

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

  • External Brooders parental care of juveniles after hatching does occur but is rare, mostly in fishesCardinal Fish

  • Asexual Reproduction Occurs via splitting, budding or fragmentation

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

  • Dispersalegg >> larvae >> juveniles >> adultsMost marine organisms have a larval stage

  • Dispersal Why the difference?egg >> larvae >> juveniles >> adultsMost marine organisms have a larval stage

    Most freshwater organisms do not

  • Dispersal

  • Dispersal

  • Dispersal

  • Development - Larvae

  • Hatch egg to larvaenot tied to specific developmental stage

    water temp and oxygen content

    tide conditions, time of day, seasonal current changes Coral Reef Flat DamselfishHatching occurs at sunset of night of strongest ebb tide

  • Larval stageDuration of larval stage dependant on resource needs in relation to currents

    Food, habitat 1 week to 18 months

  • Larval stage Two main types Lecithotrophic with yolk sac, no digestion Planktotrophic feed while larvae, digestion

    Name different across taxonomic groups

    Zoea Crustaceans

    Amphiblastula - sponges

    Veliger some molluscs

    Leptocephalus some fishes

    Hard corals - planula

  • Larva unknown for many species

  • Migration a directed movement

  • Migration a directed movement

  • Migration a directed movement

  • Migration a directed movement

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