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
