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

2. Reproduction o Behavior o Regulation/effect of hormones o Allocation of resources i.e. somatic vs. non-somatic tissue growth o Method/frequency of fertilization o Parental Care

3. Reproduction o Behavior North Atlantic Lobster – Homarus americanus   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

4. Reproduction o Behavior Opossum Shrimp   no active searching for mates or pre-spawning behavior   females secrete pheromone after molting and any nearby male is attracted

5. Reproduction o Behavior o Regulation/effect of hormones o Allocation of resources i.e. somatic vs. non-somatic tissue growth o Method/frequency of fertilization o Parental Care

6. Lifetime Reproduction -two basic strategies  Iteroparous: spawning possible more than oncespawning possible more than once most fishes and invertebratesmost fishes and invertebrates  Semelparous: spawning only once, followed by deathspawning only once, followed by death pacific salmon, some eels, lampreyspacific salmon, some eels, lampreys

7. Lifetime Reproduction -two basic strategies  Iteroparous: spawning possible more than oncespawning possible more than once most fishes and invertebratesmost fishes and invertebrates  Semelparous: spawning only once, followed by deathspawning only once, followed by death pacific salmon, some eels, lampreyspacific salmon, some eels, lampreys

8. Lifetime Reproduction  Iteroparous  Semelparous What are benefits and potential risks of each strategy?

9. Advantages / Disadvantages  Iteroparous: + several opportunities + environment unpredictable - longevity expected  Semelparous: + maximum investment - unfavorable conditions

10. Mating Systems number of mating partners an individual has during abreeding 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

11. Mating Systems  Promiscuous organisms that live in large groups organisms that live in large groups organisms with high fecundityorganisms with high fecundity sedentary organismssedentary organisms

12. Mating Systems  Polygamous – Polyandry / Polygyny none to some parental carenone to some parental care nest guardingnest guarding relatively rare in marine organisms, especially beyond egg stagerelatively rare in marine organisms, especially beyond egg stage

13. Mating Systems  Monogamous defense of territory / resourcedefense of territory / resource parental care by both parentsparental care by both parents relatively rare in marine organismsrelatively rare in marine organisms

14. Extreme/Atypical Mating Systems  Monogamous Males rely on females for nutrition - internal organs degenerate with exception of testes

15. Gender Roles  Gonochoristic: gender fixed, determined early  Hermaphrodites: either both, or sex change Simultaneous: eggs & sperm at same timeSimultaneous: eggs & sperm at same time Hamlets

16. Gender Roles  Gonochoristic: gender fixed, determined early  Hermaphrodites: either both, or sex change Simultaneous: eggs & sperm at same timeSimultaneous: eggs & sperm at same time Sequential : sex change during lifeSequential : sex change during life

17. 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

18. Sex Change Clownfish – 30 species Two large and several small fishTwo large and several small fish largest = femalelargest = female 2 nd largest = male2 nd largest = male rest = immature(even if same age as mature fish) but hiearchal by sizerest = immature(even if same age as mature fish) but hiearchal by size Body size maintained until changeBody size maintained until change

19. Parental Care very diverse across fishes very diverse across fishes Trade-off in resource allocation:  few, but high-quality  many, but low-quality ? 300,000,0007

20. Fertilization Internal External Transfer of sperm in many invertebrates is via a spermatophore Can be stored internally or attached externally Can be stored internally or attached externally May provide nutrients to female May provide nutrients to female May prevent subsequent matings by other males May prevent subsequent matings by other males Decreased surface area Decreased surface area

21. Fertilization Transfer of sperm in many invertebrates is via a spermatophore Successful system, why not more common? Successful system, why not more common?

22. Fertilization Transfer of sperm in many invertebrates is via a spermatophore Successful system, why not more common? Successful system, why not more common? Metamerism – serial repetition of body regions = more opportunity for appendage specialization

23. Fertilization Internal (in body cavity) External Rare in invertebrates Rare in invertebrates Becomes more common in “higher” vertebrates Becomes more common in “higher” vertebrates

24. External Open spawners Brooders pelagicbenthic More common in marine fishes More common in marine fishes Also known as broadcast spawners Also known as broadcast spawners Some benthic fishes will do it Some benthic fishes will do it high fecundity high fecundity

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

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

27. External Open spawners Brooders parental care of juveniles after hatching parental care of juveniles after hatching does occur but is rare, mostly in fishes does occur but is rare, mostly in fishes Cardinal Fish

28. Asexual Reproduction Occurs via splitting, budding or fragmentation Occurs via splitting, budding or fragmentation Generally rare, but more common in colonial organism at Generally rare, but more common in colonial organism at the cellular level of organization the cellular level of organization

29. Dispersal egg >> larvae >> juveniles >> adults Most marine organisms have a larval stageMost marine organisms have a larval stage

30. Dispersal Why the difference? Why the difference? egg >> larvae >> juveniles >> adults Most marine organisms have a larval stageMost marine organisms have a larval stage Most freshwater organisms do notMost freshwater organisms do not

31. Dispersal

32. Dispersal

33. Dispersal

34. Development - Larvae

35. Hatch – egg to larvae not tied to specific developmental stage not tied to specific developmental stage water temp and oxygen content water temp and oxygen content tide conditions, time of day, seasonal current changes tide conditions, time of day, seasonal current changes Coral Reef Flat Damselfish Hatching occurs at sunset of night of strongest ebb tide

36. Larval stage Duration of larval stage dependant on resource needs in relation to currents Food, habitat Food, habitat 1 week to 18 months 1 week to 18 months

37. Larval stage Two main types Two main types 1) Lecithotrophic –with yolk sac, no digestion 2) Planktotrophic – feed while larvae, digestion Name different across taxonomic groups Name different across taxonomic groups 1)Zoea – Crustaceans 2)Amphiblastula - sponges 3)Veliger – some molluscs 4)Leptocephalus – some fishes 5)Hard corals - planula

38. Larva – unknown for many species

39. Migration – a directed movement