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LIFE HISTORY PATTERNS

LIFE HISTORY PATTERNS. Spawning and Fertilization. Evolution of Anisogamy. Imagine some Precambrian creature. G. Parker. Produces undifferentiated gametes. Fertilization. Gametes produced come in a variety of sizes. Large. Medium . Small . Number produced. Mitotic competence.

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LIFE HISTORY PATTERNS

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  1. LIFE HISTORY PATTERNS

  2. Spawning and Fertilization

  3. Evolution of Anisogamy Imagine some Precambrian creature G. Parker Produces undifferentiated gametes Fertilization

  4. Gametes produced come in a variety of sizes Large Medium Small Number produced Mitotic competence

  5. Size distribution of gametes produced Gamete size Number produced

  6. External fertilization Which ones are the most likely to produce offspring?

  7. Combinations Very high Very high Very high Moderate Very high Very low Moderate Low Low High Very low Very high Competence Frequency of contact

  8. After several generations Selected against Gamete size Number produced

  9. Anisogamy

  10. FERTILIZATION TYPES OF SPERM AND EGG RELEASE AND FERTILIZATION 1. Broadcast spawners (= free spawners) -eggs and sperm are released into the water column - fertilization is external 2. Spermcastspawners -sperm are released into the water column and taken in by the female -fertilization is internal 3. Copulators -sperm placed in the body of the female usually with some intromittentorgtan -fertilization is internal

  11. SPAWNING 1. BROADCAST SPAWNING

  12. SPAWNING 1. BROADCAST SPAWNING Problems for broadcast spawners How does an animal ensure fertilization by dumping eggs and sperm in the open ocean? 1. Proximity 2. Timing 3. Currents 4. Sperm/egg contact

  13. Boradcastspawners suffer a dilution effect Quinn and Ackerman. 2011. LimnolOceanogr. 2011: 176

  14. How to get around this problem 1. Proximity oysters mussels

  15. How to get around this problem 2. Timing and synchrony Haliotisasinina Counihan et al. 2001. Mar.Ecol.Prog.Ser.213:193

  16. How to get around this problem 2. Timing and synchrony Haliotisasinina Counihan et al. 2001. Mar.Ecol.Prog.Ser.213:193

  17. How to get around this problem 2. Timing and synchrony Haliotisasinina Counihan et al. 2001. Mar.Ecol.Prog.Ser.213:193

  18. How to get around this problem 2. Timing and synchrony Haliotisasinina Counihan et al. 2001. Mar.Ecol.Prog.Ser.213:193

  19. How to get around this problem 2. Timing and synchrony Haliotisasinina Conclusions (Counihanet al. 2001) 1. Spawning season is determined by water temperature 2. Precise time of spawning is influenced by tidal regime 3. Both sexes spawn in response to an evening high tide 4. Males spawn 19 mins before high tide: females 11 mins after 5. More animals spawn in presence of opposite sex. Counihan et al. 2001. Mar.Ecol.Prog.Ser.213:193

  20. 3. Currents

  21. 3. Currents Patterns of flow – move gametes unpredictably Advection – mean direction and velocity of a gamete cloud Diffusion –rate of gamete spreading Main problem – production of eddies (vortices) – unpredictable and ephemeral

  22. 3. Currents

  23. 4. Sperm-egg contact a. Dilution -is it sperm concentration or egg:sperm ratio? If sperm and egg are at similar concentrations -sperm :egg ratio is important Sperm concentration is imporant Sperm:egg ratio important

  24. Final problem Egg and sperm longevity Horseshoe crabs Sea urchins Sea stars Ascidians hydroids Sperm live less than a few hours Sea urchins Sea stars Ascidians Eggs live about 3x longer than sperm

  25. How can sperm and egg increase the chances of contact? a) Chemical attractants

  26. How can sperm and egg increase the chances of contact? a) Chemical attractants L- Tryptophan in abalone Tryptophan ‘cloud’

  27. How can sperm and egg increase the chances of contact? b) Jelly coat Jelly coat increases the size of the egg and acts as a sperm‘trap’

  28. Fertilization Spermcast spawning -mating “by releasing unpackaged spermatozoa to be dispersed to conspecifics where they fertilize eggs that have been retained by their originator.” Bishop and Pemberton.2006. Integr.Comp.Biol. 46:398

  29. Fertilization Spermcast spawning In most spermcasters- Sperm release Intake by female Fertilization and brooding Storage of sperm Release of competent larvae

  30. Fertilization Spermcast spawning Factors influencing spermcasters 2. Conservation of energy Sperm release Sperm are inactive or periodically active Intake by ‘female’ Consequence: Fertilization can happen with fewer sperm at greater distance Sperm consistently active

  31. Fertilization Spermcast spawning Factors influencing spermcasters 3. Sperm storage -allows accumulation of a number of allosperm Diplosomalisterianum- 7 weeks Celleporellahyalina- Several weeks

  32. Fertilization Spermcast spawning Factors influencing spermcasters Diplosomalisterianum 4. Egg development Sperm release Intake by ‘female’ Celleporellahyalina Triggering of vitellogenesis Consequence: Investment in eggs is not wasted.

  33. PROPAGULES AND OFFSPRING

  34. Patterns of Development Nutritional mode 1) Planktotrophy - larval stage feeds This separates marine invertebrates from all others – can feed in dispersing medium - Probably most primitive

  35. Patterns of Development Nutritional mode 2) Maternally derived nutrition a) Lecithotrophy - yolk b) Adelphophagy – feed on eggs or siblings c) Translocation – nutrient directly from parent

  36. Patterns of Development Nutritional mode 3) Osmotrophy - Take DOM directly from sea water

  37. Patterns of Development Nutritional mode 4) Autotrophy - by larvae or photosynthetic symbionts - In corals, C14 taken up by planulae - In Porites, symbiotic algae to egg

  38. Patterns of Development Site of Development 1) Planktonic development - Demersal – close to seafloor - Planktonic – in water column 2) Benthic development - Aparental – independent of parent – encapsulation of embryo - Parental – brooding – can be internal or external

  39. Patterns of Development Dispersal Potential of Larvae 1) Teleplanic - Larval period – 2 months to 1 year + 2) Achaeoplanic – coastal larvae -1 week to < 2 months (70% of littoral species) 3) Anchioplanic - larval period – hours to a few days

  40. 1) Fertilization patterns 2) Development patterns Developmental Patterns -Kinds of eggs 3) Dispersal patterns 4) Settlement patterns Holoblastic Isolecithal • • • • • • • • • • • • • • • • • • • • • • Cleavage through entire egg • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Telolecithal Meroblastic • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Cleavage not through entire egg • • • • • • • • • •

  41. 1) Fertilization patterns 2) Development patterns Developmental Patterns -Kinds of eggs 3) Dispersal patterns 4) Settlement patterns Isolecithal - Holoblastic Telolecithal - Meroblastic

  42. 1) Fertilization patterns 2) Development patterns Developmental Patterns -Kinds of eggs 3) Dispersal patterns 4) Settlement patterns Holoblastic Isolecithal • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Planktotrophic larvae Telolecithal Meroblastic • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Lecithotrophic larvae

  43. LIFE HISTORY TRAITS Fecundity - Total number of offspring (expressed as a number of offspring over a period of time) Three categories of fecundity 1) Potential – number of oocytes in ovary 2) Realized – number of eggs produced 3) Actual – number of hatched larvae CENTRAL TO THIS – FECUNDITY – EXPENSIVE AND DIRECTLY LINKED TO FITNESS

  44. Relationship of fecundity to other traits • Egg size • - Generally egg size 1/fecundity Look at poeciliogonous species Produce both lecithotrophic and planktotrophic larvae Lecithotrophic – egg 6X larger Planktotrophic –6X as many eggs Streblospiobenedicti Same reproductive investment

  45. OFFSPRING SIZE -volume of a propagule once it has become independent of maternal nutrition Egg size – most important attribute in: 1) Reproductive energetics 2) Patterns of development and larval biology 3) Dispersal potential

  46. Effects of Offspring Size 1) Fertilization -some controversy about evolution of egg size Either a) influenced by prezygotic selection for fertilization OR b) post-zygotic selection

  47. Effects of Offspring Size 1) Fertilization One consequence of size-dependent fertilization Low sperm concentration  larger zygotes High sperm concentration  smaller zygotes (effects of polyspermy)  Size distribution of zygotes - function of both maternal investment and of local sperm concentration

  48. Effects of Offspring Size 2) Development Prefeeding period increases with offspring size Feeding period decreases with offspring size

  49. Effects of Offspring Size 2) Development Prefeeding period increases with offspring size Feeding period decreases with offspring size Evidence? Planktotrophs • pre-feeding period • -larger eggs take longer to hatch • in copepods • - in nudibranchs – no effect

  50. 2) Entire planktonic period -review of 50+ echinoids – feeding 5 echinoids – non feeding Larval period decreases with increase in egg size But for polychaetes and nudibranchs Nudibranchs Polychaetes Planktotrophic • • • Lecithototrophic • Dev. time • • • • • • • • • • • • • • • • • • • • • • • • Egg size (mm) Egg size (mm)

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