1. LIFE HISTORY PATTERNS

2. Spawning and Fertilization

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

4. Gametes produced come in a variety of sizes LargeMediumSmall Number produced Mitotic competence

5. Gamete size Number produced Size distribution of gametes produced

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

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

8. Gamete size Number produced After several generations Selected against

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. Spermcast spawners -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 intromittent orgtan -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. Boradcast spawners suffer a dilution effect Quinn and Ackerman. 2011. Limnol Oceanogr. 2011: 176

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

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

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

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

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

19. 2. Timing and synchrony How to get around this problem Haliotis asinina Counihan et al. 2001. Mar.Ecol.Prog.Ser.213:193 Conclusions (Counihan et 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.

20. 3. Currents

21. 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:egg ratio important Sperm concentration is imporant

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

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 Storage of sperm Fertilization and brooding 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’ Sperm consistently active Consequence: Fertilization can happen with fewer sperm at greater distance

31. Fertilization Spermcast spawning Factors influencing spermcasters 3. Sperm storage -allows accumulation of a number of allosperm Celleporella hyalina - Several weeks Diplosoma listerianum - 7 weeks

32. Fertilization Spermcast spawning Factors influencing spermcasters 4. Egg development Celleporella hyalina Diplosoma listerianum Sperm release Intake by ‘female’ 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, C 14 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 + 3) Anchioplanic - larval period – hours to a few days 2) Achaeoplanic – coastal larvae -1 week to < 2 months (70% of littoral species)

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

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

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

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 1)Egg size - Generally egg size  1/fecundity Look at poeciliogonous species Streblospio benedicti Produce both lecithotrophic and planktotrophic larvae Lecithotrophic – egg 6X larger Planktotrophic –6X as many eggs 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 1)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 Dev. time Egg size (  m) NudibranchsPolychaetes Planktotrophic Lecithototrophic

51. Intraspecific comparisons Larger larvae result in longer lifetimes e. Ascidians and urchins Dev. time Egg size (  m)

52. POST -METAMORPHOSIS Does egg size affect juvenile size? Echinoids Nudibranchs Conus a.Planktotrophs Size at metamorphosis is independent of egg size b. Non-feeding larvae H. erythrogramma -used for post-metamorphic survival -most maternal investment (lipid) -not necessary for larval development

53. POST -METAMORPHOSIS Does egg size affect juvenile size? b. Non-feeding larvae Bugula -larval size affects - post settlement mortality - growth -reproduction -offspring quality -need energy to develop feeding structures – 10 – 60% of reserves

54. Summary of Offspring Size Predictions -closer to metabolic minimum 1)Species with non-feeding larvae -greatest effect is on post-metamorphic survival 2) Sources of mortality - physical, disturbance, stress – size independent - biological sources – size dependent 3) Offspring size - very different effects among populations

55. SOURCES OF VARIATION IN OFFSPRING SIZE 1) Offspring size varies a) within broods b) among mothers c) among populatioins 2) Within populations a) stress – salinity, temperature, food availability, pollution b) maternal size - +ve correlation

56. 3) Among populations a) habitat quality – poorer habitat results in smaller offspring b) latitudinal variation Bouchard & Aiken 2012

57. 3) Among populations a) habitat quality – poorer habitat results in smaller offspring b) latitudinal variation Bouchard & Aiken 2012

58. OFFSPRING SIZE MODELS Same basic features 1) Trade off in size and number of offspring 2) Offspring size-fitness function 1) Trade off in size and number of offspring N =c/S c = resources N = number S = Size Refers to energetic costs to mother not energy content of eggs Size:energy content more variable

59. OFFSPRING SIZE MODELS Same basic features 1) Trade off in size and number of offspring 2) Offspring size-fitness function 1) Trade off in size and number of offspring -other costs may be involved e.g. packaging of embryos e.g. brood capacity of the mother

60. OFFSPRING SIZE MODELS Same basic features 1) Trade off in size and number of offspring 2) Offspring size-fitness function - Focused on planktonic survival Decrease in size Longer planktonic period Higher mortality

61. OFFSPRING SIZE MODELS Same basic features 1) Trade off in size and number of offspring 2) Offspring size-fitness function Other effects- fertilization rates - facultative feeding - generation time - post metamorphic effects VARIATION IN OFFSPRING SIZE AFFECTS EVERY LIFE HISTORY STAGE

62. SUMMARY OF EFFECTS Planktotrophs - Strong effects of offspring size on life history stages 1) Fertilization in free (broadcast) spawners 2) Larger eggs result in larvae that spend less time in the plankton 3) Larger larvae feed better

63. VARIATION IN OFFSPRING SIZE AFFECTS EVERY LIFE HISTORY STAGE SUMMARY OF EFFECTS 2. Non-feeders - Strong effects of offspring size on life history stages 1) Fertilization success 2) Developmental time 3) Maximize larval lifespan 4) Postmetamorphic performance 5) Subsequent reproduction and offspring size

64. VARIATION IN OFFSPRING SIZE AFFECTS EVERY LIFE HISTORY STAGE SUMMARY OF EFFECTS 3. Direct developers - Strongest effects of offspring size on life history stages - Mothers may be able to adjust provisioning to local conditions