1. PROPAGULES AND OFFSPRING

2. 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

3. 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

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

5. 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

6. 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

7. 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)

8. 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

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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

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

17. 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

18. 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

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

20. 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

21. 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

22. 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

23. 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

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

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

26. 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

27. 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

28. 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

29. 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

30. 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

31. 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

32. 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