Robert Boyd Department of Biological Sciences Auburn University

1. Reproductive Biology of the Endangered Shrub,Fremontodendron californicum subsp. decumbens,and its Conservation Implications Robert Boyd Department of Biological Sciences Auburn University

2. 3 taxa recognized • Species, or subspecies Fremontodendron californicum • Note F. decumbens,1 site in El Dorado County, CA

3. Fremontodendron californicum subsp. decumbens • Found only near Pine Hill • 2,000 shrubs (<1 mi radius) • Listed federally endangered 1996 Pine Hill from SE

4. Closer view Pine Hill chaparral F. californicum subsp. decumbens

5. Small shrub • 1-2 meters tall F. californicum subsp. decumbens

6. Beautiful flowers • Fruit covered with stiff trichomes • Seeds: orange appendage (elaiosome)

7. Study: Reproductive Biology • Document reproductive attrition • Mark flower buds • Determine fates Marking flower buds in spring Bud marked with wire at its base

8. Reproductive Biology • Answer: insects attack flower buds, flowers, fruits • 1.8% flower buds survive to produce seeds

9. Reproductive Biology • Seed fates • Predation: marked seeds (elaiosomes removed) in caged and uncaged locations under shrubs • After 9 mo: extract & count surviving seeds • Difference between locations: rodent predation

10. Basic Reproductive Biology • Seed fates: Predation • Answer: 90% seeds eaten by rodents

11. Reproductive Biology • Seedling fates • Seeds dormant unless heat-treated • Plant heat-treated seeds in caged and uncaged plots • Document fates in each case

12. Reproductive Biology • Seedling fates • Answer: • Rodents eat some • Insects eat most • Rest die from summer drought Placerville CA rainfall

13. Reproduction Model

14. Today’s story • Pollination: insect visitors to flowers • Dispersal: ants attracted to elaiosomes • Focus on pollination and seed dispersal • Important life cycle stages • Involve mutualist animals

15. Today’s story • Pollination: insect visitors to flowers • Dispersal: ants attracted to elaiosomes • Focus on pollination and seed dispersal • Important life cycle stages • Involve mutualist animals • What roles mutualists in plant reproduction? • Conservation implications?

16. Focus on pollination • Are insect visitors required to make fruits?

17. Focus on pollination • Approach: enclose branches to prevent insect visits • Mark flowers already open (one color wire) • Mark large flower buds (another color)

18. Focus on pollination • Are insect visitors required to make fruits? • 39 flower buds, 0% fruits • 22 flowers open when bagged, 32% fruits • Answer……..

19. Focus on pollination • Are insect visitors required to make fruits? • 39 flower buds, 0% fruits • 22 flowers open when bagged, 32% fruits • Answer: Yes, visits required.

20. Focus on pollination • What insects visit flowers? Which are likely pollinators?

21. Focus on pollination • What insects visit flowers? Which are likely pollinators? • Approach: watch flowers, document visitors • June: two years • 1,746 insect visits.

22. Focus on pollination Answer: Native solitary bees Bee species Percent visits

23. Focus on pollination Stretching for nectar • Dominant visitor: Tetralonia stretchii Nectaries Gathering pollen

24. Focus on pollination • What insects visit flowers? Which likely pollinators? • Answer: Native solitary bees.

25. Focus on pollination • How effective are bees? • Approach: compare fruit set and seed set hand-pollinated flowers.

26. Focus on pollination • Fruit set not significantly different: • Hand-pollinated 80% Bee-pollinated 70%

27. Focus on pollination • Fruit set not significantly different: • Hand-pollinated 80% Bee-pollinated 70% • Seed set different: • Hand-pollinated: 4.9 seeds/flower • Bee-pollinated: 2.6 seeds/flower

28. Focus on pollination • Fruit set not significantly different: • Hand-pollinated 80% Bee-pollinated 70% • Seed set different: • Hand-pollinated: 4.9 seeds/flower • Bee-pollinated: 2.6 seeds/flower • Answer: All flowers pollinated, pollen amount not maximized (seed set 53% of possible).

29. Focus on pollination • How bees find flowers? • Approach: UV photos

30. Focus on pollination • How bees find flowers? • Approach: UV photos All light UV light

31. Focus on pollination • Summary: • Native solitary bees essential to seed production • Not maximizing seed set, but maximizing fruit set.

32. Focus on seed dispersal • The ant connection • Harvester ant: Messor andrei • Attracted to elaiosomes, carry seeds to nests (in openings chaparral) • Discard some seeds on “midden”

33. Focus on seed dispersal • How do ants modify reproductive attrition? • How does ant dispersal benefit plant?

34. Focus on seed dispersal • Possibilities: • 1) Do ants stimulate seed germination (scarify seeds)?

35. Focus on seed dispersal • Possibilities: • 1) Do ants stimulate seed germination (scarify seeds)? • 2) Do ants protect seeds from rodent predation by moving them from under shrubs to open areas?

36. Focus on seed dispersal • Possibilities: • 1) Do ants stimulate seed germination (scarify seeds)? • 2) Do ants protect seeds from rodent predation by moving them from under shrubs to open areas? • 3) Do seedlings on ant middens have better chance survival?

37. Focus on seed dispersal • Possibilities: • 1) Do ants stimulate seed germination (scarify seeds)? • 2) Do ants protect seeds from rodent predation by moving them from under shrubs to open areas? • 3) Do seedlings on ant middens have better chance survival? • 4) Do benefits occur after fire stimulates seed germination?

38. Focus on seed dispersal • 1) Do ants stimulate seed germination (scarify seeds)? • Compare germination of seeds • Fresh from fruits • Given to ants and recovered from midden.

39. Focus on seed dispersal • 1) Do ants stimulate seed germination (scarify seeds)? • No statistical difference % germination Untreated seeds Heat-treated seeds Fresh seeds Ant-handled seeds

40. Focus on seed dispersal • 2) Do ants protect seeds from rodent predation by moving them from under shrubs to open areas?

41. Focus on seed dispersal • 2) Do ants protect seeds from rodent predation by moving them from under shrubs to open areas? • Seed trays in pairs • Canopy edge, 0.5 m, 1 m away in open • Seeds with elaiosomes one tray, without in other

42. Focus on seed dispersal • Compare seed removal • No effect distance • More with elaiosomes taken elaiosome no elaiosome

43. Focus on seed dispersal • 2) Do ants protect seeds from rodent predation by moving them from under shrubs to open areas? • No, seeds not more safe in open • But removal elaiosome helps seeds avoid rodent predation • This benefit of ant handling, but not benefit of elaiosome presence.

44. Focus on seed dispersal • 3) Do seedlings on ant middens have better chance survival? • Plant heat-treated seeds on middens and under shrubs • Cage some to protect from rodents Ant midden Under shrub canopy

45. Focus on seed dispersal • Results: Mean seedling longevity in days (SD) Canopy Ant midden Caged Uncaged Caging helps, survival on middens is less!

46. Focus on seed dispersal • 4) Do benefits occur after fire stimulates seed germination? • Approach: experimental burn!

47. Focus on seed dispersal • 4) Do benefits occur after fire stimulates seed germination? • Preparation/planning!

48. Focus on seed dispersal • 4) Do benefits occur after fire stimulates seed germination?

49. Focus on seed dispersal • 4) Do benefits occur after fire stimulates seed germination? Aerial view Ground view

50. Focus on seed dispersal • Seedlings counted & marked during winter (rainy) season following fire • Most under canopy/at canopy edge