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 • As species, or as subspecies of Fremontodendron californicum • Note F. decumbens, only 1 site in Eldorado County, California

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

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

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

6. Beautiful copper-colored flowers • Fruit covered with stiff trichomes • Seeds have orange appendage (elaiosome)

7. Basic Reproductive Biology • Document reproductive attrition • Mark flower buds • Determine fates Marking flower buds in spring A bud marked with wire at its base

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

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

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

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

12. Basic Reproductive Biology • Seedling fates • Answer: • Rodents eat some • Insects eat most • Rest die from drought during summer

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 of mutualists in reproduction of plant? • What are conservation implications?

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

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

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

19. Focus on pollination • Are insect visitors required to make fruits? • Of 39 flower buds, 0% fruits • Of 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 to document visitors • During June of two years • Document 1,746 insect visits.

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

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

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

25. Focus on pollination • How effective are bees? • Approach: compare fruit set and seed set of 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 • Currently not maximizing seed set, but maximizing fruit set.

32. Focus on seed dispersal • The ant connection • Harvester ant: Messor andrei • Attracted to elaiosomes of seeds

33. Focus on seed dispersal • The ant connection • Carry seeds to nest • Remove elaiosome

34. Focus on seed dispersal • The ant connection • Discard some intact seeds on midden (waste pile) around nest entrance • Nest entrances located in openings in chaparral

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

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

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?

38. 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?

39. 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?

40. 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.

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

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

43. Focus on seed dispersal • 2) Do ants protect seeds from rodent predation by moving them from under shrubs to open areas? • Use seed trays placed in pairs • Place at canopy edge, 0.5 m, 1 m away in open

44. Focus on seed dispersal • 2) Do ants protect seeds from rodent predation by moving them from under shrubs to open areas? • Use seed trays placed in pairs • Place at canopy edge, 0.5 m, 1 m away in open • Put seeds with elaiosomes in one tray, without in other of each pair • Compare seed removal.

45. Focus on seed dispersal • No effect of distance • More seeds with elaiosomes taken elaiosome no elaiosome

46. 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 of elaiosome helps seeds avoid rodent predation • This benefit of ant handling, but not benefit of elaiosome presence.

47. 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

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

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

50. Focus on seed dispersal • 4) Do benefits occur after fire stimulates seed germination? • Takes lots of preparation/planning!