Island syndromes in plants

1. Island syndromes in plants Aurea C. Cortes-Palomec

2. Hypothetical plant: Plantita

3. Many others like Plantita live in its habitat

4. And many others species

5. Herbivores Seasonal growth

6. Seed dispersal

7. Plantita’s seeds got to Isla

8. It became a tree

9. Increased the size of its seeds

10. Development of separate plant “sexes” Dioecious Monoecious

11. History of many Island plants Island Plantsyndromes

12. Questions: • What are the main adaptive syndromes present in island plants? • 2) What are the environmental and ecological factors present in islands that favor the evolution of similar traits?

13. Questions: 3) What are the advantages of developing woody tissue? How does that affect the fitness of a plant? 4) Why is it an advantage for colonizing plants to exhibit high levels of seed dispersability but island species to have reduced seed dispersability?

14. Questions: 5) How does the development of dioecy contribute to the long-term persistence of species in an island system? 6) What environmental factors lead to the loss of competitiveness?

15. Coast. Mat-like tendencies, Small leaves, round and succulent Chamaesyce degeneri

16. C. remyi Large leaves, tree-shrub Rainforest

17. Leaves small shed in dry, hot weather. Succulent stems store water. C. celastroides Tree, shrub Lowland forest

18. C. rockii Cloud forest. Up to 8 m tall

19. Directional change in stature increasing from dry to wet areas in Chamaesyce

20. Honolulu Sea level 703mm with dry season during the summer mean 23.3 C Oahu Tantalus 408m 2520mm no dry season mean 20 C

21. Brassicaceae Lepidium L. virginicum L. bidentatum

22. Plantago P. major usually rosette P. princeps long stem up to 1.5 m

23. Charpentiera Deeringia

24. Factors that favor arborescence: *Moderate climate and continuous growing season allows continuous growth *Mean temperature no lower than 10C can be the threshold for arborescent species in most areas (i.e. Hawaiian rain forest). *Absence of extremes *Absence of big herbivores

25. Dioecy: Result from selection for outcrossing Avoid inbreeding

26. Dioecy: World wide: Ca. 4 % flora is dioecious Hawaii: Carlquist: 27.7 % is dioecious Sakai: 971 native species 14.7% dioecious 20.7% dimorphic

27. Hawaiian flora: Highest incidence of dioecy of any flora surveyed

28. Higher incidence of dioecy in endemic species than in indigenous ones More in older islands (takes some time to evolve)

29. Dioecy is significantly associated with woodiness and hermaphroditism with herbaceous habit It is the result of both colonization of dioecious species as well as evolution in the islands.

30. Change in pollination syndromes: In Hawaii there are few native bees

31. Only two species of butterflies No bumblebees One native terrestrial mammal (bat) And only 50% of known orders of insects 15% of known families

32. Small green or white flowers are abundant -- these colors are presumably associated with pollination by wind or unspecialized insects. Reduced number of specialized floral syndromes Favor unspecialized dioecious flowers

33. Change in dispersal mechanism Bidens

34. Bird dispersal (coast) to Wind dispersal (inland)

35. Bidens pilosa to B. torta Ancestral Derived

36. Euphorbia celastroidesE. clausidefolia,E. rockii (Sticky seeds) (non-sticky) There is also an increase in seed size If you are too big birds can not eat you!!!

37. Chamaesyce Gigantism (Large seeds)

38. Erythrina usually dispersed by water, in Hawaii they can not float anymore (E. sandwicensis)

40. Advantages of an increase in seed size: * Poor dispersal favors establishment near the parental plant * Immigration towards wet forest where poor dispersability is common * Larger seeds better adapted to grow in shade * Change in habitat leads to loss of contact with the agent of dispersion so the ability is lost

41. Loss of competitiveness: * No mechanical defenses, no scented oils (i.e. odorless mints in Hawaii, mints are insect repellents) * Hawaii species are less competitive than continental species Develop in a safe herbivore-free environment

42. Rhus Rhus sandwicensis

43. Rubus hawaiensis Not physical defenses

44. Pritchardia Its seeds are not protected, now it is endangered due to the presence of the Polynesian rat

45. * No poison plants..... no big herbivores therefore not needed * No evolutionary pressure on them so they were lost

46. On islands, initially, more sites available, some similar to those of the ancestors and some totally different leading to speciation

47. Questions: • What are the main adaptive syndromes present in island plants? *Arborescence *Dioecy *Reduced competitiveness *Reduced dispersability

48. Questions: 2) What are the environmental and ecological factors present in islands that favor the evolution of similar traits? * Continuous growing season * Lack of herbivores * Presence of different microclimates * Lack of recolonization

49. Questions: 3) What are the advantages of developing woody tissue? How does that affect the fitness of a plant? * Increase in size => More competitive * Perennial => More seeds * Larger investment on seeds

50. Questions: 4) Why is it an advantage for colonizing plants to exhibit high levels of seed dispersability but island species to have reduced seed dispersability? High dispersability => Reach the island Low dispersability => Stay in the island