1. Predation
Great White Shark and Fur Seal

2. Plant defenses are developed at a cost to fitness when:
1. Organisms evolve more defenses if they are exposed to much damage and fewer defenses if cost of defense is high
2. More defenses are allocated within an organism to valuable tissues that are at risk
3. Defense mechanisms are reduced when enemies are absent and increased when plants are attacked - mostly true for chemicals not structures
4. Defense mechanisms are costly and cannot be maintained if plants are severely stressed by environmental factors

3. Pine beetle infestation – British Columbia

4. Pine Beetle and Pitch Tube

5. Serengeti Grazing System

6. Serengeti Grazing System

7. Serengeti Grazing System

8. Grazing facilitation
Grazing facilitation occurs when the feeding activity of one herbivore species improves the food supply for a second species

9. Opuntia stricta – prickly pear

10. Prickly pear infestation in Australia

11. Area infested with prickly pear before biocontrol

12. Same area after biocontrol

13. Biocontrol Agent – Cactoblastis cactorum

14. Symbiosis

15. Symbiosis Symbioses - species living in close association
Parasitism +,- parasite benefits, host harmed
Commensalism +,0 or 0,0 can have positive effect for one species or for neither
Mutualism +,+ both species benefit

16. Gopher Tortoise – Commensal Host

17. Gopher Tortoise Distribution

19. Epiphytes
Bird’s Nest
Fern

20. Nalini Nadkarni
studying
epiphytes

21. Epiphytes
Figure 1: Hypothetical tree illustrating how vascular epiphytes in humid forests tend to partition substrates illustrating sensitivity to micro climate, particularly humidity, and associated development of the organic rooting media required by some populations.

22. Parasitism and Disease
Lyme Disease Cycle in the UK

23. Parasitism
Parasitism - intimate association between two species in which the parasite obtains its nutrients from a host - parasite usually causes some degree of harm to its host - either reduced growth or reproduction
Pathogen – disease causing agent
Disease – abnormal condition of host due to infection by a pathogen that impairs physiological functioning

24. Parasites on
Plants

25. Insects are green,
Fungi are brown,
Worms are blue,
Protozoa are yellow

26. Parasitism occurs on a continuum from:
ectoparasites - live outside hosts body and experience same conditions as host - ticks, mites, fleas, aphids
endoparasites - live inside host's body cavity - buffered from outside conditions - tapeworms, flukes
intracellular parasites - live inside individual cells of the host - viruses, bacteria, protozoa - often called microparasites

27. Or another way to divide parasites:
microparasites - viruses, bacteria, protozoa - small, often live intracellularly, main point is that they reproduce in host and will have very large numbers in host
macroparasites - tiny to very large - nematodes, tapeworms, flukes - larger individuals that grow in host but multiply by producing infective stages that are shed by host to environment where they infect new hosts

29. Parasite Transmission
Direct transmission – from one host to another of the same species via air, water, coughing, blood, feces, etc.
Indirect transmission – from one host to another of the same species via another species called a vector
Vector – species which transmits parasite or pathogen from one host to another

30. Microparasites
Macroparasites
Direct transmission
HIV virus,
Amoebic dysentery,
Mildews on plants
Lice, fleas, ticks, aphids, hookworm, pinworm,
mistletoe
Indirect transmission
Plasmodium (mosquito),
Plant viruses (aphids),
Trypanosoma (tsetse fly)
Tapeworms,
Schistosomes (snails),
Rust fungi

31. Powdery Mildew on Grape Leaf

32. Powdery Mildew Life Cycle

34. Head Lice and Life Cycle

35. Mistletoe

36. Mistletoe Life Cycle

37. Malaria disease cycle

39. Schistosomiasis - Life cycle of the schistosome worm

40. Worldwide incidence of schistosomiasis

41. Worldwide incidence of schistosomiasis

42. Rust Fungus Canker

43. Rust Fungus Life Cycle

44. Two ways to study parasite numbers
Prevalence – percent of host population that is infected – best for microparasites
Intensity – number of parasite individuals per host – usually best for macroparasites

45. Frequency of infection
Parasites usually occur in aggregated distributions – due to 4 possible factors: 1) random colonization events followed by asexual reproduction in hosts that do get parasitized 2) environmental "hot spots" where parasite eggs and infective stages survive well 3) dispersal constraints - geographic or behavioral barriers limit dispersal of parasites to just a few hosts 4) variation in susceptibility of individual hosts - due to nutrition, genetics

46. European rabbits as pests in Australia - 1938

47. Introduced pests in Australia – red fox, rabbit, cat, pig, & goat