1. Interactions Between Populations

2. Traditional approaches to population interactions have been to consider just the direct pairwise interactions This is simplistic in that the population either interact, or they do not

3. Interactions Between Populations There are a number of ways in which the populations my impact one another, if they do

4. Interactions Between Populations Competition ( -, - ) is the most widely interaction we think of Both parties are negatively impacted If the resource is in short supply or high demand, there will be competition If that resource is prey, the form of competition is exploitation competition

5. Interactions Between Populations Other kinds of competition also occur It may be direct (agonistic) encounters such as allelopathy or territorial defense (interference)

6. Interactions Between Populations Predation, parasitism, and Batesian mimicry Predation is usually killing another organism, although can you think of exceptions? Parasitism could be considered a form of weak predation

7. Interactions Between Populations Batesian mimicry and herbivory could also be a form of weak predation

8. Interactions Between Populations Mutualism, Müllerian mimicry

9. Interactions Between Populations Commensalism

10. Interactions Between Populations Amensalism

11. Interactions Between Populations The interactions among populations can become quite intricate and therefore quite fascinating Consider the case of hummingbirds

12. Interactions Between Populations Four nectar feeding birds, two species of mites and four species of flowers Three hummingbirds are the primary pollinators Corollas differ in length Strong selection for a bird/ flower relationship

13. Interactions Between Populations One mite lives in Panterpe and Eugenes, others are specialists Even though suitable habitat is found in other flowers, they are not found there..why? Male mites will actively fight/kill other species of mites within the same flower

14. Interactions Between Populations Within this 10 species community there is (and please name them) exploitative competition, interference competition, facultative mutualism, parasitism, and commensalism

15. Interactions Between Populations Symbiosis is a term used for a general relationship in which organisms live together without harming one another Neutralism: who cares Mutualism: Acacia & ants

16. Interactions Between Populations Ants and many species of caterpillars

17. Interactions Between Populations Mesquite and root nodules housing bacteria that fix nitrogen Mycorrhizae (fungal roots)

18. Interactions Between Populations Bioluminescent bacteria and deep sea creatures Photosynthetic algae

19. Interactions Between Populations It has been hypothesized that endosymbiosis exists The certain of the cell organelles found in higher organisms, particularly chloroplasts and mitochondria, are actually the remnants of symbiotic prokaryotic organisms that have since been permanently incorporated into the eukaryotes

20. Interactions Between Populations Cattle egrets & oxpeckers

21. Interactions Between Populations Honey guides and honey badgers

22. Interactions Between Populations Cleaner wrasse Saber-toothed bleeny

23. Interactions Between Populations Think about the plant/pollinator relationships that exist Not just large animals, but many insects (e.g. euglossine bees and epiphytic orchids) Up to 23km Outcrossing

24. Interactions Between Populations Producing nectar and pollen (and fruit) has costs Rewards must be sufficient to allow returns to get them to specialize on a particular species (why?) However, they must be small enough to the animal will travel the distance between plants

25. Interactions Between Populations Obligate mutualisms are much less common than facultative ones Figs and fig wasps (100s)

26. Interactions Between Populations

27. Termites and the protozoans they house in their intestines Next generation of endosymbionts are passed to one another through shared intestinal contents

28. Interactions Between Populations Commensalism

29. Interactions Between Populations What about indirect interactions Darwin actually accounted for this E.g. clover, bees, mice and cats

30. Interactions Between Populations

31. There is the classical exploitative competition But there is also apparent competition (consider

32. Interactions Between Populations There are also food-chain mutualisms (aka cascading effects) Aquatic example: plants, minnows, and bass Is it bottom-up or top-down?

33. Interactions Between Populations Consider three species populations at the same trophic level (horizontal interactions) P1 and P3 are mutualists because they both inhibit P2

34. Interactions Between Populations A four-species system that results in an indirect mutualism is termed facilitation Consumers indirectly interact as they eat similar, but different prey items (but the plants themselves compete)

35. Interactions Between Populations Conditions that can lead to CM There is a considerable time lag in the indirect effects of CM

36. Interactions Between Populations