Ecology is the study of interactions between living and non-living components in an environment. Communities are assemblages of multiple species that live together in an environment. Over time, communities undergo succession as they evolve towards a climax community best suited to the local environment. Organisms within a community interact through symbiotic relationships that can be mutually beneficial, competitive, or involve predation. Energy and nutrients flow through the community from producers like plants through various consumer trophic levels in food webs.

1. Lecture 13a: Ecology Ecology

2. Ecology Definition: the study of interactions between all of the living and non-living components in an environment So, discussion of ecology can include Animals and plants Soil and water qualities Climate Human impacts

3. Communities Definition: assemblage of populations of multiple species within a single environment Ex: Fallen log Ex: Forest Fairly broad- can be small or large

4. Communities Because the organisms in a community have lived together over a long period of time, opportunity for coevolution When an evolutionary change in one organism influences an evolutionary change in another organism Ex: Many flowers and their pollinators

5. Coevolution

6. Interactions Communities do not exist in a vacuum- the organisms interact with each other and with the environment-- this is an ecosystem

7. Community Composition Species richness : what species make up a community- basically just a list Diversity : richness plus species distribution and relative abundance within the ecosystem If different species spread throughout, more diverse than if only one is abundant

8. Succession Communities change over time- but can take decades to see the changes Succession is the process of an ecosystem moving to a climax community after a disturbance Each particular environment will lead to a stable climax community-a specific assemblage of plants and animals best suited to that environment

9. Primary Succession Occurs when ‘new’ land becomes available- starts from bare rock or sand after glacier retreats, lava flows, etc.

10. Secondary Succession Occurs after a disturbance- fire, agriculture, etc- there is already soil present

11. Succession In either case, first species are pioneer species - small, short-lived, and quick to mature (i.e. weeds) First in primary are lichens and mosses- lichens help break down rocks into soil Gradually, more equilibrium species move in- both plants and animals

12. Ecological Niche Niche : the specific ‘role’ of the organism in the ecosystem, including what it eats, where it lives, when it is active, how it interacts with others Habitat : the part of the ecosystem that the organism in question lives in Ex: Ecosystem for hippos is African savanna, habitat is the river and surrounding shorelines

13. Interactions Organisms interact with each other constantly, both within and outside of their species Interactions, called symbiotic relationships , can be either positive or negative for each

14. Competition Competition can be for food, space, nutrients Competitive exclusion principle : no two species can occupy the same niche at the same time Leads to niche specialization , a way to reduce competition where different species use different resources, even though both could potentially use the same one

15. Competition Character displacement - organisms that have partitioned resources will evolve to suit their acquired niche, and thus the characteristics in question will become more different over time Ex: bird beaks in birds that eat different foods

16. Character displacement Spoonbill-uses bill like a shovel in sand Pelican- catches fish under water Heron- stabs larger fish Skimmer- uses bottom bill to scoop fish from surface

17. Mutualism A relationship in which both members benefit Also very important Ex. plants and pollinators Ex. lichens (algae and fungus, living together) Ex. Ants and caterpillars http://www.youtube.com/watch?v=z3bWqlPLpMg&feature=BF&list=PLD91727B50EF35272&index=2

19. Predation When one animal eats another Parasitism is a form of predation in which the predator lives in or on the prey, called the host Ex: cheetahs and gazelles Ex: owls and moles Ex: hookworm and humans!

20. Commensalism Relationship when one organism benefits and the other is neutral Ex: One animal transports another Ex: Sea anemones and clown fish

21. Fish: gets protection from predators Anemone: doesn’t care

22. Name That Relationship! Microhylid frog + tarantula?

23. Name That Relationship! Hermit crab + sea anemone

24. Name That Relationship! Ants + acacia trees

25. Name That Relationship! Cerambycid beetle + pseudoscorpion

26. Community Stability Really, communities are fragile, not stable- stability is hard to achieve because of natural disasters, human encroachment, etc. Keystone species are species that help to stabilize community, other species’ survival can depend on this one species Frequently not abundant Ex: grizzly bears Ex: bats in tropical forests

27. Keystone Species: Sea Otter Sea otters live in kelp forests Eat lots of sea urchins, keep populations low so urchins don’t eat all the kelp However, fishermen want to remove otters because they also eat abalone But, if all otters are gone kelp forest will be gone and abalone will be gone because urchins will eat all the kelp and destroy the ecosystem

29. Role of Organisms How an organism feeds is part of its niche: Autotrophs: take in inorganic nutrients (CO2, minerals) and outside energy source Plants, algae These organisms are producers , because they produce food

30. Role of Organisms Heterotrophs: need a source of organic nutrients, release CO2 Called consumers , because they consume food Four types: Herbivores: eat plants Carnivores: eat other animals Omnivores: eat both plants and animals Detritivores: decompose wastes and dead material

31. Energy and Chemical Flow Solar energy enters ecosystem through plants Plants convert this into chemical energy via photosynthesis Chemical energy is used by animals

32. At each level, some energy is used, some lost as heat Less energy is available to the next level

33. Chemical Cycles Plants use nutrients in the soil to make organic compounds Animals eat the plants and use those compounds When animals die or eliminate waste, nutrients are broken down by detritivores and returned to soil, available to plants again

35. Food Webs and Energy/ Chemical Flow Food webs represent energy flow from Producers to Primary Consumers to Secondary and Tertiary Consumers Can also be drawn to represent detrital food webs, showing what eats waste Important to realize where energy is stored- may be in living matter (rainforests) or in dead materials (temperate forests)

38. Trophic Levels There are always fewer consumers than there are producers, because energy is always lost as heat and used for cellular respiration and growth in every organism As a general rule, only 10% of energy in one level is available to the next

40. Another way to see it Biomass: it takes 10,000 g of grass to support 10g of snake

41. Primary Productivity Rate at which producers capture and store energy Depends on species, temperature, moisture, soil Highest in tropical environments, lowest at high altitudes, tundra, desert Think of how this relates to high species richness and diversity in tropical rainforest vs. tundra

42. Rainforest

43. Tundra