1. Species Communities and Niches

2. Species richness The number of species in a community
Increases near equator

3. Relative abundance
population of a given species in a specific size ecosystem
Compares the percent of each species
EX. Percent of mallards in pond compared to total bird population

4. Species diversity
Relates the number of species to the “relative abundance” of each

5. Species area effect
Larger areas usually contain more species than smaller ones
Evident on islands

6. Individualistic concept
Community is made of nothing more than different species that happen to be living in same area

7. Holistic concept
Communities are an integrated unit that depend on each other for survival.
“super organism”

8. Trophic cascade
Interactions among species (plant – animal) promote species richness.

9. Elk eat Aspen trees

10. Wolves eat elk

11. Ex. wolves influence vegetation
Wolf predation near aspen trees increases
Elk change browsing habits
Aspen increase

13. Community stability Resistance to change
Biodiversity increases stability

14. Biodiversity

15. Ecological Niche concept

16. Niche
The role an organism fills in its community

17. Niche determined by Habitat Place in food chain Specific food types
When they eat or hunt

18. Great horned owl and red tailed hawk have different niches
Both eat small rodents
Both live in same area
BUT owls hunt at night, hawks hunt during day

19. Fundamental niche
Potential niche – without any competition

20. Realized niche
The part they actually use due to competition. Usually smaller

21. Competition exclusion
One Species is eliminated from a community because of limited resources. Can not occupy same niche

22. Example paramecium
P. Caudatum paramecium declines in presence of other paramecium

23. Resource partitioning
When several similar species subdivide a niche for resources
Ex. 5 different warbler species eating different areas of a tree

24. Character displacement
One Phenotype is selected because of competition
Ex anoles.
on same island there are populations that eat different things and occupy different niches,

26. Conceptually we can look at the environment as a limited resource that can be shared by one or more species Here, an environmental resource, shown in green, must be shared between the little blue and big red species. It's possible to fill the environments with lots of little blue blocks, a few red blocks, or a mixture of reds and blues. Note that in this example, four blues equal one red individual (the blues need 1/4 of the space, food, or other resource as red individuals). From the environment's point of view, the blues are 0.25 of a red (species A as B; we'll term this as "a"), Red individuals are worth 4 blues (species B as A; we'll call this term "b"), Although in this example the two species are symmetric, they don't necessarily have to be.

27. Depending on the amount of overlap, competition may be nonexistent, weak or strong (Figure 3). Fitness varies with the strength of competition. In areas of low fitness few if any offspring will be passed on to the next generation. Organisms with medium fitness will pass on some offspring to the next generation but not as many as those with high fitness

28. Figure 4 shows some of the possible outcomes for our two species
Figure 4 shows some of the possible outcomes for our two species. Here, the resource continuum represents the limited resource that is at the center of the competition. As an example, assume that the resource is seeds and the X axis is seed size (small, medium, and large). Let's further assume that species 1 and 2 are finches. Finch 1 takes mostly smaller seeds while . finch 2 take the larger seeds. Both, however, take medium-sized seeds

30. Character displacement
When similar species share same location they have greater change in traits (character) ex. Darwin's finches
Different island = similar size
Same island = greater
difference in size