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1. Introduction to Community Ecology
2. Community estimated 1.5 million � 30 million species that live on earth today
fraction of those species that coexists in space and time and interact with one another (and the environment)
3. Organizational Hierarchy sub-organism
whole organism
population
community
ecosystem
landscape
4. Organizational Hierarchy sub-organism
whole organism
population � individuals of the same species
community
ecosystem
landscape
5. Organizational Hierarchy sub-organism
whole organism
population
community � multiple species interacting (biotic elements)
ecosystem
landscape
6. Organizational Hierarchy sub-organism
whole organism
population
community
ecosystem � biotic plus abiotic features
landscape
7. Organizational Hierarchy sub-organism
whole organism
population
community
ecosystem
landscape
separations and distinctions between levels are artificial (Vitousek 1990)
should understand processes at least one level and one down from your level of interest
8. Goal of Community Ecology to understand origin, maintenance, and consequences of biological diversity
9. Major Questions How do communities change in space/time?
What are the organizing features of communities?
How many species occur and why?
Which species are dominant and why?
Which species are common or rare and why?
What is the relationship between species composition and functional diversity?
10. Shifts in Community Ecology descriptive to experimental
mathematical modeling
improvements in statistical techniques
11. Challenges taxonomy
complexity of interactions
changing environment
natural
anthropogenic
search for generality
experimentally intractable
12. Long-term Temporal Processes evolutionary time
13. Short-term Temporal Processes affect species occurrences and dynamics
difficult to simulate/manipulate/plan for
14. Temporal trends compare sites that differ in time since disturbance to study indirectly community change (chronosequence)
assumption: sites are ecologically identical, except for time since disturbance
15. Glacial Retreat Chronosequence
16. Spatial Patterns species composition may have some degree of spatial dependency
17. Subsets of Communities Guilds � similar functions or use similar resources
Taxocene � taxonomically related group
Trophic levels � acquire energy in similar ways
Food chains/webs � energy flow between species in communities
18. Biome general type of community
terrestrial biomes distinguished mostly by their plants (see p.9 & 11, Morin for expanded list)
determined by climate
precipitation
temperature
19. Physically Defined Communities species found together
boundaries of habitats
discrete
gradual
20. Taxonomically Defined Communities use major dominant taxa
Longleaf pine/wiregrass savannas (Pinus palustris and Aristida stricta)
21. Statistically Defined Communities similarity in species composition
loosely or tightly associated species
22. Interactively Defined Communities species may be in the same geographic area but not interact
defined by those species that influence each others� abundances
of 7 common salamanders in North Carolina mountains, only 2 interact (Hairston 1981)
23. Community Properties
24. Richness number of species
difficult to obtain
does not include commonness and rarity
sufficient sampling effort?
25. Diversity indices of diversity take into account richness AND abundance AND evenness
How evenly distributed are individuals among the species present?
imagine 2 communities with 10 species and 100 individuals
One community has 91 individuals of one species and 1 individual in the other 9 species.
A second community has 10 individuals of each species present.
Which is the most diverse?
26. Diversity takes into account richness AND abundance AND evenness
How evenly distributed are individuals among the species present?
imagine 2 communities with 10 species and 100 individuals
One community has 91 individuals of one species and 1 individual in the other 9 species.
A second community has 10 individuals of each species present.
Which is the most diverse?
27. Alpha, Beta and Gamma Diversity Alpha diversity � diversity within a single type of habitat
Beta diversity � turnover in species composition among different habitats
Gamma diversity � diversity present across the broader landscape