1. Biological Communities and Species Interactions

2. Why is Earth "just right" for life?
Distance from sun
Size
Rotation
Orbit around sun
Atmospheric evolution
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3. determine abundance and distribution
Who lives where and why?
Interaction of several factors determines biogeographical distribution.
determine abundance and distribution
Species requirements and tolerances can also be used as useful indicators.

4. Tolerance Limits

5. Adaptation
Adapt is used in two ways:
Limited range of physiological modifications
Inheritance of specific genetic traits
Evolution
Microevolution
Macroevolution

6. Evolution & Adaptation
Microevolution- change in gene frequency within a population
Macroevolution- formation of new species from ancestral species
Genes mutateindividuals selectedpopulations evolve
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7. Microevolution Four processes drive microevolution:
Genetic variability
Natural selection
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8. Microevolution 3. Gene flow 4. Genetic drift:
Four processes drive microevolution, cont:
3. Gene flow
4. Genetic drift:

9. Natural Selection
Directional selection favors individuals with traits that are at one end of a distribution
giraffe example
"It pays to be different.”
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11. Natural Selection
Stabilizing selection eliminates individuals at both ends in the spectrum of variation
the average remains the same.
"It pays to be average.”
Ex. Plant height
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13. Natural Selection
Disruptive (diversifying) selection eliminates average individuals, but favors individuals at either extreme of the spectrum of variation.
"It doesn't pay to be normal.“
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15. Convergent Evolution
Species from different evolutionary branches may come to resemble one another if they live in very similar environments
Example:
1. Ostrich (Africa) and Emu (Australia).
2. Sidewinder (Mojave Desert) and
Horned Viper (Middle East Desert)

17. Coevolution Evolutionary change
Competitive relationships lead to coevolution.
Example:
Cheetah and gazelle
Insects and flowers

18. Macroevolution
Speciation-Evolution of a new species-geographical isolation or selective pressure can create an entirely new species.

19. Speciation
Geographic isolation can lead to reproductive isolation, divergence and speciation.
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20. Community Relationships
Habitat
Niche
Includes:
range of tolerance for various physical conditions (temp and water)
types and amounts of resources it uses
interactions with abiotic and biotic components
the role it plays

21. Niche Fundamental niche: theoreticaly use if there were no competition
Realized niche: actually uses

22. Resource Partitioning
Law of Competitive Exclusion
Migrate, extinct, or partition

23. Types of Species Generalist Specialist broad niches
tolerate wide range of environmental variations
Specialist
narrow niches
more likely to become endangered
do better under consistent environmental conditions

24. r and k strategists The r-strategists
High biotic potential – reproduce very fast
Are adapted to live in a variable climate
Produce many small, quickly maturing offspring = early reproductive maturity
“Opportunistic” organisms
The K-strategists
Adaptations allow them to maintain population values around the carrying capacity
They live long lives
Reproduce late
Produce few, large, offspring

25. What Different Roles Do Various Species Play in Ecosystems?
Native
Nonnative
Indicator species
Keystone species

26. Nonnative/Exotic/Alien Species
Non-native Species
Nonnative/Exotic/Alien Species
Examples: Zebra Mussels in the Great Lakes, Snakehead fish in MD, Mongoose in Hawaii, Cane Toads in Australia

27. Keystone Species
Strong interactions with other species which affect the health and survival of those species
If a keystone species is removed from a system
the species it supported will also disappear
other dependent species will also disappear

28. SPECIES INTERACTIONS
Predator
Reduce competition, population overgrowth, and stimulate natural selection.
Coevolution

29. Predator Adaptations

30. Prey Adaptations

31. Competition
Interspecific -different species
Results in: migration, population declines
Intraspecific - same species
Intense due to direct competition for same resources
Territoriality
Disadvantages?

32. Symbiosis
Symbiosis
Mutualism - Both members benefit.
Insects and flowers
Ex. Yucca plant and moth

33. Mutualism

34. Symbiosis Cont…
Commensalism
Sharks and remora
Whales and barnacles

35. Symbiosis Cont…
Parasitism –
Humans and Tapeworms

36. Ecological Processes Primary Succession Secondary Succession
Ecological Succession
Primary Succession
Secondary Succession

37. No preexisting seed bank
Primary Succession
Gradual establishment of biotic communities in an area where no life existed before
No preexisting seed bank
newly formed islands (i.e. volcanic origin)
retreat of a glacier

39. Primary Succession Glacier Retreat

40. Secondary Succession
Gradual reestablishment of biotic communities in an area where one was previously present.
Preexisting seed bank
"old field succession"
forest fire