1. Living In Ecosystems Chapter 30
Copyright © McGraw-Hill Companies
Permission required for reproduction or display
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

2. Life History Adaptations Population Demography
Outline
Population Growth
Life History Adaptations
Population Demography
The Niche and Competition
Resource Partitioning
Symbiotic Relationships
Plant and Animal Defenses
Predator-Prey Cycles
Ecological Succession
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

3. Population Dispersion Capacity for Growth
Population Growth
Populations are composed of groups of individuals of the same species living together.
Critical Properties
Population Size
Population Density
Population Dispersion
Capacity for Growth
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

4. Exponential Growth Model
Population Growth
Exponential Growth Model
Assumes population growing without limits at its maximal rate. (r = biotic potential)
dN/dt=riN
N = Number of individuals in population
dN/dt = Rate of change in population size over time
ri = Intrinsic rate of increase
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

5. Innate capacity for growth of any population is exponential.
Population Growth
A population’s actual rate of increase is the difference between birth rate and death rate corrected for migration.
Innate capacity for growth of any population is exponential.
Even when rate of increase remains constant, the actual increase in the number of individuals accelerates rapidly as the size of the population grows.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

6. Number of individuals an area can indefinitely support.
Population Growth
Carrying Capacity (K)
Number of individuals an area can indefinitely support.
Logistic Growth Model
As population approaches its carrying capacity, its growth rate slows as resources become scarce.
dN/dt = rN (K-N/K)
Sigmoid Growth Curve
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

7. Two Models of Population Growth
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

8. Life History Adaptations
Exponential Model
Describes species with r-selected adaptations.
Favor high rate of increase
Logistic Model
Describes species with k-selected adaptations.
Favor reproduction near carrying capacity.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

9. Johnson - The Living World: 3rd Ed
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

10. Influence of Population Density
Density-Dependent Effects
Effects are independent of population size and act to regulate growth (weather).
Effects are dependent on size of population and act to regulate growth (resource competition).
Have increasing effect as population size increases.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

11. Population Demography
Age Structure
Cohort - Group of individuals of same age. Each has a characteristic:
Fecundity Rate - Number of offspring produced during a standard time.
Mortality Rate - Number of individuals that die during a standard time.
Relative number of individuals in each cohort defines population’s age structure.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

12. Population Demography
Sex Ratio
Proportion of males and females in a population.
Usually directly related to number of females in the population.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

13. Population Demography
Survivorship Curves
Graphically express age distribution characteristics by plotting percentage of original population that survives to a given age.
Type I - Mortality rises in post-reproductive years.
Type II - Mortality constant throughout life.
Type III - Mortality low after establishment.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

14. Survivorship Curves
Copyright © McGraw-Hill Companies
Permission required for reproduction or display
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

15. Population Demography
Life Tables
Indicate chance of survival at any age.
Follow cohort from birth to death.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

16. The Niche and Competition
Niche - Biological role in community.
Fundamental - Theoretical role
Realized - Actual role
Competition - Two or more organisms attempt to use same resource.
Interference - Fighting
Exploitative - Consuming shared resources
Interspecific - Different species
Intraspecific - Same species
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

17. Barnacle Competition
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

18. Competitive Exclusion
Gause - No two species can coexist in the same niche indefinitely.
When two species coexist on long-term basis, their niches differ in one or more features.
Otherwise, one is eventually driven to extinction.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

19. Resource Partitioning
Sympatric Species - Occupy same geographical area but avoid competition by utilizing different portions of the habitat.
Character Displacement - Differences arise between species due to natural selection.
Allopatric Species - Do not occupy same geographical area, thus are not usually in competition.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

20. Mutualism - Both species benefit.
Symbiosis
Symbiotic Relationship - Two or more species of organisms live together, and at least one gains benefit.
Commensalism - One species benefits while other neither benefits or is harmed.
Mutualism - Both species benefit.
Parasitism - One species benefits while the other is harmed.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

21. No definite boundary between commensalism and mutualism.
Symbiotic relationship that benefits one species and neither hurts or helps the other.
Oxpeckers and Rhinos
No definite boundary between commensalism and mutualism.
Copyright © McGraw-Hill Companies Permission required for reproduction or display
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

22. Symbiotic relationship among organisms in which both species benefit.
Mutualism
Symbiotic relationship among organisms in which both species benefit.
Ants and Aphids
Ants an Acacias
Copyright © McGraw-Hill Companies
Permission required for reproduction or display
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

23. Ectoparasites - External parasites.
Parasitism
Specialized form of symbiosis in which predator is much smaller than prey. Interaction is harmful to prey but beneficial to predators.
Ectoparasites - External parasites.
Parasitoids - Lay eggs on living hosts.
Endoparasites - Internal parasites.
Brood Parasitism - Lay eggs in nests of other species.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

24. Predator-Prey Interactions Morphological Defenses
Plant Defenses
Predator-Prey Interactions
Morphological Defenses
Thorns, spines, plant hairs
Chemical Defenses
Secondary chemical compounds
Evolution of herbivores avoiding plant defense allows access to a new resource without competition from other herbivores.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

25. Feeding on plants rich in secondary compounds may have added benefit.
Animal Defenses
Feeding on plants rich in secondary compounds may have added benefit.
Blue Jays and Monarch Butterflies
Defensive Coloration
Aposomatic Coloration - Advertise poisonous nature with bright coloration.
Cryptic Coloration - Camouflage
Chemical Defenses
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

26. Predation is consumption of one organism by another.
Predator-Prey Cycles
Predation is consumption of one organism by another.
Under simple laboratory conditions, predators often exterminate their prey, and then become extinct themselves when they run out of food.
If refuges are provided for the prey, a few individuals usually exist, and then repopulate after the predators die out.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

27. Snowshoe Hares (Lepus americanus). Food - Willows
Predator-Prey Cycles
Snowshoe Hares (Lepus americanus).
Food - Willows
Predators - Canada Lynx (Lynx canadensis)
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

28. Mimics must be relatively rare.
Mimicry
Batesian Mimicry - Palatable individuals mimic distasteful or toxic individuals.
Mimics must be relatively rare.
Mullerian Mimicry - Unrelated but protected (toxic) species come to resemble one another.
Copyright © McGraw-Hill Companies Permission required for reproduction or display
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

29. Ecological Succession
Succession - Ecosystem change from simple to more complex plant communities.
Secondary Succession - Occurs in areas where an existing community has been disturbed.
Primary Succession - Occurs on bare rocks.
Climax Community
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

30. Ecological Succession
Three Critical Concepts of Succession
Tolerance
Facilitation
Inhibition
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

31. Measure of number of different types of species in an area.
Biodiversity
Measure of number of different types of species in an area.
Crucial to ecosystem preservation.
Biodiversity Promotion
Ecosystem Size
Larger ecosystems, usually have higher levels of biodiversity
Latitude
Length of growing season
Climatic stability
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

32. Latitudinal Cline in Species Richness
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

33. Island size and distance from mainland play important roles.
Island Biogeography
Equilibrium Model
McArthur and Wilson proposed island species richness is a dynamic equilibrium between colonization and extinction.
Island size and distance from mainland play important roles.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

34. Equilibrium Model of Island Biogeography
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

35. Life History Adaptations Population Demography
Review
Population Growth
Life History Adaptations
Population Demography
The Niche and Competition
Resource Partitioning
Symbiotic Relationships
Plant and Animal Defenses
Predator-Prey Cycles
Ecological Succession
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

36. Copyright © McGraw-Hill Companies Permission required for reproduction or display
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies