1. Natural Selection and Species Interactions
“Nature has given women so much power….”
- Samuel Johnson

2. The Great Leap Forward
Starting in 1958, Mao Zedong, leader of the Communist Party of China, initiated a series of policies to transform the country into a modern, industrialized, communist society.
One of the first actions taken was known as the Four Pests Campaign.
This campaign sought to eliminate rats, flies, mosquitoes, and sparrows.

3. The Four Pests Campaign
Masses of people were mobilized to eradicate the Eurasian Tree Sparrow.
Tactics included:
Banging pots and pans, preventing the birds from landing, until they were exhausted.
Tearing down nests.
Shooting them from the sky using guns and sling shots.
“Everyone come and fight sparrows.”

4. Unintended Consequences
The sparrows were hunted because they ate grain seeds; reducing crop yields.
By April of 1960, Chinese leaders came to realize that the sparrows also ate a large number of pest insects, including locusts.

5. Unintended Consequences
The government made a series of other poor agricultural decisions at this time, including:
Ordering farmers to increase the density of their planting by 6 times, believing that the same species of plant would compete with itself.
Deeper plowing of the soil, which brought up sand and rocks instead of more topsoil.

6. The Great Famine
The locust plague, overplanting, and overplowing combined with a severe drought.
The number of victims is unknown, but estimated between million.

7. Ecosystems: Everything is Connected
An ecosystem is all of the organisms living in an area.
Components of an ecosystem:
Biotic Factors – Living and once living parts of an ecosystem.
Ex: Plants, animals, dead matter, waste
Abiotic Factors – Nonliving parts of an ecosystem.
Ex: Water, rocks, light

8. Organization of Life and the Environment
Organism – An individual living thing.
Species – A group of organisms able to breed and fertile offspring.
Population - All members of a species that live in the same area at the same time.
Biological Community - All populations living and interacting in an area.
Ecosystem - A biological community and its physical environment.
Biosphere – All ecosystems in the entire Earth.

9. Ecosystem Organization

10. What lives where, and why?
Habitat – Where an organism lives
Every organism a range of factors it can survive in.
Ex: Temperature, precipitation, etc.
Critical Factor - Single factor that is the most critical in determining how species are distributed – who lives in what habitat.

11. Tolerance Limits
Tolerance Limits - Minimum and maximum levels beyond which a particular species cannot survive or reproduce.

12. Adaptation
Adaptation – A trait that allows a species to survive more easily and reproduce.
Evolution - Inheritance of specific genetic traits that control adaptations, giving a species an advantage in an environment.

13. Natural Selection
Natural Selection - Describes process where better competitors survive and reproduce more successfully.
Caused by:
Random mutations – Changes in DNA are usually bad, but can be beneficial.
Selective pressure – Limited resources mean only the best competitors survive.
Sexual selection – Females choose a mate based on certain characteristics.

14. Natural Selection

15. Artificial Selection
The selective breeding of organisms by humans for specific characteristics.

16. Origin of Life Fig. 4-3, p. 66 Modern humans (Homo sapiens)
appear about
2 seconds
before midnight
Recorded human
history begins
1/4 second
before midnight
Origin of life
(3.6–3.8 billion
years ago)
Fig. 4-3, p. 66

17. Evidence of Evolution
Physical Similarities
Most animals have similar bones in their limbs (fins, arms, wings)
Comparing DNA
Vestigial Structures
Still exist in the body but are no longer needed
Ex: Appendix, wisdom teeth

18. Factors Exerting Selective Pressure
Physiological stress due to inappropriate levels of a critical environmental factor.
Moisture, Light, pH
Predation
Organism is hunted and killed by another
Includes parasites, bacteria, viruses
Competition
Other organisms attempting to use same resources
Luck

19. Speciation
Given enough time, enough mutations occur that a new species develops from an old one.
When are two groups considered a different species?
They cannot or will not interbreed to produce healthy, fertile offspring.

20. Natural Selection

21. Speciation
Divergent - Separation of one species into new species.

22. Speciation
Convergent - Unrelated organisms evolve to look and act alike.
Not related
Caused by living in similar environments

23. Coevolution
The process of two species evolving in response to long-term interactions with
each other.

24. Same or Different Species?

25. Animal Hybrids or New Species?
More examples…

26. The Taxonomic Naming System
Crayfish
a.k.a. Crawdad
a.k.a. Spiny lobster
a.k.a. Yabby
a.k.a. Crawfish
a.k.a. Creekcrab
a.k.a. Mudbug
We need an internationally accepted name!

27. Scientific Naming System
Based on the classification system.
Includes the organism’s genus and species name.
Genus is capitalized
Species is lower case
The scientific name is written in italics
Scientific name of the crayfish:
Procambarus clarkii

28. The Taxonomic Naming System
Divides organisms into different levels of organization.
Kingdom
Phylum
Class
Order
Family
Genus
Species
The more levels two organisms have in common, the more related.

30. How related are they? Canis lupus lupus Canis familiaris European Wolf
Domesticated dog

31. How related are they? Archocentrus nigrofasciatus Corvus splendens
Convict Cichlid
Corvus splendens
House Crow

32. Phylogenetic Tree
Also known as a “tree of life”.
Organisms are grouped and classified based on three characteristics:
Physical characteristics
DNA
Behavioral characteristics
Mating rituals, territorial, aggression, etc.
The more of these characteristics two organisms have in common, the more closely related they are according to evolution.

33. Phylogenetic Tree of Life
From left to right:
Orangutan
Gorilla
Human
Chimpanzee
Bonobo

34. Ecological Niche
Habitat - Set of environmental conditions in which a particular organism lives.
Ecological Niche
Description of role played by a species in a biological community.

35. Specific Types of Niches
Opportunistic Species - Quickly appear when any opening in an ecosystem arises.
Many weeds.
Pioneer Species – Able to quickly colonize new ground where nothing else is growing.

36. Types of Niches
Keystone Species - A species whose impact on its ecosystem is especially large and influential.

37. SPECIES INTERACTIONS
Predator-Prey
Any organism that feeds directly on another living organism is termed a predator.
The organism that is eaten is the prey.

38. Competition
Intraspecific - Competition among members of the same species.
Dispersal
Seeds sent far away from parent
Territoriality
Each individual defends part of ecosystem
Resource Partitioning
Adults and larvae eat different foods
Ex: Caterpillars and butterflies
Interspecific - Competition between members of different species.

39. Resource Partitioning-

40. Symbiosis
Symbiosis - Intimate living together of members of two or more species.
Commensalism - One member benefits while other is neither benefited nor harmed.
Mutualism - Both members benefit.
Parasitism - One member benefits at the expense of other.

41. Example of Symbiosis
Barnacles create homes by attaching themselves to whales. The whales are unaffected.

42. Example of Symbiosis
Clownfish have a mucus coating that allows them to live in sea anemones. Their presence attracts other fish for the anemone to eat.

43. Example of Symbiosis
As bison walk through grass, insects are disturbed and fly away. They are eaten by cowbirds.

44. Example of Symbiosis
Ostriches and gazelles feed next to each other. Ostriches have excellent eyesight, while gazelles have stronger senses of hearing and smell.

45. Example of Symbiosis
Mistletoe extracts water and nutrients from the spruce tree directly.

46. POPULATION DYNAMICS
Population Growth
Studies of population growth are based on the idea of biotic potential.
Biotic Potential - Potential of a population to grow in the absence of limitations.

47. Exponential Growth
Exponential growth is graphed as a J curve.
Carrying Capacity - Number of individuals that can be indefinitely supported in a given area.
Overshoot - When a population surpasses the carrying capacity of its environment.
Dieback – Population experiences a sudden steep drop.

48. Population Oscillations

49. Growth to a Stable Population
Logistic Growth - Growth occurs more slowly as the population approaches carrying capacity due to environmental resistance.

50. Limiting Factors
Environmental Resistance
Any factor that slows the growth of a population.
Density-Dependent Factors – Most likely to affect dense populations.
Disease, Stress, Predation
Density-Independent Factors – Affects dense and diffuse populations evenly.
Changes in climate, natural disasters

51. Population Growth Strategies
There are two main types of growth strategies:
K-strategists focus on long-term development and a long life.
Ideal for stable, predictable environments.
R-strategists focus on reproducing as much and as quickly as possible.
Ideal for risky, unstable environments.

52. (r) Strategies
Short life
Rapid growth
Early maturity
Many small offspring
Little parental care
Little investment in individual offspring
Adapted to unstable environment
Pioneers, colonizers
Niche generalists
Prey
Regulated mainly by extrinsic factors
Low trophic level

53. (K) Strategies
Long life
Slower growth
Late maturity
Fewer large offspring
High parental care and protection
High investment in individual offspring
Adapted to stable environment
Later stages of succession
Niche specialists
Predators
Regulated mainly by intrinsic factors
High trophic level

54. COMMUNITY PROPERTIES
Primary Productivity - Rate of biomass production. Used as an indication of the rate of solar energy conversion to chemical energy.
Net Primary Productivity - Energy (amount of biomass) left after respiration.

55. Type of Strategist?

56. Type of Strategist?

57. Community Structure
Randomly Arranged
Individuals live wherever resources are available.
Clumped
Individuals cluster together for protection, assistance, or resource access.
Regularly Arranged

58. Community Structure