1. Evolution and Community Ecology5
CHAPTER
Placeholder opening page, but maybe we can duplicate the look of the SE chapter opener page by using the same fonts and colors (and maybe that Ch 14 icon?)

2. Lesson 5.1 Evolution
Scientists have identified and described over 1.5 million species. Millions more have yet to be discovered.

3. Objectives
Describe the four primary mechanisms of biological evolution
Describe how speciation and extinction affect the diversity of life on Earth

4. Evolution and Natural Selection
Lesson 5.1 Evolution
Evolution and Natural Selection
Gene: A sequence of DNA that codes for a particular trait
Gene pool: All the genes present in a population
Biological evolution: The change in a population’s gene pool over time
A starting population of fish. Genes control the color and pattern of the fish’s scales.

5. Mechanisms of Biological Evolution: Mutation and Migration
Lesson 5.1 Evolution
Mechanisms of Biological Evolution: Mutation and Migration
Mutation
Migration (gene flow)
Accidental change in DNA that can give rise to variation among individuals
Movement of individuals into (immigration) or out of (emigration) a population

6. Lesson 5.1 Evolution
Mechanisms of Biological Evolution: Genetic Drift and Natural Selection
Genetic Drift
Natural Selection
Process by which traits useful for survival and reproduction are passed on more frequently than those that are not
Evolution that occurs by chance

7. Conditions of Natural Selection
Lesson 5.1 Evolution
Conditions of Natural Selection
Image - (Creative Commons licensed)
Geyser info source - National Park Service:
(1) Organisms produce more offspring than can survive.
(2) Individuals vary in characteristics, some of which are heritable.
(3) Individuals vary in fitness, or reproductive success.
Did You Know? Darwin privately researched natural selection for two decades before publishing On the Origin of Species.

8. Conditions of Natural Selection
Individuals vary in their fitness
Fitness describes how reproductively successful an organism is in its environment
A heritable trait that increases an individual’s fitness is called an adaptation
Survival of the Fittest
Individuals of high fitness produce more offspring and therefore pass on its genes more frequently
An organism that is “fittest’’ in one place and time may not be the fittest forever

9. Checkpoint
What is the connection between adaptations and fitness?

10. Artificial Selection Selection under human direction
Lesson 5.1 Evolution
Artificial Selection
Selection under human direction
Throughout history, humans have chosen and bred animals and plants with beneficial traits.
Image - (Creative Commons licensed)
Geyser info source - National Park Service:

11. Checkpoint
What is the difference between artificial selection and natural selection?

12. Speciation Process by which new species are generated
Lesson 5.1 Evolution
Speciation
Process by which new species are generated
Can occur in a number of different ways; the most important way is called allopatric speciation (geographic separation)
Has resulted in every form of life on Earth— today and in the past
Image - (Creative Commons licensed)
Geyser info source - National Park Service:
Allopatric Speciation

13. Allopatric Speciation
One population broken into multiple smaller isolated populations
Separation may be due to glacial ice sheets, rivers changing course, dry climate, etc.
Any mutations that arise in one population can’t spread to the other; genetic divergence occurs
Populations may become different enough that they can no longer mate with each other; speciation has occurred

14. Extinction The disappearance of species from Earth
Lesson 5.1 Evolution
Extinction
The disappearance of species from Earth
Generally occurs gradually, one species at a time, when environmental conditions change more rapidly than the species can adapt (background extinction rate)
There are five known mass extinction events, each of which wiped out a large proportion of Earth’s species.
Image - (Creative Commons licensed)
Geyser info source - National Park Service:
Trilobites
Marine arthropods that went extinct at the end of the Permian period.
Did You Know? During the Permo-Triassic extinction 250 million years ago, 70% of all land species and 90% of all marine species went extinct.

15. Objectives Revisited
Describe the four primary mechanisms of biological evolution
Describe how speciation and extinction affect the diversity of life on Earth

16. Writing Prompts
On a separate sheet of paper, complete the following statements.
The four primary mechanisms of biological evolution are…
The three conditions needed for natural selection to occur are…
The process by which new species are generated is called…
The disappearance of a species from Earth is called…
MAKE SURE TO WRITE THE PROMPT ITSELF ALONG WITH YOUR COMPLETION!
Will be collected

17. Lesson 5.2 Species Interactions
The zebra mussel has completely displaced 20 native mussel species in Lake St. Clair.

18. Objectives Discuss the factors that influence an organism’s niche
Compare and contrast predation, parasitism, and herbivory
Describe mutualism and commensalism

19. Lesson 5.2 Species Interactions
The Niche
Describes an organism’s use of resources and functional role in a community
Includes organisms habitat, food it eats, how/when it reproduces, and what other organisms it interacts with
Affected by an organism’s tolerance—its ability to survive and reproduce under changing environmental conditions
Organisms with restricted tolerances – specialists
Organisms with wide tolerances - generalists
Often restricted by competition
Competition within a species – intraspecific competition
Competition among 2 different species – interspecific competition

20. Lesson 5.2 Species Interactions
Competition
Organisms compete when they seek the same limited resource.
In rare cases, one species can entirely exclude another from using resources.(competitive exclusion)
To reduce competition, species often partition resources, which can lead to character displacement.
Resource Partitioning

21. Competition
The full niche of a species is called its fundamental niche
Without competitors an organism can use its entire fundamental niche
A niche restricted by competition is called a realized niche
Realized niche represents only a portion of what an organism can do and what resources it can use.
Resource partitioning – a process that allows different species to share common resources.
Character displacement – when resource partitioning leads to the evolution of physical characteristics among competing species that reflect their specialized roles in the environment.

22. Checkpoint
How does resource partitioning affect competition between species?

23. Lesson 5.2 Species Interactions
Predation (+/–)
The process by which a predator hunts, kills, and consumes prey
Causes cycles in predatory and prey population sizes
Defensive traits such as camouflage, mimicry, and warning coloration have evolved in response to predator-prey interactions.
Some predator-prey relationships are examples of coevolution, the process by which two species evolve in response to changes in each other.
Rough-Skinned Newt
Did You Know? A single rough-skinned newt contains enough poison to kill 100 people. Unfortunately for the newt, its predator, the common garter snake, has coevolved resistance to the toxin.

24. Parasitism and Herbivory (+/–)
Lesson 5.2 Species Interactions
Parasitism and Herbivory (+/–)
Parasitism: One organism (the parasite) relies on another (the host) for nourishment or for some other benefit
Ex: tapeworms, ticks, etc.
Symbiosis – a long-lasting and physically close relationship in which at least one organism benefits.
Herbivory: An animal feeding on a plant
Hookworm (a parasite)
Did You Know? One study of Pacific estuaries suggests that parasites play an important role in keeping these ecosystems healthy by controlling host populations.

25. Mutualism (+/+) and Commensalism (+/0)
Lesson 5.2 Species Interactions
Mutualism (+/+) and Commensalism (+/0)
Mutualism: a relationship in which two or more species benefit
Ex: pollination
Commensalism: a relationship in which one species benefits while the other is unaffected
Lichen: a symbiotic relationship between a fungus and a photosynthetic partner, such as an alga
Did You Know? Symbiosis describes a long-lasting and physically close relationship between species in which at least one species benefits.

26. Objectives Revisited
Discuss the factors that influence an organism’s niche
Compare and contrast predation, parasitism, and herbivory
Describe mutualism and commensalism

27. Lesson 5.3 Ecological Communities
The sun provides the energy for almost all of the ecological communities and species interactions on Earth.

28. Objectives Explain the difference between a producer and a consumer
Explain the effect of inefficient energy transfer on community structure
Describe how feeding relationships can have both direct and indirect effects on community members

29. Primary Producers (Autotrophs)
Lesson 5.3 Ecological Communities
Primary Producers (Autotrophs)
Capture energy from the sun or from chemicals and store it in the bonds of sugars, making it available to the rest of the community
Energy from the sun is captured by plants, algae, or bacteria through photosynthesis.
Sunlight used to convert carbon dioxide and water into sugars, releasing oxygen along the way
Energy from chemicals is captured by some bacteria through chemosynthesis.
Did You Know? Deep-sea vents, far from sunlight, support entire communities of fish, clams, and other sea animals, which depend on energy converted through chemosynthesis.

30. Checkpoint
What is the primary difference between photosynthesis and chemosynthesis?

31. Consumers (Heterotrophs)
Lesson 5.3 Ecological Communities
Consumers (Heterotrophs)
Rely on other organisms for energy and nutrients
Herbivores: plant-eaters
Carnivores: meat-eaters
Omnivores: combination-eaters
Detritivores and decomposers: recycle nutrients within the ecosystem by breaking down nonliving organic matter
Detrivores consume nonliving organic material; decomposers break down nonliving organic material
Use oxygen to break bonds in sugar and release its energy through cellular respiration (primary producers do this, too)
California Condor
Did You Know? Scavengers, such as vultures and condors, are just large detritivores.

32. Lesson 5.3 Ecological Communities
Energy in Communities
An organism’s rank in a feeding hierarchy is its trophic level.
Primary producers always occupy the first trophic level of any community.
In general, only about 10% of the energy available at any trophic level is passed to the next; most of the rest is lost to the environment as heat.
Eating at lower trophic levels decreases biological footprint
Pyramid of Energy

33. Numbers and Biomass in Communities
Lesson 5.3 Ecological Communities
Numbers and Biomass in Communities
A trophic level’s biomass is the mass of living tissue it contains.
In general, there are more organisms and greater biomass at lower trophic levels than at higher ones.

34. Checkpoint
What happens to energy that is not passed from one trophic level to the next, or used to power life processes?

35. Lesson 5.3 Ecological Communities
Food Chains and Webs
Food chain: Linear series of feeding relationships
Food web: Shows the overlapping and interconnected food chains present in a community

36. Checkpoint
Why are most communities best represented with a food web instead of a food chain?

37. Lesson 5.3 Ecological Communities
Keystone Species
Species that have strong and/or wide-reaching effects on a community
Removal of a keystone species can significantly alter the structure of a community.

38. Lesson 5.4 Community Stability
A 2010 report on invasive species suggests that they cost the U.S. $120 billion a year in environmental losses and damages.
Invasive kudzu

39. Objectives Describe what happens to a community after a disturbance
Explain the conditions necessary for a species to become invasive

40. Ecological Disturbances
Lesson 5.4 Community Stability
Ecological Disturbances
A community in equilibrium is generally stable and balanced, with most populations at or around carrying capacity.
Disturbances or changes in the environment can throw a community into disequilibrium.
Severe disturbances can cause permanent changes to a community and initiate a predictable series of changes called succession.
Forest fire

41. Lesson 5.4 Community Stability
Primary Succession
Occurs when there are no traces of the original community remaining, including vegetation and soil
Bare expanse of rock, sand, or sediment is exposed for the first time
Pioneer species, such as lichens, are the first to colonize.
The environment changes as new species move in, adding nutrients and generating habitat.

42. Lesson 5.4 Community Stability
Secondary Succession
Occurs when a disturbance dramatically alters a community but does not completely destroy it
At least the soil from the previous ecosystem remains
Common after disturbances such as fire, logging, or farming
Occurs significantly faster than primary succession

43. Checkpoint
Why does secondary succession usually happen faster than primary succession?

44. Lesson 5.4 Community Stability
Succession in Water
Primary aquatic succession occurs when an area fills with water for the first time.
Disturbances such as floods or excess nutrient runoff can lead to secondary aquatic succession.

45. Lesson 5.4 Community Stability
Climax Communities
Ecologists once thought succession leads to stable “climax” communities.
Stable community that completes the succession process
Today, ecologists see communities as temporary, ever-changing associations of species.
Communities are influenced by many factors and constant disturbances.
Beech-maple forest, a classic “climax community”

46. Invasive Species Nonnative organisms that spread widely in a community
Lesson 5.4 Community Stability
Invasive Species
Nonnative organisms that spread widely in a community
A lack of limiting factors such as predators, parasites, or competitors enables their population to grow unchecked.
Not all invasive species are harmful.
Did You Know? Although the European honeybee is invasive to North America, it is beneficial because it pollinates our agricultural crops.

47. Checkpoint
What is an invasive species?

48. Objectives Revisited
Describe what happens to a community after a disturbance
Explain the conditions necessary for a species to become invasive