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Chapter 5: Chapter 5: Evolution and Evolution and
Community EcologyCommunity Ecology
Chapter 5 pages 126- Chapter 5 pages 126- ……..……..Section 1: EvolutionSection 1: Evolution
Answer the questions and define the terms:Answer the questions and define the terms:
1.1.Describe the four primary mechanisms of Describe the four primary mechanisms of biological evolutionbiological evolution
2.2.Describe how speciation and extinction Describe how speciation and extinction affect the diversity of life on Earth.affect the diversity of life on Earth.
TERMS: evolution, gene mutation, genetic TERMS: evolution, gene mutation, genetic drift, natural selection, fitness, drift, natural selection, fitness, adaptation, artificial selection, speciation, adaptation, artificial selection, speciation, extinction. extinction.
Incredible Diversity of LifeIncredible Diversity of Life
►1.5 to 1.8 million 1.5 to 1.8 million known speciesknown species
►Possibly 13-20 Possibly 13-20 millionmillion
►Tropical Rain Tropical Rain Forests, Coral Forests, Coral Reefs and Reefs and everywhere elseeverywhere else W
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EvolutionEvolution
►What makes you, What makes you, YOU?YOU?
What makes each species unique and different?
GenesGenes►Sequences of DNA Sequences of DNA
codes for each codes for each particular trait particular trait
►Tall, small, blue Tall, small, blue eyes, human, eyes, human, goldfish, pine treegoldfish, pine tree
►Evolution is a Evolution is a change of genes change of genes over timeover time
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EvolutionEvolution
►““Change over Change over time”time”
►Change of Gene Change of Gene Pool over timePool over time
►Why would Why would genes change genes change over time?over time?
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4 Ways Evolution Occurs4 Ways Evolution Occurs
►MutationMutation►MigrationMigration►Genetic DriftGenetic Drift►Natural Natural
SelectionSelection
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MutationMutation
Accidental change in DNA that can give rise to variation among individuals
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Migration: GENE FLOWMigration: GENE FLOW
Movement of individuals into (immigration) or out of (emigration) a population
Sometimes called “Gene Flow”
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Gene Flow (Migration)Gene Flow (Migration)
Genetic DriftGenetic Drift
Evolution that occurs by chance
•Natural Disasters•Run in with human nets, etc.
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Natural SelectionNatural Selection
►Process by Process by which traits which traits useful for useful for survival and survival and reproduction reproduction are passed on are passed on more more frequently than frequently than those that are those that are notnot
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3 Conditions for Natural 3 Conditions for Natural SelectionSelection
(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
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3 Conditions for Natural 3 Conditions for Natural SelectionSelection
(1) Organisms produce more offspring than can survive.
• Nature has limitations (limiting factors)
• Struggle for survival
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3 Conditions for Natural 3 Conditions for Natural SelectionSelection
(2) Individuals vary in (2) Individuals vary in characteristics, some characteristics, some of which are heritableof which are heritable►Not every species is Not every species is samesame►Some fish are faster, Some fish are faster, darker, smallerdarker, smaller►Genes differentGenes different►Heritable DifferencesHeritable Differences
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3 Conditions for Natural 3 Conditions for Natural SelectionSelection
(3) Individuals vary in (3) Individuals vary in fitness, or reproductive fitness, or reproductive successsuccess►Survival of FittestSurvival of Fittest►Fittest for its environmentFittest for its environment►Adaptation: an Adaptation: an inherited trait that inherited trait that increases an organisms increases an organisms chance of survival and chance of survival and reproduction.reproduction.
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AdaptationsAdaptationsDesert plants have small or no leaves at all
The insect that blends in and is able to survive may be more likely to reproduce.
AdaptationsAdaptationsBig ears of desert jack rabbit allow it to cool off quickly Long neck of
giraffe allow it to reach food
White coat of polar bear helps in hunting
Results of natural selection all around us
NATURE SELECTS
Artificial Selection: How Artificial Selection: How Humans Use EvolutionHumans Use Evolution
Artificial Selection: Artificial Selection: selective selective breeding of breeding of organisms by organisms by humanshumans
►Selecting certain Selecting certain desirable traitsdesirable traits
►Size, sweetness, Size, sweetness, color, shape, color, shape,
►Very commonVery common
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Artificial SelectionArtificial Selection
Selecting desirable traits and breeding only those with those traits.
ResistanceResistance
Resistance: the Resistance: the ability of one or ability of one or more organisms to more organisms to tolerate a chemical tolerate a chemical designed to kill itdesigned to kill it
►Able to survive and Able to survive and reproducereproduce
►Pesticide Pesticide resistanceresistance
►Antibiotic Antibiotic resistanceresistance
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Impacts of Natural Selection: Impacts of Natural Selection: ResistanceResistance
Why is Why is this a this a probleproble
m?m?
Speciation: How did we get Speciation: How did we get millions of species? millions of species?
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Speciation•Process by which new species are generated
•Can occur in a number of different ways; the most
important way is called allopatric allopatric speciation– speciation– Geographic Isolation Geographic Isolation •Has resulted in every form of life on Earth— today and in the past
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The canyon is a barrier to dispersal by small mammals, and as a consequence the isolated populations can diverge.
Sympatric SpeciationSympatric speciation is the process through which new species evolve from a single ancestral species while inhabiting the same geographic region. Sympatric refers to organisms whose ranges overlap or are even identical, so that they occur together at least in some places, such a distribution may be the result of sympatric speciation.
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ExtinctionExtinction• The disappearance of species The disappearance of species
from Earthfrom Earth
• Generally occurs gradually, one Generally occurs gradually, one species at a time, (species at a time, (BACKGROUND BACKGROUND RATE of EXTINCTION)RATE of EXTINCTION). When . When environmental conditions change environmental conditions change more rapidly than the species more rapidly than the species can adapt extinction occurs.can adapt extinction occurs.
• There are five known There are five known mass mass extinction extinction events, each of which events, each of which wiped out a large proportion of wiped out a large proportion of Earth’s species.Earth’s species.
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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.
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.
Biodiversity has increased over time, but mass extinctions are also natural events (5 major events)How do we get this data?
ExtinctionsExtinctions
► Species gone foreverSpecies gone forever► NORMALNORMAL► Mass Extinction: short Mass Extinction: short
period of time when period of time when large number of large number of species go extinct (65 species go extinct (65 MYA)MYA)
► Currently in mass Currently in mass extinction…caused by extinction…caused by humanshumans
► Rapid climate changeRapid climate change
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Invasive SpeciesInvasive Species
The zebra mussel has The zebra mussel has completely displaced 20 completely displaced 20 native mussel species in native mussel species in Lake St. Clair.Lake St. Clair.
The zebra mussel has The zebra mussel has completely displaced 20 completely displaced 20 native mussel species in native mussel species in Lake St. Clair.Lake St. Clair.
Invasive SpeciesInvasive Species• Adversely affect the habitats and
bioregions.• They invade economically,
environmentally, and/or ecologically.
• Invasive species can be either plants or animals and disrupt by dominating habitats.
• The problem is they have no natural controls such as predators or competition for resources.
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Invasive SpeciesInvasive Species
Invasive species damage the lands and waters that native plants and animals need to survive. They hurt economies and threaten human well-being. The estimated damage from invasive species worldwide totals more than $1.4 trillion – five percent of the global economy
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Section 1: Evolution ReviewSection 1: Evolution Review
►Describe the four primary mechanisms Describe the four primary mechanisms of biological evolutionof biological evolution
►Describe how speciation and extinction Describe how speciation and extinction affect the diversity of life on Earth.affect the diversity of life on Earth.
►TERMS: evolution, gene mutation, TERMS: evolution, gene mutation, genetic drift, natural selection, fitness, genetic drift, natural selection, fitness, adaptation, artificial selection, adaptation, artificial selection, speciation, extinctionspeciation, extinction
Section 1 QuizSection 1 Quiz1) Which of the following best describes a successful
individual in evolutionary terms?A. A successful individual possesses traits that are
different from the traits of the rest of the population.B. A successful individual produces many offspring that
possess unique traits.C. A successful individual is well adapted to its
environment and produces offspring that survive to pass on genes.
D. A successful individual will be well adapted to its environment and produce a few high quality offspring.
C. A successful individual is well adapted to its environment and produces offspring that survive to pass on genes.
2) In the history of the world, how many mass extinctions have occurred?A. 5B. 7C. 10D. 13
A. 5
3) In a mass extinction, the rate of extinction exceedsA. 99 percent.B. 85 percent.C. the rate of environmental change.D. the rate of background extinction.D. the rate of background extinction
4) A reintroduced population of wolves in a national park is 90% grey and 10% black, consistent with the wolf population in other regions. After several generations in isolation, the national park’s wolf population is 60% grey and 40% black. The wolf population has likely experiencedA. natural selection.B. genetic drift.C. mutations.D. migration.
B. genetic driftEvolution that
occurs by chance
5) When the environment changes 5) When the environment changes too quickly for an organism to too quickly for an organism to adapt, what will occur?adapt, what will occur?A) EvolutionA) EvolutionB) SpeciationB) SpeciationC) Genetic DriftC) Genetic DriftD) ExtinctionD) Extinction
D. Extinction
True or FalseTrue or False
6) Two populations of a deer species are separated when a glacier forms. After the glacier melts, the two populations have become different species. This is an example of allopatric speciation. TRUE
Short AnswerShort Answer7) A disaster wipes out 50 percent of a small population of birds. Prior to the disaster, about half the birds had a green wing patch and half had a blue wing patch. Several generations after the disaster, only 10% have a blue wing patch, and 90% have a green wing patch. What do you infer happened, and why?The bird population experienced genetic drift as the result of a sudden catastrophe. The disaster reduced genetic diversity in the population and changed the proportion of birds with a green wing patch vs. a blue wing patch.
Short AnswerShort Answer8) Pronghorn are a species of extremely fast hooved mammal that live on the plains of western North America. They are so fast that no current North American predator can catch them. During the ice age, cheetahs occupied North America. Speculate about how pronghorn became so fast.Pronghorn probably evolved in an evolutionary “arms race” with the cheetah population. They became faster and faster to escape from cheetahs, which were probably fast enough to catch them.
Section 2: Species InteractionSection 2: Species Interaction
►Discuss the factors that influence an Discuss the factors that influence an organisms nicheorganisms niche
►Compare and contrast predation, Compare and contrast predation, parasitism, herbivoryparasitism, herbivory
►Describe mutualism and commensalismDescribe mutualism and commensalism►TERMS: TERMS: niche, tolerance, resource niche, tolerance, resource
partitioning, predation, coevolution, partitioning, predation, coevolution, parasitism, symbiosis, herbivory, parasitism, symbiosis, herbivory, mutualism, commensalism. mutualism, commensalism.
Species InteractionSpecies Interaction
What resources are the plants in this picture competing for?Competition for
resources all around us
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Niche: Organisms JOB in lifeNiche: Organisms JOB in life►Describes an Describes an
organism’s use of organism’s use of resources and resources and functional role in a functional role in a communitycommunity
►HabitatHabitat►Food It EatsFood It Eats►When, How When, How
ReproducesReproduces►What organisms What organisms
does it interact withdoes it interact with
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Niche Impacted By Niche Impacted By ToleranceTolerance and and CompetitionCompetition
• Affected by an Affected by an organism’s organism’s tolerance—its tolerance—its ability to survive ability to survive and reproduce and reproduce under changing under changing environmental environmental conditionsconditions
• Often restricted by Often restricted by competitioncompetition
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Tolerance LimitsTolerance Limits
A species with a restricted tolerance for environmental conditions is a specialist
• A species with a Wide tolerance is called a generalist
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Fundamental vs. Realized Fundamental vs. Realized NicheNiche
Fundamental = Fundamental = Without Without competition competition
Realized = With Realized = With competition competition (restricted niche)(restricted niche)
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Competition Competition ►Organisms compete Organisms compete when they seek the when they seek the same limited resource.same limited resource.
►In rare cases, one In rare cases, one species can entirely species can entirely exclude another from exclude another from using resources.using resources.
►To reduce competition, To reduce competition, species often species often partition partition resources, resources, which can which can lead to character lead to character displacement.displacement.
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Resource PartitioningResource Partitioning
►The zebra mussel has completely The zebra mussel has completely displaced 20 native mussel species in displaced 20 native mussel species in Lake St. Clair.Lake St. Clair.
►The zebra mussel has completely The zebra mussel has completely displaced 20 native mussel species in displaced 20 native mussel species in Lake St. Clair.Lake St. Clair.
PredationPredation (+/-) (+/-)► The process by which a predator The process by which a predator
hunts, kills, and consumes preyhunts, kills, and consumes prey
► Causes cycles in predatory and Causes cycles in predatory and prey population sizesprey population sizes
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PredationPredation► Defensive traits Defensive traits
such as such as camouflage, camouflage, mimicry, and mimicry, and warning warning coloration have coloration have evolved in evolved in response to response to predator-prey predator-prey interactions.interactions.
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Predation and Co-evolutionPredation and Co-evolution
►Some predator-Some predator-prey relationships prey relationships are examples of are examples of coevolutioncoevolution, the , the process by which process by which two species evolve two species evolve in response to in response to changes in each changes in each other.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.
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.
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Example of Co-evolutionExample of Co-evolutionThe Madagascar star orchid produces nectar at the bottom part of its slim, foot-long throat. After observing a specimen, Charles Darwin predicted the existence of a moth with a proboscis long enough to reach that nectar. Sure enough, decades later the giant hawk moth of Madagascar was discovered.
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Parasitism and Herbivory Parasitism and Herbivory (+/–)(+/–)
• Parasitism: One Parasitism: One organism (the organism (the parasite) relies on parasite) relies on another (the host) another (the host) for nourishment or for nourishment or for some other for some other benefitbenefit
• Herbivory: An animal Herbivory: An animal feeding on a plantfeeding on a plant
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Parasitism and Herbivory Parasitism and Herbivory (+/–)(+/–)
Malaria is a disease caused by a parasite called Plasmodium that is spread to humans by the bite of an infected Anopheles mosquito.
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Parasitism and Herbivory Parasitism and Herbivory (+/–)(+/–)
MutualismMutualism (+/+) and (+/+) and CommensalismCommensalism (+/0) (+/0)
• Mutualism:Mutualism: a a relationship in relationship in which two or more which two or more species benefitspecies benefit
• CommensalismCommensalism: a : a relationship in relationship in which one species which one species benefits while the benefits while the other is unaffectedother is unaffected
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EXAMPLE of Mutualism (+/+)
Clown Fish and Sea Clown Fish and Sea Anemones demonstrate Anemones demonstrate mutualism because mutualism because Anemones provide the Anemones provide the Clown Fish with Clown Fish with protection from protection from predators while Clown predators while Clown fish defend the fish defend the Anemones from Anemones from Butterfly fish who like Butterfly fish who like to eat Anemones. to eat Anemones.
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Example of Commensalism (+/0)
Desert trees (Polo verde) and shrubs provide shade and leaf litter to the soil beneath the tree which allows the soil underneath to hold moisture. The area underneath the tree remains cooler and more moist than the surrounding desert area making it easier for other desert plants to germinate and grow
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Section 2 Review Species Section 2 Review Species InteractionInteraction
►Discuss the factors that influence an Discuss the factors that influence an organisms nicheorganisms niche
►Compare and contrast predation, Compare and contrast predation, parasitism, herbivoryparasitism, herbivory
►Describe mutualism and commensalismDescribe mutualism and commensalism►TERMS: TERMS: niche, tolerance, resource niche, tolerance, resource
partitioning, predation, coevolution, partitioning, predation, coevolution, parasitism, herbivory, mutualism, parasitism, herbivory, mutualism, commensalism. commensalism.
Section 2 QuizSection 2 Quiz1) Madagascar, several species of lemur eat bamboo, but each species specializes in one part of the bamboo—one species eats mature bamboo stalks, one species eats bamboo shoots, and one species eats leaves. This is an example of►A. speciation.►B. resource partitioning.►C. competition.►D. niche partitioning.
B. Resource Partitioning
2) In the example above, one lemur species eats only bamboo shoots. Bamboo shoots contain a high level of cyanide, a toxic chemical. This lemur species has developed a tolerance for a certain amount of cyanide. What do you think will happen over time?A. The level of cyanide in the bamboo population will increase.B. The level of cyanide in the bamboo population will decrease.C. The level of cyanide in the bamboo population will remain the same.
D. The level of cyanide in the lemur population will decrease.
A. The level of cyanide in the bamboo population will increase.
3) Two species of finch live in the same environment. Over time, one develops a larger beak to consume larger seeds, while the other develops a narrow beak to consume more delicate seeds. This is an example ofA. resource partitioning.B. character displacement.C. coevolution.D. competitive exclusion.C. coevolution.
4) An interaction in which an individual of one species kills and consumes an individual of another is calledA. predation.B. parasitism.C. herbivory.D. symbiosis.
A. predation
5) In the western United States, at the southern edge of their range, moose are sometimes so severely infested with ticks that they die. The tick/moose relationship is best described asA. predatory.B. parasitic.C. symbiotic.D. mutualistic.B. parasitic.
6) A beehive depends on pollen from flowers to survive. Flowers depend on bees to pollinate them. The relationship among these two sets of organisms isA. parasitic.B. commensalist.C. herbivoryD. mutualistic.
D. mutualistic.
7) A niche restricted by competition is aA. fundamental niche.B. realized niche.C. resource partitioned niche.D. displaced niche.
B. realized niche
8) A deer browsing on a shrub is an example ofA. predation.B. parasitism.C. herbivory.D. photosynthesis.
C. herbivory.
True or FalseTrue or FalseYou have many species of bacteria living in your gut that help you with digestion. This relationship is best defined as commensalism.
False: Mutualism
Short AnswerShort Answer9) 9) Explain the difference between mutualism and commensalisms, with examples.
In mutualism and commensalism, both species are unharmed. In mutualism, both species benefit, as in the example of the hawk moth pollinating the flower; the flower is pollinated and the moth is fed. In commensalism, one species benefits while the other doesn’t experience a negative or a positive effect. Trees providing shade and moisture to desert shrubs is an example of commensalism.
Explain why a food web is a better representation of energy flow in a community than a food chain.
Explain how a sudden change in the environment either through a disaster or through shifts in conditions might affect the evolution of species in the area.
Compare and contrast what is likely to happen to an area that has just experienced a forest fire to what has happened to an area exposed to glaciations over centuries of time. Which will regrow more quickly and WHY?
NOW you can answer these 2 NOW you can answer these 2 questions you wrote down at the questions you wrote down at the
beginning of this chapter.beginning of this chapter.
