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Chapter Overview Questions (cont’d) How do extinction of species and formation of new species affect biodiversity? What is the future of evolution, and what role should humans play in this future? How did we become such a powerful species in a short time?
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Chapter 4Chapter 4
Evolution and Evolution and BiodiversityBiodiversity
Chapter Overview QuestionsChapter Overview Questions How do scientists account for the How do scientists account for the
development of life on earth?development of life on earth? What is biological evolution by natural What is biological evolution by natural
selection, and how can it account for the selection, and how can it account for the current diversity of organisms on the earth?current diversity of organisms on the earth?
How can geologic processes, climate change How can geologic processes, climate change and catastrophes affect biological evolution?and catastrophes affect biological evolution?
What is an ecological niche, and how does it What is an ecological niche, and how does it help a population adapt to changing the help a population adapt to changing the environmental conditions?environmental conditions?
Chapter Overview Questions (cont’d)Chapter Overview Questions (cont’d)
How do extinction of species and formation of How do extinction of species and formation of new species affect biodiversity?new species affect biodiversity?
What is the future of evolution, and what role What is the future of evolution, and what role should humans play in this future?should humans play in this future?
How did we become such a powerful species How did we become such a powerful species in a short time?in a short time?
Core Case StudyCore Case StudyEarth: The Just-Right, Adaptable Earth: The Just-Right, Adaptable
PlanetPlanet During the 3.7 billion During the 3.7 billion
years since life years since life arose, the average arose, the average surface temperature surface temperature of the earth has of the earth has remained within the remained within the range of 10-20range of 10-20ooC.C.
Figure 4-1Figure 4-1
ORIGINS OF LIFEORIGINS OF LIFE
1 billion years of chemical change to form the 1 billion years of chemical change to form the first cells, followed by about 3.7 billion years first cells, followed by about 3.7 billion years of biological change. of biological change.
Figure 4-2Figure 4-2
Biological Biological EvolutionEvolution
This has led to This has led to the variety of the variety of species we species we find on the find on the earth today.earth today.
Figure 4-2Figure 4-2
How Do We Know Which Organisms How Do We Know Which Organisms Lived in the Past?Lived in the Past?
Our knowledge Our knowledge about past life about past life comes from fossils, comes from fossils, chemical analysis, chemical analysis, cores drilled out of cores drilled out of buried ice, and DNA buried ice, and DNA analysis.analysis.
Figure 4-4Figure 4-4
EVOLUTION, NATURAL EVOLUTION, NATURAL SELECTION, AND ADAPTATIONSELECTION, AND ADAPTATION
Biological evolution by natural selection Biological evolution by natural selection involves the change in a population’s genetic involves the change in a population’s genetic makeup through successive generations.makeup through successive generations. genetic variabilitygenetic variability Mutations: random changes in the structure or Mutations: random changes in the structure or
number of DNA molecules in a cell that can be number of DNA molecules in a cell that can be inheritedinherited by offspring. by offspring.
Natural Selection and Adaptation: Natural Selection and Adaptation: Leaving More Offspring With Leaving More Offspring With
Beneficial TraitsBeneficial Traits Three conditionsThree conditions are necessary for biological are necessary for biological
evolution:evolution: 1: 1: Genetic variability, Genetic variability, 2: 2: TTraits must be heritable, raits must be heritable,
3: 3: TTrait must lead to rait must lead to differential reproductiondifferential reproduction. . An An adaptive traitadaptive trait is any heritable trait that is any heritable trait that
enables an organism to survive through enables an organism to survive through natural selection and reproduce better under natural selection and reproduce better under prevailing environmental conditions.prevailing environmental conditions.
CoevolutionCoevolution: A Biological Arms Race: A Biological Arms Race
Interacting species can engage in a back and Interacting species can engage in a back and forth genetic contest in which each gains a forth genetic contest in which each gains a temporary genetic advantage over the other.temporary genetic advantage over the other. This often happens between predators and prey This often happens between predators and prey
species.species.
Hybridization and Gene Swapping: Hybridization and Gene Swapping: other Ways to Exchange Genesother Ways to Exchange Genes
New species can arise through New species can arise through hybridizationhybridization.. Occurs when individuals to two distinct species Occurs when individuals to two distinct species
crossbreed to produce an fertile offspring.crossbreed to produce an fertile offspring. Some species (mostly microorganisms) can Some species (mostly microorganisms) can
exchange genes without sexual reproduction.exchange genes without sexual reproduction. Horizontal gene transferHorizontal gene transfer
Limits on Adaptation through Limits on Adaptation through Natural SelectionNatural Selection
A population’s ability to adapt to new A population’s ability to adapt to new environmental conditions through natural environmental conditions through natural selection is limited by its gene pool and how selection is limited by its gene pool and how fast it can reproduce.fast it can reproduce. Humans have a relatively slow generation time Humans have a relatively slow generation time
(decades) and output (# of young) versus some (decades) and output (# of young) versus some other species.other species.
GEOLOGIC PROCESSES, CLIMATE GEOLOGIC PROCESSES, CLIMATE CHANGE, CATASTROPHES, AND CHANGE, CATASTROPHES, AND
EVOLUTIONEVOLUTION
The movement of solid (tectonic) plates The movement of solid (tectonic) plates making up the earth’s surface, volcanic making up the earth’s surface, volcanic eruptions, and earthquakes can wipe out eruptions, and earthquakes can wipe out existing species and help form new ones.existing species and help form new ones. The locations of continents and oceanic basins The locations of continents and oceanic basins
influence climate.influence climate. The movement of continents have allowed The movement of continents have allowed
species to move.species to move.
Fig. 4-5, p. 88
135 million years ago
Present65 million years ago
225 million years ago
Climate Change and Natural Climate Change and Natural SelectionSelection
Changes in climate throughout the earth’s Changes in climate throughout the earth’s history have shifted where plants and history have shifted where plants and animals can live.animals can live.
Figure 4-6Figure 4-6
Catastrophes and Natural SelectionCatastrophes and Natural Selection
Asteroids and meteorites hitting the earth and Asteroids and meteorites hitting the earth and upheavals of the earth from geologic upheavals of the earth from geologic processes have wiped out large numbers of processes have wiped out large numbers of species and created evolutionary species and created evolutionary opportunities by natural selection of new opportunities by natural selection of new species.species.
ECOLOGICAL NICHES AND ECOLOGICAL NICHES AND ADAPTATIONADAPTATION
Each species in an ecosystem has a specific Each species in an ecosystem has a specific role or way of liferole or way of life.. Fundamental nicheFundamental niche: the full potential range of : the full potential range of
physical, chemical, and biological conditions and physical, chemical, and biological conditions and resources a species could theoretically use.resources a species could theoretically use.
Realized nicheRealized niche: to survive and avoid : to survive and avoid competition, a species usually occupies only part competition, a species usually occupies only part of its fundamental niche.of its fundamental niche.
Generalist and Specialist Species: Generalist and Specialist Species: Broad and Narrow NichesBroad and Narrow Niches
GeneralistGeneralist species tolerate species tolerate a wide range of a wide range of conditions.conditions.
SpecialistSpecialist species can species can only tolerate a only tolerate a narrow range of narrow range of conditions.conditions.
Figure 4-7Figure 4-7
SPOTLIGHTSPOTLIGHTCockroaches: Nature’s Ultimate Cockroaches: Nature’s Ultimate
SurvivorsSurvivors 350 million years old350 million years old 3,500 different species3,500 different species Ultimate generalistUltimate generalist
Can eat almost anything.Can eat almost anything. Can live and breed almost Can live and breed almost
anywhere.anywhere. Can withstand massive Can withstand massive
radiation.radiation.
Figure 4-AFigure 4-A
Specialized Feeding NichesSpecialized Feeding Niches
Resource partitioning Resource partitioning reduces competition reduces competition and allows sharing of limited resources.and allows sharing of limited resources.
Figure 4-8Figure 4-8
Evolutionary DivergenceEvolutionary Divergence
Each species has a Each species has a beak specialized to beak specialized to take advantage of take advantage of certain types of certain types of food resource.food resource.
Figure 4-9Figure 4-9
SPECIATION, EXTINCTION, AND SPECIATION, EXTINCTION, AND BIODIVERSITYBIODIVERSITY
SpeciationSpeciation: A new species can arise when : A new species can arise when member of a population become isolated for member of a population become isolated for a long period of time.a long period of time. Genetic makeup changes, preventing them from Genetic makeup changes, preventing them from
producing fertile offspring with the original producing fertile offspring with the original population if reunited.population if reunited.
Geographic IsolationGeographic Isolation
……can lead to reproductive isolation, can lead to reproductive isolation, divergence of gene pools and speciation.divergence of gene pools and speciation.
Figure 4-10Figure 4-10
Extinction: Lights OutExtinction: Lights Out
ExtinctionExtinction occurs occurs when the when the population population cannot adapt to cannot adapt to changing changing environmental environmental conditions.conditions.
The golden toad of Costa Rica’s The golden toad of Costa Rica’s Monteverde cloud forest has Monteverde cloud forest has become extinct because of become extinct because of changes in climate.changes in climate.
Figure 4-11Figure 4-11
Fig. 4-12, p. 93
Tertiary
Bar width represents relative number of living speciesEra Period
Species and families experiencing
mass extinctionMillions ofyears ago
Ordovician: 50% of animal families, including many trilobites.
Devonian: 30% of animal families, including agnathan and placoderm fishes and many trilobites.
500
345
Cambrian
Ordovician
Silurian
Devonian
Extinction
Extinction
Pale
ozoi
cM
esoz
oic
Cen
ozoi
c
Triassic: 35% of animal families, including many reptiles and marine mollusks.
Permian: 90% of animal families, including over 95% of marine species; many trees, amphibians, most bryozoans and brachiopods, all trilobites.Carboniferous
Permian
Current extinction crisis causedby human activities. Many speciesare expected to become extinctwithin the next 50–100 years.Cretaceous: up to 80% of ruling reptiles (dinosaurs); many marine species including manyforaminiferans and mollusks.
Extinction
Extinction
Triassic
Jurassic
Cretaceous
250
180
65Extinction
ExtinctionQuaternary Today
Effects of Humans on BiodiversityEffects of Humans on Biodiversity
The scientific consensus is that human The scientific consensus is that human activities are decreasing the earth’s activities are decreasing the earth’s biodiversity.biodiversity.
Figure 4-13Figure 4-13
GENETIC ENGINEERINGGENETIC ENGINEERING AND THE AND THE FUTURE OF EVOLUTIONFUTURE OF EVOLUTION
We have used We have used artificial selectionartificial selection to change to change the genetic characteristics of populations with the genetic characteristics of populations with similar genes through similar genes through selective breedingselective breeding..
We have used We have used genetic engineeringgenetic engineering to transfer genes to transfer genes from one species to from one species to another.another.
Figure 4-15Figure 4-15
Genetic Engineering:Genetic Engineering: Genetically Modified Organisms (Genetically Modified Organisms (GMOsGMOs))
GMOsGMOs useuse recombinant recombinant DNADNA genes or portions genes or portions
of genes from of genes from different different organisms.organisms.
Figure 4-14Figure 4-14
THE FUTURE OF EVOLUTIONTHE FUTURE OF EVOLUTION
Biologists are learning to rebuild organisms Biologists are learning to rebuild organisms from their cell components and to clone from their cell components and to clone organisms.organisms. Cloning has lead to high miscarriage rates, rapid Cloning has lead to high miscarriage rates, rapid
aging, organ defects.aging, organ defects. Genetic engineering can help improve human Genetic engineering can help improve human
condition, but results are not always condition, but results are not always predictable.predictable. Do not know where the new gene will be located Do not know where the new gene will be located
in the DNA molecule’s structure and how that will in the DNA molecule’s structure and how that will affect the organism.affect the organism.
Controversy Over Controversy Over Genetic EngineeringGenetic Engineering
There are a number of privacy, ethical, legal There are a number of privacy, ethical, legal and environmental issues.and environmental issues.
Should genetic engineering and development Should genetic engineering and development be regulated?be regulated?
What are the long-term environmental What are the long-term environmental consequences?consequences?
Case Study:Case Study:How Did We Become Such a Powerful How Did We Become Such a Powerful
Species so Quickly?Species so Quickly? We lack:We lack:
strength, speed, agility.strength, speed, agility. weapons (claws, fangs), protection (shell).weapons (claws, fangs), protection (shell). poor hearing and vision.poor hearing and vision.
We have thrived as a species because of We have thrived as a species because of our:our: opposable thumbs, ability to walk upright, opposable thumbs, ability to walk upright,
complex brains (problem solving).complex brains (problem solving).