understanding the diversity of life part 2
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Understanding the Diversity of Life Part 2. EVOLUTION & SPECIATION. 1. MODERN EVOLUTIONARY THEORY. By combining the work of Charles Darwin with modern genetics, evolutionary biologists have a much better understanding of how evolution works. MODERN EVOLUTIONARY THEORY. What is a population? - PowerPoint PPT PresentationTRANSCRIPT
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Understanding the Diversity of LifePart 2
EVOLUTION & SPECIATION1
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MODERN EVOLUTIONARY THEORY
•By combining the work of Charles Darwin with modern genetics, evolutionary biologists have a much better understanding of how evolution works
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MODERN EVOLUTIONARY THEORY
•What is a population?
•What is a gene pool?
• Group of individuals of the same species that interbreed
• All of the genes that a population has in common
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MODERN EVOLUTIONARY THEORY
•What is relative frequency?
• In genetic terms, evolution is…
• How often an allele occurs in a gene pool
• any change in relative frequency of alleles in a population
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MODERN EVOLUTIONARY THEORY
• What are the 2 main sources of genetic variation
1. Mutations
2. Gene Shuffling
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MODERN EVOLUTIONARY THEORY
•What is a mutation ?•Why does a
mutation occur?
• Change in DNA sequence
•Mistakes in replication • Exposure to
radiation • Chemicals in the
environment 6
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MODERN EVOLUTIONARY THEORY
•What is gene shuffling?
•What happens during gene shuffling?
• Distribution of different alleles during meiosis
• Each new gamete gets a different set of alleles
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BEYOND MUTATIONS & GENE SHUFFLING
• Non-random mating is…
• Examples:
• Results:
• Some members of the population have more opportunity to mate than others
• Fighting (lions & walrus)• Dances/songs (birds)
• Better fighters/dancers mate with more females
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BEYOND MUTATIONS & GENE SHUFFLING
• Gene flow is…
• Gene flow has…
• Why?
• Gain or loss of genes as organisms move in and out of populations
• Less effect on large populations
• Genes are diluted by large pool
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BEYOND MUTATIONS & GENE SHUFFLING
• Genetic Drift is…
• Occurs more often in…
•Why?
• Random change in allele frequency causes an allele to become more common
• Small populations
• Fewer alleles to counteract affects
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BEYOND MUTATIONS & GENE SHUFFLING• Types of genetic drift:1. Bottleneck effect –
happens due to…
Examples:
• Catastrophic events• Random survivors whose
genes do not reflect original population
• Bald Eagle• American Bison
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BEYOND MUTATIONS & GENE SHUFFLING
1963 – 417 mating pairsDDT Buildup
1890’s – 750 animalsOverhunting
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BEYOND MUTATIONS & GENE SHUFFLING
• Types of genetic drift:2. Founder effect -
happens when…
Examples:
• A few organisms from a larger population are transferred to another location
• Darwin’s Finches• Seeds carried by
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SPECIATION15
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SPECIATION• What is a species?
• What is speciation?
• A group of organisms capable of interbreeding and producing fertile offspring
• A change in organisms that leads to new species
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SPECIATION• How does speciation
happen?• Organisms from a
population must be reproductively isolated from each other
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SPECIATION• Geographic isolation
leads to speciation because…
• Examples:
• It puts a physical barrier between members of a population
• Earthquakes• Mountain ranges• Human activity
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SPECIATION• Behavioral isolation
leads to speciation because…
• Geographically isolated members of a population develop new mating behaviors
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SPECIATION• Temporal isolation
leads to speciation because…
• Members of a population start to reproduce at different times
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PATTERNS OF EVOLUTION
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MACROEVOLUTION• What is
macroevolution?• Large-scale history of
life on earth
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MACROEVOLUTION
1. Extinction is…
• Extinction happens because…
• The complete loss of a species from Earth• Organisms are unable
to adapt to changes in the environment
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MACROEVOLUTION
2. Adaptive radiation is…• Adaptive radiation
happens when…• Example:
• Evolution of one species into several species• A species moves into a
new, unoccupied region• Darwin’s Finches
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MACROEVOLUTION
3. Coevolution is…
• Examples:
• The evolution of 2 different species due to their interactions with each other• Mutualism• Predator-Prey• Parasitism
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MACROEVOLUTION
4. Convergent evolution is…
• These structures are called…
• Convergent evolution happens because…
• The development of body structures with similar functions that are structurally different• Analogous structures
• Vastly different organisms face similar environmental demands
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MACROEVOLUTION• Examples of
convergent evolution in organisms:• Birds• Bats• Bugs
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MACROEVOLUTION
5. What are Hox genes?
• Where are Hox genes found?
• Why are Hox genes important?
• A specific sequence of nucleotides about 180 units long• In the DNA of most
animals• They are the master
genes that control embryological development of body plans 28
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MACROEVOLUTION6. Punctuated equilibrium is…
• Punctuated equilibrium occurs after…
• Example…
• Rapid period of speciation between long periods of stability
• A catastrophic event• Some sort of massive
mutation occurs in a gene pool• Cambrian Explosion
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MACROEVOLUTIONCatastrophic Event Massive Mutation in Gene Pool
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