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Evolution in the Small Scale

By Brandon Harrison,2014-05-29 21:59
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Evolution in the Small Scale

    Evolution in the Small Scale Evolution in the Small Scale

    ; Discussed components of evolution ; Discussed components of evolution

    ; Natural selection ; Natural selection

    ; Common descent ; Common descent

    ; Time ; Time

    ; Populations ; Populations

    ; Variation ; Variation

    ; Put all together ; Put all together

    Evolution at Its Smallest Scale Evolution at Its Smallest Scale

    ; A species is a group of organisms able to successfully interbreed in nature ; A species is a group of organisms able to successfully interbreed in nature ; A species generally consists of several smaller groups called populations ; A species generally consists of several smaller groups called populations

    ; All the members of a species that live in a defined geographic region at a given time ; All the members of a species that live in a defined geographic region at a given time ; Populations, not individuals, are the units that evolve ; Populations, not individuals, are the units that evolve

    Evolution at Its Smallest Scale Evolution at Its Smallest Scale

    ; Evolution can be defined as a change in the characteristics of a population over time ; Evolution can be defined as a change in the characteristics of a population over time

    ; Populations are often isolated to some degree from other populations ; Populations are often isolated to some degree from other populations

    ; The environments inhabited by each population is different ; The environments inhabited by each population is different

    ; Each population faces the natural selection pressures of its own environment ; Each population faces the natural selection pressures of its own environment

    ; Different populations can evolve differently ; Different populations can evolve differently

    Evolution at Its Smallest Scale Evolution at Its Smallest Scale

    ; e.g., Two different frog populations in two different environments may both evolve coloration ; e.g., Two different frog populations in two different environments may both evolve coloration patterns making them less visible to predators patterns making them less visible to predators

    ; A lighter coloration may benefit one population in their particular environment, while a ; A lighter coloration may benefit one population in their particular environment, while a

    darker coloration pattern may benefit a second population in their (different) environment darker coloration pattern may benefit a second population in their (different) environment

    Evolution at Its Smallest Scale Evolution at Its Smallest Scale

    ; Natural selection acts upon the phenotypes of individuals ; Natural selection acts upon the phenotypes of individuals

    ; Individuals with one phenotype may be more fit than individuals with a different ; Individuals with one phenotype may be more fit than individuals with a different

    phenotype phenotype

    ; These phenotypes are influenced by genes ; These phenotypes are influenced by genes

    ; More specifically, different alleles of genes ; More specifically, different alleles of genes

    Evolution as a Change in the Frequency of Alleles Evolution as a Change in the Frequency of Alleles ; An individuals phenotype may make it more likely to survive longer ; An individuals phenotype may make it more likely to survive longer

    ; Surviving individuals may reproduce ; Surviving individuals may reproduce

    ; Individuals that do not survive certainly cannot reproduce ; Individuals that do not survive certainly cannot reproduce

    Evolution as a Change in the Frequency of Alleles Evolution as a Change in the Frequency of Alleles ; Some individuals are more successful at breeding ; Some individuals are more successful at breeding

    ; Their alleles are passed on to the next generation in relatively greater numbers ; Their alleles are passed on to the next generation in relatively greater numbers

    ; Alternative alleles possessed by less successful frogs are passed on to the next generation ; Alternative alleles possessed by less successful frogs are passed on to the next generation

    in reduced numbers in reduced numbers

    Evolution as a Change in the Frequency of Alleles Evolution as a Change in the Frequency of Alleles ; The evolution of a population involves a difference in reproductive output between individuals ; The evolution of a population involves a difference in reproductive output between individuals

    ; This is often the result of a difference in survival between individuals ; This is often the result of a difference in survival between individuals

    ; Surviving individuals may reproduce ; Surviving individuals may reproduce

    ; Individuals that do not survive certainly cannot reproduce ; Individuals that do not survive certainly cannot reproduce

    Evolution as a Change in the Frequency of Alleles Evolution as a Change in the Frequency of Alleles ; Microevolution is a change in allele frequencies in a population over a relatively short ; Microevolution is a change in allele frequencies in a population over a relatively short period of time period of time

    ; This is evolution within a population ; This is evolution within a population

    ; Macroevolution is evolutionary change that results in the formation of new species ; Macroevolution is evolutionary change that results in the formation of new species

    ; Larger changes resulting in the same way as microevolution ; Larger changes resulting in the same way as microevolution

    Five Agents of Microevolution Five Agents of Microevolution ; There are five agents of microevolution that can alter allele frequencies in populations ; There are five agents of microevolution that can alter allele frequencies in populations

    ; Mutation ; Mutation

    ; Gene flow ; Gene flow

    ; Genetic drift ; Genetic drift

    ; Sexual selection ; Sexual selection

    ; Natural selection ; Natural selection

    Five Agents of Microevolution Five Agents of Microevolution ; A mutation is any permanent alteration in an organisms DNA ; A mutation is any permanent alteration in an organisms DNA

    ; Mutations can be small ; Mutations can be small

    ; Point mutations: change in single base pair ; Point mutations: change in single base pair

    ; Mutations can be large: addition or deletion of whole or parts of chromosomes ; Mutations can be large: addition or deletion of whole or parts of chromosomes

    ; Some mutations are heritable ; Some mutations are heritable

    Five Agents of Microevolution Five Agents of Microevolution ; Mutation rates are very low ; Mutation rates are very low

    ; Perhaps just one base pair per billion ; Perhaps just one base pair per billion

    ; Very few of these mutations are beneficial ; Very few of these mutations are beneficial

    ; Most are neutral, some are harmful ; Most are neutral, some are harmful

    ; Beneficial mutations are very important ; Beneficial mutations are very important

    ; Mutations are the source of new genetic variation ; Mutations are the source of new genetic variation

    ; New proteins are produced, which can modify the form or capabilities of the organism ; New proteins are produced, which can modify the form or capabilities of the organism

    Five Agents of Microevolution Five Agents of Microevolution ; The evolution of eyes, wings, and other structures depends upon many mutations ; The evolution of eyes, wings, and other structures depends upon many mutations

    ; Many mutations, followed by rounds of genetic shuffling and natural selection are required ; Many mutations, followed by rounds of genetic shuffling and natural selection are required

    ; This process may take millions of years ; This process may take millions of years

    Five Agents of Microevolution Five Agents of Microevolution ; Allele frequencies can change as a result of migration ; Allele frequencies can change as a result of migration

    ; Arrival of members from a different population ; Arrival of members from a different population

    ; Immigration ; Immigration

    ; Loss of individuals to a different population ; Loss of individuals to a different population

    ; Emigration ; Emigration

    Five Agents of Microevolution Five Agents of Microevolution ; This movement may involve individuals, or may involve gametes ; This movement may involve individuals, or may involve gametes

    ; e.g., Movement of pollen ; e.g., Movement of pollen

    Five Agents of Microevolution Five Agents of Microevolution ; Allele frequencies can change simply as a matter of chance ; Allele frequencies can change simply as a matter of chance

    ; Random fluctuations in allele frequencies are termed genetic drift ; Random fluctuations in allele frequencies are termed genetic drift

    ; Alleles can increase or decrease in frequency ; Alleles can increase or decrease in frequency

    ; Alleles that are removed can only be replaced through new mutations or through ; Alleles that are removed can only be replaced through new mutations or through

    migration migration

    Five Agents of Microevolution Five Agents of Microevolution ; These fluctuations have the greatest impact on smaller populations ; These fluctuations have the greatest impact on smaller populations

    ; The bottleneck effect ; The bottleneck effect

    ; The founder effect ; The founder effect

    Five Agents of Microevolution Five Agents of Microevolution ; The bottleneck effect is a change in a populations allele frequencies due to chance ; The bottleneck effect is a change in a populations allele frequencies due to chance

    following a sharp reduction in population size following a sharp reduction in population size

    Five Agents of Microevolution Five Agents of Microevolution

    ; e.g., Northern elephant seals were hunted very heavily in the 1890s ; e.g., Northern elephant seals were hunted very heavily in the 1890s

    ; Only 50 individuals remained ; Only 50 individuals remained

    ; Protective measures have increased these numbers somewhat ; Protective measures have increased these numbers somewhat

    Five Agents of Microevolution Five Agents of Microevolution

    ; All members of the current population of northern elephant seals have descended from this ; All members of the current population of northern elephant seals have descended from this few individuals that survived the bottleneck few individuals that survived the bottleneck

    ; Many alleles were removed from the population during the bottleneck ; Many alleles were removed from the population during the bottleneck

    ; All of the members of todays population are genetically very similar ; All of the members of todays population are genetically very similar

    Five Agents of Microevolution Five Agents of Microevolution

    ; Pull a dozen M&Ms from a two pound bag ; Pull a dozen M&Ms from a two pound bag

    ; Will all of the colors be represented? ; Will all of the colors be represented?

    ; Will the colors be represented in the same proportions as in the original bag? ; Will the colors be represented in the same proportions as in the original bag?

    ; If these dozen M&Ms reproduce to fill a new two pound bag, what proportions might you ; If these dozen M&Ms reproduce to fill a new two pound bag, what proportions might you

    expect? expect?

    ; How do your answers differ if you pull 120 M&Ms from the bag? ; How do your answers differ if you pull 120 M&Ms from the bag?

    Five Agents of Microevolution Five Agents of Microevolution

    ; The founder effect occurs when a small population migrates to a new area to start a new ; The founder effect occurs when a small population migrates to a new area to start a new population population

    ; The allele frequencies in this small population will not precisely mirror those of the larger ; The allele frequencies in this small population will not precisely mirror those of the larger

    population population

    ; The effects of genetic drift can be profound in such a small population ; The effects of genetic drift can be profound in such a small population

    Five Agents of Microevolution Five Agents of Microevolution

    ; Sexual selection involves differential reproductive success based on success in obtaining ; Sexual selection involves differential reproductive success based on success in obtaining mating partners mating partners

    ; A form of natural selection ; A form of