Evolution speciation
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EVOLUTION & SPECIATION. VOCABULARY REVIEW. EVOLUTION – CHANGE OVER TIME NATURAL SELECTION INDIVIDUALS BETTER ADAPTED TO THE ENVIRONMENT ARE ABLE TO SURVIVE & REPRODUCE A.K.A. “SURVIVAL OF THE FITTEST”. NEW VOCABULARY. POPULATION GROUP OF INDIVIDUALS OF SAME SPECIES THAT INTERBREED

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EVOLUTION & SPECIATION

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Evolution speciation

EVOLUTION & SPECIATION


Vocabulary review

VOCABULARY REVIEW

  • EVOLUTION – CHANGE OVER TIME

  • NATURAL SELECTION

    INDIVIDUALS BETTER ADAPTED TO THE ENVIRONMENT ARE ABLE TO SURVIVE & REPRODUCE

    • A.K.A. “SURVIVAL OF THE FITTEST”


New vocabulary

NEW VOCABULARY

  • POPULATION

    GROUP OF INDIVIDUALS OF SAME SPECIES THAT INTERBREED

  • GENE POOL

    COMMON GROUP OF ALL GENES PRESENT IN A POPULATION


Gene pool

Gene Pool

Combined genetic information of all members

Allele frequency is # of times alleles occur


Variation in populations

Variation in Populations

2 processes can

lead to this:

Mutations -

change in DNA

sequence

Gene Shuffling –

from sexual

reproduction


Evolution speciation

  • Genetic Drift = changes to allele frequency as a result of chance

  • Bottleneck effect = dramatic reduction in population size usually resulting in significant genetic drift


Genetic drift changes populations

Genetic Drift changes populations…….

  • Random change in allele frequency causes an allele to become common


Evolution speciation

  • Founder Effect:

    - Genetic Drift that occurs when individuals from a large population leave to establish a new population

    - Allele frequencies of the new population will not be the same as those of the original


Evolution speciation

  • Gene Flow: genetic exchange due to the migration of fertile individuals or gametes between populations (reduces differences between populations)


Evolution speciation

  • Nonrandom mating: inbreeding and assortive mating (both shift frequencies of different genotypes)


Evolution speciation

  • Natural Selection: differential success in reproduction; only form of microevolution that adapts a population to its environment


Sexual selection

Sexual selection

  • Sexual dimorphism: secondary sex characteristic distinction

  • Sexual selection: selection towards secondary sex characteristics that leads to sexual dimorphism


Evolution of populations

Evolution of Populations

Occurs when there is a change in relative frequency of alleles


Natural selection on polygenic traits

Natural Selection on Polygenic Traits

  • Shifts to

    middle range

  • Shifts to

    2 extremes

  • Shifts to

    1 extreme


Speciation

SPECIATION

  • THE FORMATION OF NEW SPECIES

  • AS NEW SPECIES EVOLVE, POPULATIONS BECOME REPRODUCTIVELY ISOLATED

  • REPRODUCTIVE ISOLATION – MEMEBERS OF 2 POPULATIONS CANNOT INTERBREED & PRODUCE FERTILE OFFSPRING.


Evolution speciation

These squirrels live on opposite sides of the Grand Canyon. This is an example of allopatric speciation.


Speciation in darwin s finches

SPECIATION IN DARWIN’SFINCHES

  • SPECIATION IN THE GALAPAGOS FINCHES OCCURRED BY:

    - FOUNDING OF A NEW POPULATION,

    - GEOGRAPHIC ISOLATION which led to -- REPRODUCTIVE ISOLATION and

    CHANGES IN THE NEW POPULATION’S GENE POOL due to COMPETITION.


Evidence of evolution

Evidence of Evolution

  • Fossil Record

  • Geographic Distribution of Living Species

  • Homologous Body structures

  • Similarities in Embryology


Evolution speciation

Evidence of

Evolution

Fossil Record provides evidence that living things have evolved

Fossils show the history of life on earth and how different groups of organisms have changed over time


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