Multicellular Algae Seaweeds ( macroalgae) Multicellular algae.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Oldest multicellular...
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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Oldest multicellular fossil Oldest fossil prokaryotic cell Evolution – genetic change over time
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Transcript of Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Oldest multicellular...
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Oldest multicellular fossil
Oldest fossilprokaryotic cell
Evolution – genetic change over time
LE 13-1bLE 13-1b
NorthAmerica
GreatBritain
ATLANTICOCEAN
PACIFICOCEAN
SouthAmerica
An
des Cape of
Good Hope
Cape Horn
Tierra del Fuego
Africa
Europe Asia
Equator
PACIFICOCEAN
Australia
TasmaniaNewZealand
TheGalápagosIslands
Pinta
Fernandina
Isabela
Santiago
MarchenaGenovesa
DaphneIslandsPinzón
SantaCruz
SantaFe San
Cristobal
Florenza Española
Equator
0
0 40 miles
40 km
PACIFICOCEAN
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Natural SelectionDarwin proposed natural selection as the mechanism of evolution
•Organisms vary in many characteristics that can be inherited•Excessive numbers of organisms lead to a struggle for survival•Organisms produce more offspring than the environment can support
What is a Species?
LE 13-2cLE 13-2c
African wild dog Coyote Wolf Fox Jackal
Thousands tomillions of years
of natural selection
Ancestral canine
Natural selection is supported by evidence from artificial selection
LE 13-4aLE 13-4a
Human Cat Whale Bat
–Common embryonic structures in all vertebrates are evidence for common descent
LE 13-4bLE 13-4b
Chick embryo
Pharyngealpouches
Post-analtail
Human embryo
LE 13-5bLE 13-5b
Chromosome with geneconferring resistanceto pesticide
Pesticide application
SurvivorAdditionalapplications of thesame pesticide willbe less effective, andthe frequency ofresistant insects inthe populationwill grow
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Examples of evolutionary adaptation reveal three key points about natural selection
– Natural selection is more of an editing process than a creative mechanism
– Natural selection is contingent on time and place
– Significant evolutionary change can occur in a short time
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Studying evolution at the population level
– Evolution: change in the prevalence of certain heritable characteristics in a population over a span of generations
– Gene pool: the total collection of genes in a population at any one time
– Microevolution: a change in the relative frequencies of alleles in a gene pool
– Species: a group of populations capable of interbreeding and producing fertile offspring
LE 13-9aLE 13-9a
Originalpopulation
Bottleneckingevent
Survivingpopulation
In addition to natural selection, other events can contribute to evolution
LE 13-12aLE 13-12a
Parents
Meiosis
Gametes
A1 A1 A2 A3
A3A2A1
LE 13-12bLE 13-12b
Fertilization
Offspring,with newcombinationsof alleles
and
A1 A2 A1 A3
A3A2A1
Gametes
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
CONNECTION
13.13 The evolution of antibiotic resistance in bacteria is a serious public health concern
• Natural selection has led to the evolution of antibiotic-resistant bacteria
• Overuse and misuse of antibiotics has contributed to the proliferation of antibiotic-resistant strains
– Example: tuberculosis
Neutral traits
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
13.15 The perpetuation of genes defines evolutionary fitness
• Evolutionary fitness is the relative contribution an individual makes to the gene pool of the next generation
• Survival of genes depends on production of fertile offspring
• Selection indirectly adapts a population to its environment by acting on phenotype
LE 13-16LE 13-16
Originalpopulation
Evolvedpopulation
Stabilizing selection
Phenotypes (fur color)
Originalpopulation
Fre
qu
ency
of
ind
ivid
ual
s
Directional selection Disruptive selection
Natural selection can alter variation in a population
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
13.18 Natural selection cannot fashion perfect organisms
• There are at least four reasons why natural selection cannot produce perfection
– Organisms are limited by historical constraints
– Adaptations are often compromises
– Chance and natural selection interact
– Selection can only edit existing variations
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
