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Evolution Chapters 21-25
Evolution (chapter 22) Change over time
in the genetic composition of a population
Descent with modification
Evolution history
1812Cuvier publishes hisextensive studies ofvertebrate fossils.
1809Charles Darwin
is born.
1809Lamarck publishes his
hypothesis of evolution.
1798Malthus publishes
“Essay on the Principleof Population.”
1795Hutton proposes
his principle ofgradualism.
1790 18701831–1836
Darwin travelsaround the world
on HMS Beagle. 1844Darwin writes hisessay on descentwith modification.
1859On the Origin ofSpecies is published.
1830Lyell publishesPrinciples of Geology.
Sketch of a flyingfrog by Wallace
1858While studying species in theMalay Archipelago, Wallace(shown above in 1848) sendsDarwin his hypothesis ofnatural selection.
Marine iguanain the
GalápagosIslands
Evolution History Aristotle “Scala naturae” Organisms arranged in increasing
complexity Each form of life was permanent
Evolution History Linnaeus Taxonomy Naming &
classifying organisms
Binomial system (Genus & species)
Grouping similar species in general categories
Evolution history Georges Cuvier Paleontology Study of fossils Noted species in some layers of rocks Each layer represented catastrophic
events
Sedimentary rocklayers (strata)
Younger stratumwith more recentfossils
Older stratumwith older fossils
Evolution history Hutton Change can take
place through cumulative effect
Slow but continuous processes
Gradualism
Evolution history Lyell Geological
processes are happening now
As they were in the past
Evolution history Lamacrk Two principles 1. Use and disuse Parts of the body
used became stronger
Those not used deteriorate
Lamacrk 2. Inheritance of
acquired characteristics
Giraffes stretched necks to reach the leaves
Pass on the stretched neck
Charles Darwin
Darwin’s voyage
Darwin’s voyage
Darwin’s voyage
Darwin’s voyage
Darwin’s voyage Observed adaptations of many species Collected fossils Resembled animals living in S.
America Collected different species of birds
from Galapagos Islands Species on the island were similar to
the species only on SA mainland
Finches
Darwin’s voyage Conclusion Birds adapted to environment to
survive Adapted to food source that is
available
Darwin Adaptation Accumulation of inherited
characteristics Enhance an organism’s ability to survive & reproduce in specific environment Result of natural selection
Adaptation
Adaptation
Fig. 22-12a
(a) A flower mantid in Malaysia
Fig. 22-12b
(b) A stick mantid in Africa
Wallace Developed a
theory of natural selection similar to Darwin’s
Forced Darwin to publish his writings
Charles Darwin November 24, 1859 Origin of
Species Focused on diversity of animals Origins & relationships Similarities & differences Geographic distribution Adaptations to surroundings
Darwin Descent with modification “ through time species accumulate
differences; As a result: When new species are formed Descendent species differ from its
ancestor”
Descent with Modification All organisms are related Descent from an ancestor that lived
awhile ago Descendants were in various
habitats Diverse modifications or adaptations Specific ways of life
Descent with Modification History of life as a tree Trunk is the common ancestor Branches represent an ancestor of all
the lines that evolve from that point Recent divergence--closely related
species Many branches dead end Many species are extinct
Fig. 22-8
Hyracoidea(Hyraxes)
Sirenia(Manateesand relatives)
Moeritherium
Barytherium
Deinotherium
Mammut
Elephas maximus(Asia)
Stegodon
Mammuthus
Loxodontaafricana(Africa)
Loxodonta cyclotis(Africa)
010425.52434
Millions of years ago Years ago
Platybelodon
Artificial selection Modification of crops Modification of animals for desired
trait Domesticated foxes Choosing most docile in the offspring Mating them Over time produced a fox very similar
to domesticated dogs
Variation Variation in the population Leads to differences in individuals
in survival & reproduction Variation among individuals must
be genetically transmitted
Fig. 22-10
Natural Selection Mechanism for evolution Organisms with specific heritable traits Produce more offspring with the traits Population grows with more offspring
with advantageous traits
Natural selection Populations evolve not individuals Affects inheritable traits Environment greatly influences
selection of traits Trait favorable in one environment Detrimental in another Change in environment causes
change in adaptation
Evolution Evidence 1. Direct Observations 2. Paleontology 3. Homology
Anatomy Embryology Molecular biology
4. Biogeography
1. Direct Observations Industrial Melanism Peppered moth Variation of traits Increased industrial use caused
blackened trees Favored darker moth 1956 restrictions on pollution Favored lighter colored moth
Industrial Melanism
Bacterial antibiotic resistance
250,000 base pairs
500,000
750,000
1,000,000
1,250,0001,500,000
1,750,000
2,000,000
2,250,000
2,500,000
2,750,000
Chromosome mapof S. aureus clone USA300
Key to adaptations
Methicillin resistanceAbility to colonize hostsIncreased disease severityIncreased gene exchange(within species) andtoxin production
1
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50
100
150
200
250
300
350
400
HIV Drug resistance 3TC drug affects HIV reverse
transcriptase Enzyme makes DNA from RNA
genome Virus DNA inserted into host DNA 3TC Is similar to cytosine Resistant HIV carry a different reverse
transcriptase (enzyme0 Prevents drug from working
2. Fossils Show change over time Fossils of extinct whales Supports idea whales came from a
species that was a land animal Fossil evidence that birds came
from dinosaurs
Fig. 22-16
(a) Pakicetus (terrestrial)
(b) Rhodocetus (predominantly aquatic)
(c) Dorudon (fully aquatic)
Pelvis andhind limb
Pelvis andhind limb
(d) Balaena (recent whale ancestor)
3. Anatomy Homologous structures Structures with different
appearances & function Derived from a common ancestor Forelimbs in humans, cats, whale &
bats Show same arrangement of bones
but different uses
Homologous structures
Fig. 22-17
Humerus
Radius
Ulna
Carpals
Metacarpals
Phalanges
Human WhaleCat Bat
Embryology Study of early development Shows evidence of structures that
do not develop into adult structures
Tail Gills/ears and throat
Fig. 22-18
Human embryoChick embryo (LM)
Pharyngealpouches
Post-analtail
Vestigial organs Remnants of organs Do not serve any function now Resemble structures of their
ancestors Appendix in humans Pelvis/leg bones in snakes
Molecular biology DNA RNA Similar in organisms Organisms that are very different
share a common code Genes have different functions
Molecular biology Compare aa sequence for human
hemoglobin Animals closely related to humans Have a higher percent of similar aa
than those not as closely related Rhesus monkey has 95% identical
aa Frog has 54% identical aa
Evolutionary tree Diagram that shows evolutionary
relationships Descent from common ancestor
Fig. 22-19
Hawks andother birds
Ostriches
Crocodiles
Lizardsand snakes
Amphibians
Mammals
Lungfishes
Tetrapod limbs
Amnion
Feathers
Homologouscharacteristic
Branch point(common ancestor)
Te
trapo
ds
Am
nio
tes
Bird
s
6
5
4
3
2
1
Convergent evolution Independent development of
similar structures in organisms Not directly related Found in organisms that live in
similar environment Sugar glider (Australia) (marsupial) Flying squirrel (Europe) (placental)
Sugarglider
Flying squirrel
AUSTRALIA
NORTHAMERICA
Convergent evolution Analogous structures Evolve independently Not common ancestor Adapted to similar environments
4. Biogeography Geographic distribution of species Closely related species live in the
same geographic region Distant regions are occupied by
very different species
Biogeography Australia Home to marsupials Embryo develops in a pouch Isolated by geography Placental mammals Embryo develops in uterus
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