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

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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)

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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