Honors

Biology

Ch. 15

Honors

Biology

Ch. 15

The Theory of EvolutionThe Theory of Evolution

I. Darwin’s Theory of Evolution by Natural Selection

I. Darwin’s Theory of Evolution by Natural SelectionEvolution:hereditary change in populations of organisms over time

A. Developing the Theory of Evolution

A. Developing the Theory of Evolution1.Charles Darwin

(1809-1882) - developed the

theory of evolution by

natural selection

- traveled around the world as a naturalist (1831-1836)

Galapagos wildlife

- Compared changes in species by farmers through artificial selection to what can happen in nature

Artificial Selection in the Mustard Family

Artificial Selection in the Mustard Family

‘Fancy Pigeon’ Bred by Artificial Selection‘Fancy Pigeon’ Bred by Artificial Selection

2. Natural Selection2. Natural Selection- Natural Selection is based on 4 principles:

a) Variation:a) Variation:- All organisms produced sexually

are genetically unique.

Variation in Human Height

b) Heredityb) Heredity- Variations are

inherited from parents.

c) Over Production:c) Over Production:- Populations produce more offspring

than can survive.

Female octopus with thousands of eggs

Dozens of newly hatched sea turtles

Thousands of dandelion seeds

d) Reproductive Advantaged) Reproductive Advantage- Those best suited will survive

longer and reproduce.- Those less suited won’t survive or

reproduce as often.

Peppered MothPeppered Moth

d) Reproductive Advantaged) Reproductive Advantage- Those best suited will survive

longer and reproduce.- Those less suited won’t survive or

reproduce as often.

Rock Pocket Mouse

10:25

Sandstone Environmen

t

Sandstone Environmen

t

Basalt Environment

Basalt Environment

The Rock Pocket Mouse10:25

3.The Origin of Species3.The Origin of Species- On the Origin of Species published

in 1859

- Darwin presented two main ideas:- Darwin presented two main ideas:(1) Descent with modification explains

life’s unity and diversity.(2) Natural selection is

a cause of adaptiveevolution

II. Evidence of EvolutionII. Evidence of Evolution- Evidence comes

from a wide variety of observations.

Archaeopteryx Fossil

Archaeopteryx Fossil

- provides direct evidence for evolutionary relationships

A. The Fossil Record

A. The Fossil Record

- provides direct evidence for evolutionary relationships

A. The Fossil Record

A. The Fossil Record

- many ‘missing links’ have been found

(a) Pakicetus (terrestrial)

(b) Rhodocetus (predominantly aquatic)

(c) Dorudon (fully aquatic)

Pelvis andhind limb

Pelvis andhind limb

(d) Balaena (recent whale ancestor)

B. Comparative AnatomyB. Comparative Anatomy

1) Homologous Structures: - organs in related organisms with a similar underlying anatomy- examples: forelimbs of humans,

bats, whales, etc.

Homologous Structures

Homologous Structures

FlyingFlying Swimming

Swimming

Running

Running GraspingGrasping

2) Vestigial Structures: - organs with no apparent function that are homologous to functional organs in related organisms- examples: coccyx, appendix, ear muscles, etc.

Salamander

Gray Whale

Gibbon Viper

Vestigial StructuresVestigial

Structures

C. Comparative EmbryologyC. Comparative Embryology- Organisms with common

ancestors share similarities in embryonic development.

Pharyngealpouches

Post-analtail

Chick embryo Human embryo

D.Comparative BiochemistryD.Comparative Biochemistry

- All organisms contain DNA, RNA, and proteins made of the same 20 amino acids.

- The more recent two organisms share a common ancestor, the more similar their DNA and proteins.DNA Differences

in Cytochrome CDNA Differences in Cytochrome C

E. BiogeographyE. Biogeography

- Biogeography explains why certain species are found in certain places.

- Islands have many endemic species that are often closely related to species on the nearest mainland or island.

Biogeogaphy of a Group of Pacific Island

Monarchs

Biogeogaphy of a Group of Pacific Island

Monarchs

Biogeography of

Members of the Camel

Family

Biogeography of

Members of the Camel

Family

F. Types of AdaptationF. Types of Adaptation

1. Camouflage

Leafy Sea Dragon

F. Types of AdaptationF. Types of Adaptation

1. Camouflage

Octopus near Cayman

Island (1:15) .

Octopus near Cayman

Island (1:15) .

F. Types of AdaptationF. Types of Adaptation

1. Camouflage

Octopus

F. Types of AdaptationF. Types of Adaptation

1. Camouflage

Scorpionfish

Scorpionfish

Dead Leaf ButterflyDead Leaf Butterfly

Walking StickWalking Stick

MantisMantis

CheetahCheetah

2. Mimicry 2. Mimicry

- A harmless species may imitate a harmful species.

Coral SnakeCoral Snake

Milk SnakeMilk

Snake

2. Mimicry 2. Mimicry

- A harmless species may imitate a harmful species.

Green parrot snakeGreen parrot snake

Hawkmoth larvaHawkmoth larva

- 2 harmful species may reinforce each other’s warning colors.

Spring SalamanderGyrinophilus porphyriticus

Spring SalamanderGyrinophilus porphyriticus

Red Salamander Pseudotriton ruber Red Salamander Pseudotriton ruber

Median Wasp

Median Wasp

Paper WaspPaper Wasp

Hoverfly

Hoverfly

Hoverfly

Hoverfly

Longhorn BeetleLonghorn Beetle

Hoverfly

Hoverfly

Müllerian vs. Batesian Mimicry Müllerian vs. Batesian Mimicry

III. Shaping Evolution Theory

III. Shaping Evolution Theory

A.Mechanisms of Evolution1. Population Genetics

- Microevolution is a change in relative frequency of alleles in the gene pool of a population.

- A population is at genetic equilibrium if 5 conditions are met:

Large size, No mutations, No gene flow, Random mating,

and No natural selection.

2.Genetic Drift2.Genetic Drift- a random change in allele frequencya) Founder Effect

- occurs when a new population is established from a small sample of a population separated from the rest of the

original population.

Ellis-van Creveld syndrome is more common among the Amish and can

be traced back to a single family who helped establish the colony in 1744.

Ellis-van Creveld syndrome is more common among the Amish and can

be traced back to a single family who helped establish the colony in 1744.

2.Genetic Drift2.Genetic Drift

Blue Iguana Cyclura lewisi

Cuban Iguana Cyclura nubila

Blue iguanas, endemic to the Grand Cayman Island, is believed to have originated from a single pregnant Cuban iguana 3 MYA.

Blue iguanas, endemic to the Grand Cayman Island, is believed to have originated from a single pregnant Cuban iguana 3 MYA.

2.Genetic Drift2.Genetic Drift

Masai Giraffe

Rothschild Giraffe

Reticulated Giraffe

2.Genetic Drift2.Genetic Drift

b)Bottleneck Effect b)Bottleneck Effect - occurs when a population is reduced in

size that no longer reflects the original population’s gene pool.

Cheetah populations were nearly hunted into extinction.

Cheetah populations were nearly hunted into extinction.

“King” Cheetah variation

“King” Cheetah variation

3.Mutation 3.Mutation - random change in DNA- usually harmful or neutral, occasionally

advantageous (depends on environment)- source of all heritable

variation

3.Mutation 3.Mutation - random change in DNA- usually harmful or neutral, occasionally

advantageous (depends on environment)- source of all heritable

variation

‘Blue eyes’ in humans stem from a single

genetic mutation that occurred 6,000 - 10,000

years ago.

‘Blue eyes’ in humans stem from a single

genetic mutation that occurred 6,000 - 10,000

years ago.

Evolving Lactase Persistence

14:30

4.Natural Selection 4.Natural Selection - acts on phenotypes and changes allele

frequency in a pop.- favors individuals best adapted to

environment

Original population

Fre

quen

cy o

f in

divi

dual

s

Phenotypes (fur color)

Originalpopulation

Evolvedpopulation

Fre

quen

cy o

f in

divi

dual

s

Phenotype

a) Stabilizing Selection a) Stabilizing Selection - eliminates extreme

expressions of a trait

b) Directional Selection b) Directional Selection - increases one

extreme expression of a trait

Fre

quen

cy o

f in

divi

dual

s

Phenotypes (fur color)

Original population

Originalpopulation

Evolvedpopulation

Fre

quen

cy o

f in

divi

dual

s

Phenotypes (fur color)

b) Directional Selection b) Directional Selection Rock Pocket Mouse:One Species, Two

Varieties10:25

Rock Pocket Mouse:One Species, Two

Varieties10:25

Sandstone EnvironmentSandstone

EnvironmentBasalt

EnvironmentBasalt

Environment

b) Directional Selection b) Directional Selection Rock Pocket Mouse:One Species, Two

Varieties

Rock Pocket Mouse:One Species, Two

Varieties

c) Disruptive Selection c) Disruptive Selection - favors both extreme

expressions of a trait; eliminates average exp. of trait F

requ

ency

of

indi

vidu

als

Phenotypes (fur color)

Original population

Originalpopulation

Evolvedpopulations

Fre

quen

cy o

f in

divi

dual

s

Phenotypes (fur color)

c) Disruptive Selection c) Disruptive Selection Timema cristinae:One Species, Two

Varieties

Timema cristinae:One Species, Two

Varieties

Adenostoma ecotype

Adenostoma ecotype

Ceanothus ecotype

Ceanothus ecotype

c) Disruptive Selection c) Disruptive Selection

5.Sexual Selection 5.Sexual Selection - selection that favors the ability to attract

a mate- produces differences between males and

females

5.Sexual Selection 5.Sexual Selection A Bower of the Satin Bower Bird

A Bower of the Satin Bower Bird

5.Sexual Selection 5.Sexual Selection

Male Stalk-eyed Flies

Male Stalk-eyed Flies

Intersexual Selection

Intersexual Selection

Intrasexual Selection

Intrasexual Selection

GemsbokGemsbok

African ElephantAfrican Elephant

Bird of ParadiseBird of Paradise

Sandhills Crane

Sandhills Crane

5.Sexual Selection 5.Sexual Selection

Male Irish Elk

Male Irish Elk

B.Speciation B.Speciation - the origin of a new species

Phylogeny of the Pig Family

Phylogeny of the Pig Family

1.Reproductive Isolation 1.Reproductive Isolation - Members of a new

population of organisms can no longer produce fertile offspring with members of the original population.

Salamanders in CaliforniaSalamanders in California

Salamanders in

California3:21

a) Prezygotic Isolationa) Prezygotic Isolation- prevents fertilization

Prezygotic barriers impede mating or hinder fertilization if mating does occur

Individualsof differentspecies

Matingattempt

Habitat isolation

Temporal isolation

Behavioral isolation

Mechanical isolation

HABITAT ISOLATION TEMPORAL ISOLATION BEHAVIORAL ISOLATION MECHANICAL ISOLATION

(b)

(a)(c)

(d)

(e)

(f)

(g)

Liriodendron tulipifera

Liriodendron tulipifera

Liriodendron chinensis

Liriodendron chinensis

2 Very Similar Species: One in Eastern U.S., One in Eastern Asia

2 Very Similar Species: One in Eastern U.S., One in Eastern Asia

Pinus taeda

April Pollinatio

n

Pinus taeda

April Pollinatio

n

Pinus palustris

February Pollination

Pinus palustris

February Pollination

2 Species of Southern Pine: Time of Pollination Differs

2 Species of Southern Pine: Time of Pollination Differs

Eastern Meadowlark, Sturnella magna

Eastern Meadowlark, Sturnella magna

Western Meadowlark, Sturnella neglecta

Western Meadowlark, Sturnella neglecta

Behavioral IsolationBehavioral Isolation

b) Postzygotic Isolationb) Postzygotic Isolation- A hybrid offspring is born but is either

not viable or fertile.

Viablefertile

offspring

Reducehybrid

viability

Reducehybridfertility

Hybridbreakdown

Fertilization

Gameticisolation

GAMETIC ISOLATION REDUCED HYBRID VIABILITY

REDUCED HYBRID FERTILITY HYBRID BREAKDOWN

(h) (i)

(j)

(k)

(l)

(m)

2.Allopatric Speciation

2.Allopatric Speciation- speciation that occurs

when a physical barrier separates a population into 2 or more populations

Kaibab SquirrelAbert

Squirrel

Allopatric SpeciationAllopatric Speciation

3.Sympatric Speciation3.Sympatric Speciation- speciation that occurs

without a physical barrier that separates a new population

C.Patterns of EvolutionC.Patterns of Evolution1.Adaptive Radiation

(Divergent Evolution)- when one species gives rise to several new species

Hawaiian Honeycreepe

rs

Hawaiian Honeycreepe

rs

2.Coevolution2.Coevolution- when 2 species evolve together forming

symbiotic relationships

Darwin’s Orchid and the Orchid Fly

Darwin’s Orchid and the Orchid Fly

2.Coevolution2.Coevolution- when 2 species evolve together forming

symbiotic relationships

Coevolution of the Garter Snake and the California

Newt

Coevolution of the Garter Snake and the California

Newt

California Newt

Garter Snake

2.Coevolution2.Coevolution- when 2 species evolve together forming

symbiotic relationships

Coevolution of the Garter Snake and the California

Newt

Coevolution of the Garter Snake and the California

Newt

California Newt

Garter Snake

3.Convergent Evolution

3.Convergent Evolution- When 2 unrelated species evolve similar

traits due to living in similar environments

Swordfish

Swordfish

DolphinDolphin

Ichthyosaur

Ichthyosaur

SharkShark

Convergent Evolution

Convergent Evolution

Convergent Evolution

Convergent Evolution

American CactusAmerican CactusAmerican CactusAmerican Cactus African EuphorbAfrican EuphorbAfrican EuphorbAfrican Euphorb

Convergent Evolution

Convergent Evolution

4.Rate of Speciation4.Rate of Speciationa) Gradualism

- when evolutionary change occurs as a series of small, gradual changes

b) Punctuated Equilibrium- when evolutionary change occurs in rapid spurts followed by longer periods of little change

GradualismGradualism Punctuated EquilibriumPunctuated Equilibrium

The EndThe EndTriassic Landscape, Karen

Carr