EVOLUTION

The change of populations of organisms over generations.

The process by which all organisms have developed from older forms of life

Old species go extinct (mass extinction) and new species arise.

*Evolution

DAY 1

A group of organisms similar in structure and heredity capable of producing fertile offspring

*breeding within the species…always exceptions to every rule…

Examples?

*Species

Extra-terrestrial originCreation/Divine force*Originate from non-living matter

3 ways life could have began on Earth:

*Ch 21

IS THIS EVOLUTION?Once Life is here…evolution can occur-evolution is how life/species change and develop over time.

Abiotic synthesis of small, organic molecules (amino acids, nitrogenous bases) Miller/Urey 1953

◦ “prebiotic soup”, no free O2 + lightning + volcanoes = molecule

◦ Meteorites + Clay from volcanic ash Making macromolecules… proteins, nucleic acids Protocells/Protobionts/vesicles Origin of self replication inheritance …RNA or DNA?

◦ First genetic material- RNA, ribozymes-catalytic RNA (ribosomes); protein synthesis

Conditions on early Earth made the origin of life possible

Anaerobic Heterotrophs > Chemautotrophs > Photoautotrophs (cyanobacteria) Splitting water*O2 > Aerobes, Ozone layer > Endosymbiosis

Exploring Life’s Origins

End

osym

bios

is

The road to all Eukaryotes:• Endosymbiosis leads

to-• Membrane bound

organelles• Cytoskeleton • Chromosomes/nucleus• Cellular membranes,

transport systems

Cyanobacteria

Endosymbiosis

Land Plants, Animals

200,000- Homo Sapiens (11:59:30)

~3.5 bya Stromatolites Oldest fossils-cyanobacteria

Stromatolites

http://www.ucmp.berkeley.edu/precambrian/archean_hadean.phpShark Bay, Austrailia 2-3,000yo high salt content 100yrs to grow 5cm living fossilsCyanobacteria + sediment + Calcium Carbonate form limestone layers…

Oldest fossils on Earth

End

osym

bios

is

*Eukaryotes or Prokaryotes?*Anaerobic or Aerobic?*Heterotrophs or Autotrophs?*Marine or Land?*Cyanobacteria- Importance?*Oldest Fossil?*Endosymbiotic Theory?*Why the diversity explosion?*Amphibians or Reptiles?*Warm or Cold Blooded?

WHAT

CAME

FIRST??

+

FYI… Eon Eras Periods

◦ “firsts”◦ Major

changes in diversity

Epochs Ages

Mass Extinction Events

Widespread and rapid decrease in the amount of life on earth.

Sharp change in diversity and abundance.

98% of Documented Species are nowExtinct.

Mass Extinction Events

How long will it take?What causes the changes?

What evidence do scientists have to support the Theory of Evolution?

Evolution: Change in species (populations) over time…

1. Fossils2. Homologous Structures3. Vestigial Structures4. Embryonic Development5. Biochemical Similarities:

DNA Sequencing- Universal Code

*Evidence of Evolution

The remains or evidence of any creature or plant that once lived on the Earth.

Fossils are often found in sedimentary rock, which is formed from layers of silt and sand covering dead organisms.

Types of Fossils??

1. Fossils

Remains or traces…Insects in Amber, Bones, teeth, shells, footprints

In what ways is the fossil record considered biased?

2. Homologous Structures

Similar structure and anatomical position (but not necessarily the

same function) in different

organisms: “ICA”

“ICA” = Indicates Common AncestorHand, Paw, Fin, Wing??

Divergent Evolution

• Same lineage, evolving apart to be more different.

• For example, bats and horses. Both share the same lineage as mammals, but the limb of the bat became wings while the horse developed hooves.

• Produces homologous structures

Similar Appearance and Function-does NOT indicate ICA

Ex- Bird and Insect Wings Porpoise and Shark Fins

*Analogous Structures

Built on a different blueprint

3. Vestigial StructuresStructures or organs that seem to serve no useful function. Poorly developed

Organisms having vestigial structures: ICA with organisms in which the

homologous structure is functional

……….humans??

Text p399

4. Comparative EmbryologyThe more closely related any two species are, the more similar their development: ICA

The closer the DNA sequences of 2 organisms are, the more closely related they are.

◦ Humans and chimps have DNA that is 98.4% identical

5. Biochemical/DNA Evidence

• DNA and RNA are carriers of genetic information • The genetic code is universal• Some Metabolic pathways are conserved (same/similar) across all

domains

Evolutionary Relationships among major groups….

Overheads: 5 Kingdoms >7Animal KingdomMammalianPrimates

Primate Evolutionary Tree

ARISTOTLE ~335 BCSpecies change over time, moving toward a “perfect state”.

LAMARCK 1744-1829FIRST to clearly state: Types of organisms changed over time because

of natural phenomenon not divine force. New species were modified descendants of

older species.

EARLY EVOLUTION THEORY

DAY 2

“OUT”/ Discredited Ideas….

Theory of Need: a change in the environment produced a need for change in organisms

1. Use and Disuse If organs were used- they remained, if unused, they would disappear.

“Use it or Lose It”….all inheritable changes

2. Inheritance of Acquired Characteristics Not determined by heredity; ‘acquired traits’ are acquired in ones lifetime in response to ones experience or behavior.

*LAMARCK 1744-1829

THEORY OF NATURAL SELECTIONOrganisms with traits more

favorable to a particular environment are more likely to pass on those traits to their offspring. *Environment plays a key role.

(HW Ch 18)

*DARWIN 1809-1882(co-discoverer- Wallace)

WHERE LAMARCK FAILED: INDIVIDUALS DO NOT EVOLVE, POPULATIONS DO

Giraffes and Natural Selection

H.M.S. Beagle 1831-1836

DARWIN BACKGROUND EDUCATION REV. JOHN HENSLOW VOYAGE

DARWIN’s Finches 1856 Alfred Wallace 1858 Papers of Darwin

& Wallace read 1859 Publishes his

work

1. VARIATIONS exist in individuals within a species (caused by mutations/genetic recombination). Those with favorable variations have an advantage for survival.

Live Longer > Produce more offspring > Genes passed on

2. OVERPRODUCTION of offspring: More offspring are produced than can survive, but the population remains fairly constant.

3. STRUGGLE FOR EXISTENCE: Competition for food, space, mates (limiting factors).

4. NATURAL SELECTION –the best adapted are ‘selected’. Survival of the Fittest = best suited for the environment

*Theory of Natural Selection

Darwin’s Fittest = Differential Reproductive Success

*HW Ch 18

DESCENT OF MODIFICATION: Similarities in related species are due to common ancestry

Idea of ‘common descent’ was inspired by BIOGEOGRAPHY (geographical distribution of species)

Natural Selection favors Reproductive Success of certain individuals over others in a population.

Individuals do not evolve, populations do

*DARWIN

The study of the past and present geographic distribution of organisms.

DARWIN: Species found on ocean islands tend to resemble species of the nearest mainland, even if the environment is different.

Galapagos (South America) Cape Verde Island (Africa)

AUSTRALIA: (separate land mass for millions of years). Has distinctive organisms not found anywhere else in the world even though climate is the same.

Monotremes: Marsupials

*BIOGEOGRAPHY

HHMS-Mice Natural Selection

Review timelines lab assignment and completed timelines in the classroom◦ NOTE: 1 Meter stick = 1 Billion Years

4.6 Billion (Age of Earth) = ? 10 cm = ?..........1 cm = ?.........1 mm = 1 million

years

Evolutionary Timelines

DAY 3 Textbook….Ch 21

CAN ALSO BE DEFINED AS:

Any change in the frequency of alleles from one generation to another.

A change in the gene pool of a population over time.

A change in frequencies of alleles in the gene pool of a population.

Biological Evolution

Ch 19 -text

MICROEVOLUTION:• Genes Mutate• Individuals are selected• Populations evolve

MACROEVOLUTION:• LARGE changes, as when new species are formed.

• Can SEE the changes

Process of Evolution:

The study of genetic variability within a population and the evolutionary forces that act on it.

Distinguishes genetic equilibrium* from evolutionary change

(*relates to the HARDY-WIENBERG PRINCIPLE; ‘population is at

equilibrium’)

Population Genetics

1. Genetic Drift – due to chance; relates to size of the population; causes a decrease in variation within the population; Ex- Bottleneck effect; founder effect

2. Gene Flow – relates to isolation; increases variation within a population;

Ex- Immigration/Emigration3. Mutation – substitution of alleles4. Non-random mating – Ex- Inbreeding (self-

pollinating plants); assortive mating (like:like)5. Natural Selection – differential success in

reproduction; only cause likely to be adaptive.

5 Potential Agents that cause microevolution (Pop. Genetics Handout,

slides)

*(These are the ANTITHESIS of H-W conditions)

Microevolution:Genetic Drift: random

Gene flow: random migration

http://evolution.berkeley.edu

Mutation: random

Variation ~ Differential Reprod. ~ Heredity

Genetic Shuffling; Non-random* Mating

1

2

3

4

5

Adaptive; Not Random

Evolutionary Fitness- The number of surviving offspring left to produce the next generation; measure of evolutionary success

The Peppered Moth and Natural Selection

• Explain the increased frequency of dark moths during the 1880’s in Britain.• Explain the decreased frequency of dark (melanic) moths from 1960’s to

80’s• Other ways humans have had an impact on variation in other species (or

our own)?

Essentially, went from Punnett Square/Mendelian predictions of the probability of specific offspring

genotypes based on parental genotypes to determining expected allelic frequencies for

entire populations.

This definition of evolution was developed largely as a result of independent work in the early 20th century by Godfrey Hardy, an English mathematician, and Wilhelm Weinberg, a German physician. Through mathematical modeling based on probability, they concluded in 1908 that gene pool frequencies are inherently stable but that evolution should be expected in all populations virtually all of the time. They resolved this apparent paradox by analyzing the net effects of potential evolutionary mechanisms.

Hardy-Weinberg Principle

Hardy1877-1947

Weinberg1862-1937

The mathematical prediction that allele frequencies do not change from generation to generation in a large population in the absence of micro-evolutionary processes (mutation, genetic drift, etc.)

Does NOT exist in nature, however, provides: A means to calculate allelic frequencies A baseline for comparison (non-evolving population to an evolving population)

1. We have a very large population size

2. Isolation from other populations exists (no emigration/immigration)

3. There are no net mutations

4. There is random mating; all breed and produce the same number of offspring

5. There is no natural selection

Hardy-Weinberg equilibrium is maintained ONLY if all 5 of the following conditions are met:

(Handout)

HW formula on the AP Equations Handout

• p + q = 1p (dom trait) + q (rec) = 1

• (p + q)2 = p2 + 2pq +q2 = 1

• WHERE: In a population….

p = freq of the Dominant alleleq = freq of the Recessive allele p2 = freq of individual AAq2 = freq of individual aa2pq = freq of individual Aa

H-W Problems

Diagram of Hardy-Weinberg genotype proportions from male (sperm) and female (egg) contributions. Given a locus with two alleles designated A and a that occur with frequencies p and q, the chart shows the genotype frequencies (p2, 2pq, and q2) as differently colored areas. Note that the heterozygotes (blue + yellow = green) can be formed in two different ways.

Albinism is a rare genetically inherited trait that is only expressed in the phenotype of homozygous recessive individuals (aa). The most characteristic symptom is a marked deficiency in the skin and hair pigment melanin. This condition can occur among any human group as well as among other animal species. The average human frequency of albinism in North America is only about 1 in 20,000.

What have we been given?:

Sample Problem

Referring back to the Hardy-Weinberg equation (p² + 2pq + q² = 1), the frequency of homozygous recessive individuals (aa) in a population is q². Therefore, in North America the following must be true for albinism:

q² = 1/20,000 = .0005What can we find out from this information?By taking the square root of both sides of this equation, we get: (rounded off)

q = .007 In other words, the frequency of the recessive albinism allele (a) is .00707 or ~1 in 140.

With this information, what can we solve for?Knowing one of the two variables (q) in the Hardy-Weinberg equation, it is easy to solve for the other (p). P = 1 – q = 1 - .007 = .993 The frequency of the dominant, normal allele (A) is, therefore, .99293 or about 99 in 100.

How can we use this information to determine genotypic frequencies?

The next step is to plug the frequencies of p and q into the Hardy-Weinberg equation:p² + 2pq + q² = 1

(.993)² + 2 (.993)(.007) + (.007)² = 1

.986 + .014 + .00005 = 1

p² (AA) = 98.6% No ‘a’ allele

2pq (Aa) = 1.4% carriers

q² (aa) = .005% Albinos

REVIEW WORKSHEET- Problems 1-8,10 front, 1-6

back TEXT p415 1,2 (3) **QUIZ: Day 5

**Given a Phenotype = p2, q2, 2pq Allele/Gene Frequency = p,q

DAY 3-4

Types of Selection

The types of selection relate to the bell curve. The bell curve is altered due to forces of nature favoring certain traits over other. Text p419-21

Day 4

Clutch size (amount of eggs laid) in starlings is between 3 and 6.

Clutch size is a genetic trait

Stabilizing – the average is favored, the extremes are eliminated

Human Birth Weight: The optimum birth weight is the one with the lowest mortality weight

Directional Selection – Favors one extreme in a population, the other is eliminated

Galapagos finches- extended drought, wet periods. The male widowbird collects females for his “harem” by

attracting them by the length of his tail. The longer the tail, the more females he attracts and mates with.

Rock Pocket MouseHHMI- Rock Pocket Mouse 10.25

Relatively rare Galapagos Finches Male salmon mate at either 2 years old

(Jacks) or 3 yo (hooknoses). Males fight over who will fertilize the female’s eggs. The male salmon are either very small or very large, very few are average size.

Disruptive Selection – favors the extremes in a population. The average is eliminated

Text p424 Gradual change in genotype and phenotype through a series of

geographically separated populations as a result of an environmental gradient

Cline: Geographic Variation

The creation of a new species. Evolution of a new species when a population becomes isolated from other members of the species.

Scientists put every living thing in one of 8 different taxonomic groups:

DOMAIN KINGDOM PHYLUM CLASS ORDER FAMILY GENUS SPECIES HUMANS?

Speciation

Macroevolution

Beak of the Finch 15.54

REPRODUCTIVE ISOLATING MECHANISMS

Prevention of interbreeding between two different species whose ranges (habitats) overlap. Most species have two or more mechanisms that block

a chance occurrence of interbreeding between closely related species.

Evolution of a New Species

I. PREZYGOTIC BARRIERS: Barriers in place to prevent fertilization/ mating of two different species

1. Temporal isolation2. Habitat isolation3. Behavioral Isolation4. Mechanical Isolation5. Gametic Isolation

Reproductive Barriers that isolate a species- Factors that prevent different species from coming together

TEXT p430

II. POSTZYGOTIC BARRIERS: Functions after fertilization, prevents development of viable, fertile offspring

1. Reduced Hybrid Viability2. Hybrid Sterility3. Hybrid Breakdown

Reproductive Barriers that isolate a species- Factors that prevent different species from coming together

TEXT p430-431

*Preserve genetic integrity of a species by preventing

gene flow

Two species of garter snakes: one lives mainly in water while the other is mainly terrestrial.

The eastern spotted skunk mates in late winter; the western spotted skunk mates in late summer.

Blue-footed boobies of the Galapagos perform a courtship display unique to the species. Boobies:

These 2 species of snails have opposite spirals in their shells so their genital openings are not aligned. http://bio1151b.nicerweb.net/Locked/media/ch24/

Gametes of red and purple sea urchins are released into the water, but are unable to fuse.

Some salamander subspecies of the genus Ensatina can hybridize, but hybrids do not complete development or are frail.

A mule is the robust but sterile hybrid between a male donkey and a female horse.

Hybrids of two rice strains are vigorous and fertile, but the next generation (center) may be sterile.

I. Allopatric Speciation: “Different /native land”

Subpopulation becomes physically separated from the original population…how?

1. Mountains emerge2. Glaciers migrating3. Land Bridges Develop4. Rivers Shift

Biological Mechanisms of Speciation Allopatric and Sympatric

TEXT p433

*Most Common Method of speciation, especially in

animals

II. Sympatric Speciation: “Together/native land”

New species develops in the same geographic region as the parent population◦**Common in Plants◦Polyploidy (2 or more chromosome sets)◦Allopolyploidy (interspecific hybrid- multiple

sets of chromosomes from 2 or more species)

Biological Mechanisms of Speciation Allopatric and Sympatric

TEXT p435, fig 20-9

*Can occur in animals, but how is debated. (Not due to

polyploidy)

1. New species may not compete successfully with parent species; goes extinct

2. New species may co-exist with the parent species

3. New species may outcompete parent species; hybrid may replace the parent(s)

Sympatric Speciation by Allopolyploidy

TEXT p436, fig 20-10

Types of Speciation

Geographic Isolation Kaibab Squirrels- Gr.Canyon

Common in plants; change in ploidy (# chromosomes) and ecology 80% of all flowering plants- polyploids hybridization

Lizards in an evolutionary tree 17.45

I. Gradualism: Continuous over long periods of time; gradual accumulation of adaptive characteristics

2. Punctuated Equilibriumlong periods of stasis interrupted by short* periods of rapid speciation (*’short’may be thousands of years)

TEXT p438

*

Rate of Evolutionary Change

Large-scale phenotype in populations warrant their placement in taxonomic groups at the species level and higher.

Dramatic evolutionary changes that occur over long time spans.

Dominated by multiple microevolutionary processes or external, chance events…or both?

Important Aspects of Macroevolution:1. Appearance of evolutionary novelties2. Adaptive Radiation3. Mass ExtinctionAlso related:4. Earth’s Geological History

Macroevolution

Ch 20 p439

Huge differences in phenotype leading to different taxonomic groups. Comes from pre-existing structures….examples?

Jointed appendages, feathers Originate from modifications of pre-existing

structures

May be due to: Changes in control/regulatory genes (on/off switch) Preadaptions (changed from one role/repurposed) Changes in Allometric Growth “different measure”

Paedomorphosis “child form”

1. Appearance of Evolutionary Novelties

Epigenetics 1.47

Epigenetics and Gene Expression utah.edu

Due to Allometric

Growth

Varied rates of growth for different body partsExamples…

(Text p440) sunfish Skull Fiddler crab T Rex

Appearance of Evolutionary Novelties

When juvenile characteristics are retained into the adult stage

This is an example of varied changes in timing of development

Due to- Paedomorphosis

Text p 440

Appearance of Evolutionary Novelties

2. Adaptive Radiation The evolutionary

diversification of many

related species from one or a few ancestral species in a

relatively short period.

Adaptive zones- new ecological

opportunities.*Divergent Evolution

Opening of ‘adaptive zones’ – allowed for new species to develop

3. Mass Extinction

4. Earth’s Geologic History

http://www.biozoomer.com/2011/03/speciation-in-organic-evolution.html

“The Descent of Man” Darwin, 1871- human and apes shared a common ancestry

Taxonomy◦ 3 Domains ◦ 6 Kingdoms

Evolution of Primates Ch22

3 Domains:Bacteria /EubacteriaArchaeaEukaryota

Classification of a Leopard

Homo sapiens (Man) (thinking)

Chordata

Mammalia

Primates

Hominidae

Homo

Animalia

Sapiens

Anthropoids:Monkeys, Apes, Humans~45mya Africa/Asia

Hominoids: Apes, Humans~23-25 mya

Hominids: Humans & ancestors~6-7mya

PROSIMIANS-

“before

primates”

PROSIMIANS

Lemurs

Tarsiers and

Lorises

PROSIMIANS

“MISSING LINK" FOUND:

New Fossil Links Humans,

Lemurs?

47mya“Ida”

Prosimian-Monkey Link

2009

Anthropoids

-Ability to walk upright-6mya

Most Profound Evolutionary Novelty?

Advanced brain Eyes forward- stereoscopic vision/depth

perception Color vision Acute hearing Dental formula- same #, type, arrangement of

teeth Long slender limbs/rotate freely at hips/shoulders 5 flexible digits with flattened nails/not claws Opposable thumbs Complex social behaviors Usually 1 offspring at a time; longer parental care

Characteristics of Primates

New World vs Old World Primates

Bipedal Skeletal Changes (Hominids)

Shape of the Spine, PelvisForamen magnum positionLeg vs arm lengthAlignment of great toe

Skull: brain, brow, jaw and teeth

Human Evolution:Australopithecines Homo habilis Homo erectus Homo sapiens

*Many alive at the same time… competing with each, not a straight line

“Lucy”- 1974*locking knee

“Handy Human”,Tools

Migration