{ EVOLUTION & SPECIATION. EVOLUTION – CHANGE OVER TIME NATURAL SELECTION - INDIVIDUALS...

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EVOLUTION & EVOLUTION & SPECIATIONSPECIATION

EVOLUTIONEVOLUTION – CHANGE OVER TIME – CHANGE OVER TIME

NATURAL SELECTIONNATURAL SELECTION - INDIVIDUALS - INDIVIDUALS BETTER ADAPTED TO THE ENVIRONMENT BETTER ADAPTED TO THE ENVIRONMENT ARE ABLE TO SURVIVE & REPRODUCE.ARE ABLE TO SURVIVE & REPRODUCE. A.K.A. “SURVIVAL OF THE FITTEST”A.K.A. “SURVIVAL OF THE FITTEST”

VOCABULARYVOCABULARY

POPULATIONPOPULATION – GROUP OF INDIVIDUALS OF – GROUP OF INDIVIDUALS OF SAME SPECIES THAT INTERBREEDSAME SPECIES THAT INTERBREED

GENE POOLGENE POOL – COMMON GROUP OF ALL GENES – COMMON GROUP OF ALL GENES PRESENT IN A POPULATIONPRESENT IN A POPULATION

VOCABULARYVOCABULARY

Combined Combined genetic genetic info. of all info. of all membersmembers

Allele Allele frequency frequency is # of is # of times times alleles alleles occuroccur

Gene Gene PoolPool

2 processes can 2 processes can

lead to this:lead to this:

MutationsMutations - -

change in DNA change in DNA

sequencesequence

Gene ShufflingGene Shuffling – –

from sexual from sexual

reproductionreproduction

Variation in Variation in PopulationsPopulations

Random change in allele Random change in allele frequency causes an allele to frequency causes an allele to become commonbecome common

Genetic Drift changes Genetic Drift changes populations…….populations…….

Founder Effect:Founder Effect: a a cause of genetic drift cause of genetic drift attributable to attributable to colonization by a colonization by a limited number of limited number of individuals from a individuals from a parent populationparent population

Gene FlowGene Flow: genetic : genetic exchange due to the exchange due to the migration of fertile migration of fertile individuals or gametes individuals or gametes between populations between populations (reduces differences (reduces differences between populations)between populations)

Nonrandom matingNonrandom mating: inbreeding and assortive : inbreeding and assortive mating (both shift frequencies of different mating (both shift frequencies of different genotypes)genotypes)

Natural SelectionNatural Selection: : differential success in differential success in reproduction; only form reproduction; only form of microevolution that of microevolution that adapts a population to adapts a population to its environmentits environment

Sexual Sexual selectionselection

Sexual dimorphismSexual dimorphism: : secondary sex secondary sex characteristic distinctioncharacteristic distinction

Sexual selectionSexual selection: : selection towards selection towards secondary sex secondary sex characteristics that leads characteristics that leads to sexual dimorphismto sexual dimorphism

Evolution of Evolution of PopulationsPopulations

Occurs when there is a Occurs when there is a change in relative change in relative frequency of allelesfrequency of alleles

Generation 1: 1.00 not resistant0.00 resistant

Resistance to antibacterial soap

How natural selection works

Resistance to antibacterial soap

Generation 1: 1.00 not resistant0.00 resistant

How natural selection works

Resistance to antibacterial soap

mutation!

Generation 1: 1.00 not resistant0.00 resistant

Generation 2: 0.96 not resistant0.04 resistant

How natural selection works

Resistance to antibacterial soap

Generation 1: 1.00 not resistant0.00 resistant

Generation 2: 0.96 not resistant0.04 resistant

Generation 3: 0.76 not resistant0.24 resistant

How natural selection works

Resistance to antibacterial soap

Generation 1: 1.00 not resistant0.00 resistant

Generation 2: 0.96 not resistant0.04 resistant

Generation 3: 0.76 not resistant0.24 resistant

Generation 4: 0.12 not resistant0.88 resistant

How natural selection works

Depends on Depends on how many how many genes genes control that control that traittrait

Phenotype ExpressionPhenotype Expression

Single-GeneSingle-Gene::

2 Distinct Phenotypes2 Distinct Phenotypes

PolygenicPolygenic::

Many PhenotypesMany Phenotypes

Single-Gene vs. Polygenic Single-Gene vs. Polygenic TraitsTraits

(EG: tongue rolling)

Allele Frequencies

Natural Selection Genetic Drift

Single Gene Traits

PolygenicTraits

Directional Selection

Stabilizing Selection

Disruptive Selection

Shifts to Shifts to

middle rangemiddle range

Shifts to Shifts to

2 extremes2 extremes

Shifts to Shifts to

1 extreme1 extreme

Natural Selection on Polygenic Natural Selection on Polygenic TraitsTraits

If I see you, I will eat you

Conditions needed for Conditions needed for Genetic Genetic EquilibriumEquilibrium

THE THE FORMATION OF NEW SPECIESFORMATION OF NEW SPECIES

AS NEW SPECIES EVOLVE, POPULATIONS AS NEW SPECIES EVOLVE, POPULATIONS BECOME REPRODUCTIVELY ISOLATEDBECOME REPRODUCTIVELY ISOLATED

REPRODUCTIVE ISOLATIONREPRODUCTIVE ISOLATION – MEMEBERS OF 2 – MEMEBERS OF 2 POPULATIONS CANNOT INTERBREED & POPULATIONS CANNOT INTERBREED & PRODUCE FERTILE OFFSPRING.PRODUCE FERTILE OFFSPRING.

SPECIATIONSPECIATION

BEHAVIORAL ISOLATION-BEHAVIORAL ISOLATION- CAPABLE OF BREEDING CAPABLE OF BREEDING BUT HAVE DIFFERENCES IN COURTSHIP RITUALS BUT HAVE DIFFERENCES IN COURTSHIP RITUALS (EX. MEADOWLARKS)(EX. MEADOWLARKS)

GEOGRAPHICAL ISOLATIONGEOGRAPHICAL ISOLATION – SEPARATED BY – SEPARATED BY GEOGRAPHIC BARRIERS LIKE RIVERS, MOUNTAINS, GEOGRAPHIC BARRIERS LIKE RIVERS, MOUNTAINS, OR BODIES OF WATER (EX. SQUIRREL)OR BODIES OF WATER (EX. SQUIRREL)

TEMPORAL ISOLATIONTEMPORAL ISOLATION – 2 OR MORE SPECIES – 2 OR MORE SPECIES REPRODUCE AT DIFFERENT TIMES.REPRODUCE AT DIFFERENT TIMES.

3 ISOLATING 3 ISOLATING MECHANISMS……..MECHANISMS……..

Table 23.1aTable 23.1a

TigonTigonResult of male tiger and female lion mating in captivity. Offspring are infertile.

Separated both geographically and ecologically.

LigerLiger

Result of male lion and female tiger mating in captivity. Offspring are infertile.

Table 23.1bTable 23.1b

Fig. 23.6Fig. 23.6Four species of leopard frogs: differ in their mating calls. Hybrids are inviable.

These squirrels live on opposite sides of the Grand Canyon. This is an example of allopatric speciation.

Hawaiian HoneycreepersHawaiian Honeycreepers

FOUNDER SPECIES

An example of adaptive radiation – these species all diverged from a common ancestor (founder species)

SPECIATION IN THE GALAPAGOS FINCHES OCCURRED SPECIATION IN THE GALAPAGOS FINCHES OCCURRED BY: BY:

- - FOUNDINGFOUNDING OF A NEW POPULATION, OF A NEW POPULATION, - - GEOGRAPHIC ISOLATION GEOGRAPHIC ISOLATION

which led to -- which led to -- REPRODUCTIVE ISOLATIONREPRODUCTIVE ISOLATION and and CHANGES IN THE NEW POPULATION’S GENE POOL due CHANGES IN THE NEW POPULATION’S GENE POOL due to COMPETITION.to COMPETITION.

SPECIATION IN DARWIN’SSPECIATION IN DARWIN’S FINCHESFINCHES

1.1. Fossil RecordFossil Record

2.2. Geographic Distribution of Living Geographic Distribution of Living SpeciesSpecies

3.3. Homologous Body structuresHomologous Body structures

4.4. Similarities in EmbryologySimilarities in Embryology

Evidence of EvolutionEvidence of Evolution

Evidence of Evidence of EvolutionEvolution

Fossil Record Fossil Record provides provides evidence that evidence that living things have living things have evolvedevolved

Fossils show the Fossils show the history of life on history of life on earth and how earth and how different groups different groups of organisms of organisms have changed have changed over timeover time

Rat like common ancestor

Mammalia

Placental mammals

Marsupial Mammals

Sugar Glider

Flying Squirrel

Convergent Evolution

andAnalogous Structures

Big Question!!!Big Question!!!

How did life arise on the big blue planet??How did life arise on the big blue planet??

Scientists attempt to answer this Scientists attempt to answer this question scientifically.question scientifically.

Relative Relative Dating Dating

versus versus Absolute Absolute DatingDating

Relative DatingRelative Dating

Can determine a Can determine a fossil’s relative agefossil’s relative age

Performed by Performed by estimating fossil age estimating fossil age compared with that of compared with that of other fossilsother fossils

Drawbacks – provides Drawbacks – provides no info about age in no info about age in yearsyears

Absolute datingAbsolute dating

Can determine the absolute Can determine the absolute age in numbersage in numbers

Is performed by radioactive Is performed by radioactive dating – based on the amount dating – based on the amount of remaining radioactive of remaining radioactive isotopes remainisotopes remain

Drawbacks - part of the fossil Drawbacks - part of the fossil is destroyed during the testis destroyed during the test

Carbon-14 DatingCarbon-14 Dating

Fossil FormationFossil Formation

A cosmic explosion that hurled matter and in all A cosmic explosion that hurled matter and in all directions created the universe 10-20 billion years directions created the universe 10-20 billion years agoago

Evidence Evidence

it explains why distant galaxies are traveling it explains why distant galaxies are traveling away from us at great speeds away from us at great speeds

Cosmic radiation from the explosion can be Cosmic radiation from the explosion can be observedobserved

The Big Bang theory probably will never be The Big Bang theory probably will never be proven; consequentially, leaving a number of tough, proven; consequentially, leaving a number of tough, unanswered questions. unanswered questions.

Big Bang TheoryBig Bang Theory

What was early earth like?What was early earth like?Earth was Hot!!Earth was Hot!!

Little or no oxygenLittle or no oxygen

Gasses in atmosphere:Gasses in atmosphere:

Hydrogen cyanide (poison to you!)Hydrogen cyanide (poison to you!)

Hydrogen sulfideHydrogen sulfide

Carbon dioxideCarbon dioxide

Carbon monoxideCarbon monoxide

NitrogenNitrogen

waterwater

So how did the earth So how did the earth get oxygen?get oxygen?

Some of that oxygen was generated by Some of that oxygen was generated by photosynthetic cyanobacteriaphotosynthetic cyanobacteria

Some came from the Some came from the chemical chemical separationseparation of water molecules into of water molecules into oxygen and hydrogen.oxygen and hydrogen.

Volcanic eruptions released oxygenVolcanic eruptions released oxygen

Oxygen drove some life Oxygen drove some life forms to extinction forms to extinction Others evolved ways of Others evolved ways of using oxygen for respirationusing oxygen for respiration

How did life begin?How did life begin?

Miller and Urey’s Miller and Urey’s Experiment Experiment

Passed sparks Passed sparks through a mixture of through a mixture of hydrogen methane hydrogen methane ammonia and waterammonia and water

This produced This produced amino acids – the amino acids – the building blocks of lifebuilding blocks of life

Miller’s Miller’s experiment experiment suggests that suggests that lightning could lightning could have produced have produced amino acidsamino acids

How can simple amino acids How can simple amino acids result in life?result in life?

There are 3 theoriesThere are 3 theories11. Formation of microspheres. Formation of microspheres

Large organic molecules can Large organic molecules can sometimes form tiny proteinoid sometimes form tiny proteinoid microspheresmicrospheres

Store and release energy, selectively Store and release energy, selectively permeable membranes, may have permeable membranes, may have acquired more characteristics of living acquired more characteristics of living cellscells

22ndnd Hypothesis for Life Hypothesis for Life

Evolution of RNA to DNAEvolution of RNA to DNA

• RNA was assembled RNA was assembled from simple organic from simple organic molecules in a primordial molecules in a primordial soupsoup

• RNA was able to RNA was able to replicate itself and replicate itself and eventually form DNAeventually form DNA

• Not scientifically proven Not scientifically proven to be possibleto be possible

33rdrd Theory of Life Theory of LifeEndosymbiotic theoryEndosymbiotic theory

eukaryotic cells arose eukaryotic cells arose from living communities from living communities formed by prokaryotic formed by prokaryotic organismsorganisms

Ancient prokaryotes Ancient prokaryotes entered primitive entered primitive eukaryotic cells and eukaryotic cells and remained there as remained there as organellesorganelles