EVOLUTION!EVOLUTION!

EvolutionEvolution Evolution- Is the cumulative change Evolution- Is the cumulative change

in the heritable characteristics of a in the heritable characteristics of a populationpopulation

http://www.youtube.com/watch?v=KUshLAzXJm4

Darwinian Evolution is based on five different 'sub Darwinian Evolution is based on five different 'sub theories:theories:

1. Evolution1. Evolution: that all life is and has been perpetually : that all life is and has been perpetually changing. This contrasts strongly with notions that all changing. This contrasts strongly with notions that all forms of life are constant an unchanging.forms of life are constant an unchanging.

2. Common descent2. Common descent: that all living things share a : that all living things share a common ancestor if the traced back far enough.common ancestor if the traced back far enough.

3. Gradualism:3. Gradualism: that evolutionary change takes that evolutionary change takes places slowly and gradually. This contrasts with places slowly and gradually. This contrasts with saltation in which changes are sudden and extreme.saltation in which changes are sudden and extreme.

4. Multiplication of species:4. Multiplication of species: the diversity of life is the diversity of life is a consequence of speciation. Populations adapting to a consequence of speciation. Populations adapting to locations and becoming reproductively isolated from locations and becoming reproductively isolated from other populations.other populations.

5. Natural selection5. Natural selection: a two stage process in which: : a two stage process in which: – producing genetic variationproducing genetic variation– selectionselection

Evidence for EvolutionEvidence for Evolution 1) Fossil record1) Fossil record: A fossil is the : A fossil is the

ancient preserved remains of an ancient preserved remains of an organism. organism.

The fossil can be dated from the age The fossil can be dated from the age of the rock formation. of the rock formation.

Sequences of fossil can show the Sequences of fossil can show the gradual change of an organism over gradual change of an organism over geological time. geological time.

2) Homologous structures:2) Homologous structures: All of life is connected through All of life is connected through

evolutionary history and consequently evolutionary history and consequently those organisms more closely those organisms more closely connected might reasonably be connected might reasonably be expected to share common structures expected to share common structures or homologous.or homologous.

Group of organisms closely related Group of organisms closely related share a common form orshare a common form or derived trait derived trait which has been inherited from the which has been inherited from the common ancestor. common ancestor.

This classic example of homologous This classic example of homologous structures is the pentadactyl limb of structures is the pentadactyl limb of the vertebrate.the vertebrate.

a) Humerusa) Humerus b) Radiusb) Radius c) Ulnac) Ulna

3) Selective breeding: 3) Selective breeding: If an animal posses a If an animal posses a

characteristic that is characteristic that is considered useful or considered useful or valuable then this animal valuable then this animal is selected for breading. is selected for breading.

The hope then is that this The hope then is that this characteristic will be characteristic will be present in the next present in the next generation and at a higher generation and at a higher frequency than before. frequency than before.

Selection of high muscle yields Selection of high muscle yields in cowsin cows

– In a population of cows (generation 1 = G1) it is noticed that In a population of cows (generation 1 = G1) it is noticed that some produce more muscle than others.some produce more muscle than others.

– These cows are selected for breeding and the other cows are These cows are selected for breeding and the other cows are rejected for breeding. rejected for breeding.

– The calves of these muscle yielding cows (G2) are then The calves of these muscle yielding cows (G2) are then produced and once mature they themselves will have calves. produced and once mature they themselves will have calves.

– These now mature cows (G2)will be producing on average, a These now mature cows (G2)will be producing on average, a higher muscle than G1 cows.higher muscle than G1 cows.

– The G2 population of cows will show variation in muscle The G2 population of cows will show variation in muscle – The breeder will select higher yielding G2 cows for the next The breeder will select higher yielding G2 cows for the next

breeding population.breeding population.– The cycle is repeated until the cow population is producing The cycle is repeated until the cow population is producing

very large muscle way beyond level seen in the G1 very large muscle way beyond level seen in the G1 population.population.

http://www.youtube.com/watch?v=rW54_vM9SF0

5.4.3 Population size and 5.4.3 Population size and evolution. evolution.

Populations tend to produce more Populations tend to produce more offspring than the environment can offspring than the environment can support.support.

The population produces more The population produces more offspring than the carrying capacity offspring than the carrying capacity of the environment can support of the environment can support

Offspring/population compete for limited Offspring/population compete for limited resources (Intraspecific competition)resources (Intraspecific competition)

Some individuals have characteristic (or Some individuals have characteristic (or combination ) that give them a combination ) that give them a competitive advantage.competitive advantage.

These individuals are consequently 'fitter' These individuals are consequently 'fitter' in terms of freedom from disease, food in terms of freedom from disease, food availability etc. availability etc.

These individuals are more likely to These individuals are more likely to successfully reproduce (offspring survive)successfully reproduce (offspring survive)

Through inheritance the frequency of these Through inheritance the frequency of these characteristics become greater in the next characteristics become greater in the next generation. generation.

By definition these characteristic have a By definition these characteristic have a genetic basis genetic basis

The alleles for the advantageous The alleles for the advantageous characteristic becomes more frequent in the characteristic becomes more frequent in the populationpopulation

Lyre Bird VideoLyre Bird Videohttp://www.youtube.com/watch?v=VjE0Kdfos4Yhttp://www.youtube.com/watch?v=VjE0Kdfos4Y

OverpopulationOverpopulation the consequence of the potential

overproduction of offspring is a struggle for survival.

The struggle takes the form of The struggle takes the form of individuals in the population being individuals in the population being 'selected for' or 'selected against' .'selected for' or 'selected against' .

Survivors form the new breeding Survivors form the new breeding population.population.

The frequency of advantageous alleles The frequency of advantageous alleles has increased.has increased.

The change in the heritable The change in the heritable characteristics is by definition evolution.characteristics is by definition evolution.

Darwin’s Dangerous Idea Pt. 2http://www.youtube.com/watch?v=_9p5fQVvR_E

5.4.5 Variation in a species. 5.4.5 Variation in a species.

Populations of a species show Populations of a species show variation. variation.

Variation means differences in Variation means differences in phenotypes.phenotypes.

Variation shows two basic patterns.Variation shows two basic patterns.

Discontinuous VariationDiscontinuous Variation There are distinct classes of There are distinct classes of

individualindividual e.g. Blood groups of a human e.g. Blood groups of a human

population population Discontinuous variation usually Discontinuous variation usually

indicates the condition is controlled indicates the condition is controlled by one to two genes.by one to two genes.

Continuous VariationContinuous Variation This type of variation is called This type of variation is called

continuous variation with no distinct continuous variation with no distinct classes but a complete range of the classes but a complete range of the characteristiccharacteristic

e.g. Height of a trees in a forest e.g. Height of a trees in a forest Continuous variation like this Continuous variation like this

normally indicates a polygenic normally indicates a polygenic condition or multiple alleles condition or multiple alleles

5.4.6 Sexual reproduction and 5.4.6 Sexual reproduction and variation variation

Asexual and sexual populations both Asexual and sexual populations both experience mutation which increases experience mutation which increases the variation within the members of the variation within the members of a population.a population.

However sexually reproducing However sexually reproducing populations also experience populations also experience significant additional sources of significant additional sources of variation. variation.

http://images.google.com/imgres?imgurl=http://www.gunthersclass.com/crossingover.JPG&imgrefurl=http://www.gunthersclass.com/meiosis.html&usg=__uemNVRRrovoEXy1jbpdsYPK9kkY=&h=812&w=541&sz=105&hl=en&start=1&um=1&tbnid=Uo5o0X6IUrAXZM:&tbnh=144&tbnw=96&prev=/images%3Fq%3Dmeiosis%2Bvariation%26um%3D1%26hl%3Den%26rls%3Dcom.microsoft:en-ca:IE-SearchBox%26rlz%3D1I7SKPB_en

Meiosis and the independent Meiosis and the independent assortment of chromosomes creates assortment of chromosomes creates new combinations of chromosome snew combinations of chromosome s

Random fertilisation increases the Random fertilisation increases the variation in the population variation in the population

The number of different genetic The number of different genetic variations is increased further by variations is increased further by cross-over in meiosiscross-over in meiosis

5.4.7 Natural selection 5.4.7 Natural selection

'''........can we doubt (remembering that many '........can we doubt (remembering that many more individuals are born than can possible more individuals are born than can possible survive) that individuals having any survive) that individuals having any advantage, however slight, over others, advantage, however slight, over others, would have the best chance of surviving and would have the best chance of surviving and procreating their kind? On the other hand, we procreating their kind? On the other hand, we may feel sure that any variation in the least may feel sure that any variation in the least injurious would be rigidly destroyed. This injurious would be rigidly destroyed. This preservation of favourable variations and the preservation of favourable variations and the rejection of injurious variations, I call Natural rejection of injurious variations, I call Natural Selection'Selection' Darwin C. (1859)Darwin C. (1859) The Origin of The Origin of SpeciesSpecies

Natural selection is a two stage Natural selection is a two stage process:process:

VariationVariation SelectionSelection

When a population evolves there is a When a population evolves there is a cumulative change in the heritable cumulative change in the heritable characteristics of the population.characteristics of the population.

Natural selection can act on a Natural selection can act on a population without speciation population without speciation occurring.occurring.

In effect the genetic profile of the In effect the genetic profile of the population is adapting to changes in population is adapting to changes in local conditions. local conditions.

Every phase in the process of Every phase in the process of evolution is affected by variation and evolution is affected by variation and by selection.by selection.

In colonies of bluegill In colonies of bluegill Lepomis macrochirusLepomis macrochirus, some males , some males provide parental care for broods in nests, whereas other provide parental care for broods in nests, whereas other males steal fertilizations and do not provide parental care. males steal fertilizations and do not provide parental care. Using experimental pond populations of bluegill of known Using experimental pond populations of bluegill of known genotype (determined through protein electrophoresis), we genotype (determined through protein electrophoresis), we demonstrate that cuckolder males successfully fertilize eggs demonstrate that cuckolder males successfully fertilize eggs in parental male nests. Using electrophoretic techniques to in parental male nests. Using electrophoretic techniques to assess the fertilization success of nesting parental male assess the fertilization success of nesting parental male bluegill in Lake Opinicon, Ontario, we demonstrate that bluegill in Lake Opinicon, Ontario, we demonstrate that paternity of these males ranges from 41% to 100% among paternity of these males ranges from 41% to 100% among four colonies studied. This difference among colonies is four colonies studied. This difference among colonies is related to the density of cuckolder males. related to the density of cuckolder males.

Option D: EvolutionOption D: Evolution

Spontaneous Origin of Life on Spontaneous Origin of Life on EarthEarth

We have learned that all cells come We have learned that all cells come from pre-existing cells. from pre-existing cells.

At some point, the first cells must At some point, the first cells must have been formed. have been formed.

Four Processes are needed to for the Four Processes are needed to for the cells to first formcells to first form

1) The non-living synthesis of 1) The non-living synthesis of simple organic moleculessimple organic molecules

Chemical reactions produce simple Chemical reactions produce simple organic molecules such as amino organic molecules such as amino acids, from inorganic molecules such acids, from inorganic molecules such as water, carbon dioxide and as water, carbon dioxide and ammoniaammonia

2) The assembly of molecules 2) The assembly of molecules into polymersinto polymers

Organic molecules are synthesized Organic molecules are synthesized together to form polymers together to form polymers

Ex. Polypeptides from amino acidsEx. Polypeptides from amino acids

3) The origin of self replicating 3) The origin of self replicating molecules that made molecules that made inheritance possibleinheritance possible

The formation of polymers that have The formation of polymers that have the ability to self replicate. the ability to self replicate.

This allows their characteristics to be This allows their characteristics to be inherited into subsequent inherited into subsequent generationsgenerations

4) The packaging of molecules 4) The packaging of molecules into membranes with an into membranes with an

internal chemistry different internal chemistry different from their surroundings.from their surroundings.

The development of membranes to The development of membranes to form spherical droplets, including the form spherical droplets, including the polymers that hold the genetic polymers that hold the genetic informationinformation

The The Miller–Urey Miller–Urey experimentexperiment

was an was an experimentexperiment that simulated that simulated hypothetical conditions thought at the time hypothetical conditions thought at the time to be present on the to be present on the early Earthearly Earth, and tested , and tested for the occurrence of for the occurrence of chemical evolutionchemical evolution..

Specifically, the experiment tested Specifically, the experiment tested HaldaneHaldane's 's hypothesishypothesis that conditions on the that conditions on the primitive Earth favored chemical reactions primitive Earth favored chemical reactions that synthesized that synthesized organic compoundsorganic compounds from from inorganic precursors. inorganic precursors.

Considered to be the classic experiment on Considered to be the classic experiment on the the origin of lifeorigin of life

http://www.youtube.com/watch?v=j9ZRHoawyOg

They mixed ammonia, methane and They mixed ammonia, methane and hydrogen to form a reducing hydrogen to form a reducing atmosphere.atmosphere.

Electrical discharges and boiling Electrical discharges and boiling water and condensing water water and condensing water simulated lightning and rainfall. simulated lightning and rainfall.

ConclusionsConclusions After one week, the water turned a After one week, the water turned a

murky brown.murky brown. Many organic compounds, including Many organic compounds, including

fifteen amino acids.fifteen amino acids. Miller and Urey concluded that Miller and Urey concluded that

organic compounds could have organic compounds could have formed spontaneously on earth formed spontaneously on earth before living organismsbefore living organisms

Origin of Organic Origin of Organic CompoundsCompounds

Possible locations for the origin on life:Possible locations for the origin on life:1)1) Synthesis of chemical reactions in the Synthesis of chemical reactions in the

atmosphere and water on the surface of atmosphere and water on the surface of the earththe earth

2)2) Hydrothermal vents deep in the oceans. Hydrothermal vents deep in the oceans. Could have led to the spontaneous Could have led to the spontaneous synthesis of organic compounds.synthesis of organic compounds.

3)3) Extraterrestrial origin for organic Extraterrestrial origin for organic compounds. Protocells from space could compounds. Protocells from space could have been delivered by meteorites 400 have been delivered by meteorites 400 million years ago.million years ago.

RNA and the Origin of LifeRNA and the Origin of Life RNA is a substance that many believe RNA is a substance that many believe

plays an important role in the origin of plays an important role in the origin of life.life.

RNA has 2 characteristics to make it a RNA has 2 characteristics to make it a likely choice for helping originate life.likely choice for helping originate life.

They are:They are:-Ability to Self Replicate-Ability to Self Replicate-Ability to Produce Catalytic Activities-Ability to Produce Catalytic Activities

Self ReplicateSelf Replicate RNA is capable of self replicatingRNA is capable of self replicating

forming one molecule from the forming one molecule from the template of anothertemplate of another

This will produce a replica of the This will produce a replica of the original and information will be original and information will be passed on between generationspassed on between generations

Catalytic ActivitiesCatalytic Activities RNA catalyses many chemical RNA catalyses many chemical

reactionsreactions It may have replaced the need for It may have replaced the need for

enzymes in order for chemical enzymes in order for chemical reactions to occurreactions to occur

Membranes and ProtobiontsMembranes and Protobionts Living cells may have been preceded

by protobionts Protobionts have an internal

chemical environment different from their surroundings.

Examples include coacervates and microspheres membrane bound spheres that enclose droplets of fluid to contain the cytoplasm and carry out metabolism

Prokaryotes and the Prokaryotes and the AtmosphereAtmosphere

Prokaryotes had a significant impact on the creation of an oxygen-rich atmosphere

Prokaryotes began to use water as a source of hydrogen during photosynthesis and oxygen began to build up in the atmosphere over 100 million years.

Endosymbiotic Theory forthe Origin of Eukaryotes.

The endosymbiotic theory concerns the origins of mitochondria and chloroplasts, which are organelles of eukaryotic cells.

According to this theory, these organelles originated as separate prokaryotic organisms which were taken inside the cell as endosymbionts.

Mitochondria developed from proteobacteria and chloroplasts from cyanobacteria.

http://www.youtube.com/watch?v=zufaN_aetZI

Characteristics of Mitochondria Characteristics of Mitochondria and Chloroplastsand Chloroplasts

They grow and divide like cellsThey grow and divide like cells They have a naked loop of their own They have a naked loop of their own

DNADNA They synthesize some of their own They synthesize some of their own

proteinsproteins They have double membranes They have double membranes

(similar to cells that are taken into a (similar to cells that are taken into a vesicle by endocytosis.)vesicle by endocytosis.)

ReadingReading Pg. 512-516 in the textPg. 512-516 in the text

D2- Species and SpeciationD2- Species and Speciation

SpeciesSpecies Species-Species- a group of actually or a group of actually or

potentially interbreeding populations, potentially interbreeding populations, with a common gene pool, which are with a common gene pool, which are reproductively isolated from other reproductively isolated from other such groupssuch groups

http://www.youtube.com/watch?v=l25MBq8T77w&feature=related

DefinitionsDefinitions Gene Pool- any genes available in the Gene Pool- any genes available in the

interbreeding population.interbreeding population. Allele Frequency- is the amount of Allele Frequency- is the amount of

times an allele is present, as a times an allele is present, as a proportion of all alleles in the proportion of all alleles in the population. population.

Allele frequency ranges from 0.0-1.0Allele frequency ranges from 0.0-1.0 evolution always involves a change in evolution always involves a change in allele frequency in a population’s gene allele frequency in a population’s gene pool.pool.

Barriers Between Gene Barriers Between Gene PoolsPools

Geographical isolation Hybrid infertility Temporal isolation- populations may

mate or flower at different seasons or different times of day

Behavioural isolation

PolyploidyPolyploidy Contributions to speciation:Contributions to speciation: Polyploidy Polyploidy is a state different from most is a state different from most

organisms which are normally organisms which are normally diploiddiploid meaning they have only two sets of meaning they have only two sets of chromosomes - polyploidy may occur due chromosomes - polyploidy may occur due to abnormal to abnormal cell divisioncell division

It is most commonly found in plants. It is most commonly found in plants. existing plants and most of the animals are existing plants and most of the animals are

polyploids or have undergone an event of polyploids or have undergone an event of polyploidization in their evolutionary history polyploidization in their evolutionary history

SpeciationSpeciation Speciation: the formation of a new species by

splitting of an existing species. 2 methods: -Allopatric Speciation- referring to organisms

whose ranges are entirely separate, so that they do not occur in any one place together

-Sympatric Speciation- organisms whose ranges overlap or are even identical, so that they occur together at least in some places

http://upload.wikimedia.org/wikipedia/commons/5/53/Speciation_modes.svg

Allopatric SpeciationAllopatric Speciation-Allopatric Speciation- referring to

organisms whose ranges are entirely separate, so that they do not occur in any one place together

Ex- http://www.youtube.com/watch?Ex- http://www.youtube.com/watch?v=YCoEiLOV8jc&feature=relatedv=YCoEiLOV8jc&feature=related

Sympatric SpeciationSympatric Speciation-Sympatric Speciation- organisms

whose ranges overlap or are even identical, so that they occur together at least in some places

Ex- Tennessee Cave SalamanderEx- Tennessee Cave Salamander

Adaptive RadiationAdaptive Radiation An An adaptiveadaptive radiationradiation is a rapid is a rapid

evolutionary evolutionary radiationradiation characterized characterized by an increase in the morphological by an increase in the morphological and ecological diversity of a single, and ecological diversity of a single, rapidly diversifying lineage. rapidly diversifying lineage.

Phenotypes adapt in response to the Phenotypes adapt in response to the environment, with new and useful environment, with new and useful traits arising. traits arising.

Convergent EvolutionConvergent Evolution Convergent evolutionConvergent evolution describes describes

the acquisition of the same biological the acquisition of the same biological trait in unrelated lineages. trait in unrelated lineages.

The wing is a classic example of The wing is a classic example of convergent evolution in action convergent evolution in action (analogous structures)(analogous structures)

Common niches will have similar Common niches will have similar characteristicscharacteristics

Divergent EvolutionDivergent Evolution Divergent evolutionDivergent evolution is the is the

accumulation of differences between accumulation of differences between groups which can lead to the groups which can lead to the formation of new speciesformation of new species

usually a result of diffusion of the usually a result of diffusion of the same species adapting to different same species adapting to different environments, leading to natural environments, leading to natural selection defining the success of selection defining the success of specific mutations. specific mutations.

Ex. For example, the vertebrate limb Ex. For example, the vertebrate limb is one example of divergent is one example of divergent evolution. evolution.

The limb in many different species The limb in many different species has a common origin, but has has a common origin, but has diverged somewhat in overall diverged somewhat in overall structure and function. structure and function.

Pace of EvolutionPace of Evolution Gradualism- Gradualism- the

slow change from one form to another.

Punctuated Punctuated Equilibrium- Equilibrium- long periods without appreciable change and short periods of rapid evolution.

On the Origin of Species Darwin clearly stated that "Species of different genera and classes have not changed at the same rate, or in the same degree. In the oldest tertiary beds a few living shells may still be found in the midst of a multitude of extinct forms...

PolymorphismPolymorphism PolymorphismPolymorphism in biology occurs in biology occurs

when two or more clearly different when two or more clearly different phenotypes exist in the same phenotypes exist in the same population of a species population of a species

                           

  Light-morph Jaguar (typical)

                           

  Dark-morph or melanistic Jaguar (about 6% of the South American population)

2 Different Types of 2 Different Types of PolymorphismPolymorphism

Transient Polymorphism- natural Transient Polymorphism- natural selection is acting as an erosive force selection is acting as an erosive force to eliminate altogether one of the to eliminate altogether one of the two alternative alleles. two alternative alleles.

Balanced Polymorphism- selection is Balanced Polymorphism- selection is acting as a creative force to preserve acting as a creative force to preserve genetic variation. genetic variation.

Option D3- Human EvolutionOption D3- Human Evolution