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FSU / Biology / BSC 2011 / what are the difference between evolution and natural selection?

what are the difference between evolution and natural selection?

what are the difference between evolution and natural selection?

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School: Florida State University
Department: Biology
Course: Biological Sciences II
Professor: Kevin dixon
Term: Fall 2016
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Cost: 50
Name: Exam 3 Study Guide
Description: Check this out for a review of what you need to know for Exam 3!
Uploaded: 11/10/2016
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Lecture 19: Evolution Intro (Material for Exam 2, you can skip this, I just wanted to put it  here as a reminder for the final)


what are the difference between evolution and natural selection?



Section 22.2

• Multi locus inheritance

o Some traits are determined by more than one locus

o Additive inheritance  

o Think about loci A, B, C

▪ Each as: A1/A2, B1/B2, C1/C2

▪ They all code for resistance to harm

▪ A1A1B1B1C1C1= SUPERMAN

▪ A2A2B2B2C2C2= Mosquito, wimpy  

▪ Cross mosquito and superman

• Produces: A1A2B1B2C1C2

• 16 different results  

A1 

B1C1C2 

B2C1C2A2 

B1C1C2 B2C1C2

• Traits are often influenced by environment  

o Hydrangea- pH in the soil

o Siamese cat- Temperature influences the development of fur

▪ Parts of body with lower temp have darker hair, feet and head are darker  o Quantitative trait- measured rather than divided into categories

o Edward East theory- the more loci affecting a trait, the more possible phenotypes  o Phenotype is affect of all genes combined into one category plus the affect of the  environment  


what are the basic principles of natural selection?



Lecture 20 Evolution Intro (section 22.2)  

• Be able to explain the difference between natural selection and evolution

Natural Selection

Evolution

individuals with certain traits tend to  reproduce and survive at higher rates than  others because of those traits

the actual change in genes

Individuals do not evolve

populations evolve over time

a cause/mechanism of evolution  

Populations becoming genetically  different from each other

Mosquitoes that emerge earlier are more  successful at producing offspring

G allele used to be more common than g  allele, now g allele is more common.

• Be able to explain the basic principles of natural selection

o Can amplify or diminish only heritable traits that differ in the individuals in the  population

o A trait that is favorable in one place may not be in another place  


what is Artificial Selection?



o Genetic variation underlying phenotypic variation is necessary for natural selection  to lead to evolution  We also discuss several other topics like What is the effect of using double declining balance on depreciation?

o THREE THINGS NEEDED FOR NATURAL SELECTION

1. variation in phenotype

2. variation in fitness- ability to reproduce  

3. Association between fitness and phenotype  

• Be able to distinguish between evolutionary change and other kinds of changes o Population- group of one species  

o Evolution-series of forces that change the genetic nature of populations

▪ Can lead to changes in the mean phenotype of populations Don't forget about the age old question of What is Xenophobia?

▪ Can lead to the differentiation of populations

▪ Can lead to the formation of new species

▪ Changes are due to changes in genes that can be inherited

▪ Results in branching pattern of change over time

• Know that evolution produces allele frequency changes, inherited phenotypic  changes, differences among populations, new phenotypes and new species, and  phylogenetic relationships

o More on this later

Lecture 21- Evidence for Evolution and Modern Evolutionary Biology

Readings - 22.2, 22.3

• Two sides of evolutionary biology (probably not something to memorize, just a way  to think about things) We also discuss several other topics like What fraction of the original 14C remains in a sample after 11,460 years?

1. Process- how evolution happens, why does life evolve? What processes cause  evolution?  

2. Pattern- what has happened in the history of life

• Be able to describe the different types of evidence for evolution and their significance  o Life on Islands

▪ Lots of species that were found on the island and nowhere else

▪ Similar to mainland but unique (endemic)

▪ Darwin  

• hypothesized that the Galápagos had been colonized by organisms  

that had strayed from South America and then diversified, giving rise  

to new species on the various islands.  

• Inferred that individuals arrived on the islands followed by evolution  

of new forms

o Fossil Record

▪ Many people looked at these before Darwin, Darwin explained it

▪ documents the pattern of evolution, showing that past organisms differed  from present-day organisms and that many species have become extinct

▪ show the evolutionary changes that have occurred in various groups of  

organisms  

▪ nonrandom change in form over time

▪ not just different in the past but different in a consistent pattern  

o Observation of Natural Selection

▪ Darwin observed many examples of adaptations (inherited characteristics of  organisms) that enhance their survival and reproduction in specific  

environments

▪ perceived adaptation to the environment and the origin of new species as  closely related processes We also discuss several other topics like What are the various pieces of evidence supporting evolutionary theory?
Don't forget about the age old question of what is isotopes?

▪ Darwin thought natural selection was REALLY slow (KNOW THIS)

• People realized that you can see evolution happening in real time by

looking at the risk

o If the risk of getting eaten is high=mature faster in order to  

reproduce more

o If safer=investing in growth is better so mature later

▪ Examples

• Birds and beaks, beak shape shifted based on seeds  

• Difference between lizard and guppy experiment  

o Lizard- move them to new place and saw what happened  

(phenotypic)  

o Guppy- also did lab experiments to look at genetic basis  Don't forget about the age old question of what is Economic Growth?

(genotypic and phenotypic)  

• Spines on cactus- spines increased over time as they were eaten  

more by other animals  

o Artificial Selection

▪ Humans have modified other species over many generations by selecting  and breeding individuals that possess desired traits  

▪ Selective breeding is similar to natural selection  

▪ Human selective breeding is stronger because they can focus on one trait  ▪ Darwin and pigeons example

o Comparative Anatomy

▪ homologous structures

• Homology= ancestry  

• Similarity resulting from common ancestry

• Function may or may not be the same

• Not the opposite of convergence  

• Example: Our skull and the skull of a snake share a common ancestry  ▪ vestigial structures- remnants of features that served a function in the  organism’s ancestors  

• generally homologous to a functional structure in some other species  • example: tailbone, has become small because no longer functional  ▪ convergent evolution

• independent evolution of similar features in different lineages

• the resemblance is said to be analogous (share similar function), not  homologous (share common ancestry)

• similar form due to action of natural selection

• example: hemoglobin similar in birds and mammals and flying  

squirrels from the United States and sugar gliders from Australia  

have similar traits

Homology

Convergence

Common ancestry

Similar form and function

Form and function may or may not  be the same

Similarity is not due to common ancestry

Wing of bat and wing of bird are both  separately modified to form a broad flat  surface

o Ontogeny

▪ the development of an individual organism or anatomical or behavioral  feature from the earliest stage to maturity.

o Phylogeny

▪ the evolutionary development and diversification of a species or group of  organisms, or of a particular feature of an organism. (he really went over this  more in the last section)  

o Molecular Evolution

▪ change in the sequence composition of cellular molecules such as DNA, RNA,  and proteins across generations

▪ random changes in non-coding DNA reflects ancestry  

• noncoding- doesn’t code for amino acids 

• if not coding for anything it is not subject to natural selection 

• can mutate over time but not natural selection  

o Development and Evolution

▪ Detailed understanding of how differences in genes can lead to different  developmental pathways.

• Terminology - Homology, Endemic, Fitness, Selection, Convergence, Phylogeny, Non-coding  DNA

Lecture 22 - Evolution and Genetics

Readings - 23.1, 23.2, 23.3, 23.4 (pages 479-481)

• Know that evolutionary change means genetic change

o Changes in allele frequency underlies everything in this section

• Be able to calculate allele and genotype frequencies from genetic data and explain  that evolution can be described as change in allele frequency in a population. o Gene pool- genetic makeup of population  

o Example:

▪ 500 individuals have a total of 1,000 copies of the gene for flower color

• 320 plants with red flowers

• 160 with pink flowers

• 20 with white flowers

▪ CR allele accounts for 800 of these copies  

• (320 * 2 = 640 for CR CR plants, plus 160 * 1 = 160 for CR CW plants)

• frequency of the CR allele is (640+160)/1,000=800/1,000 = 0.8 (80%)

• p: frequency of one allele (CR), p = 0.8 (80%)

• q: represent the frequency of the other allele (CW), q = 1 - p = 0.2 (20%)

• Be able to explain how the Hardy-Weinberg equilibrium shows that Mendelian  inheritance will not change allele frequencies

o Hardy equilibrium- In a population that is not evolving, allele and genotype  frequencies will remain constant from generation to generation, if only Mendelian  segregation and recombination of alleles are used

o If in Hardy W the following must be true

▪ p= freq of one allele (A)

▪ q= freq of the other allele (a)

▪ p+q=1

▪ AA=p2 

▪ aa=q2 

▪ Aa=2pq

▪ p2+2pq+q2=1 is true for all of the problems he will give us, not just HW! DON’T  BE FOOLED BY THIS!

o Now I’m going to drive you crazy with examples.

o example

▪ 10 AA, 10 aa, 80 Aa

▪ 200 alleles  

▪ (10+40)/100=0.5=p

▪ (10+40)/100=0.5=q

▪ p2=0.52=0.25 so you would expect 25 of them to be AA but only 10 are AA ▪ not in HW eq

o example

▪ Purple and white flowers

▪ Population in Hardy Weinberg

▪ 16% of the flowers are white

▪ what is the allele frequency of p?

▪ p+q=1

▪ q2=0.16

▪ q=0.4

▪ p=1-0.4

▪ p=0.6  

o example

▪ 100 individuals that are all Aa

p=q=0.5

▪ there is no p2 or q2 so it is not in  

HW equilibrium  

▪ To be in HW it would have to be:

• p2=0.25

• q2=0.25

• 2pq=0.5

▪ What about 50 AA, 50 aa?  

• not in HW

▪ The correct answer that is in HW is:  

• 25AA

• 50Aa

• 25aa

o Homozygotes  

▪ Probability that two CR alleles will come together: p * p = p2 = 0.8 * 0.8 = 0.64 • about 64% of the plants in the next generation will have the genotype CR CR 

▪ for CW CW individuals frequency is about q * q = q2= 0.2 * 0.2 = 0.04, or 4% • about 4% of the plants in the next generation will have the genotype CW CW 

o Heterozygotes  

▪ sperm provides the CR and egg provides the CW 

• p*q=0.8*0.2=0.16, or 16% of the total

▪ sperm provides CW and egg CR 

• q * p = 0.2 * 0.8 = 0.16, or 16%.  

▪ frequency of heterozygotes is the sum of these possibilities:  

• pq + qp = 2pq = 0.16 + 0.16 = 0.32, or 32%.  

• Group assignment:

o Population of snakes that has locus with codominance

▪ AA-black

▪ aa-red

▪ heterozygotes have red and white bands

▪ The population has 10 black snakes, 15 red snakes, and 25 banded snakes.  o What is the frequency of A?

▪ [2(10) +25]/ [2(10+15+25)] =45/100=0.45

Four evolutionary forces overview:

1. Genetic drift

a. change in allele frequency due to random change from one generation to the next  b. More important in small populations  

c. Can cause allele frequencies to change at random

d. Can lead to a loss of genetic variation between populations by the loss of an allele  from the gene pool

e. Example: Cows eating flowers with certain traits randomly

2. Gene flow= migration

a. genetic change due to movement among populations

b. the transfer of alleles into or out of a population due to the movement of fertile  individuals or their gametes

c. tends to reduce the genetic differences between populations

d. example

i. suppose that near the wildflower population (CR CR) there is another population  consisting primarily of white-flowered individuals (CW CW)

ii. Insects may pollinate plants in our original population  

iii. introduced CW alleles would modify our original population’s allele frequencies  in the next generation

3. Natural selection

a. natural selection is the evolutionary force producing adaptive change

i. adaptive evolution- evolution that results in a better match between organisms  and their environment

b. Three types:

Picture: http://swh.schoolworkhelper.netdna-cdn.com/wp

content/uploads/2011/12/types-of-natural-selection.jpg?x37075 

i. Directional selection  

1. when conditions favor one extreme of a phenotypic range

2. Shifts a population’s frequency curve for the phenotype in one direction  ii. Disruptive selection  

1. when conditions favor individuals at both extremes of a phenotypic  

range over individuals with intermediate phenotypes

iii. Stabilizing selection  

1. acts against both extreme phenotypes and favors intermediate variants

2. reduces variation and tends to maintain the status quo for a particular  

phenotypic character

4. Mutation- more later

Terminology - Fitness, Selection, Allele Frequency, Hardy Weinberg, Drift, Migration Darwin’s Five ‘Theories’ (KNOW THIS- he said to, not me)

1) Evolution has happened - not new to Darwin, not in any doubt of it being true 2) All life has a common ancestor - Darwin had little evidence of this, but was later strongly  supported by molecular and cellular data

3) The diversity of life is the result of a series of splits in the lineage (family tree) of living things generally true although other patterns occur

4) Natural selection is the primary mechanism driving evolutionary change - multiple evolutionary  forces (he drew a fair amount of attention to this)

5) Evolution occurs gradually over time – disputed among biologists, but evolution can happen  quite rapidly as in the lizards

Lecture 21: Sexual Selection, Genetic Variation, Evolutionary Thinking Reading 23.4 (all)

• Know that selection, drift, mutation, and migration are important in different  situations.

o All evolutionary forces act on allele frequencies

o Natural Selection can only act where there are fitness differences acting on  phenotype  

o Drift and Migration can act on any locus- changes in allele frequency  

▪ Distinct from natural selection  

▪ Drift

• random changes in allele frequency, doesn’t need movement  

• Founder effect- small number of individuals leaving and starting a  

new population

o Perhaps a few members of a population were blown by a  

storm to a new island (see how it is different than  

migration!)

• Bottleneck effect- a severe drop in population size can effect the  

allele frequencies  

o Think about a heard of elephants stampeding through a field  

of multicolored flowers, the severe reduction may cause a  

change in allele frequency depending on the original  

frequencies

o There is a fabulous example about chicken on pg 489 of your  

textbook

▪ Migration (aka Gene flow)

• Movement of alleles between populations

o seeds blowing

o humans traveling and mating- the melting pot

o Note: Mutation and Drift are much more powerful forces in small populations • Be able to explain how sexual selection can act through interactions between or  within the sexes.

o Sexual selection

▪ form of natural selection  

▪ individuals with certain characteristics are more likely than others to get mates  

o Sexual dimorphism

▪ a difference in secondary sexual characteristics (size, color, ornamentation,  and behavior) between males and females of the same species  

o Intrasexual selection

▪ selection within the same sex, individuals of one sex compete directly for  mates of the opposite sex  

o Intersexual selection

▪ also called mate choice, individuals of one sex (usually the females) are  

choosy in selecting their mates from the other sex

• Be able to explain why the good genes model of sexual selection is controversial o They found that female mate choice can be based on a trait that indicates whether  the male has “good genes.”  

o Some traits don’t seem to favor survival of individuals

▪ color of peacock - female choice

▪ dobsonfly’s jaw- competition for mates between males

o female gametes are more valuable- intersexual selection  

o lots of different ideas proposed to explain animal attraction, mostly health o problem:  

▪ A1= healthy, long tail

▪ A2= sick, short tail

▪ Frequency of A1 will go up. This will happen fast. Sexual selection is  

powerful. Soon, A1 will be 100% and everyone will have the same gene.  

Controversial…

• Be able to explain why the maintenance of genetic variation is a central problem in  evolution… So many possibilities!!!  

o Both Drift and Selection (normally) remove genetic variation

o What forces can increase or maintain variation?

▪ Mutation

▪ ‘Hidden’ variation

▪ Some forms of Selection

o Genetic hitchhiking: tight linkage to a favorable gene can protect a less favorable  gene from selection.

o Why things are not perfect:

▪ Selection can act only on existing variations and those variations may not be  the fittest possible

▪ Evolution is limited by the history of the species  

▪ Adaptations are often compromises (turtle shell is protective but very  

heavy)

o Just because there is a tradeoff, that by itself does not make variation  

▪ Whines- live 1 year (0.5 mates per month)

▪ Chuck- live 6 months (2 mates per month)

▪ Mutation selection balance  

▪ If the rate that the alleles are being lost is small, mutations can add them  back in

• Know that heterozygote advantage, frequency dependent selection and dominance  can all preserve genetic variation but that tradeoffs alone cannot maintain variation o heterozygote advantage- if individuals who are heterozygous at a particular locus  have greater fitness than do both kinds of homozygotes  

o balancing selection- this type of selection includes heterozygote advantage and  frequency-dependent selection

▪ frequency-dependent selection is when the fitness of a phenotype of one  individual depends on the frequency relative to the others in the population o dominance- when one phenotype of an allele masks another

Terminology: Neutral variation, Heterozygote advantage, intrasexual selection,  intersexual selection, good genes, individual selection, selection, fitness, adaptation

Lecture 22: Evolution and Many Loci

Reading: pages 279-281 (chapter 14)

• Be able to explain how multiple loci and alleles can influence a phenotype in an  additive fashion

o Quantitative Genetic Parameters

▪ Both environment and genes contribute to phenotype

▪ For an individual there is no way to estimate how much of phenotype is due  to a specific factor

▪ Instead ask what proportion of variation is due to a specific factor

• Be able to explain the concept of heritability in a non-mathematical way o VP = Phenotypic variance for a trait

o VG = Genetic variance for a trait

o VE = Environmental variance for a trait

o VP = VG + VE

o VG/VP = broad sense heritability

• Be able to explain the equation R=h2S and use it to solve any one of the three values. o h2 is a measure of similarity of parents and offspring due to genes it allows us to  predict how populations will respond to natural selection.

▪ The closer to 1 means that natural selection will create an exactly equivalent  evolutionary  

o R = h2S

o P = parental population mean

o S = Pbreed– P = selection differential

o R = O – P = response to selection  

o Example  

▪ Before El Nino, mean bill depth of fledglings= 9.0 mm.  Birds that survived  the drought had bills that were 9.9 mm.  

▪ h2 = 0.80

▪ A:  R = 0.8 * 9 mm = 0.72 mm.  

▪ Bill depth next generation = 9 + 0.72 = 9.7 mm.

o Example  

Population mean

Selected mean

100

110

Gen 1

105

Gen 2

▪ 110-100=10= S

• (difference between ones that succeed and ones that didn’t succeed)

▪ 105-100=5= R  

▪ h2=0.5

• Be able to relate the equation R=h2S to the concepts of selection and evolution. o Predict evolutionary response if know selection and heritability

o Estimate strength of selection if know response and heritability

o Estimate heritability in a selection experiment if R and S are controlled

Lecture 23 Speciation

Reading 24.1-24.2 (24.3 and 24.3 - in part)

• Know that there are multiple species concepts

o Species exist - the variety of life on earth is not continuous.  How do you get from  one to another?

▪ Biological Species Concept - Reproductive Isolation

• Start out with one set of population and somehow they become  

different enough that they can no longer interbreed

• Powerful idea for how species become separate

• Doesn’t apply in every situation  

o lions and tiger, donkeys and horses  

o Asexual reproduction  

• Drift and natural selection tend to cause populations to lose  

variation

• Migration tends to make them more different  

▪ Morphological Species Concept - Different morphology, distinguishes a  

species by body shape and other structural features.

• Problem- can have identical looking things that are from different  

species  

▪ Not as important  

• Ecological Species Concept - Separate Niches, defines a species in  

terms of its ecological niche, the sum of how members of the species  

interact with the nonliving and living parts of their environment  

• Phylogenetic Species Concept – Separate Evolutionary Lineage,  

defines a species as the smallest group of individuals that share a  

common ancestor, forming one branch on the tree of life

• Know that there are a number of different reproductive barriers between species  

(read about reproductive barriers – not covered in lecture)

o reproductive isolation

▪ biological factors (barriers) that impede members of two species from  

interbreeding and producing viable, fertile offspring

▪ barriers block gene flow between the species and limit the formation of  

hybrids, offspring that result from an interspecific mating

o Prezygotic barriers (“before the zygote”)  

▪ block fertilization from occurring

▪ hindering fertilization if mating is completed successfully

▪ problems after birth may cause hybrids to be infertile or decrease their  

chance of surviving long enough to reproduce

Mating  

Attempt

Fertilization

Viable 

fertile 

offspring

Habitat  

isolation

Temporal  

isolation

Behavior  isolation

Mechanical  isolation

Gametic  

isolation

Reduced  

hybrid  

viability

Reduced  

hybrid fertility

Hybrid  

break

down

Two  

species  

occupy  

different  

habitats

Species that  

breed during  deferent

times of the  

day or year

Unique  

courtship  rituals

Mating is  

attempted  

but  

morphologi

cal  

differences  

prevent  

completion

Sperm of one  species might  not be able to  fertilize

sperm of  

another  

species

Genes of  

different  

parent  

species may  

impair the  

hybrid’s  

development  or survival

Hybrids may be  sterile

Some first  

generation  offspring  

are viable  

but when  

they mate,  their  

offspring  

are feeble  

and sterile

Garter  

snakes  

live in the  same  

area but  

one lives  

in the  

water  

and the  

other on  

land

Eastern and  

western  

spotted  

skunk

breeding  

times overlap  but one is  

more in the  

winter and  

one more in  

the summer

Blue  

footed  

boobies  

mate only  after a  

certain  

display of  courtship

Shells of  

two species  of snails  

spiral in  

different  

directions

so genital  

openings  

aren’t  

aligned

Sea urchins  

release  

sperm into  

surrounds  

and different  species have  different

binding  

proteins to  

accept sperm

Some  

salamander  

subspecies  

live in a  

region where  they  

sometimes

hybridize,  

usually they  

don’t. If they  do, they are  

frail.

Hybrid offspring  of a male  

donkey and  

female horse is  a mule which is  sterile. A hinny,  (offspring of  

female donkey  and male horse  is sterile too.)

Strains of  

rice that  

carry too  

many  

recessive  

alleles are  

small and  

sterile

• Understand that species formation can be allopatric or sympatric

o Sympatric Speciation

▪ No geographic separation  

▪ caused by disruptive selection (remember? It’s a kind of natural selection.) ▪ more extreme phenotypes are favored

▪ polyploidy-

• allopolyploid- involves hybridization among species

• autopolyploid- occurs within one species

▪ problem- the two extremes can still mate and make the intermediates  

o Allopatric speciation-

▪ gene flow is interrupted when a population is divided into geographically  isolated sub populations

• Separate houses

• Distance

• Cliffs

• Prevents migration  

• Understand that secondary contact can lead to fusion, reinforcement or a stable  hybrid zone.

o Look at this: http://image.slidesharecdn.com/ap-chapter-24-the-origin-of-species 1233694873300955-3/95/ap-chapter-24-the-origin-of-species-36- 

728.jpg?cb=1233673357 

o Reinforcement- hybrids gradually decrease  

o Fusion- two species fuse

o Stability- continued production of hybrid individuals  

Terms: Different species concepts, isolating

mechanisms, allopatric, sympatric, hybrid zone, fusion, reinforcement

Lecture 24 Building and Using Phylogenies

Reading Chapter 26 (emphasis on points below – can skip parts of 26.5, 26.6) *These last few concepts are pretty straightforward and he should talk more about them in class on  Monday which is why I have not gone into detail.

• Evolutionary relationships can be depicted by a phylogeny

o the evolutionary history of a species or group of species  

o branching pattern that we see when we look at evolution  

o terms to know

▪ sister taxa- groups that share a common ancestor that they don’t share with  anyone else

▪ branch points (node)

▪ polytomy

▪ common ancestor of taxa

▪ taxon- any named group

• Phylogenies are used to classify organisms and to map the evolution of traits o The taxonomic system, hierarchical  

o The named taxonomic unit at any level of the hierarchy is called a taxon o Time is along the x axis and the organism is along the y axis  

• Convergence and character loss can make estimating a phylogeny difficult o Just think about this one, the traits will get all mixed up

• Shared Derived Characters are used to determine evolutionary relationships

• Neutral Genetic Variation is useful in determining phylogenies

• Phylogenies can provide information about genetic distance or time since divergence • Life consists of three major domains: Archea, Bacteria, Eukarya

Terms: phylogeny, node, polytomy, convergence, monophyletic, polyphyletic, paraphyletic,  character state, parsimony

Bonus questions on next exam based on last     

There will definitely be a draw meiosis 

Congrats on making it to the end of this study guide…

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