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132 Cards in this Set
- Front
- Back
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Direct benefit
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Hypothesis as to why some females prefer particular traits
1. Provision of resources through males to females: nuptial gifts example: dung beetles are attracted to bigger dung balls example: praying mantises get resources by eating the male and given to young 2. Territory Red-headed weaber birds impress females with nests and red collared widow birds. big brains connection 3. Avoidance of disease |
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Good genes
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Hypothesis as to why some females prefer particular traits
"handicap princible" - Zahavi says sexual ornaments are costly. Therefore exaggerated sexual traits must indicate that the male carrying those must be in good shape and carry good genes. Under this hypothesis, sexual ornaments are advertisements for good genes. It does not say " if i am handicap and i survive, i must be intrinsically stronger" .... It means sexual attractive quality must come at the expense of something else-- so sexual ornaments must signify good genes for survival. parasite resistance |
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Sensory Bias
example |
Hypothesis as to why some females prefer particular traits
Certain traits may be intrinsically stimulating and evoke a greater response simply because of the organization of the sensory nervous system. Priapella fish ( no sword fish) . Females of the species had an intrinsic preference for males of their own species that had a fake sword attached to the tail due to a pre-existing sense. |
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Runaway Selection
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Simply there is a pairing between the preferences in the female and the traits of the male.
Even in the absence of resources, good genes or sensory bias can sexually select and give rise to weird adaptations. Runaway selection can occur when the genes that give a male a certain phenotypic trait are linked to the genes that make females prefere these traits |
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4 different hypothesis on sexual selection
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1. Direct benefits
2. Good Genes 3. Sensory Bias 4. Runaway Selection |
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Male Scroprian flie
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Male provides salivary secretion to get female to mate with him.
The longer the excretions, the increased copulation duraiton Experiment: Females mated and half of them provided extra secretions artividially controleld form mlaes. Bascially the more of the liquid the more eggs she provided |
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Why did red-collared window bird males have long tales?
principle |
1. 120 male birds were caught: 60 had their tails trimmed, 60 were left untreated
The longer tails are more attractive to females because tail length correlates to with good genes (resistance to parasites) Handicap principle? |
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Red-comb signaling according to Hamilton Zuk Hypothesis
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when a bird gets sick, the comb gets pale. So a red comb shows that this bird is carying genes that makes it more resistance to infection.
" good genes" |
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Hamilton zuk 3 assumptions
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1. parasites reduce host fitness
2. co-evolution between the host and the parasite so that the host evolves genes that make them resistiant to 3. hosts with higher resistance are in better health and able to show better sexual displays |
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How to female peacocks pick a male?
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When the females spot a nice mate with the most eye spots aggregated in " leeks".
Males with more eyes will have more mating success. When added with LPS- the brids with more eyes were more able to fight off of the LPS infection. Conclusion: Found that more eyespots indicated genes that could over come LPS infection. |
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Barn Swallows and Moller
Direct Fitness consequences What hypothesis does this prove? |
Good genes
1. shortened tail and glued it back on ( to have it maintain the deep V shape) 2. control1: Cut the bird without shortening 3. Control 2: didn't touch the brid 4. Glued on longer feathers Shorter tails: took a long time find a mate, Artifically elonged tails: took an even shorter time to find a mate than the controls and even MATED TWICE! Measured Fledge: artifical elongated tail had a better mating success. |
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Why are males with longer tails more attractive to females in Barn Swallows. What hypothesis?
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Good genes.
Moller followed up with another exeriment to test Hamilton and Zuk. Genetic coding for mite resistance correlating to long tail length. Found there is a biological connection between Mites on Paternal father and offspring. Also., the longer the tail , the fewer the mites there will be. There is a correlation between the number of mites on the male parent and the number of mits on the offspring in Nest. But. There is no relationship between the number of mites on fostering offspring in own nest |
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Why would a female prapella fish prefer a species with a sword tail?
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1. they used to have a common ancestor that that had a sword.
2. but no, because the sword developed after the common ancestors 3. Preference prexists the evolution of long swords- due to a sensory perception |
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Why do bower birds prefer blue?
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some studdies suggest that sensory bias also play a role in bower birds, where preference for certain colors may arise because of their association with ripe fruit. other species have a similar blue excitiory-- wavelength.
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Eyestalkes of flies
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1. daughter's preferences match the sun's trait depending on if he had a short or long stalk.
2. example of RUNAWAY selection linkage between daughter and son will drive greater longer eyestalks which drives greater strong preferences. |
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What form of sexual selection causes speciation and why?
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Runaway slection.
Run away selection causes dramatc increase in traits and FAST. |
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What is true of the sexual preference and fitness of red-bowered birds?
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Longer tail males had more NESTS in their territory: It seemed that control males with long tales could attract more females to the long tail. BUT the short tailed lost less weight than the long tailed contorl.
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What are the 4 attributes of the Scala Naturae
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Embraces the whole of nature
continuous in structure men are at the mid-point of perfection Women are somwhere between men and naimals. |
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Where does the scala naturae develop from and when does it reach its zenith?
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The scala naturae rooted in aristotle but reach its zenith during the enlightment.
Alexandre Pope followed the Scala naturae in ESsay on Man |
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Mark Dion**
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Artist who depicted the scala naturae as an art piece
secular- doesn't believe in mystics |
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3 ways the scala naturae- perfection of man began to be questioned
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1. discoer of fossils
2. geology as a science 3. the discovery of non european race " primitive races |
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What was the first example of the evolutionary tree?
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Chain of Being: still only a results of PROGRESSIVE DEVELOPMENT.
Lamaraks 1809 first example worms and insects developed to mollusks- the fish reptiles-- amphibious mamals such as whales, hoofed mammals and mammals |
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La Marche de la Nature
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Jean Baptiste Lamark(19744-1829) proposed the Parade of nature as a transformed scala to an escalator.
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Felt need
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A mechanisstic and progressive theory leading to steady improvements through the inheritance of ACQUIRED characteristics.
Because usesful organs would be used, exercised, and more fully developed than other organs. |
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Darwins Birthday and length of voayge
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1809-1882 and a beagle voyage that lasted five years from 1831-1836
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What influenced Darwins thinking on the beagle?
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Geology. Darwin's mentor Henslow gave him the PRINCIPLES OF GEOLOGY by Charles Lyelll
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Uniformitarianism and Gradualism
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Lyell's ideas in Principles of Geology which were formulated by hutton
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Henslow
Hutton Lyell Lamark Malthus: Wallace Hooker |
Henslow- Darwin's mentor on the Beagle
Hutton- originally formed philosophies of uniformitarisnism and gradualism Lyell: wrote Principles of Geology Lamark: marche de la nature, felt need. Malthus: Essay on population Wallace: research from Malay Archipelago Hooker: publishes wallace and Darwin's essays simultaneously |
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What was darwins first great insight stimulated by?
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Descent with Modification developed after studying finches in the Galapagos island.
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First Principal of Theory of Evolution by Natural Selection
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Variation. There occurs, within every species, natural variations among individuals of that species and these variations arise strictly by chance
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Second Princ of Theory of evolution by NS
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Heritability Variations are passed on to offspring.
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3rd princ. of theory of evolution by NS
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Among these heritable variations some variations will lead to a great propensity for reproduction and survival, hence leading to an increase in the appearance of this favored trait.
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Polymorphism
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Variation among humans due polymorphisms, so this variation is due to both genetic and environmental factors.
Human hight- and the Heliconius butterfly wing pattern |
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Cryptic Variation
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Recessive lethal alleles like Cystic Fibrosis, tay-sachs disease, sickle-cell anemia and barchydactyly
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Why aren't lethal alleles purged from the population in cryptic variation?
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j
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Clinical Variation and Ecotypes -- is it due to genetic or environmental differences?
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ex. variation in plant height along an altitudinal gradient.
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Is molecular variation under natural selection
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Enzymes polymorphism's, alloenzympes Sequence variations like SNPs, microsaellite sequences and amplified fragment length polymorphisms (aflps)
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What was Darwin's biggest problem?
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What the mechanism of inheritance was. If blending inheritance is true ( that was the only proposed mechanism) then why would the net effect of mating be loss of variation.
I.Red and white seems to yields pink... not more red and white... |
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HBD Kettlewell
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First person to do experimental evolution in natural populations.
1. Pinned moths to trees in different habitats and observer predation rates on each type by birds 2. released mixed populations of moths in different habitats and examined recapture frequencies |
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What principle do the Peppered moth show?
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It showed how natural selection can maintain variation of polymporhism through differential predation.
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What are the recessive and dominate types of the Peppered moth?
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The dominant type: Carboneria found in polluted areas to blend into darker/ poluted tree bark
The Recessive: Typcia is on cyptic normal trees |
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What selective force accounts for the differentiation between banded land snail?
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Slective predation from the Song thrush bird effects the color morphs of the banded land snail in different habitats.
Snails that live in the dark woody areas have dark bands. Snail that live in the grassy habitats have yellow bands. |
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What do various pelage colors in the oldfield mouse signify?
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There is a selective advantage of cryptic coloration. There are less predator attacks if the mouse blends in with its habitat.
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Does Pelage Color follow Mendelian inheritance?
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Yes. George mendel says that particular interitance maintains variation.. mixing a pink rose with a pink rose will not lead to 4 pink roses, but 2 pink roses and a red and white rose
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What is true under the Hardy-Weinberg Law?
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Under random assortment of gametes ( no natural selection), allele distribution and variation is maintained from generation to generation at the same fequency
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What does HW assume?
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No Migration
No Mutations Large enough population Random mating No gene linkage ( linkage equilibrium) akak. no selection. |
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What is the significance of HW if it rarely occurs?
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HW forms the null hypothesis for evolutionary dynamics- and will tell us if one of the assumptions have been violated if the population genotype significantly differs from HW Values
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p=
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frequency of A1 Alle
p^2+ .5(2pq) |
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q=
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frequency of A2 allele
q^2 + .5(2pq) |
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p^2 and q^2=
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Initial genotype frequencies
P^2 is therefor the frequency of A1A1 genoytypes (NOT ALLELE FREQUENCIES) |
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How do we calculate the genotype frequencies after selection?
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1. The frequency of that genotype (before selection), p^2
2. The genotypes fitness W 3. the average fitness of the population Wavg (p^2 * W11) / W avg |
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Calculate the average probability of survival in the population at hand
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Use normal hardy Weinberg BUT must include the genotype's fitness
w= p^2W11 + 2PQ12 + q^2 w22 |
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w=
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relative fitness of the genotype!
The viability of that genotype/ the highest viability |
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How do we calculate frequency of an allele?
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It will be determined by the frequency of individuals homozygous for that allele (and their fitnesses), the frequency of individuals heterozygous with that allele (and their fitnesses), and the average fitness of the population.
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How does selection effect allele frequency?
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allele frequency changes due to selection and are a function of initial allele frequencies, population mean fitness, and mean fitness changes as a result of allele frequencies. ..
So we can therefore predict the change in the frequency of an allelechange that is a result of selection |
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S1
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the selection coefficient AGAINST the A1, A1 gentotype
When s is big |
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natural selection is a force that ______ individuals from a population. Explain how this effects the strength of selection of a particular phenotype.
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1. we view natural selection as force that REMOVES individuals from a opulation
Therefore- we measure the strength compared to the maximum fitness, which we scale to 1. The fitness of the A2A2 would= 1- S2.. and s2 s the selection coefficient against A2 genotype |
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h=
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heterozygous effect, or the degree of allelic expression of the heterozygotes...
H shows us which which allele is dominant in the heterozygote, which will allow us to calculate the degree to which A2 is expressed in the population |
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When h=1
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heterozygotes express ALL of the A2 allele and it is completely dominant
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when h=0
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heterozygotes express NO A2 allele and A1 is dominant
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what is the pattern of selection for a heterozygote advantage in order to maximize population mean fitness.
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A1A1= 1-s1
A1A2=1 A2A2= 1-S2 |
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What is the pattern of selection for homozygote advantage in order to mazimaize population mean fitness?
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A1A1= 1+s1
A1A2= 1 A2A2=1+S2 |
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Formula for heterozygote advantage
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w= 1- p^2- P^2s1- q2s^2
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Equilibrium value for A2
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frequency of the A2 at which the population mean fitness is maximized.
Q HAT |
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q hat for heterozygotes
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qˆ =s1/
(s1+ s2) Which is saying that the equilibrium value for A2 is determined by the strenglth of selection against the Homozygotes: A1A1 ( se) relative to the sum of seletion against A1A1 (sS1) and A2A2 (s2) |
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How will the A1 and A2 stablize in a heterozygote advantaged population.
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They will not fix because A2 will reach a stable equilibrium which maximizes the frequency of heterozygotes
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When would theA1 and A2 alleles be maintained at the same equilibrium?
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I'm not sure-
i think when q hat and p hat are equal.. when S1=s2 |
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What is the difference between q and qhat?
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q= value of q in H-W conditions occurs when there is no evolutionary forces
Q hat=equilibrium value of q however in a heterozygot advantage shows that delta q stops changing because population mean fitness has been maximized- and if theq has any change in frequency then there will a reduction in population mean fitness. |
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Viability
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observed/expected
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directional selection
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One or the other phenotype extreme is selected agains and reduces phenotypic variation in a population
After a round of selection, the average value of a trait has shifted (bell curove) |
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What type of selection describes antibiotic resistance and why?
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Directional selection.
1. The antibacterial resistance gene exists 2. apply antibiotics After ONE round of selection the population variation moves dramatically to resemble the bacteria that had the resistance gene and variation is reduced. |
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Stabilizing selection
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After one round of selection, the average phenotype is favored an other phenoytypes dissappear.
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What type of selection is clutch size in birds and why?
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It is stabilizing selection because the average number of eggs produced to favor the bird's clutch size.
After selection, the average number of eggs laid will stabilize to the optimal number of young that the parent can provide enough food/resources for with the average clutch size. |
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disruptive selection:
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When phenotype intermediates are selected against and a bimodal distribution phenotype value is produced. It INCREASES phenotypic variation in a population
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What type of selection relates to phenotypic fur color?
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Disruptive selection. Occurs when mice end up clonizing in two different enviornments that require different colors of camouflage in order to avoid preation. It increases phenoytypic varation.
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What type of selection relates to the mimaism moth?
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Disruptive selection-- the low polution areas have lighter moths to blend into the trees and the high pollution areas have darker moths to blend in to the polluted darker trees.
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Frequency dependent selection
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The fitness of a phenotype depends on its frequency in the population. Usually occurs if there is selective pressure against a host by a particular pathogen. If pathogens are more adapted to a particular genotype-- than that genotype is slected against, and the rare genotype will have the advantage.
Population mean value will oscillate to keep population mean fitness stable. |
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Why are oscillations in genotypes of a frequency-depenant selection required to
stabilize population mean fitness at its maximum level? |
sfgh
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What type of selection increases phenotypic variation among a population?
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disruptive selection. This occurs often in patchy environments, when mice average colors or something provides no benefit to camouflage. It can even result in speciation if the two different environments are so different that the mice will stop interacting.
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What type of selection is the African fish that attack the sides of other fish?
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Frequency depenetn selection. Because the fish that does not attack the same side of the other fish... will be able to sneak attack on the prey's learned defensive response.
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the _______ of ineffectively traits of the ______ will change in response to the rare genotypes having an ____ and will push the ______ into a _____ pattern.
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requency of
infectivity traits of the pathogen will change in response to the rare geneotypes having an advnatage, _pushing the hosts into oscillating pattern |
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canalizing selection
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important traits are stablizied by mulitple factors in the genome so population mean value will stay the same with almost no variation.
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Why do genotypes that have more or less kidneys than 2 have have a large coefficient of selection against them?
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Due to the canalizing selection theory-- that the optimal number of kdiness is so important that kidneys have evolved to be resistant to change. Also the theory predicts that there might be variation in the mechanisms but there were be other mechanisms to mitigate the physical effects of that variation-- so any new variation will remain hidden from selection.
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3 hypothesis of hamilton and zuk
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1. Parasites reduce host fitness
2. no coevolution between hosts and parasites, and hosts evolve genetic resistance to their parasites 3. the hosts with higher resistance are in general better health and have stronger sexual displays |
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Examples of Selection that can cause speciation and Why?
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1. Runaway selection
Innate female fondness for the same traits as the brother, decreases genetic diversity? 2. Disruptive selection If the 2 habitats of the same species are so different and cause phenotypic variation that prevents the one phenoytype from moving to other habitats to mate with the other phenoytpe; |
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What is migration implicitly recognized as?
On an _______ level, ________ engage in a type of locomotory activity that is "______,"_______ and ____ __" |
An adaptation.Migration is based on transitory availability and location of resources like space, food, climate, shelter, mates.
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Can migration lead to redistribution?
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Yes- as populations, organisms may exhibit movement leading to redistribution within a spatially extended population.
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On an _______ level, ________ engage in a type of locomotory activity that is "______,"_______ and ____ __"
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On an individual level organisms engage in a type of locomotory activity that is undistracted, persistent and straighten out.
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Why do grasshoppers turn into locusts at a certain threshold?
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At first, grasshopers are solitary living in greater distances between scarce vegetation and are cryptically colored green to blend in.
There is a density dependent response of the ( vegetation of the other grasshoppers) during which the grasshopper's antenna will touch another grasshoppers leg receptor and cause a physiological change into a gregarious locust. |
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What is the genetic combination of locus interaction?
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Gene Flow
migration |
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What is gene flow?
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Gene flow is the transfer of alleles of genes from one population to another. Gene flow introduces new alleles to a population and makes the 2 separate populations more similar.
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The change in alele frequency due to migration within a population depends on 2 things?
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1. The proportion of immigrants
2. The Difference in allele frequencies between the 2 populations |
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What is the frequency of allele A in island population after migration?
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Pm= (1-m)pi + m (pc)
(1-m)= fraction of island that is native pi= frequency of A allele on island m= fraction of island that is immigrants Pc= frequency of A allele on continent |
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What is the CHANGE in frequency of the A allele in island population after migration?
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Delta P= m( pc- pi)
m= fraction of island that is immigrant Pc= frequency of A allele on continent ) the original Pi=Frequency of A allele on island ( the new) |
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When delta P is negative?
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The change in the A1 allele frequency is negative means that the relative number of A1 alleles is decreasing due to the introduction of the q alleles.
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What is the only source of new variation?
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MUTATION. it is the only source of genetic variation.
Single nuclotide polymorphism ( point mutation to the duplication of an entire genome) GENOME DUPLICATION CAN CREATE NEW SPECIES |
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chromosomal inversion
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alleles inside the inversion are likely to be transmitted together. mutation
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point mutation
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causes new alleles
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What has the highest and lowest rates of mutations?
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highest 10^2= viroids
lowest 10^-11= higher eukaryotes The more complicated you are the least amount of mutations you have |
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how do selection and mutation relate?
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Selection acts to eliminate deleterious mutations from populations. While mtuation creates genetic variation over time, because most of the mutations are neutral and even non- neutral mutations are deleterious-- unlesss they are peristed over time .
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How can harmful recessive alleles be maintained in the population?
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mutation rate and selection against the mutation are in equilibrium of q hat.
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What is the selection coefficient agianst the gene for cystic fibrosis
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the selecitve fitness is 1- YOU WILL DIE
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If the calculated mu or mutation rate is significantly lower than it should be to maintain the mutation selection balance..
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Then something else must be keeping q in the population-- the heterozygote advantage.
CF hetrozygotes are resistant to CTFr typohoid fever somehow. |
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q hat for mutation-selection balance=
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square root of ( u/s)
u= mutation rate s= selection coefficient |
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R A fisher and his contribution to evolutionay synthesis
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In general populations are "large" and slection is efficient
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sewall wrigtht and his contribution to evolutionary synthesis
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-Populations may be “subdivided”, and
drift may reduce the efficiency of selection - populations occurred in small isolated units: reduces efficiency of selection |
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genetic drift
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Chance events can come to dominate the allele frequency in small populations
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what needs to happen for genetic drift to occur
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there must be a small population
allele frequencies have to change on the basis of chance alone and if there are no other evolutionary forces then genetic drift can result in gene fixation |
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Founder effect:
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loss of genetic variation when a small population is made from a small.
This is an exampe of genetric drift |
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genetic drift in humans example
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autism-
founder effect: d. Humans: porphyria is a genetic disorder that disrupts haem metabolism. Found in population in Afrikaan- speaking south Africans ( 1/300) i. A C-T transition in the protoprophyinogen PPo geneThe allele is not in British ii. Studies have suggested that most carriers in South Africa descend from a single couple from the Netherlands who married in Cape Town in 1688 |
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What happens in large populations and genetic drift
verus small populations |
genetic drift can affect the trajetory of allele frequency chagne but not the eventual fate of the allele.
In small populationsdrift is more powerful than selection and drives evolution to fix alleles that are not favored by selection Fishecer did not except this. |
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b. Snake: Natrix tesellata
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example of founder effects in animals:
endangered snake that occurs in natural and introduced populations c. Two natural and two introduced populations were studied for genetic variation using 8 microsatellite loci |
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What is the probability of an alleles fixation in genetic drift?
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the probability of the fixation of an allele is equal to its initial frequency only if the population is SMALL and genetic drift is the ONLY evolutionary froce
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How does flipping a coin show how chance events can dominate the allele frequency in small populations?
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The more tosses you have, the deviations become less and less likely, but the probability of it being 50% heads/ 50% hands, the more likely occur
• Example: if you only do 1 trial the probability of have 50% heads is 1 |
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Dobhanzky fly experiment
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jjj
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Genetic drift v flow
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Flow: the spreading of alleles across space
Movement of genetic variation in space across populations Drift: only can occur in small populations! Allele fixation is due to a poor sample size |
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Wallace vs. Darwin
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Never agreed on the role of “sexual selection”
Wallace only believed in natural selection Darwin beleieves that sexual selection is not due to survival but about reproduction. These traits that increase mating success, if heritable, will cause natural selection. |
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parental investment
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the energy and time expended in constructing an offspring and caring for it.
-increase the reproductive success of the offspring Decrease the reproductive success that the investing parent may achieve in the future through additional offspring In general : females invest more in offspring than males, the eggs are large full of nutrients an expensive to produce. So females a more maternally invested in offspring than males who only donate dna sperm |
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What are the limits of female and male reproduction?
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Female reproductive success is limited by the number of eggs, the energy investment but not by partners
Male reproductive success is Limited by number of females he can convenience to mate with him Limited by competition. Male fitness determined by access- so the major dynamic among males is competition The mate with a greater parental investment an be more cchoosey. |
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3 main ways of male competition
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1. direct combat: access to mating
2. sperm competition: access to eggs 3. Infanticide: removal of other males offspirngs |
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The male iguana is bigger because...
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of sexual selection of direct combat larger indivudals are better at head bobbing which is good for
1. visual display 2. holding larger territories ( which result in more copulation and more reproductive success) |
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Visual display of male direct combat example
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i. The female red-winged blackbird are attracted to red eppletes and aerial displays and their songs
ii. Experiment: in 7 control birds, they maintained territory, but the ones that lost their red color due to painting did not maintain territory |
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example of sperm competition in rodents
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relative size of the testes were proportional to the amount of offspring that were sired.
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Sperm competition among fruit flies
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ii. Fruit flys: when raised in the prescence of other males- they will produce more sperm than when raised in isolation
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Mating plugs/anti-aphrodisiacs/sperm scoops
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sperm competition:
i. Sperm plugs: ii. Butterfly Antiaphrodisiacs in Heliconius iii. Males produce chemicals that they transfer to females during copulation iv. The active chemical ((E)-β-Ocimene) makes females unattractive to subsequent males v. These males interrupt mating before sperm transfer plugs: bettles have spines on penis that use to remove the sperm from other males |
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Mate gaurding example
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In many species, such as the Seychelles warbler, female birds seek extra-pair copulations.
Males guard females during most fertile period, until female lays an egg. Study compared 20 pairs in which there were normal levels of mate guarding with 20 pairs in which mate guarding was reduced by placing a fake model egg in the nest Control males spent 53% of their time near their mates. Experimental males spent 8% of their time near their mates. |
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Infanticide
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a. Important and different: highlights the nature of evolutionary fitness .
i. Be better in terms of reproduction ii. Or make everyone else BAD b. Lion, males take over prides let by other males then kill nursing cubs. c. Direct positive fitness advantage by reducing the success of the other male. d. This results in a faster return to breeding condition of females |
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detrimental
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deleterious
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When does W bar go to 1?
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under directional selection- the alleles will be displayed in a way to maximiaze evolutionary fitness
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Q hat=
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The value when allele frequencies stop changing when the population is at MAX fitness or when the w bar is zero. If q hat is not equal to the q we have no we are not at mix fitness.
Q hat you're at w max |
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delta q=0
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delta q = q1-q0
delta q is how we can predict the q in the next generation. occurs the maximum amount of fitness. |
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Selection coefficient
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s=1-W
A huge S means heterozygote disadvantage |
