Bio Exam 4

Why did the drosophila experiment involving bristle number so quickly evolve into those with low or high bristles? What was the mean number of bristles in the original population?

Because of mutation, different forms of a gene, or alleles may exist at a locus 40

What differences would you see when you are studying this phenomena in species sympatrically (living together) vs. those living allopatrically (geographically separated).

Bills of similar sizes wen living apart decreased faster than bills of different sizes when living together

What is the heterozygote advantage for sickle cell anemia in an area with Malaria?

Carries on the disease who are heterozygous, have one normal allele and one for the disease, can survive. The allele spread throughout the population and is where genetic diseases are common

How did drought influence the survival of offspring in these finches?

Drought led to severe reduction of seeds available

How does the supergene complex explain the evolution in a single species of Heliconius numata seven morphotypes that mimic seven different species of Melinaeae? How many gene clusters are present?

Each supergene has a segment of DNA in reverse order to the usual sequence 18

Acetylation of Lysine (K) residues in histones facilitates transcription. T or F?

False

Transcription usually occurs when cytosine resides around the promoter are methylated. T or F?

False

Why is there an asymmetry in reproductive success between males and females in many species?

Females usually invest more in their offspring than males do

How do expression levels vary in the genes in Fry's study of snake venom?

Gene duplication and change in enhancer (control) regions led to specific expression

Which of these mechanisms involves differential survival and reproductive success?

Genetic drift

What material did researchers use to study historical genetic diversity in Greater Prairie chickens?

Genetic drift caused them to go through bottlenecks

What factors influence the genetic structure of African elephant populations in Addo National Park in S. Africa and in some isolated populations in Indian Elephants due to hunting?

Hunting and genetic drift can influence sexual dimorphism in elephants

How does stabilizing selection explain optimal number of eggs a bird lays, when fitness implies having as many young as possible?

If the bird lays too little eggs, predators could eat them all and the generation wont be passed, if she lays too many then she might not be able to provide for all of them and they could starve.

What is inbreeding?

In small populations matings between relatives are common

Which is the phenotype that is not selected in disruptive selection?

Intermediate phenotypes are selected against ad extreme phenotypes are favored

Based on Stephen Fry's study of snake venom is it the product of just one gene or many genes? Where does selection act in these genes?

Many genes Selection can operate on many genes that influence a trait

What quantitative measure did scientists show to heterozygote advantage of black wolves in Yellowstone?

Mean fitness

What comparisons did Michael Lynch carry out to study mutation rate? Why is this important?

Natural selection pushes mutation rates down to lower limit set by the power of random genetic drift rather than by physiological limitations.... Results in reduces levels of replications, transcription, translation in eukaryotes relative to prokaryotes

Is Darwin's finches cited as an example for evolution when Darwin initially wrote his "Origin' book?

No. In fact he did not even label them by islands and just briefly mentions finches ( and these are not the finches he was referring to, but he does mention mocking birds).

Can variation be created on demand?

No. Selection works only upon preexisting variation.

Can acquired traits be inherited?

No. The reason why Lamark's explanation for evolution is incorrect.

. If natural selection operates on individuals, why does evolutionary change occur at the population level?

Only populations evolve, not individuals

What is the study of biological evolution all about?

Origin of species - process of speciation

Where would find the highest rate of nt substitutions?

Pseudogenes

Where and what is the role of enhancer sites?

Sites where transcription factors bind.

Describe Dudash's study on inbreeding depression in plants. Where is it the highest and where is it the lowest?

Strongest under natural filed conditions which are likely to be more stressful that the highly controlled conditions of the greenhouse

Which major bone related to flight is absent in Archaeopteryx?

Supracoracoideus muscles (raises wings)

Why is it difficult to trace the very first life that gave arise to all species today?

Swapping of genetic material between bacteria, .i.e., horizontal gene transfer has made it difficult to follow linages.

How does inbreeding depression affect zoo populations and what measures would one take to offset it?

The inbred species are increased by almost more than half

What evidence does he provide to show that these genes were present before the evolution of snakes?

The same gene has variant that produces defensing protein against bacteria in mammals

Why did cheetah cubs show increased infant mortality?

The species has much lower disease resistance than related species, 20-75 cubs die within 6 months of birth

How did they show that individual that survived during the drought period was not just random but natural selection played a significant role in it?

Tribulus cistoides seeds (larger/harder) were the only ones available during the drought. Only large bird with narrow beaks can eat these... only 16% survived. More offspring were produced than survived.

Amino acids residues in histones can be phosphorylated. T or F?

True

Both DNA as well as protein can be methylated. T or F?

True

How did they correlate survival of offspring with variations due to inherited traits?

Variation can be passed on to offspring, distribution of these genetic variation can change across generations

How did MRSA arise?

Variation for the antibiotic resistance was already present, but introduction of the antibiotic resulted in selection for those resistant to it.

What is character displacement?

When two similar species inhabit the same environment

If the Hardy-Weinberg assumptions are met, then after a generation of random mating what will happen to genotype frequencies?

Will remain constant form generation to generation

What is the Hardy-Weinberg formula?

[ p2 + 2pq + q2 = 1]

Define "genetic drift" and explain why it is especially prevalent in small populations.

any change in the allele frequencies in a (small) population that is due to random change. Small populations results from founder or bottleneck events

Methylated amino acids in histones are most likely to be

both arginine and lysine

Alfred Wallace-

came up with a similar explanation to account for biological evolution as Darwin

VRSA

can grow in the presence of vancomycin appeared in people with diabetes

MRSA-

cannot grow in the presence of vancomycin

1. Evolution

change over time, occurs in populations (not individuals)

What kind of selection could lead to speciation events in the short video clip on butterfly we watched in class?

directional selection.. leads to change in phenotype of individuals in certain populations decreeing the # of individuals with the undesirable trait

How did MRSA also become VRSA?

horizontal gene transfer.

Where is the gene for antibiotic resistance?

in plasmids.

Lamarck - Use and disuse theory is incorrect because

of mutations and acquired traits cannot be inherited. He published theory of inheritance of acquired characteristics

Hardy-Weinberg conditions are met:

random mating, no mutation, large populations (no drift), no migration, no natural selection

Synonymous:

(silent) does not change the encoded amino acid '

What are two ways in which fitness can be measured?

- Absolute reproductive fitness: raw number of gene copies or offspring transmitted to the nest generation - Relative reproductive fitness: expressed as a proportion of a reference genotype

What are 4 evolutionary mechanisms that change allele frequencies within populations?

- Mutation: introduced new genetic diversity into the population -Gene flow: gene flow -Genetic drift: random sampling of small populations -Natural selection: only mechanism that results in adaption and leads to increased fitness

What do transcription factors do? -

- aid and activate RNA polymerase to transcribe genes

What other factors influences selection?

- migration: movement of alleles between populations (gene flow) - genetic drift - bottlenecks - inbreeding - sexual selection

What is a "population bottleneck" Give examples of population bottlenecks that reduced genetic diversity?

some individual survive from single population but then population grows large ex - elephant seals, cheetahs, elephants, Florida panthers, Greater Prairie chicken.

How can gene flow be quantified?

telemetry: used to track translocated tortoises paternity analysis: long distance gene dispersal in Ficus

How does inbreeding influence the proportion of heterozygotes? What is the cause (mechanism) of inbreeding depression?

-Increase the proportion of homo and reduces the proportion of hetero -Loss of fitness

Charles Darwin- Two books that influenced Darwin when he was developing the concept of Natural selection:

the naturalist on the HMS Beagle 1. Charles Lyell - Principles of geology (1830-1833) - slow changes over time 2. Thomas Malthus - Essay on Populations (1798)

Where does RNA polymerase bind?

to the Promoter sites on DNA

Nonsynonymous:

usually deleterious but can be selectively neutral or advantageous

Handicap Principle and sexual selection. How is a morphological (or behavioral) feature that is a disadvantage for survival in dimorphic males, enhance their evolutionary fitness?

when individuals differ in their ability to attract mates, type of natural selection due to non-random mating.

How did the Grants' follow the role of natural selection in these birds? What did they measure?

-Wanted to know is evolution occurred as a response to natural selection -The offspring of their survivors Beak depth changed predictably year after year

'mate choice' What would you predict in species such as the sea horse where males provide more parental care than females?

-males provide more parental care -Mutations, dimorphism?

Stabilizing Natural Selection

-occurs when individuals with intermediate traits reproduce more than others -favors average individuals -decreases pop variation over time

Disruptive Natural Selection

-occurs when intermediate phenotypes are selected against, extreme favored -favors individuals that vary in both directions from the mean -maintains variations

Directional Natural Selection

-occurs when natural selection increases frequency of one allele -favors individuals that vary in one direction from the mean -reduces pop diversity over time -Always proceed only in one direction

Darwin's Theory of Natural Selection is based on

1. Populations have a potential to increase exponentially. 2. Populations are fairly constant in size - Logistic growth model (K=carrying capacity) 3. Natural resources are limited 4. variation among individuals in a population and variations are inherited 5. Only some organisms survive and there is a 'struggle' for existence 6. Individuals with favorable variations are more likely to survive and reproduce 7. Accumulation of inheritable variation over many generations is evolution

How is evolutionary change quantified?

A change in the frequency of a heritable trait over time, ex.: change in allele frequency

What was the major abnormality found in the Florida panthers after they were reduced to just six individuals?

Abnormal sperm

What are the assumptions of the Hardy-Weinberg Theorem (model)?

Allows population geneticists to test for a change in allele frequencies.

Voyage of the beagle-

Australia, Africa, Europe, South America (mostly), and Galapagos Islands