BIOL 309 Lecture Notes - Lecture 6: Red Queen Hypothesis, Mutational Meltdown, Mutation Rate

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coralchimpanzee997

19 Nov 2018

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Harmful mutations can be eliminated from the population more quickly: in asexual populations, harmful mutations just accumulate and accumulate until the lineage collapses (mutational meltdown, two hypotheses are not exclusive!!! In sexual populations, cannot reproduce as much offspring, but they are of higher. Quality >>>> quantity: in the experiments involving the four different strains of yeast (slides 6-12 on 9-17- Sex provided no advantage in the permissive environment where beneficial mutations were rare. In the stressful environments, the yeast was going through constant adaptations because they were not adapted to the environment. This led to the production of beneficial and harmful mutations. In the stressful environment all the beneficial mutations were spread through sexual reproduction (red queen hypothesis). In placental mammals, females have xx chromosomes; whereas, males have xy chromosomes. Under light microscopy, the condensed x chromosome of the females can be seen, and this is known as a barr body (the inactivated chromosome).

Related Questions

Need help with evolution questions:

1.) A haplotype is best defined as the ________________.

	haploid genotypes of all the gametes produced by a diploid individual

ABO blood type conferred by an individual gamete

genotype of either the paternal or maternal chromosomal complement

multilocus genotype of a chromosome or gamete

2.) Which of the following statements regarding linkage disequilibrium is true?

Exists when D is less than zero, but not when it is greater than zero.

Is reduced by sexual reproduction.

Is increased by crossing-over during meiosis.

Is increased by any random sampling error that happens to create or destroy certain chromosome genotypes but not others.

Is reduced by selection that favors certain combinations of genotypes.

3.) Selection on multilocus genotypes in random-mating populations leads to linkage disequilibrium when _______________.

it reduces mutation rates

it eliminates all haplotypes from the population

it prevents crossing-over during meiosis

some allele combinations confer greater fitness than do others

4.) When two loci are in linkage equilibrium, the allele carried on a chromosome at one locus is independent of the allele carried on the chromosome at another locus. When this is the case, _________________.

allele frequencies will not change over time

the two loci (or, more specifically, their protein products) do not interact

the frequency of each haplotype can be calculated by multiplying the frequency of its two alleles

all possible haplotypes occur at equal frequency

5.) Which of the following accurately characterize(s) Muller's ratchet model for the selective advantage of sexual reproduction?

Drift establishes linkage disequilibrium because multilocus genotypes with few mutations are eliminated by chance events.

In populations without sexual reproduction, deleterious mutations accumulate, eventually imposing such a burden that the population goes extinct.

Sex is favored selectively because it recreates the zero-mutation genotypes lost due to drift.

All of the above correctly characterize Muller's ratchet model for the evolution of sexual reproduction.

6.) The genetic signature of recent positive selection on a locus is _______________.

high frequency and low linkage disequilibrium

low frequency and low linkage disequilibrium

low frequency and high linkage disequilibrium

high frequency and high linkage disequilibrium

7.) Sexual reproduction is advantageous both in changing environments and in constant environments, compared to asexual reproduction.

True

False

8.) Sexual reproduction causes genetic recombination via crossing-over, which combines genotypes from different parents.

True

False

9.) One reason sex may be maintained in natural populations is proposed by the "Red Queen Hypothesis", which states that.....

genotypes created by sex are created by natural selection over and over

recombination creating novel genotypes that can resist infection by parasites

mutation load is reduced by novel adaptive mutations

the ability of sex to fix multiple

As temperatures in an African savanna increase and rainfall decreases, it would most likely change into

tiaga

desert

tropical rainforest

temperate forest

What is imprinting? Give an example.

fixed assocation, such as hatching ducks recognizing the first animal they see as their mother

a learned behavior, such as a wasp circling during a search for food, so that it can return to its nest

alteration of instinct, such as a spider changing the type of web it weaves depending upon the environment

Opportunistic species

provide extensive care for their offspring

produce many offspring

reproduce later in life

What are the five agents of microevolution?

gamete production; mating; fertilization; caring for offspring; formation of herds

photosynthesis; respiration; mitosis; meiosis; fertilization

mutation; gene flow; nonrandom mating; genetic drift; natural selection

Microevolution is

new species

minor extinction of species

changes in allele frequency in a population

Which of the following is does not help defend against predators?

Toxins made by plants that injure caterpillars feeding on the plant

The large eyespots on a moth's wing that can startle a hungry bird

Thorns on a plant

Many plants have brightly colored fruit and flowers

Humans have a favored birth weight, neither too small nor too large. This is

stabilizing selection

disruptive selection

artificial selection

directional selection

What is a keystone species?

the first organism that populates an area

an organism upon which the entire ecosystem depends

the first fossils found in the earliest rock strata

As temperatures in the Arctic warm, which of the following changes may occur?

Tundra will be replaced by taiga

Taiga will be replaced by tundra

Temperate forest will be replaced by taiga

Tundra will be replaced by desert

Taiga will be replaced by temperate rain forest

What is desertification?

restoration of vegetation and water to deserts

areas adjacent to deserts also become deserts

abandonment of a habitat by animals

Evolution occurs at the level of

individuals

populations

communities

The maximum population that the environment can support is called the

biotic potential

environmental resistance

carrying capacity

replacement reproduction

demographic transition

A population with relatively more pre-reproductive individuals is common in _____-developed countries

less

Endangered species sometimes breed in captivity. Why are such species endangered in the wild?

Their population density is too high

Loss of habitat

Their environment is polluted

Abiotic components of an ecosystem include

only animal life

only plant life

living components only

nonliving components only

both living and nonliving components

Carbon returns to the atmosphere

as carbon dioxide

from respiration of plants

by the burning of fossil fuels

from respiration of animals

All of the answer choices are correct

Why does the Tropical Rain Forest contain an abundance of antibiotic compounds?

The area is crowded, leading to random production of useful compounds

The area is wet. plants had to develop resistance to fungi and bacterial infections

There is a great diversity of plants, leading to random production of useful compounds

The carrying capacity of the environment for a species is determined by

the reproductive rate of the organism

the number of organisms of that species

the state and national wildlife laws pertaining to that species

a complex

the limited productivity of the environment and the environmental resistance to the biotic potential of the organism

An introduced species that breeds and spreads is

resourceful

harmful

native

dominant

invasive

What is disruptive selection?

environmental influences that select against change

environmental influences that promote one phenotype versus all others

environmental influences that promote two or more phenotypes versus all others

Natural selection acts on

individuals

populations

communities

Two populations of birds live in the same area but have different sleep/wake cycles. This is

behavorial isolation

mechanical isolation

geographical isolation

temporal isolation

An insect that resembles the face of a snake avoids predation by

camouflage

warning coloration

mimicry

chemical defense

mutualism

Unselfish acts that help others in a group so that they increase their chances of surviving and reproducing is called

imprinting

mimicry

altruism

learning

instinct

If an environment changes rapidly, organisms with ____ will be more likely to survive and reproduce.

the correct allele frequency

existing neutral mutations

existing beneficial mutations

How did geology influence Darwinâs thoughts?

It demonstrated that the earth was very old, therefore there was enough time for species to evolve

it demonstrated that all continents were similar

it demonstrated the presence of many fossils

The founder effect occurs when

large groups of individuals leave their home population and establish new settlements, mating only among themselves

many members of a population die, resulting in a great loss of genetic diversity

many members of a population reproduce causing too much genetic diversity within the population

small groups of individuals leave their home population and establish new settlements, mating only among themselves.

The greenhouse effect is due to high atmospheric

Nitrogen

Ammonia

Carbon monoxide

Carbon dioxide

Oxygen

What are the Reproductive Barriers that keep species separate?

lack of food; lack of habitat; lack of potential mates; lack of nesting sites; lack of genetic variation

mountains; canyons; glaciers; bodies of water (for terrestrial animals); areas of land (for aquatic animals)

habitat isolation; temporal isolation; behavioral isolation; mechanical isolation; gamete isolation

What is directional selection?

environmental influences that select against change

environmental influences that promote one phenotype versus all others

environmental influences that promote two or more phenotypes versus all others

Which of the following is correct when describing a predator-prey cycle?

A decline in the numbers of predators causes a decline in the number of prey

A decline in the numbers of prey causes a decline in the number of predators

An increase in the number of predators triggers an increase in the number of prey

An up-and-down cycle will be seen for the prey animal

A seasonal die-off that will occur without the other species present

Why are top-level predators (lions, eagles, humans) so rare in a community?

Only a small amount of the energy is passed from one trophic level to the next

They do not breed as fast as other animals

Because of predation by higher predators

It is difficult for them to learn how to capture prey

Their job is to keep the population size of other animals in check

Alleles conferring bright color to male guppies are common because

they make males less visible to predators

they help males identify each other

they are preferred by females

Organisms that obtain their energy from producers or other consumers are

autotroph

heterotroph

producer

autotroph and producer

heterotroph and producer

What is the environmental impact of strip mining?

lack of trees exposes the surface of the earth, promoting runoff and loss of adjacent trees

removal of minerals from the soil hampers growth of vegetation

it causes a potential increase in volcanic activity

Two populations of squirrels are separated by a mountain range and would not be capable of interbreeding. This is an example of:

behavorial isolation

mechanical isolation

geographical isolation

temporal isolation

What is a danger of overfishing?

humans will become dependent upon fish

selection for smarter fish that can avoid being caught

driving the population back into the lag phase

What is meant by prezygotic versus postzygotic speciation mechanisms?

before versus after formation of a zygote

before versus after meiosis

before versus after gamete formation

The relatively short term changes in allele frequencies within a species or population is

artificial selection

microevolution.

speciation

macroevolution

Avoidance of a location with predators is the result of

imprinting

mimicry

altruism

learning

instinct

What is the difference between Density-Dependent and Density-Independent Factors on populations?

density-dependent factors exert a greater influence when there are more individuals; density-independent exerts the same influence on all individuals regardless of their number

density-dependent factors exert a greater influence on larger, more dense individuals; density-independent factors exert the same impact on individuals of all size

density-dependent factors exert the same influence on all individuals regardless of their number; density-independent factors exert a greater influence when there are more individuals regardless of their number

All of the organisms in a given location or area is termed a

peer group

flock

community

population

herd

The concentration of the pesticide DDT would be highest in

a minnow

a mosquito larva

a seagull

plankton

algae

Our biosphere is

the Earth

the atmosphere

the ocean

land on Earth

fresh and salt water

What is meant by âcarrying capacityâ?

the amount of food produced in an ecosystem

the extent of energy required to maintain an ecosystem

the number of individuals that can be supported by an ecosystem

Species living on another is

resource partitioning

coevolution

symbiosis

predation

niche sharing

One species feeding on another is

competition

a community

an ecosystem

predation

symbiosis

Populations of different species interacting with one another in a natural environment is called

competition

a community

a biome

predation

symbiosis

Which of the following is not a biogeochemical cycle?

ATP cycle

water cycle

carbon cycle

phosphorus cycle

nitrogen cycle

Horses became larger and faster to escape predators. This is

stabilizing selection

disruptive selection

artificial selection

directional selection

Tasmanian devils (Sarcophilus harrisii), the worldâs largest carnivorous marsupials, are facing extinction. Not from hunting, or habitat loss, but from within; a transmissible cancerous derivative of Schwann cells, responsible for devil facial tumour disease (DFTD). First seen in 1996, the disease has spread widely though the population, and is now estimated to be present in 80% of the population. With the grim prognosis of ~100% mortality in 12-18 months, animals that once went through multiple breeding cycles are now lucky to reproduce once before death, resulting in a 70% decline in their population over the past decade. The cancer is transmitted by biting (a common ritual used by these animals to establish and maintain social position), with cancer cells from one animal (the biter) being implanted in the wound inflicted on the other animal. Equally common in both sexes, the disease itself is more prevalent in animals higher on the social scale, presumably reflecting higher levels of social interaction (biting). The cancer is usually first evident as facial tumors, from which metastasis to cervical lymph nodes occurs, often followed by dissemination to other organ systems. Cause of death is by organ failure or by malnutrition in those with facial tumors large enough to prevent feeding. Based on what we have covered regarding the Major Histocompatibility Complex, you would expect the passage of a cancer from one individual to another* to be a rare event (to see just how rare, read the accompanying popular press piece from the New York Times). Here are some things that you already know: *Yes, some viruses can cause cancer (example: Hepatitis B virus and liver cancer), and you can transmit a virus from one individual to another; but that is not the same thing as passing the cancer itself. v Almost all nucleated cells express high levels of class I MHC proteins on their surface. v Class I MHC proteins collect peptides produced from endogenous proteins and display them at the cell surface. v Different Class I MHC proteins bind and display different peptides. v Developing cytotoxic T-cells that recognize self-antigens are eliminated. v Mature cytotoxic T-cells conduct surveillance by scanning the peptides displayed by class I MHC proteins. v Mature cytotoxic T-cells that recognize an antigen on a cell will kill that cell (recall that cytotoxic T cell activity is important in rejection of tissue transplants).

Before the questions:
v Tasmanian Devils are not immunosuppressed.
v Tasmanian Devil cytotoxic T-cells are not broken, they can kill cells.
So neither of those should be part of your answers.
This is an ongoing research topic with large gaps in our knowledge; we really donât fully understand how this works
and so there is no âcorrectâ answer. Your job is to provide a logical argument, with some research and details to
support your contention. Note that in questions 1 & 2 class I MHC should be part of your answer, but not in
question 3.

Questions:
1.) Acquiring DFTD is basically like receiving a transplant that is not rejected. How can that be? Suggest a possible
way this could occur. Be sure to explain why you think this would work, and then explain how you would test
that model to determine if it were correct. (10 point question).
2.) Canine Transmissible Venereal Tumor (CTVT) is the other know transmissible cancer in mammals. Unlike
DFTD, CTVT does not usually result in death. Do a little research on this disease and summarize how it is
different from DFTD. Provide an explanation as to why one is lethal and the other is generally not. (10 point
question).
3.) Recently, researchers at Washington State University determined that some Tasmanian devils had developed
resistance to this cancer. By scanning partial genome sequences of resistant and susceptible animals (a
complete devil genome has yet to be assembled) they identified a set of genes where mutations appeared to
enhance resistance. Speculate as to the function of the proteins these genes encode, and explain why that
might provide for resistance (note: they were NOT MHC genes).

Mainly need guidance/ideas for #1's 1 and 3!

BIOL 309 Lecture Notes - Lecture 6: Red Queen Hypothesis, Mutational Meltdown, Mutation Rate

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