Known Questions

Question 1

What is meiotic drive?

Answer 1

Intragenomic conflict, whereby one or more loci within a genome will affect a manipulation of the meiotic process in such a way as to favor the transmission of one or more alleles over another, regardless of its phenotypic expression. More simply, meiotic drive is when one copy of a gene is passed on to offspring more than the expected 50% of the time

Question 2

What is heritability?

Answer 2

An estimate of the degree of variation in a phenotypic trait in a population that is due to genetic variation between individuals in that population.

In other words, the concept of heritability can alternately be expressed in the form of the following question: “What is the proportion of the variation in a given trait within a population that is not explained by the environment or random chance?”

Question 3

What is the equation for broad-sense heritability?

Answer 3

H2= Variance of Genotype/Variance of Phenotype

Question 4

What mechanisms does broad-sense heritability include?

Answer 4

This reflects all the genetic contributions to a population’s phenotypic variance including additive, dominant, and epistatic (multi-genic interactions), as well as maternal and paternal effects, where individuals are directly affected by their parents’ phenotype, such as with milk production in mammals.

Question 5

What is an additive effect? What is additive variance?

Answer 5

The contribution an allele makes to a phenotype that is independent of the identity of the other alleles at the same or different loci.

Differences among individuals in a population that are due to additive effects of genes.

Question 6

What are the genetic components of heritability?

Answer 6

Additive and dominance variance

Question 7

Which is the most important to narrow sense heritability?

Answer 7

Additive, because these are differences due to additive genetic factors, rather than gene interactions as in dominance variation.

Question 8

What are the different hypotheses for instantaneous speciation?

Answer 8

ADD

Question 9

What is more common—autopolyploidy or allopolyploidy? Why?

Answer 9

auto

Question 10

Who developed kin selection?

Answer 10

Darwin - talking about honeybees

Question 11

Who developed the 1:1 sex ratio in animals?

Answer 11

Hamilton, made popular by Fisher

Question 12

Can you describe the 1:1 sex ratio?

Answer 12

If the number of male offspring, for instance, is lower than the female ones, the male offspring have better chances of mating since they are outnumbered by female offspring. This leads to the proliferation of genes that produce male offspring, which in turn improves the sex ratio until it reaches parity.

Question 13

Can you give me an example of not 1:1 sex ratio—like that found in parasitoid wasps?

Answer 13

ADD

Question 14

How many functional genes does the human genome have? How does this compare to plants?

Answer 14

Humans ~20,000 functional genes, 3 billion base pairs

Plants have ~30,000 functional, 135 million base pairs so higher percentage of functional genes

Question 15

What are some ways hybrids are not as fit as their parents (on a genetic level)? (Answer: bad combinations of the two gene pools)?

Answer 15

If parents are from different habitats and offspring has interme

Question 16

If we repeated the process of evolution, would you expect to get the same results? Why or why not?

Answer 16

Probably not, because early life would have been very sensitive to external factors. That mutations and weather events were random, a change in these early conditions would likely have sent life down separate paths. If we repeated the process since the Cambrian, we would be more likely to see similar innovations repeat.

Question 17

You said group selection isn’t as important anymore? Why is that?

Answer 17

Many evolutionary biologists have dismissed group selection because there hasn’t been any evidence that shows the evolution of one trait advanced by selection on a group.

Question 18

Do you think that most mutations are neutral? Why or why not? Could you draw a graph of that with frequency on the y-axis and -, 0, and + values on the x-axis?

Answer 18

Yes, most are neutral because most will be on a piece of non-coding, non-regulatory junk DNA.

Question 19

How do mutations occur?

Answer 19

• gene duplication - unequal crossing over
• mutation in chromosomes or number of chromosomes
• genome mutations - polyploidy (important in plants)

Question 20

Are mutations common?

Answer 20

Mutation rates are low.

Question 21

What is reinforcement?

Answer 21

A process of speciation where natural selection increases the reproductive isolation between two populations of species.

This occurs as a result of selection acting against the production of hybrid individuals of low fitness. The idea was originally developed by Alfred Russel Wallace and is sometimes referred to as the Wallace effect.

Question 22

Why do organisms age?

Answer 22

Because late-acting deleterious mutations are weakly selected against due to lack of reproduction.

Question 23

Where does variation come from?

Answer 23

Genetic variation: differences among genome transferred from parent to offspring

Environmental variation: environment determines which phenotype forms

Genotype-by-Environmental variation: how the environment affects phenotype is heritable

Question 24

Why is heritability important?

Answer 24

Without heritability there would be no evolution, helps predict what will happen in breeding programs.

Question 25

More about selection

Answer 25

ADD

Question 26

What underlies post-zygotic isolation?

Answer 26

• epistasis - WHY?

- incompatibilities between genes

Question 27

Can alleles have no dominance? Why?

Answer 27

Yes, they can have no dominance. ADD

Question 28

When did life on earth start?

Answer 28

3.77 billion years

Question 29

What is Hamilton’s rule?

Answer 29

According to Hamilton’s rule, kin selection causes genes to increase in frequency when the genetic relatedness of a recipient to an actor multiplied by the benefit to the recipient is greater than the reproductive cost to the actor. The rule is difficult to test but studies of red squirrels appear to confirm it.

Hamilton proposed two mechanisms for kin selection. First, kin recognition allows individuals to be able to identify their relatives. Second, in viscous populations, populations in which the movement of organisms from their place of birth is relatively slow, local interactions tend to be among relatives by default. The viscous population mechanism makes kin selection and social cooperation possible in the absence of kin recognition. In this case, nurture kinship, the treatment of individuals as kin as a result of living together, is sufficient for kin selection, given reasonable assumptions about population dispersal rates. Note that kin selection is not the same thing as group selection, where natural selection acts on the group as a whole.

Question 30

When did the Cambrian explosion happen? What was it?

Answer 30

~540 million years ago, when most major animal phyla appeared in the fossil record. It resulted in the divergence of most modern metazoan phyla. The event was accompanied by major diversification of other organisms.

Question 31

Why do you get deleterious mutations?

Answer 31

-

Question 32

Menopause does not exist in our primate relatives, why would females survive so long past reproductive age?

Answer 32

Grandmothers can help collect food and feed children before they are able to feed themselves, enabling mothers to have more children. Without grandmothers present, if a mother gives birth and already has a two-year-old child, the odds of that child surviving are much lower, because unlike other primates, humans aren’t able to feed and take care of themselves immediately after weaning.

Question 33

Why did sexual reproduction evolve when there are so many competing strategies?

Answer 33

advantageous mutations can be combined across lineages