BIO120H1 Lecture Notes - Lecture 7: Gene Flow, Gamete, Epistasis

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15 Jan 2016

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BIO120H1 Full Course Notes

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Wright saw an important role for population structure and genetic drift in an evolution. Fisher disagreed and argued that most evolution occurred in large populations by natural selection. The north facing slope and south facing slope have different microclimates the facing to the sun. Population: a group of individuals of a single species occupying a given area at the same time (difficult to count) Migration: the movement of individuals from one population to. Gene flow: the movement of genes from one population to another (where the real genetic effect comes) Effects of selection, gene flow and genetic drift on population another divergence. Natural selection and genetic drift are causing population to differentiate through time. Gene flow slows it down and brings the population back together again (population are exchanging genes) When the exchange genes stop (because of boundary or different mating time), it makes the differentiate more likely to happen.

Related Questions

What must occur in order for a new trait to appear in a population and then reach a steady, high frequency within that population?

New traits appear through gene mutations or through genetic drift. In order to reach a steady, high frequency in the population, there must be many mutagens, such as UV radiation, in the environment to produce many mutations.

New traits appear through gene mutations or through genetic drift. In order to reach a steady, high frequency in the population, there must be a consistent source of immigrant individuals with the allele.

New traits appear through gene mutations or through evolution. In order to reach a steady, high frequency in the population, the allele must code for a favorable adaptation.

New traits appear through gene mutations or through gene flow. In order to reach a steady, high frequency in the population, the trait associated with the gene must be favored by either natural or sexual selection.

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Question 5

Which of the following is FALSE:

Natural selection has foresight, and can mold organisms in accordance with environments in the far future. This is why organisms have a good "fit" to their environments long after they have arisen through speciation.

Selection is an undirected process that can only ever work with the materials at hand.

Human beings have foresight because they possess brains that can think about possible outcomes and the consequences of actions. This is different to a process like natural selection.

The fact that natural selection has no foresight does not mean that it is incapable of producing beings that have foresight.

Question 6

The wings of bats, birds and flying insects are examples of:

Convergently evolved traits (at least in terms of their basic functionality).

Homologous traits.

Plesiomorphies.

None of the above.

Question 7

The effect of a trait depends on the environment because:

Organisms decide to change their behavior every so often to evade predators.

It is only ever in the context of an environment that these traits can exist, and whether they assist the organism or inhibit it will depend on the particularities of that environment in which it must interact.

Sexual selection will not tolerate wasteful and extravagant displays.

The environment is changing too fast for the organism to keep up with in terms of its conscious appreciation of it, so it must rely on its traits to do the work.

Question 8

Which of the following is TRUE:

Natural selection is not random; mutation is random; speciation is necessarily driven by natural selection.

Natural selection is not random; mutation is random; speciation is not necessarily driven by natural selection.

Natural selection is random; drift is random; speciation is not necessarily driven by natural selection.

Natural selection is not random; mutation is random; speciation must occur through the evolution of pre-zygotic barriers to mating.

Question 9

Heritability is:

The same as inheritance.

Another way of stating the degree to which a trait is genetic (for example, you could say that the color of your skin is "80 percent genetic and 20 percent environmental")

The proportion of variance of a trait in a population that is attributable to genetic variance in that population.

Present in populations, but not necessary for evolution by natural selection.

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44.Why donât similar genotypes always produce the same phenotype?

A. Parent alter their phenotype and pass on this phenotype to progeny

B. Phenotype is the product of many environmental influences

C. Genetic variations of ADH enzyme produce the same phenotype

D. Animals display different phenotypes dependent on diet, not genotype

46.Which of the following attributes has the least effect on the contribution an individual makes to the gene pool of the next generation?

A. spas of mating privileges

B. more efficient at obtaining food

C. produces more offspring

D. camouflage from predators

47.âUntil the agricultural evolution 10,000 years ago, people used to live in small populations with little gene flow between them. That is the best situation for rapid evolution.â said Sewall Wright. one of the founders of population genetics. This conclusion on gene flow conflicts with Hardy Weinberg equilibrium, which states that no gene flow means

A. natural selection

B. no evolution

C. no random mating

D. no genetic drift

58 Larval flies (maggots) express the Ubx gene in all of their segments, and thereby lack appendages. If this same gene continued to be expressed throughout subsequent developmental stages, except in the head region, and if the result was a fit, sexually mature organism that still strongly resembled a maggot, this would be an example of

A. homochrony

B. exaptation

C. paedomorphosis.

D. adaptive radiation

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BIO120H1 Lecture Notes - Lecture 7: Gene Flow, Gamete, Epistasis

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