BIO 122 Lecture Notes - Lecture 5: Allele Frequency, Genotype Frequency, Genetic Drift

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15 Apr 2019

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Galapagos finches beak form and body size are heritable. Natural experiments allow researchers to compare treatment groups created by an unplanned change in conditions the grants could test whether natural selection occurred by comparing the population before and after the drought. Large, deep beaks were an adaptation for cracking large fruits and seeds. Alleles that led to the development of deep beaks had increased in frequency. During natural selection, individuals do not change only the population polygenic many genes each exert a relatively small effect does. (reproductive success) Acclimatization occurs when an individual"s phenotype changes in response to changes in the environment the individual"s genotype remains fixed adaptation occurs when the allele frequencies in a population change in response to natural selection. Evolution by natural selection is not goal directed. Evolution is not progressive meaning it does not produce better or more complex organisms. Scientifically, there is no such thing as higher or lower organisms.

Related Questions

Which statement about evolution by natural selection isfalse?

Natural selection allows organisms with higher fitness toreproduce more successfully.

Natural selection favors those traits that confer higherfitness in the environment.

Natural selection is a random change in characteristics of apopulation over generations.

Evolution by natural selection affects populations oforganisms, not individual organisms.

An organism's fitness depends on its _____.

ability to survive and reproduce

ability to swap genetic material with other organisms

physical size

ability to mutate

population

Consider the heavily armored stickleback fish population thatcolonized the lake. If all the individuals in that population weregenetically identical, what do you predict would happen when theycolonized the freshwater lake?

The population would increase, as it has increased foodresources.

The population would evolve through natural selection to bebetter adapted to its environment.

The population would decrease due to more juvenile fish beingeaten.

No answer text provided.

Which of the following are adaptations?

Thicker beaks on finches that allows them to eat large seeds,when large seeds are the most abundant.

Less armor on stickleback fish in freshwater that allows themto grow faster to avoid predation.

More armor on stickleback fish in the ocean that prevents themfrom being eaten by larger predators.

None of the above.

All of the above.

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23.

Peter and Rosemary Grantâs research on Darwinâs finches demonstrated that dry years on the Galapagos Island Daphne Major favored deep beaks in the medium ground finch (Geospiza fortis) and that very wet years favored narrow beaks. In years that were neither wet nor dry (intermediate years), many different types of foods were available, and birds with intermediate beak sizes were favored. Immediately following an intermediate year, average beak size in G. fortis is expected to be

A) narrower than after a wet year and wider than after a dry year.

B) wider than after a wet year and narrower than after a dry year.

C) the same as after a wet year and wider than after a dry year.

D) the same as after a dry year and narrower than after a wet year.

13.

Select the evidence that would support the hypothesis that peppered moths and industrial melanism are an example of evolution by natural selection. Check all that apply.

A) Different color morphs exist naturally in the peppered moth population.

B) The genetic basis of melanism in peppered moths is unknown.

C) Dark moths are recaptured more in polluted areas than light moths.

D) Birds looking for food often miss moths that are the same color as the mothâs background.

Check all of the statements that are supported by studies of artificial selection.

A) Artificial selection shows that evolutionary change can occur over a short time.

B) Artificial selection shows that natural selection is capable of producing major evolutionary change.

C) Artificial selection occurs when humans selectively breed individuals of a species with desirable traits.

D) Artificial selection results only in minor changes within a species.

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Q1. What is the founder effect?

Sampling error that occurs during the establishment of a newpopulation by a small number of migrants.

Strong natural selection acting on the founders of a newpopulation because the environment they are now living in is sodifferent from the environment they came from.

A phenomenon named after William Founder, who observed that toppredators generally have low genetic diversity.

Rapid population growth following a bottleneck.

Q2. The effects of genetic drift are more pronounced in largerpopulations.

True

False

Q3. Inbreeding tends to increase the proportion of homozygousindividuals in a population (i.e. individuals that have two copiesof the same allele).

True

False

Q4. The effective size of a population is:

The size of an idealized randomly-mating population that is notunder selection and has the same heterozygosity as the actualpopulation.

The size of an idealized randomly-mating population that has thesame heterozygosity as the actual population, but does not loseheterozygosity over time.

The size of an idealized randomly-mating population losinghomozygosity at the same rate as the actual population.

The size of an idealized randomly-mating population losingheterozygosity at the same rate as the actual population.

Q5. Which of the following tends to reduce the effective size ofa population?

Check all that apply:

Increasing the population size.

A biased sex ratio.

Non-random mating.

Q6. If gametes from a gene pool combine randomly to make only asmall number of zygotes, the allele frequencies among the zygotesmay be different than they were in the gene pool because:

The effects of natural selection are more pronounced in smallpopulations.

The effects of genetic drift over several generations are morepronounced with small numbers of gametes.

The effects of differences in frequencies for different allelesare more pronounced with small numbers of zygotes.

The effects of sampling error are more pronounced with smallsamples.

Q7. Genetic drift is different from natural selectionbecause:

In natural selection allele frequencies change because somealleles confer higher fitness, whereas in genetic drift allelefrequencies change because of chance sampling error.

Natural selection acts primarily in large populations, whereasgenetic drift acts primarily in small ones.

Natural selection is a mechanism of evolution, whereas geneticdrift is an outcome of evolution.

Natural selection tends to cause rapid evolution, whereasgenetic drift tends to cause slow evolution.

Q8. Imagine a population evolving by genetic drift in which thefrequency of allele K is 0.65. What is the probability that at somepoint in the future allele K will drift to a frequency of 1?

Q9. A dwindling population of 1000 frogs occupies an isolatedwatershed in Costa Rica. To help preserve the species, scientistscaught 20 frogs to start a new population in a nearby watershed.This species has a gene that affects eye shape. The 1000-memberwild population has two alleles for this gene: R and r, withfrequencies 0.7 and 0.3, respectively. What will be the allelefrequencies of R and r in the 20-member founder population?

The frequencies will be 0.7 for R and 0.3 for r.

The frequencies will be 1.0 for R and 0 for r.

The expected frequencies are 0.7 for R and 0.3 for r. The actualfrequencies could be different.

The founder populations's allele frequencies will necessarily bedifferent than the source population's frequencies.

Q10. For a population containing 90 females and 10 males, whatis the effective population size, N_e ?

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BIO 122 Lecture Notes - Lecture 5: Allele Frequency, Genotype Frequency, Genetic Drift

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