Week 5 Launchpad

A good example of vicariance is a: - rise in sea level floods a coastal area and breaks it up into several small islands distant from each other - .change in allele frequencies in two closely related populations that are isolated from each other by a geographic barrier.

- .change in allele frequencies in two closely related populations that are isolated from each other by a geographic barrier.

Indicate whether genetic drift, if it acted alone, could cause changes in the allele frequency(ies) of a population. - Acting alone could change allele frequency. - Acting alone could not change allele frequency.

- Acting alone could change allele frequency.

Indicate whether natural selection, if it acted alone, could cause changes in the allele frequency(ies) of a population. - Acting alone could not change allele frequency. - Acting alone could change allele frequency.

- Acting alone could change allele frequency.

_____ is the gradual emergence of two or more species as a result of the geographic separation of two or more groups of animals of the same species. - Allopatric speciation - Adaptive speciation - Instantaneous speciation - Co-speciation - Sympatric speciation

- Allopatric speciation

Which of the statements are true regarding hybridization? Select all that apply. - Hybridization can result in fertile offspring. - Hybridization involves the transfer of genetic material between members of similar species. - Hybridization occurs in plants more often than in animals. - Hybridization cannot result in the formation of new species. - Natural selection sometimes acts against progeny that results from hybridization.

- Hybridization can result in fertile offspring. - Hybridization involves the transfer of genetic material between members of similar species. - Hybridization occurs in plants more often than in animals. - Natural selection sometimes acts against progeny that results from hybridization.

Which phrase best describes how natural selection results in evolution? - Individuals with particular traits survive better than individuals with other traits. - Individuals with particular traits leave behind more offspring than individuals with other traits. - Weak individuals are eliminated by strong individuals. - Individuals adapt to their environment by undergoing mutations.

- Individuals with particular traits leave behind more offspring than individuals with other traits.

You are an experienced naturalist and biologist and you observe two birds mating that you do not believe are members of the same species. The eggs from this breeding do not hatch, and when you obtain one of the eggs, you find embryonic development stopped not long after fertilization. Which of the conclusions is supported by these observations? - This evidence suggests the two types of birds are a single species. - Pre-zygotic isolation prevented successful production of offspring. - Post-zygotic factors prevented successful production of offspring. - Behavioral isolation prevented successful production of offspring. - Temporal isolation prevented successful production of offspring.

- Post-zygotic factors prevented successful production of offspring.

Sympatric speciation: - whenever hybrids mate with parental species. - occurs whenever a physical barrier between two species is removed (i.e., a river dries up) and the two species start to interbreed. - only occurs in bacteria. - can occur instantaneously through formation of polyploid offspring.

- can occur instantaneously through formation of polyploid offspring.

A deleterious mutation: - increases survival and/or reproduction. - decreases survival and/or reproduction. - does not affect survival or reproduction.

- decreases survival and/or reproduction.

The graph shows the frequency of individuals with a range of fish sizes for generation 1 (black dashed curve) and generation 100 (blue curve). Which mechanism is responsible for the changes in fish size between generation 1 and generation 100? - stabilizing selection - directional selection - Hardy-Weinberg equilibrium - disruptive selection

- directional selection

Over time, in a population, new mutations of a given gene may: - become fixed as the only form of the gene in the population. - disappear, remain at low levels, or become fixed. - disappear from the population. - remain at relatively low levels in the population.

- disappear, remain at low levels, or become fixed.

Speciation has occurred when: - organisms from a single species are separated by a physical barrier. - divergent populations evolve to the point where interbreeding does not produce viable, fertile offspring. - a DNA sequence is changed, resulting in an altered protein product. - mutations in a population reach 100% of the organisms in that population. - an alteration in an organism's genetic material becomes permanent.

- divergent populations evolve to the point where interbreeding does not produce viable, fertile offspring.

A neutral mutation: - increases survival and/or reproduction. - does not affect survival or reproduction. - decreases survival and/or reproduction.

- does not affect survival or reproduction.

The reason that lions, which live in Africa, and tigers, which live in Asia, do not produce ligers (infertile offspring of lions and tigers) in the wild is likely the result of: - an incompatible lock-and-key mechanism between the species. - behavioral isolation of tigers and lions. - temporal isolation of lions and tigers. - both temporal and ecological separation of lions and tigers. - ecological isolation of lions and tigers.

- ecological isolation of lions and tigers.

Which species concept might differentiate species on the basis of specific dietary requirements? - morphospecies concept - phylogenetic species concept - ecological species concept

- ecological species concept

A geologic barrier between two populations of one species can contribute to speciation because of: - similar environmental conditions in the two locations. - increased mutation rates due to separation. - lack of gene flow between populations.

- lack of gene flow between populations.

Imagine a scenario in which a common population of animals is separated into two groups by a natural event. Over time, you might expect the two populations to become ______ genetically similar. This process is known as _____ speciation. - less; allopatric - less; sympatric - more; allopatric - more; sympatric

- less; allopatric

Unlike the biological species concept, the morphospecies concept relies on: - phenotype. - physiology. - behavior. - offspring.

- phenotype.

The relationship between the genotype and allele frequencies of two alleles, A and a, is shown in the graph. At which point are the frequencies of genotypes AA and aa equal? - point B - point D - point C - point E - point A

- point C

In the southwestern desert of the United States there are temporary ponds that form only after heavy summer rains. As a naturalist, you visit these ponds and notice that female frogs mate with males of their own species, which are identified solely by listening to male calls. The lack of mating between species would be an example of _____ and _____. - post-zygotic isolation; temporal separation - pre-zygotic isolation; behavioral isolation - post-zygotic isolation; behavioral isolation - pre-zygotic isolation; temporal separation

- pre-zygotic isolation; behavioral isolation

Two species of frog mate in the same pond. One breeds in early summer and one in late summer. This is an example of what kind of reproductive isolation? - post-zygotic, temporal separation - pre-zygotic, temporal separation - pre-zygotic, ecological separation - post-zygotic, ecological separation - pre-zygotic, behavioral isolation

- pre-zygotic, temporal separation

Group selection is not typically seen as an evolutionarily stable strategy because: - it cannot explain behaviors for species with solitary individuals. - selfish behaviors are more likely to increase individual fitness. - average relatedness is very low among individuals in a population; therefore, individual fitness cannot increase. - None of the other answer options is correct

- selfish behaviors are more likely to increase individual fitness.

In order for the gene pools of two closely related species to remain distinct, there must be: - different selection pressures on each species. - some form of reproductive isolation. - different mutation rates in each species. - a geographic barrier between them.

- some form of reproductive isolation.

Meerkats are small desert mammals that live in groups of 20-50 individuals. You observe one meerkat standing upright on a stump, looking around, while other meerkats forage for food. You hypothesize that this is an example of kin selection. What additional information would you need to know to evaluate your hypothesis? - the body size of this meerkat relative to other members of the group - the degree of genetic relatedness of this meerkat to all members of the group - the foraging success of this meerkat as well as that of all other members of the group - the gender of this meerkat as well as that of all other members of the group all other activities of this meerkat as well as those of all other members of the group-

- the degree of genetic relatedness of this meerkat to all members of the group

While in South America, you come across what you think are two groups of birds in the same location. They are nearly identical aside from their color. After years of observation, you conclude that the birds eat similar diets and share similar behaviors but do not reproduce with each other. These groups of birds appear to be an example of: - a single ecological species. - two different species on the basis of the ecological niche each group occupies - a single biological species. - two different species on the basis of reproductive behavior.

- two different species on the basis of reproductive behavior.

Speciation occurs when: - partial reproductive isolation between two populations is achieved. - two populations become reproductively isolated from one another. - all deleterious mutations have been eliminated from two populations. - any two mutations become fixed differences between two populations. - two populations become physically separated from each other.

- two populations become reproductively isolated from one another.

Refer to Animation: Speciation by Vicariance. Vicariance is defined as: - variation in frequency of mutations among different genes in a population. - when a geographic barrier arises that isolates two populations. - variation in allele frequencies within a population of organisms. - migration to a distant, isolated island resulting in isolated populations.

- when a geographic barrier arises that isolates two populations.

When a mutation is fixed in a population, what percentage of individuals have this mutation? 10% 100% 25% 75% 50%

100%

Which scenario(s) depict allopatric speciation in process? Select all that apply. - Two individuals from different plant species in the same geographic location mate to create a hybrid species that cannot mate with individuals from either of the parent populations. - A small portion of the population on the mainland moves to an island. Over time, the island population genetically diverges from the mainland population. - A mutation appears in several individuals of a population that prevents these members from mating with individuals that lack the mutation. - Humans set up a dam in the middle of a river, splitting a fish population in two. The two resulting fish populations accumulate different sets of mutations over time.

A small portion of the population on the mainland moves to an island. Over time, the island population genetically diverges from the mainland population. Humans set up a dam in the middle of a river, splitting a fish population in two. The two resulting fish populations accumulate different sets of mutations over time.

_____ is a special case of explosive speciation in which new species form rapidly in response to numerous "open" ecological niches. Allopatric speciation Co-speciation Sympatric speciation Adaptive radiation Peripatric speciation

Adaptive radiation

The table lists the number of individuals with genotypes corresponding to fin size in generations 1 through 4 of a fish population. In this species, fin size is determined by two alleles, S and s. Refer to the data in the table to determine which statement describes what happened between generations 1 and 4 of this fish population. - Fin size did not affect the selection of fish mating partners. - An influx of fish with medium fin size entered the population. - No new mutations appeared in the population. - The population remained under Hardy-Weinberg equilibrium

An influx of fish with medium fin size entered the population

Assume population B and population C evolve until they reach adaptive peaks and experience stabilizing selection. Both populations have the same mutation rate. Which population will have less variability in size? Population B Population C Population B & C will be equally variable We don't have enough information to tell

C

When we look at islands across the planet (think about the islands of the Galápagos and Hawaii) we see a remarkable number of island endemic species - species that are found nowhere else. What is a possible explanation for this observation? - Extinction rates are lower in islands so species that have gone extinct elsewhere persist on islands. - Vicariance events are more common on islands than in mainland environments. - Sympatric speciation on islands is easier than in mainland environments because rates of chromosomal evolution are higher on islands. - Island isolation promotes allopatric speciation. - Sympatric speciation on islands is easier than in mainland environments because levels of disruptive selection are higher on islands.

Island isolation promotes allopatric speciation.

_____________ is the primary force responsible for changes in allelic frequency of deleterious mutations. _______________ is the primary force responsible for changes in allelic frequency of neutral mutations. Natural selection; Genetic drift Genetic drift; Natural selection

Natural selection; Genetic drift

A large population of mice (2000 individuals) lived in an area in the desert dominated by small shrubs. When the population size got too high, a small group of 6 individuals left and colonized an area adjacent to the original population's home, but the adjacent area was primarily dominated by trees instead of shrubs. There is no gene flow between the dispersers and the original population. A researcher sequenced the genomes of representative individuals from both populations and found substantial genetic differences between them. Which of the statements would most account for the amount of genetic differences observed? - Divergence between the two populations was caused solely by drift. - Divergence between the two groups is high because of gene flow. - The divergence between populations could only have been caused by stabilizing selection. - Since the original dispersal event, the small population could have accumulated more mutations than the original population.

Since the original dispersal event, the small population could have accumulated more mutations than the original population.

Seven species of snapping shrimp are found on either side of the Isthmus of Panama. What data provides good evidence that this is speciation by vicariance? - The rate of evolution can be calculated because the populations have been separated for about 3 million years. - That it takes about 3 million years for accumulation of enough mutations to result in new species of snapping shrimp. - That populations on opposite sides of the Isthmus are reproductively incompatible. - The DNA of each current species is most similar to that of a species found on the opposite side of the current Isthmus.

The DNA of each current species is most similar to that of a species found on the opposite side of the current Isthmus.

In general, sympatric speciation requires the action of _____ selection acting against hybrids. - - directional - stabilizing - artificial - ecological - disruptive

disruptive

Within a population, several mutations appear, resulting in four alleles, A through D. Consider the graph of allele frequency. Which allele becomes fixed in the population? allele B allele C allele D allele A

allele A

The graph depicts changes in allele frequencies across several generations for four alleles, A through D. Which allele underwent negative selection? allele D allele C allele A allele B

allele D

Different species of fruit flies occupy each of the islands in the Hawaiian island chain, a group of volcanic islands that formed one after the other. One hypothesis for how the different fruit fly species formed is that, after each new island was formed, fruit flies from existing islands colonized it and subsequently diverged. If this hypothesis is correct, it would be an example of: - sympatric speciation by vicariance. - sympatric speciation by dispersal. - peripatric speciation by vicariance. - allopatric speciation by dispersal. - allopatric speciation by vicariance.

allopatric speciation by dispersal.

Two species of antelope ground squirrels are separated by the Grand Canyon. They are hypothesized to have descended from a common ancestor population that was divided when the Grand Canyon formed. If this hypothesis is correct, it would be an example of: allopatric speciation by vicariance. peripatric speciation by vicariance. allopatric speciation by dispersal. sympatric speciation by vicariance. sympatric speciation by dispersal.

allopatric speciation by vicariance.

You are a biologist on a trip to an island in the South Pacific. While there, you are allowed to collect DNA samples from a local species of rat that resembles a species seen on a nearby continent. If your DNA analysis also indicates the two species are closely related, you might conclude that the evolution of the two separate species was an example of _____ through _____. - sympatric speciation; vicariance - allopatric speciation; vicariance - sympatric speciation; dispersal - allopatric speciation; dispersal

allopatric speciation; dispersal

Evidence indicates that a number of finches from Ecuador dispersed to the Galapagos Islands more than 300 miles away and ultimately gave rise to the different species of Galapagos finches that exist today. This is good evidence of speciation by vicariance. true false

false

In general, allopatric species will evolve pre-zygotic isolating mechanisms more rapidly than sympatric species. false true

false

Mutations always result in either an increase or a decrease in an organism's reproductive fitness. false true

false

Refer to Animation: Speciation: Speciation Depends on Random, Inherited Mutations in the Genome. Once a mutation is introduced into a population, it will eventually be passed on until it is found in 100% of the individuals in that population. false true

false

The figure below shows results from a series of observations and experiments on tail length in male African widowbirds. Black bars represent tail lengths manipulated by researchers (they artificially added long feathers to the tails of the experimental birds). Number of active nests is a proxy for estimating the ability of males to attract mates. Consider both graphs when evaluating the statement below the graphs as true or false. The longer a male's tail is, the more likely the male is to survive.

false

You are working with a population of snails. During the mating season, you observe that individuals in the population will only mate with others of the same genotype (for example, Mm individuals will only mate with Mm individuals). There are only two alleles at this locus (M is dominant; m is recessive); you have determined that the frequency of the M allele = 0.4 and that selection acts against homozygous recessive individuals. Consider what will occur in this population over the course of many generations, and evaluate the following statement. Allele frequencies will stay the same, but genotype frequencies will change over time. true false

false

You would expect similar species with a different number of chromosomes to be genetically compatible and, therefore, able to reproduce fertile offspring. false true

false

Most speciation is allopatric because: - disruptive selection between forms of traits in sympatric populations is always very strong. - gene flow between diverging populations is strong in allopatry. - vicariance events are common. - gene flow between populations prevents genetic divergence in sympatry. - related species are always found in allopatry rather than in sympatry.

gene flow between populations prevents genetic divergence in sympatry.

The accumulation of different mutations in genetically separated populations is known as _____ and is the key to speciation. reinforcement intersexual selection genetic divergence reproductive fitness

genetic divergence

New species can form through allopatric or sympatric speciation. Which of the mechanisms will act more strongly on populations that are initially separated in allopatry than on those initially separated in sympatry? - genetic drift - reinforcement - gene flow - disruptive selection

genetic drift

In the animation, fish with a larger body size have a ____________ reproductive fitness than fish with a smaller body size because ____________. higher; they can swim farther distance slower; they cannot access as many different environments higher; they are less vulnerable to predators higher; they are less susceptible to additional mutations lower; they swim more slowly

higher; they are less vulnerable to predators

In some large groups of plants, including dandelions, oaks, and willows, the biological species concept is complicated because the process of _____ allows gene flow to occur between _____ that can be easily distinguished based on appearance. - hybridization; ecological species - allopatric speciation; ring species - hybridization; morphospecies - polyploidy; evolutionary species - polyploidy; ring specie

hybridization; morphospecies

If B = the benefit of a behavior to a recipient, C = the cost of the behavior of the donor, and r = the degree of relatedness between the recipient and donor, then if rB ___ C, altruism can evolve. is less than (<) is greater than (>) equals (=)

is greater than (>)

In the animation, fish with less streamlined fins have a ____________ reproductive fitness than fish with more streamlined fins because ____________. lower; they are less able to escape predators higher; they swim more quickly lower; their ability to acquire food is impaired lower; the increased fin size hinders mating higher; the increased fin size is more likely to attract a mate

lower; they are less able to escape predators

The process by which sympatric speciation might occur would most likely be the result of: natural selection. adaptive radiation. convergent evolution. vicariance.

natural selection.

Which type of mutation does not undergo natural selection in a population? beneficial deleterious neutral

neutral

Which type of mutation is most likely to undergo genetic drift in a population? beneficial deleterious neutral

neutral

The table lists the number of individuals with genotypes coding for blue, red, and green coloration in generation 1 of a fish population in Hardy-Weinberg equilibrium. Fish coloration is determined by two alleles, B and G. p = 0.20, q = 0.80; p^2 = 0.04, 2pq = 0.32, q^2 = 0.64 p = 1.00, q = 0; p2 = 1, 2pq = 0, q2 = 0 p = 0.70, q = 0.30; p2 = 0.49, 2pq = 0.42, q2 = 0.09 p = 0.50, q = 0.50; p2 = 0.25, 2pq = 0.50, q2 = 0.25

p = 0.70, q = 0.30; p2 = 0.49, 2pq = 0.42, q2 = 0.09

Within a species, there is a given trait determined by two alleles. The allele frequencies for these two alleles are represented by p and q. If Hardy-Weinberg conditions are met, which is not a possible genotype frequency? q^2 2pq p^2q^2 p^2

p^2q^2

In a population in Hardy-Weinberg equilibrium, the relationship between the genotype and allele frequencies of two alleles, A and a, are shown in the graph. At which point is 100% of the population exhibiting the recessive phenotype? point D point E point A point C point B

point A

Consider several species with varying population sizes. In which population are the effects of genetic drift most extreme? population size = 400 population size = 4,000 population size = 4 population size = 40

population size = 4

Adaptive radiation is an acceleration of speciation and adaptation when there are a large number of ecological opportunities available. true false

true

Imagine that you had two populations of red-tailed hawks: one with long tail feathers and one with short tail feathers. Mating discrimination in this species could entail either hawks with long tail feathers preferentially mating with other hawks that have long tail feathers, or hawks with short tail feathers preferentially mating with other hawks that have short tail feathers. false true

true

In co-speciation, two groups of organisms speciate in response to each other and in a coordinated manner. true false

true

Mark true (A) or false (B) about the following statement relative to Hamilton's key insight about how natural selection works. Indirect fitness can only be gained by helping kin and not by helping unrelated individuals. True False

true

Speciation can occur in the absence of natural selection; for example, speciation resulting from genetic drift. true false

true

The figure below shows results from a series of observations and experiments on tail length in male African widowbirds. Black bars represent tail lengths manipulated by researchers (they artificially added long feathers to the tails of the experimental birds). Number of active nests is a proxy for estimating the ability of males to attract mates. Consider both graphs when evaluating the statement below the graphs as true or false. Male tail length is subject to both natural and sexual selection in wild populations.

true

The longer two species have been separated, the greater the number of genetic differences between them. true false

true