LS7b week 5

what is inclusive fitness

direct fitness and indirect fitness

A deleterious mutation: a. decreases survival and/or reproduction. b. does not affect survival or reproduction. c. increases survival and/or reproduction

a. decreases survival and/or reproduction.

T or F: In general, allopatric species will evolve pre-zygotic isolating mechanisms more rapidly than sympatric species.

false

what are sympatric populations

speciation occurs when populations are in the same geographical location

T or F: Hamilton's rule helps us predict when we'll see "kindness" among genetic relatives

true

what equation describes when altruism occurs (Hamilton's rule) and what does each variable stand for

rB>C -r= degree of relatedness (between 0-1) -B= benefits of the behavior (how many individuals does this save) - C= cost of the behavior (how many offsprings lost)

what two things lead to speciation

reproductive isolation and genetic divergence

what is reinforcement

selection against hyrbidizing behavior between individuals from diverging populations It is selection in favor of enhanced prezygotic isolation to prevent the production of inferior hybrid offspring

what are allopatric populations

separated geographically - requires separation and time for mutations to occur

What has occurred if population is not in HWE

nonrandom mating or evolution

what are 5 examples of prezygotic isolation

- behaviorally isolated: mate based on specific behaviors - gametic isolation: incompatibilities between the gametes of 2 different species - mechanical incompatibility: structural configuration of genitalia prevents mating - temporal isolation: when individuals are reproductively active at different times - geographical/ecological isolation

what are the limitations to the BSC

- classifying asexual species: asexual reproduction doesn't involve interbreeding - classifying fossil species: differences in size and shape of fossil bones cannot reveal whether there was reproductive isolation between the individuals from which the bones came - determining when one species has changed into another: there is rarely a definitive moment marking the transition from one species to another - classifying ring species: two non-interbreeding populations may be connected to each other by gene flow through another population, so there is no exact point where one species stops and the other begins - classifying hybridizing species: hybridization sometimes occurs and produces fertile offspring, suggesting that the borders between the species are not clear cut

what is the relatedness between a parent and offspring (0-1)

0.5

in sympatric populations for speciation to occur , natural selection ____ gene flow

>

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

a. Acting alone could change allele frequency.

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

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

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? a. The DNA of each current species is most similar to that of a species found on the opposite side of the current Isthmus. b. The rate of evolution can be calculated because the populations have been separated for about 3 million years. c. That populations on opposite sides of the Isthmus are reproductively incompatible. d. That it takes about 3 million years for accumulation of enough mutations to result in new species of snapping shrimp.

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

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

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

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

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

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? a. genetic drift b. reinforcement c. gene flow d. disruptive selection

a. genetic drift When populations are initially separated, it is not likely that allele frequencies in each sub-population will be identical to the original population before it was divided.

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

a. natural selection.

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? a. p2q2 b. q2 c. 2pq d. p2

a. p2q2

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

a. some form of reproductive isolation.

reinforcement can _______ speciation

accelerate

______ 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

Which scenario(s) depict allopatric speciation in process? Select all that apply. a. 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. b. A small portion of the population on the mainland moves to an island. Over time, the island population genetically diverges from the mainland population. c. A mutation appears in several individuals of a population that prevents these members from mating with individuals that lack the mutation. d. 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.

b. A small portion of the population on the mainland moves to an island. Over time, the island population genetically diverges from the mainland population. d. 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.

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

b. Acting alone could change allele frequency.

___________ 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. a. Genetic drift; Natural selection b. Natural selection; Genetic drift

b. Natural selection; Genetic drift

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

b. can occur instantaneously through formation of polyploid offspring. When chromosome numbers change in a single generation, it can be considered an instantaneous speciation event. The polyploidy individuals cannot mate with either parent species because the chromosome number in cells that are the product of meiosis cannot pair with gametes from either parent species. This renders them immediately reproductively isolated.

A neutral mutation: a. increases survival and/or reproduction. b. does not affect survival or reproduction. c. decreases survival and/or reproduction.

b. does not affect survival or reproduction.

Which species concept might differentiate species on the basis of specific dietary requirements? a. phylogenetic species concept b. ecological species concept c. morphospecies concept

b. ecological species concept

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

b. genetic divergence

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

b. population size = 4

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? a. pre-zygotic, ecological separation b. pre-zygotic, temporal separation c. pre-zygotic, behavioral isolation d. post-zygotic, temporal separation e. post-zygotic, ecological separation

b. pre-zygotic, temporal separation The two species of frog described in the question mate at different times of the year. Hence, the females of each species are only able to mate at the species' specific time, so they are temporally isolated form one another. Because there is no chance for them to mate with an individual of the other species, no zygote will form and this is pre-zygotic isolation.

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

c. Adaptive radiation

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? a. Vicariance events are more common on islands than in mainland environments. b. Extinction rates are lower in islands so species that have gone extinct elsewhere persist on islands. c. Island isolation promotes allopatric speciation. d. Sympatric speciation on islands is easier than in mainland environments because levels of disruptive selection are higher on islands. e. Sympatric speciation on islands is easier than in mainland environments because rates of chromosomal evolution are higher on islands

c. Island isolation promotes allopatric speciation.

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 _____. a. sympatric speciation; dispersal b. sympatric speciation; vicariance c. allopatric speciation; dispersal d. allopatric speciation; vicariance

c. allopatric speciation; dispersal Close relatedness would indicate that one may have arisen from the other. If some mainland individuals dispersed to the island and genetic differences accumulated, it would lead to speciation.

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: a. temporal isolation of lions and tigers. b. behavioral isolation of tigers and lions. c. ecological isolation of lions and tigers. d. both temporal and ecological separation of lions and tigers. e. an incompatible lock-and-key mechanism between the species

c. ecological isolation of lions and tigers.

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

c. 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. a. more; allopatric b. less; sympatric c. less; allopatric d. more; sympatric

c. less; allopatric There would be no gene flow between the separated populations. Unique mutations would accumulate in each population and they would increase the genetic differentiation between the two divided populations.

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

c. selfish behaviors are more likely to increase individual fitness.

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

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

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? a. Divergence between the two populations was caused solely by drift. b. The divergence between populations could only have been caused by stabilizing selection. c. Divergence between the two groups is high because of gene flow. d. Since the original dispersal event, the small population could have accumulated more mutations than the original population.

d. Since the original dispersal event, the small population could have accumulated more mutations than the original population. Drift may have had an initial impact on differences in allele frequencies. Natural selection could select for mutations that affect fitness in the tree dominated habitat of the dispersers.

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: a. sympatric speciation by dispersal. b. sympatric speciation by vicariance. c. peripatric speciation by vicariance. d. allopatric speciation by dispersal. e. allopatric speciation by vicariance.

d. allopatric speciation by dispersal. Sympatric or peripatric speciation did not occur in this case because the speciation events happened on multiple islands. The fly populations are separated by the water between the islands, so they occur in allopatry. The speciation event was not the result of vicariance because the formation of the island, through volcanic activity, did not divide the original population into two.

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: a. peripatric speciation by vicariance. b. sympatric speciation by vicariance. c. allopatric speciation by dispersal. d. allopatric speciation by vicariance. e. sympatric speciation by dispersal.

d. allopatric speciation by vicariance. The formation of the Grand Canyon is a vicariant event that resulted in separating one large population into two smaller populations.

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

d. gene flow between populations prevents genetic divergence in sympatry.

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 _____. a. pre-zygotic isolation; temporal separation b. post-zygotic isolation; behavioral isolation c. post-zygotic isolation; temporal separation d. pre-zygotic isolation; behavioral isolation

d. pre-zygotic isolation; behavioral isolation

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. a single biological species. b. a single ecological species. c. two different species on the basis of the ecological niche each group occupies. d. two different species on the basis of reproductive behavior.

d. two different species on the basis of reproductive behavior. The situation states that there is no interbreeding between the two species. This is a condition of the biological species concept. If they were the same species, then it would be expected that the two groups would interbreed.

what are the two ways an allele can increase its "market share"

direct fitness: increase the number of offspring I produce indirect fitness: increase the number of offspring my kin produce.

In general, sympatric speciation requires the action of _____ selection acting against hybrids.

disruptive

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? a. This evidence suggests the two types of birds are a single species. b. Behavioral isolation prevented successful production of offspring. c. Temporal isolation prevented successful production of offspring. d. Pre-zygotic isolation prevented successful production of offspring. e. Post-zygotic factors prevented successful production of offspring.

e. Post-zygotic factors prevented successful production of offspring. Fertilization occurred, but the zygote did not develop into a viable offspring. Pre-zygotic isolating mechanisms prevent fertilization. Since fertilization occurred, but there are not viable offspring, this would be a post-zygotic isolating mechanism

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. a. polyploidy; ring species b. hybridization; ecological species c. polyploidy; evolutionary species d. allopatric speciation; ring species e. hybridization; morphospecies

e. hybridization; morphospecies

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? a. all other activities of this meerkat as well as those of all other members of the group b. the foraging success of this meerkat as well as that of all other members of the group c. the gender of this meerkat as well as that of all other members of the group d. the body size of this meerkat relative to other members of the group e. the degree of genetic relatedness of this meerkat to all members of the group

e. the degree of genetic relatedness of this meerkat to all members of the group If this behavior is related to kin selection, knowing how related the individual is to other members of the group would help evaluate your hypothesis. If the individual is unrelated to all other individuals in the group, then it would not be due to kin selection.

what is the phylogenetic species concept

emphasizes that members of a species all share a common ancestry and a common fate -useful when thinking about asexual species

T or F: 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.

false

T or F: 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.

false

T or F: my kin don't carry many of my alleles

false

T or F: over time, the frequency of a dominant allele gradually increases

false

T or F: species are distinct biological entities with dependent evolutionary trajectories

false : they have independent evolutionary trajectories

T or F: You would expect similar species with a different number of chromosomes to be genetically compatible and, therefore, able to reproduce fertile offspring.

false: Fertilization may occur when these two species mate, but the zygote cannot develop normally. The chromosomes cannot accurately undergo separation between daughter cells during meiosis.

T or F: gene flow has to be stronger than natural selection to counteract the homogenizing effect

false: natural selection must act strongly to counteract the homogenizing effect of gene flow

what does a flat and steep fitness curve indicate about the variation

flat: more variation steep: more sensitive so less variation

We say that the population is in HWE if the _________ frequencies are the _______ in each generation

genotype; same that means that no evolution occurred

hybridization

interbreeding between 2 different varieties or species

what is post zygotic isolation

isolating factors that cause the failure of the fertilized egg to develop into a fertile individual

what is prezygotic isolation

isolating factors that prevent the fertilization of an egg

When "r" in Hamilton's rule is _______, cooperation becomes extreme

large - especially in inbred species

The more _______ related, the ______ extreme the genetic incompatibility

more; less

What type of mutation does not undergo natural selection in a population

neutral

Which type of mutation is most likely to undergo genetic drift in a population

neutral

Unlike the biological species concept, the morphospecies concept relies on

phenotype

what are two ways reproductive isolation can occur

pre-zygotic and post zygotic isolating factors

what causes postzygotic isolation

the genetic dissimilarity between 2 organisms, such as different number of chromosomes.

what is the ecological species concept

the idea that there is a one-to-one correspondence between a species and its niche

T or F: Adaptive radiation is an acceleration of speciation and adaptation when there are a large number of ecological opportunities available.

true

T or F: 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.

true

T or F: In co-speciation, two groups of organisms speciate in response to each other and in a coordinated manner.

true

T or F: Indirect fitness can only be gained by helping kin and not by helping unrelated individuals.

true

T or F: Speciation can occur in the absence of natural selection; for example, speciation resulting from genetic drift

true

T or F: The longer two species have been separated, the greater the number of genetic differences between them.

true

T or F: when looking at fitness curves, the steeper it is, the faster it reaches the peak

true

what is the biological species concept

way of defining species: species are groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups

what does vicariance mean

when a geographical barrier arises within a single population, separating it into 2 or more isolated populations

what does dispersal mean

when some individuals colonize a distant place away from main population