BIS 2B Final Study Questions

What is the evidence that natural selection favors the evolution of leg length in cane toads as they expand their range in Australia? If you wanted your toads to win a race, where would you collect them?

"Offspring reared in a common environment exhibited similar geographical divergences in morphology as did wild-caught animals, suggesting a genetic basis to the changes. Limb dimensions showed significant heritability (2-17%), consistent with the possibility of an evolved response. Cane toad populations thus have undergone a major shift in sexual dimorphism in relative limb lengths during their brief (81 years) spread through tropical Australia."

From an evolutionary perspective, which of the following is the most appropriate level for measuring genetic variation: (1) the cell; (2) the individual; (3) the population; (4) the community; (5) the ecosystem Why did you choose the answer that you did?

(3) the population because it takes in account all species living in that environment. It is not an individual because that would not take in account for variation of the population. It is no the cell because it does not make up the entire individual (also cells mutate). It is not the community because that takes in account for more than one species (will have too much genetic variation because of vastly different ancestries). It is not the ecosystem because... yah no

Net Reproductive Rate

(R0) = average number of offspring produced by an individual during its entire lifetime. The product of survival and fecundity, summed over all age classes

Explain why application of the biological species concept is difficult or impossible in each of the following situations: (a) examples of natural hybridization, (b) the existence of strictly asexual organisms, and (c) disjunct (allopatric) distributions of species.

(a): the mating of two genetically different populations make it hard to tell if the offspring produced will be relatively fit and fertile. (horse + zebra , wolves + coyotes) (b): because asexual organisms do not reproduce with other individuals it is impossible to apply the biological species concept. (c): allopatric species rarely breed with one another due to the isolation of breeding units.

The main problem with understanding how genes responsible for reproductive isolation could increase in frequency is... a) such genes would reduce the fitness of an individual that carries them. b) such genes would rapidly spread due to sexual selection. c) genetic drift would immediately eliminate them from a population. d) hybrids carrying these genes would be competitively superior to parental genotypes. e) none of the above.

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A population of peppered moths has the following genotypic frequencies: aa: 0.16, Aa: 0.04, AA: 0.80. The frequency of the 'a' allele in this population is... [show your work for full credit]

0.18 The five conditions required for a Hardy-Weinberg equilibrium are: 1. No mutation 2. Random Mating 3. No gene flow (i.e. no immigration or emigration) 4. Large population size (genetic drift does not affect allelic frequencies) 5. No selection (i.e., no advantage to individuals carrying particular alleles or genotypes at a locus)

Describe the intermediate disturbance hypothesis (IDH) and use this hypothesis to predict how diversity will change throughout the course of succession.

1. Facilitation: Ulva could modify the environment to make it more suitable for Gigartina 2. Inhibition: Ulva may be excluding Gigartina but is removed by biotic or abiotic stresses 3. Tolerance: Gigartina is slower growing, and it just takes it longer to dominate the community.

Which of the following is most likely to occur in populations that are reduced to a very small number of breeding individuals? Choose one answer from each pair: 1 a) Variation in genotypes and phenotypes is likely to increase, relative to the amount of variation in the original population, OR b) Variation in genotypes and phenotypes is likely to decrease, relative to the amount of variation in the original population. 2 a) Genotypes and phenotypes are likely to occur at the same frequencies as they did in the original populations, OR b) Genotypes and phenotypes are likely to occur at different frequencies than in the original population. 3 a) The probability of extinction would probably be similar for the reduced population than for a similar population with large numbers of breeding individuals, OR b) The probability of extinction over a specified period of time (say 104 years) would probably be higher

1. b 2. b 3. b

Explain how each of the following factors affect local species diversity. Provide an example to illustrate your answer. A. Foundation species B. Productivity (resource availability) C. Habitat complexity D. Competition E. Keystone predators F. Disturbance

A. Foundation Species will always make the community less diverse B. Resource availability will lead to organisms either dying or adapting to fit the fundamental niche of the environment C. Habitat complexity will lead to much more diversity (ex. rainforests) D. Competition will push organisms to occupy different niches promoting diversity (beak size) E. A classic keystone species is a predator that prevents a particular herbivorous species from eliminating dominant plant species F. Disturbance commonly destroys diversity (ex. forest fires)

If an adult male has the genotype AABbcc, list all the possible sperm genotypes that could be produced by this male.

ABc, Abc

Why do most evolutionary biologists agree that allopatric speciation is common but sympatric speciation is not? Focus your discussion on the fundamental difference between these two alternatives, and why that difference is likely to be important for divergence and the evolution of reproductive isolation.

Allopatric: the splitting of species into two or more repoductivly isolated groups due to a geological barrier or change making it impossible to interact. Sympatric: the splitting of an ancestral species into two or more reproductively isolated groups without geographical isolation of those groups. Most biologist will agree with this because sympatric speciation is very rare in nature as it requires the species to behaviorally isolate themselves from one another to the point where they are genetically different.

Using Hamilton's Rule (rB>C = rB-C>0)), explain the evolutionary reasoning underlying J. B. S. Haldane's famous quote, "I would lay down my life for two brothers or eight cousins."

Altruistic Trait. Relationships have value in relation to your own genetic make up meaning, it will take two brothers to make up for my lack of reproductive success and eight cousins to make up for my lack of reproductive success. "When relatedness is high, benefit to the recipient is high, and cost to the actor is low, then natural selection should strongly favor individuals that help their kin."

The ability to recognize kin may promote the evolution of altruistic traits. What is an altruistic trait? What is the evolutionary rationale for this argument?

An altruistic trait is a behavioral trait that compromises ones own reproductive success for a relatives. The evolutionary rational for this is that the relative will pass on the same genetics that they have so it will have the same effect.

Sympatric speciation is generally thought to be a rare event because sympatry should promote gene flow. Explain clearly the evidence that speciation occurred sympatrically in the crater lake cichlid fish inhabiting Barombi Mbo in Cameroon. In particular, explain how the phylogenetic relationships of the 11 species of cichlids in this lake support the argument for sympatric speciation. How does this contrast with the phylogenetic evidence for vicariant allopatric speciation in snapping shrimp?

Based on lecture it was said that sympatric speciation within the lake following a singe initial colonization of the lake shows how green species migrates into the lake and then the green species gives rise to the blue species and so on. Genetic variants w/i a population use specific microhabitats or consume diff prey that select for diff traits. 4 speciation of cichlids must have been sympatric because daughter species equally speciated, meaning that the majority of divergent lake species came from a single river ancestor.

What is the basic difference between intersexual and intrasexual selection? Give examples of each mode. Can you imagine an example in which both modes of sexual selection operate?

Before copulation, intrasexual selection - usually between males - may take the form of male-to-male combat (giraffes). Also, intersexual selection, or mate choice, occurs when females choose between male mates. (humans, peacocks)

If a budgerigar (a little bird) with the genotype YY (green feathers) is crossed with a budgerigar with the genotype yy (blue feathers), the offspring all have green feathers. In what ways are these two examples (see previous slide) similar? How are they different?

Both examples have homozygote genotyped parents, one with dominate and one with recessive. In this situation one of the alleles exemplify complete dominance in its phenotype. In the other example, there are also two phenotypes presented by the parents but neither of them are expressed completely, instead a new phenotype is created.

What is ecological character displacement and explain how it can result in low niche overlap between similar competing species?

Character displacement occurs when similar species that live in the same geographical region and occupy similar niches differentiate in order to minimize niche overlap and avoid competitive exclusion.

What are the characteristics of typical early successional species and late successional species? Describe the tradeoffs that make it difficult for species to thrive in both early and late successional communities.

Early successional species: dominant species in early stages of succession - characteristics: high growth rates, small in size, high degree of dispersal, high rates of population growth - often require or tolerate high light and tolerant of dry conditions Late successional species: dominant species in late stages - characteristics: low growth rate, larger in size, lower degree of dispersal, lower rates of population growth - often shade tolerant and prefer moist conditions - sugar maple is an example

Describe how tradeoffs can allow species to coexist even if they use the same resources and one is a vastly superior competitor to the other. Offer a plausible example (there are many possible examples if you look back at your notes from lectures on tradeoffs).

Ex: Resource partitioning- species of bumblebees specialized in flying in different altitudes. They also have shorter and longer proboscis (thing used to get nectar from flowers) and can use the same resources in the same niche. Trade-offs are the energy it takes to fly at different heights. Ex: Barnacles and Chthalamus; Although Balanus are better competitors than Chthalamus. they can coexist because of their tradeoffs. Chthalamus is a poor competitor but can withstand stress better (being dried out during low tides) and Balanus is an efficient competitor, therefore, allowing it to live over a broad range but is more sensitive to desiccation (extreme dryness).

Explain the difference between exploitative and interference competition and give an example of each.

Exploitive competition is when individuals use the same resources but don't come in contact with each other. This is most common between species such as deer and squirrels competing for acorns. Interference competition is when direct contact between individuals competing for the same resource. This is most common with in a species such as red winged blackbird competing for nesting grounds.

Name and describe the three "models" or "mechanisms" of succession. B. Be able to relate an example of succession in a real community and explain how successional change in that community is determined by one or more of these mechanisms.

Facilitation: when pioneer species is needed for colonization of habitat by modifying environment (Ex: Alder trees fix nitrogen in soil, improving conditions for the growth of spruces). Inhibition: when pioneer species inhibits subsequent colonization of habitat by making environment less suitable (Protection) Tolerance: Early-successional species neither increase nor reduce rates of recruitment and growth of later-successional species. Species sequence is solely a function of life history. Late-successional species arrive, then grow slowly Late-successional spp. are able to grow and reproduce despite the presence of early- successional spp. Succession: Predictable changes in community composition through time.

Age specific fecundity

Fecundity (Mx) - average number of offspring produced by individual of age x

Historically, the population of California Condors probably numbered in the thousands of birds. However, because of human use of pesticides, hunting, and habitat destruction, the population declined to no more than 13 individuals. Now, thanks to captive breeding, re-introduction programs, pesticide control, and habitat preservation, the population is increasing in size. What would you predict would be the primary difference in numbers of alleles per locus and allelic frequencies in the pre-historic versus modern (recovered) populations of condors? What effect caused the change? What HW assumption is being broken due to this? If the California Condors choose to mate on the basis of tail length, which assumption of Hardy-Weinberg equilibrium would be violated?

Founders effect will occur leading to less diversity in allelic frequency. High population size is being violated. Random mating would be violated.

Distinguish between the fundamental and realized niche.

Fundamental niche is the entire set of conditions under which an animal (population, species) can survive and reproduce itself. Realized niche is the set of conditions actually used by given animal (pop, species), after interactions with other species (predation and especially competition) have been taken into account.

Define the following terms: genotype; homozygote; phenotype; dominant; gene; recessive; pleiotropy; epistasis; locus; heterozygote; allele.

Genotype: combination of alleles Homozygote: Same alleles Phenotype: how the gene is expressed Dominant: Controls the other allele within the genotype to express a specific phenotype Gene: Genetic make up of a trait that is heritable Recessive: is irrelevant when placed with a dominate allele in a heterozygote genotype. Pleiotropy: Locus affects more than a single trait epistasis: phenotypic expression of one gene is influenced by another gene; multi locus control of a phenotype expression Locus: the location on the chromosome where a gene is found heterozygote: a genotype that has the dominant allele and the recessive allele (Aa) Allele: a version of a gene. There are many versions of a gene, but a diploid will only ever have up to two versions.

Explain the concept of herd immunity and explain why different fractions of the population must be immune in order to achieve herd immunity for different diseases.

Herd immunity - the resistance to the spread of a contagious disease within a population as many individuals are immune. Different fractions of the populations must be immune because it will even out immunity and disease won't shred through particular communities when resources are available.

How will species diversity change when you increase the average supply rate of available resources vs. increasing the variation in resource types or amounts? Provide one example to support your reasoning in each case.

Increasing mean amount: Adding resources decreases diversity. More biomass; fewer species. Furthermore, the species that already used those resources effectively will continue to do so. So merely increasing the mean amount of available resources will just aid the growth and prominence of the already successful species. "Increased nutrients leads to higher productivity and biomass, but decreased diversity and increased dominance" increasing variation in resource types: Increasing the variation of resources might create more niches on which species can specialize.

How does intraspecific competition contribute to stabilization of predator-prey cycles? Or, put another way, how could intraspecific competition actually PREVENT a prey species from going extinct?

Infraspecific competition actually helps a population because the competition between individuals keeps the population in check. Without this competition, the resources could be completely consumed causing the population to overshoot their carrying capacity. Then once their resources are gone, the population is at risk of extinction.

How does natural selection versus genetic drift act to promote the evolution of intrinsic barriers to gene exchange in allopatric (both vicariance and peripatric/dispersal modes) versus parapatric versus sympatric models of speciation? (What is an intrinsic barrier to genetic exchange, and how does it differ from an extrinsic barrier?)

Intrinsic barriers are circumstances such as behavioral isolation or the infertility of two species offspring. Extrinsic barriers are physical barriers that separate two species from each other and prevents genetic exchange.

How is genetic variation introduced into natural populations? How do recombination, segregation, independent assortment, and fertilization affect patterns of genetic variation?

It is introduced into natural populations via mutation. Recombination is the processing of crossing over during meiosis between the different homologs of the mother and father produces new combinations of alleles at different loci. Segregation ensures that the alleles on the homolog will be assigned randomly to each gamete. Independent assortment follows the same principle. Both of which establish the presence of randomness thus variation. The beginning of this process of meiosis first stems from the inherent mismatching of genes by fertilization whereby half of the offspring's genes come from the mother and the other from the father.

Define monophyletic, paraphyletic, and polyphyletic clades/taxa

Monophyletic: a taxonomic group (relative level of a group of organisms in a taxonomic hierarchy) that includes all of the taxa species descended from a specific common ancestor. Paraphyletic: A taxonomic group that excludes some of the descendants from a specific common ancestor Polyphyletic: A taxonomic group that does not contain the most recent common ancestor of its members

An unfertilized chicken egg contains 39 chromosomes. In this species, N = _____________ and 2N = ____________. Cells taken from a chicken feather have _________ chromosomes.

N=39, 2N=78, 78 chromosomes

Why might natural selection favor variants of a disease that are LESS virulent? Describe one example of this phenomenon.

Natural selection could favor a disease less virulent because it will be easier to transmit. It is a trade off. Covid-19.

Imagine a population of birds living on an island near the mainland. If 6 birds from the mainland join the island population, which assumption of the Hardy-Weinberg model will be violated?

No gene flow/ migration

Post-zygotic

Postzygotic isolation prevents the formation of fertile offspring

Pre-zygotic

Prezygotic isolation prevents the fertilization of eggs

What is the difference between quantitative (or polygenic traits) and mendelian traits? Give examples of each.

Quantitative genetics: deals with continuous phenotypic variation in traits, controlled by many genes, appear to change gradually (have a "normal" curve)- height Mendelian genetics: deals with discontinuous (discrete) traits, controlled by one or a few genes, they appear to change rapidly from mutation- hair color

Explain the difference between r and Ro. Under which values of each is population growth positive, negative, and zero?

R is the population rate over time. R0 is the average number of offspring produced by an individual during its entire lifetime. If R0>1, the population is growing. R0<1 the population is decreasing. If R0=1, the population is remaining constant.

What are the characteristics of species with "r" and "K" selected life histories? What are the characteristics of environments that are likely to favor each type? Why do you think these two groups were given the names "r" and "K"?

R selected species have a high intrinsic rate of population growth. They have a large number of offspring with little parental care. K selected species have traits that are favored when the population is nearing capacity. They have a large investment in few offspring, reproduce continuously. They have their names because r selected species grow quickly (like exponential growth) and K selected species are species that have survived lots and are chosen to be a part of the environment when the population nears K.

List the genotypes of all the different gametes that could be formed by an individual with the genotype RrSsTt.

RST, RsT, Rst, RSt, rST, rSt, rst, rsT

What is recombination and how does it work? Is it the same thing as crossing-over? If an organism practiced self-fertilization, could recombination occur? If an organism practiced self-fertilization, would all of its offspring be genetically identical? Why/why not?

Recombination is the product of crossing-over. If the organism is heterozygous for a gene then yes recombination can occur. No, because if they are heterozygous for a certain gene then recombination can occur and the offspring can be different.

How many different possible egg genotypes could be made by a female with the genotype RRssTt?

RsT, Rst

Explain the rationale for the evolution of sterile female workers in social Hymenoptera. Can you use the same reasoning to explain why young acorn woodpeckers often help their parents rear offspring, rather than reproduce themselves? Can you use the same reasoning to explain the human demographic transition?

Some individuals in a population serve a different purpose other than increasing the overall net population. For example helping guild a stronger gene pool by selective breeding a queen will produce a stronger hive. Woodpeckers that help their parents rear offspring indicates their value as future potential mates will increase as well as the number of individuals available for breeding. The same goes for humans, by choosing when and how many children to have, humans are providing as many resources as they can to their offspring. Furthermore, by helping their families be successful, they are ensuring future benefits perhaps via inheritance or good health habits or even a positive representation of them selves for future mates.

Give a simple genetic definition of evolution. How does this differ from a purely phenotypic definition of evolution?

The change in allelic and genotypic frequencies of a population over a long period of time. This is different than the phenotypic definition because that takes in account for environment and relative fitness of a population.

What is the competitive exclusion principle? What general condition must be met for two potential competitors to avoid competitive exclusion (i.e. to coexist)?

The competitive exclusion principle says that two species can't coexist if they occupy exactly the same niche (competing for identical resources). Two species whose niches overlap may evolve by natural selection to have more distinct niches, resulting in resource partitioning.

Many textbooks imply that the reason Irish elk, in which males had enormous antlers (spanning nearly 3 m), became extinct is that the males simply could no longer haul around such large ornaments without collapsing. What is the flaw in this argument?

The flaw is that the elk with too large of antlers will not be able to reproduce because they would die before being able to pass on the trait. The trait of enormously large antlers will not be fit if the body size of the elk did not increase to hold up the weight.

Identify the four fundamental processes that dictate whether a population is growing or declining, and define an open versus closed population in terms of these processes.

The four fundamental processes that dictate whether a population is growing and declining are births, deaths, immigrants, and emigrants. If a population is closed, it does not account for immigrants and emigrants.

Why have island archipelagoes played such an important role in the development of the science of speciation? What lessons have we learned from studies of speciation in places like the Hawaiian or Galápagos Islands?

They have played an important role in the development of speciation because they are isolated from other climates allowing them to allopatrically diverge from one another despite being on the same island. Founder effects and diversifying selection are important for the evolution of new species within an island.

As far as we know, natural selection cannot adapt organisms to future changes in the selective regime. Yet, many organisms exhibit responses in advance of natural events. For example, geese migrate south from the summer breeding grounds long before the weather changes. How can these "anticipatory" behaviors have evolved?

Those geese that don't anticipate the weather changes, will either die from the cold or from starvation or will start migrating too late and will encounter bad weather and die. If you die, you can't pass on your alleles.

In nature, there is never truly random mating, populations are finite, individuals carry genes from population to population, mutations occur, and natural selection acts. Why, then, does it make any sense for evolutionary biologists to use the H-W model, which is based on a set of assumptions that are generally false?

To estimate the allele frequencies to tell if the population is evolving.

In terms of genetic control, what is the basic difference between traits that exhibit continuous variation versus discrete variation?

Traits that exhibit continuous variation: multiple alleles/genes contribute to the development of the phenotypic trait; there isn't one or two concrete options for the trait, there are many different possibilities; creates a normal, smooth bell curve distribution. Traits that exhibit discrete variation are controlled by one or two loci, not multiple

In terms of Mendel's discoveries about inheritance, how is possible for two individuals to have different genotypes and the same phenotype? How could two individuals have the same genotype, but different phenotypes?

Two individuals could have two different genotypes but the same phenotype if the genotype is heterozygous and homozygous (Xx or XX) because the dominate allele is still in control. Phenotypes are also affected by the environment they are exposed to

Age specific survivorship

Type 1: low mortality until the later stages of life (mammals) Type 2: probability of surviving until the next year is independent of age (birds) Type 3: high juvenile mortality but low adult mortality (insects, plants)

Explain why positive interactions play a prominent role under "stressful" conditions.

Under stressful conditions, positive interactions can help mitigate the effects of those negative interactions. These interactions are not preformed in an attempt to help the other species but because without them, their survival is threatened. These interactions can also help shape the size of the fundamental niche. Furthermore, studies show that these types of positive interactions increase as the stress level increases

Offer 2 possible ways to reduce disease spread that both involve decreasing the number of susceptible organisms in the population.

Vaccination and herd immunity

How does vaccination reduce disease frequency and how can small decreases in the number of people being vaccinated lead to large changes in the extent of outbreaks of the disease?

Vaccines help the organism who is vaccinated develop an immune response to the disease before it has it. Mutations can occur more easily if people do not get vaccinated.

Compare and contrast the processes that drive cycles of measles outbreaks (or other infectious diseases) with cycles of predator-prey as in the lynx-hare example from lecture.

When the disease persists in the prey population and the predators have a sufficient feeding efficiency to survive, the disease also persists in the predator population. The spread begins to spread faster in both creating a positive feedback loop.

Explain how a finite availability of resources can produce density dependent population growth. What other factors can cause density dependence?

With limited resources it is common for a population to stop reproducing as much because the environment cannot support as many individuals and death will occur more frequently. Disease is also a great example of a density dependent factor.

What is the biological species concept, and what are its main criteria for defining a species?

a group of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups. Contains breeding units (Populations, gene pools, etc.) "species are breeding units that are evolutionarily independent from other breeding units."

A population of cats has the following genotypic frequencies at a locus controlling spotting pattern: ss: 0.36, Ss: 0.04, SS: 0.60. (a) The frequency of the S allele in this population is___________ [show your work for full credit] (b) Is this population in Hardy-Weinberg equilibrium? [show your work for full credit]

a) .62 b)no- genotypic frequency of population is not expected

You know that a population of elk has 2 alleles, E and e, at a single locus that controls the color of a rump patch. The frequency of allele E, p(E) = 0.10 in the parental generation. In the offspring of this parental generation, the genotypic frequencies are EE = 0.01, Ee = 0.18, and ee = 0.81. You suspect that... a) the population is in Hardy-Weinberg equilibrium. b) elk are mating with close relatives. c) the elk are preferentially mating with individuals with the same color patch. d) heterozygotes have lower relative fitness than ee genotypes. e) ee genotypes have higher relative fitness than other genotypes.

a) HW equilibrium prove p(E) is still equal to 0.10 p(E)(offspring)= 0.01+1/2(0.18) = 0.10 therefore no evolution so HW equilibrium is consistant.

What do you expect will happen to means and variances of phenotypes in a population subject to the following kinds of selection? Be sure to be able to show diagrammatically how the distribution of normally distributed trait will change after being subjected to each of these kinds of selection. Make sure you understand the relationship between a fitness and response function for stabilizing selection, directional selection, and disruptive selection. Give examples of each. a) Stabilizing selection b) Disruptive, or diversifying, selection c) Directional selection d) Heterosis e) Frequency-dependent selection

a) Stabilizing selection - population genotypic frequencies will favor the average example: height b) Disruptive, or diversifying, selection- Favors the extreme example: beak size c) Directional selection - Leans in favor towards a trait d) Heterosis - the improved or increased function of any biological quality in a hybrid offspring; An offspring exhibits heterosis if its traits are enhanced as a result of mixing the genetic contributions of its parents. example mule e) Frequency-dependent selection - Depending on how many individuals have a trait, the population size of the other trait will react in response to that example: fish with different facing mouths

Give two examples of phenotypic traits controlled by multiple (more than two) alleles: a) b)

a) eye color b) height + skin, hair color and blood type

The ancestors of modern saguaro cacti did not have long and sharp spines. Consider the first ancestor of saguaro cacti to grow spines that were as long and sharp as the spines on saguaro cacti living in Arizona today. Why did this cactus grow such sharp spines? a) It was fortunate a genetic mistake gave it extra sharp spines. b) The cactus needed sharper spines to stop animals from eating it. c) Animals chewing on the cactus caused it to grow sharper spines. d) Mutations changed the DNA of this cacti because it was injured by an herbivore. e) Spines allow the cactus to use C3 photosynthesis.

a) it was a fortunate genetic mistake that led to the success of the cactus and allowed it to reproduce.

You carefully study adjacent populations of two very similar meadow mice, one from Woodland (about 15 km north of Davis), the other from Davis. You want to know whether the Woodland and Davis populations belong to the same biological species or to two different species. You could most confidently decide this if you could... a) show that where the ranges of the two mice overlap there is no hybridization. b) bring the two types of mice into the laboratory to see if they will mate. c) demonstrate that the natural ranges of the two types of mice are entirely allopatric. d) show that there are statistically significant coat color differences between the two types. e) show that the Woodland mice prefer to eat meat, but the Davis mice prefer to eat tofu.

a) show that where the ranges of the two mice overlap there is no hybridization.

All else being equal, according to kin selection theory, which of the following represents the order in which you should be willing to help another individual with respect to its degree of relatedness to you? a) your identical twin, your full-sibling, your parents, your grandparents, your 2nd cousin b) your full-sibling, your parents, your identical twin, your 2nd cousin, your grandparents c) your 2nd cousin, your grandparents, your parents, your full-sibling, your identical twin d) your parents, your grandparents, your full-sibling, your identical twin, your 2nd cousin e) You should never help another individual unless it directly benefits you

a) your identical twin, your full-sibling, your parents, your grandparents, your 2nd cousin

When a gene has several different versions that create slightly different gene products, each version of the gene is called an ______________.

allele

Life table

an age-specific summary of the survival pattern of a population

In the lynx-hare example we discussed in class, explain how changes in predator abundance over time is both a cause and a consequence of the abundance of prey. You need not be able to reproduce the equations, but you should be able to take a graph of predator and prey abundance and explain carefully what causes each population to go up or down in size over time.

as the number of prey increase, the predator abundance increases as food supplies increase, as the number of prey decrease, as does the number of predators as food becomes more scarce; it is possible for predators to drive their prey to extinction

During the time period when saguaro cacti were evolving to their current form, there were years with very little rain. What likely happened to the saguaro cacti during the driest years? a) Some of the saguaro cacti managed to obtain the water they needed. b) Saguaro cacti with the shortest roots were more likely to die. c) Some of the saguaro cacti survived with less water than normal. d) Some of the saguaro cacti grew longer roots. e) None of the above is true. f) a) - d) are all true.

b)

Every individual plant and animal is affected by the environment during its lifetime. For example, a tree will grow slanted if it lives on a windy ridge. What role did the responses of individuals to their hot and dry environment play in the evolution of waxy "skin" among saguaro cacti? a) The environment caused mutations in individuals for waxy skin. b) Individuals with mutations for waxier skin left more surviving offspring than those with genes for less waxy skin. c) Wax can be used as an energy source during stressful conditions. d) Humans could use the wax to make candles, and so they used artificial selection to breed waxier cactus for the gardens.

b)

Saguaro cacti produce fruits that contain thousands of seeds. These seeds are often eaten by birds. When a seed is eaten, it passes through the bird's digestive system unharmed and falls to the ground. If a seed lands in suitable soil, escapes being eaten by mice, and receives enough rainfall during the first years of its life, it may eventually grow into a seedling. Which of the following is the best description of what influences whether saguaro cacti produce seedlings? a) The production and survival of seedlings is purely a matter of chance. b) Chance plays a big role, but the characteristics of individual cacti are also important. c) The production and survival of seedlings is not influenced by chance.

b)

What might you conclude from the observation that the bones in your arm and hand are similar to the bones that make up a bat's wing? a) The bones in the bat's wing are vestigial structures, no longer useful as "arm" bones. b) The bones in a bat's wing are homologous to your arm and hand bones. c) Bats and humans evolved in the same geographic area. d) Bats lost their opposable digits during the course of evolution. e) Our ancestors could fly.

b)

Which of the following represents a major obstacle to the evolution of altruism? a) Close association of kin. b) The presence of genetically based traits that cause selfish behavior. c) The ability to help relatives produce more offspring than they could on their own. d) The existence of sterile castes of workers in social insects. e) All of the above are obstacles.

b)

A population of plants has 2 alleles, P and p, at a locus controlling petal color: f(P) = 0.60 and f(p) = 0.4. When you study the frequency of heterozygotes in the population you find that f(Pp) = 0.24. This would be expected if... a) the population is in Hardy-Weinberg equilibrium. b) the plants self-fertilize. c) the population has gone through a bottleneck. d) heterozygotes are fitter than homozygotes. e) the P allele is dominant to the p allele.

b) Expected is .48 but because of imperfect inbreeding the value is halved

A moth has three alleles at a locus that controls antenna color: X1, X2 and X3. X1 is dominant to X2 and X3; X1 produces red antennae. X2 is co-dominant to X3; X2X2 produces yellow antennae, X3X3 produces white antennae, and X2X3 produces light yellow antennae. The phenotypic frequencies in a population are as follows: 0.04 WHITE 0.16 LIGHT YELLOW 0.16 YELLOW 0.64 RED Þ Assuming that this population is in Hardy-Weinberg equilibrium, what is the frequency of the X3 allele in this population? a) 0.04 b) 0.20 c) 0.16 d) 0.32 e) 0.64

b) 0.20

If a female has the genotype AABbCc, what is the probability that any one of her gametes will have the genotype ABC? a) 1/2 b) 1/4 c) 1/8 d) 1/16 e) 1

b) 1/4

Which of the following processes is LEAST likely to change ALLELIC frequencies? Why or why not? a) Inbreeding b) Mutation c) Genetic Drift d) Gene Flow e) Directional Selection

b) Mutation because of how rare it is to occur and most mutations are recessive

Imagine a population of frogs with 2 color morphs (forms); green (genotypes Gg and GG) and yellow (genotype gg). The population is initially in Hardy-Weinberg equilibrium. Then, frogs begin to mate assortatively for color. After one generation of positive assortative mating, you would expect to observe a change in... a) the number of eggs laid. b) the genotypic frequencies. c) the population size. d) the number of offspring produced. e) all of the above.

b) genotypic frequencies

Which of the following is the best description of how saguaro cacti evolved to have long roots? a) Saguaro cacti needed to develop longer roots to survive in the desert. b) Mutations occurred because the climate of Arizona and Mexico was hot. c) Saguaros with short roots produced fewer seeds each year than saguaros with longer roots. d) Each generation of saguaro cacti worked hard to grow roots as long as possible, and so their offspring had longer roots, too. e) Changes like this depend on many factors, so it is impossible to answer.

c)

If the frequency of the C allele is 0.2 in a population with only 2 alleles at this locus, what will the frequency of heterozygotes be if the population is in Hardy-Weinberg equilibrium? a) 0.04 b) 0.16 c) 0.32 d) 0.64 e) 0.80

c) 0.32 Calculate the 2(pq) value to find the frequency of heterozygotes.

One of the major eye color loci in humans has 2 alleles, b and B. The frequency of the bb genotype is 0.36. If the population is in Hardy-Weinberg equilibrium, the frequency of the B allele should be... a) 0.04 b) 0.18 c) 0.40 d) 0.60 e) 0.64

c) 0.40

Why do most evolutionary biologists agree that allopatric speciation is common, but sympatric speciation is rarer? a) Because reproductive isolation CANNOT evolve in sympatry. b) Because sympatric species cannot occupy separate niches. c) Because there is no extrinsic barrier to gene flow in sympatry. d) Because inbreeding is too common in sympatry and populations go extinct. e) Because disruptive selection can only act on allopatric populations.

c) Because there is no extrinsic barrier to gene flow in sympatry.

If chickens with black feathers are crossed with chickens with white-splashed feathers, the F1 generation has gray feathers. This is an example of ... a) overdominance b) Mendel's second law c) incomplete dominance d) the law of segregation e) independent assortment

c) incomplete dominance

Explain how it is possible for a cross between two plants, one with red flowers and one with white flowers, to produce all pink-flowered offspring, when a cross between two pink-flowered plants produces pink-, white- and red-flowered offspring.

codominance; one flower (lets say red) is dominant homozygous for color, while white is homozygous recessive. When they are crosses, they yield heterozygotes that exhibit codominance. The heterozygous offspring, if crossed, yield the original homozygous dominant and recessive phenotypes

Recombination can only occur between two (or more) _______________, ___________ of which is/are _______________. a) locuses; one; homozygous b) loci; both; heterozygous c) locata; both; heterozygous d) loci, one; heterozygous e) locis; both; heterozygous

d)

Which of the following statements is NOT true about allele frequencies? a) The sum of all allele frequencies at a locus is 1. b) If there are two alleles at a locus, and we know the frequency of one of them, we can obtain the frequency of the other by subtraction. c) If an allele is absent from a population, its frequency is 0. d) If two populations have the same alleles, they will have the same allelic frequencies. e) If there is only one allele at a locus, its frequency is 1.

d) If two populations have the same alleles, they will have the same allelic frequencies.

Natural selection that preserves mean phenotypic values for a trait is called... a) unidirectional selection. b) bidirectional selection. c) correcting selection. d) stabilizing selection. e) sexual selection.

d) Stabilizing selection

Two species of wild lettuce grow sympatrically, but one flowers in the early spring, and the other flowers in the summer. This is an example of... a) post-zygotic reproductive isolation b) gametic incompatibility c) behavioral isolation d) temporal isolation e) reinforcement f) hybrid incompatibility

d) temporal isolation

You measure the allele frequencies in the parental generation of a cheetah population, and find that f(A) is 0.6. There are only two alleles at this locus. In the next generation of cheetahs you find the following genotype frequencies: f(AA) = 0.36, f(Aa) = 0.48, f(aa) = 0.16. Which assumption of Hardy-Weinberg equilibrium is likely being violated? a) random mating b) large population size c) no advantage to particular alleles d) b and c e) none of the assumptions is violated

e) none

In a natural population of 1252 wild radish plants at the UC Davis airport, you notice that there are two flower colors, red and white. You breed the plants in the lab, and show that flower color is controlled by a single gene with two alleles. The red allele is dominant to the white allele. You go back out to the airport and notice that both honeybees and bumblebees pollinate the radish flowers. The bumblebees primarily visit white-flowered plants, but sometimes visit red-flowered plants also. The honeybees primarily visit red-flowered plants, but sometimes visit white-flowered plants. You are asked to estimate the genotypic and allelic frequencies at the flower color locus in the Airport population. You need to do this accurately and efficiently, you should... a) count only red-flowered plants. b) count only white-flowered plants. c) count both red-flowered and white-flowered plants. d) count the num

e) none of the above because we are not given sufficient information to efficiently calculate the frequencies. Population is not in HW equilibrium...

You are interested in the inheritance of body color (the B-locus) and wing shape (the W locus) in house flies (NOT fruit flies). At the body color locus, the B-allele (gray body) is dominant to the b-allele (black body). At the wing shape locus, the W-allele (normal wings) is dominant to the w-allele (vestigial, or shriveled wings). You perform the following dihybrid cross between two flies, one of which has a gray body and normal wings (genotype: BbWw), the other of which has a black body and vestigial wings (bbww). In the F1's, you observe the following genotype frequencies: BbWw: 103 bbww: 115 Bbww: 111 bbWw: 114 The simplest interpretation of these data is that... a) the body color locus and the wing shape locus have epistatic effects. b) Mendel's 2nd law of independent assortment is somehow violated. c) the body color locus and the wing shape locus have pleiotropic effects. d) the parents are h

e) the body color locus and the wing shape locus assort independently.

Our local land snail comes in two basic colors: brown-striped and black-striped. Color is determined by alleles at a single locus, where the black allele is dominant to the brown allele. Last week, you collected 1000 snails from your garden in Davis: 64% of these snails were brown, and 36% were black. Based on these data, you conclude that the frequency of the black allele in your garden population is... a) 0.40 b) 0.60 c) 0.20 d) 0.80 e) You can't tell from the information given.

e) you cannot tell because we are not given the percentage of heterozygote to homozygote dominant

The allele responsible for the peculiar markings of Siamese cats is also responsible for crossed-eyes and excessive meowing that occur in many members of this breed. This example best illustrates which of the following general principles: a) quantitative genetics b) heterozygote advantage c) pleiotropy d) the law of segregation e) codominance f) linkage g) a and c h) a, b, and d

g) a and c (quantitative genetics and pleiotrophy)

At which level of biological organization is it most appropriate to use the term "adaptation": individuals, populations, species, communities? Why did you choose your answer? Does it matter whether you define adaptation as a process or a state of being?

individuals because Adaptation is a process (by which changes in the relative frequencies of different phenotypes and genotypes in a population accumulate)

A population of a marine snail at Bodega Bay has 4 alleles at a locus that controls shell color. Each genotype expresses a unique color. What is the maximum number of phenotypes in the population? a) 4 b) 6 c) 10 d) 64 e) 256

n(n+1)/2= number of phenotypes n = number of alleles C

Taxonomic groups

refer to picture...

Plant pollen is analogous to animal _____________.

sperm

What is a functional response? Explain what biological processes or phenomena would cause each type of functional response, and what three main shapes can they take? What are the three types of functional responses? Compare how changing from a type I to a type III functional response affects the oscillations of predator and prey populations?

the functional response is how the number of prey consumed per predator changes with prey density; we have a linear functional response: number of prey consumed per predator is an increasing function of prey density; functional response can also appear sigmoidal or logistic in its graphical curve logistic: number of prey eaten per predator increases to a capacity where which the predator is satiated; the predators hit the limit at which they can reproduce and the number of prey eaten per predator evens out (type 2 curve) sigmoidal: type 3 curve; predators under-consume prey at very low densities due to refuges or prey switching (limited prey), when prey is more abundant, the number or prey eaten per predator increases rapidly then levels out at a capacity where the predator is satiated

Two closely related grasshopper species occur sympatrically. No hybrids have been reported in nature. However, when an evolutionary biologist brings the two species into the lab, she discovers that they can hybridize to produce fertile offspring. How can you explain these observations? Should the grasshoppers be considered separate species?

the species are isolated from geologically or behaviorally each other so that is why it is not common to see the hybrid species in nature. They should be considered a different species because they do not reproduce with each other in nature.