final questions bis2b

A population of snakes contains three phenotypes controlled by a single gene with two alleles. The observed frequencies were: for heavily banded snakes f (BB) = 0.15, for lightly banded snakes f(Bb) = 0.70, and for plain snakes f (bb) = 0.15. If evolution is not occurring in this population, what should the frequency of heavily banded snakes be? a) 0.05 b) 0.15 c) 0.25 d) 0.5 e) 1.0

.15 squared??? c

It is frequently observed that populations of pathogenic bacteria that have evolved resistance to antibiotics will slowly become more susceptible to those antibiotics if the antibiotics are no longer prescribed to treat the bacterial infections. Explain briefly how this reversion to susceptibility might evolve through the process of natural selection. Be sure to explain how each of the three conditions that are necessary and sufficient for evolution by natural selection to operate can be satisfied in this case.

1. inherited characteristics: resistance is inhereted 2. variation: some are resistant, some are not 3. different fitness: It might be harder for the antibiotic reisistant gene to remain prevalent in the gene pool without exposure to the antibody. There is a slight cost to this adaptation to the fitness thus it is not favored

You are studying a single population of plants that has two alleles at a locus controlling flower color: B alleles code for blue flowers, and b alleles code for white flowers. The b allele is recessive and the B allele dominant, such that BB and Bb genotypes produce blue flowers, and bb genotypes produce white flowers. From your study population you decide to collect pollen from a large number of plants that have blue flowers. You then use this pollen to fertilize the ovules of a large number of plants that have white flowers. Among the offspring of this cross (call them the F1 population) you find 67% of the plants produce blue flowers and 33% of the plants produce white flowers. (A) Diagram with a Punnett Square the cross that is described, showing both the gamete types (and their frequencies) present in the ovules and the gamete types (and their frequencies) present in the pollen. (B) Calculate the frequency of the B and b alleles in the F1 population

67% not white and 33% bb => 2/3 have dominate B B B => No bc no bb B B b B => No bc no bb B b b B => No bc no bb B B b B => No bc 50/50 b b b B Yes b B)

Which of the following does NOT contribute to highly complex trophic interactions within communities, in which trophic levels are hard to define a. specialized herbivores, that feed on only a single host plant b. omnivores, that feed on both plants and on animal prey c. cannibalism d. predators that consume both herbivores and other predators e. generalist consumers (either herbivores or predators) that exploit many different resources

A

Energy flow through a typical forest ecosystem a. usually involves high values (>50%) of trophic level transfer efficiency b. may be characterized by the majority of primary productivity being shunted to the decomposer/detritivore food web (the "brown" food web). c. is characterized by high values (>50%) for the consumption efficiency of the primary producers by herbivores d. is characterized by high values (>50%) for the production efficiency of vertebrate herbivores e. all of the above are true

B

two populations of the same species that find themselves in allopatry may undergo genetic divergence. Imagine that after diverging genetically the populations re-establish contact with one another, and mating between members of the diverged populations occurs. The resulting offspring are sterile. We might then expect natural selection to favor a. any trait causing random mating, thereby moving the populations closer to Hardy-Weinberg conditions b. further reductions in the fitness of the hybrid individuals to 'reinforce' the speciation event c. any traits causing assortative mating, thereby contributing to the establishment of a pre-zygotic barrier to gene flow between the two populations d. hybrid individuals that prefer to mate with other hybrid individuals e. stabilizing selection on traits related to mate preferences

C. sterile offspring create a a reproductive barrior independent of the previous barrier.

In Australia, when red-bellied black snakes first encountered cane toads, most of the snakes were highly susceptible to the cane toad toxin, and died soon after eating them. The graph shown below compares susceptibility to toad toxin of individual snakes, from two populations, one never exposed to cane toads (TOAD NAÏVE), the other having been exposed to cane toads for 50 years (TOAD EXPOSED). You suspect that natural selection has caused the changes shown in the graph. We know that snakes reproduce, meeting the first condition for natural selection to occur. What are the additional 3 key conditions that must be met in the snake population in order for natural selection to have occurred? Based on the information in this graph, is there evidence that each of these conditions is met? If so, how is each met? If not, what kind of evidence would convince you?

Condition 1: (2 pts.) Variation in the trait within the population How met? (2 pts.) In both toad naïve and toad exposed populations of snakes individuals differ in their susceptibility to toad poison. Condition 2: (2 pts.) The trait is heritable [The trait has a genetic basis is also acceptable] How met? (2 pts.) No evidence for this. Possible ways to show this include: show that offspring resemble parents, perform crosses to demonstrate heritability (don't need to detail the crosses at all), identify the gene responsible for tolerance of toad poison Part credit (+1): Show that the trait is heritable or demonstrate heritability (no mention of HOW they would demonstrate this. Condition 3: (2 pts.) The trait confers a fitness advantage How met? (2 pts.) Being less susceptible to toad poison increases snake survival; OR individuals that lack resistance to toad poison more often die before reproducing than those that have this trait.

Stabilizing selection acting on a trait within a population with abundant genetic variation will generally cause a. a large change in the mean trait value with little change in variance c. a large change in the mean trait value with a decrease in variance b. little change in the mean trait value with an increase in variance d. little change in the mean trait value with a decrease in variance e. none of the above is true

D

Symbionts that are vertically transmitted can confer novel adaptations on their hosts that are a. heritable, because symbionts are inherited in the same way that host nuclear genes are inherited b. not heritable, and therefore are not stable over multiple host generations c. inherited though male gametes, but not female gametes d. inherited through female gametes, but not male gametes e. likely to lead to an obligately parasitic relationship between the symbiont and its host

D

The observation that asexually reproducing species are often found just at the tips of the 'Tree of Life' rather than as large branches (or clades) all of whose members are asexual suggests that a. asexual reproduction is not associated with a large initial (short-term) benefit b. asexual reproduction is a stable and successful strategy for very long periods of evolutionary time c. sexual reproduction is likely to be replaced eventually by asexual reproduction across the entire Tree of Life d. sexual reproduction may be disadvantageous in the short-term, but is advantageous in the long- term e. asexual reproduction may be disadvantageous in the short-term, but is advantageous in the long- term

D

The ecological species concept a. emphasizes barriers to reproduction (either pre-zygotic or post-zygotic) b. emphasizes the different morphologies of different species c. emphasizes that hybrids between two species will be either inviable or sterile d. emphasizes that hybrids between two species express traits that do not make them adapted for any existing 'niche', and therefore will have low expected reproductive success e. emphasizes that triploid individuals are generally sterile, because they produce aneuploid gametes

D ecological species concept is a concept of species in which a species is a set of organisms adapted to a particular set of resources, called a niche, in the environment.

Genetic recombination a. occurs within chromosomes, through crossing over b. occurs across chromosomes, through meiosis (and the associated independent assortment of chromosomes) and subsequent fertilization (i.e., normal sexual reproduction) c. occurs only when a new combination of alleles is needed for evolution to occur d. occurs only in small populations e. both a and b are correct

E

The initial stages of sympatric speciation in the apple maggot fly through the formation of 'host races' a. have occurred within the last 400 years, showing that the initial stages of speciation can occur rapidly b. have been favored by a partial barrier to gene flow due to the different emergence times of apple- adapted flies and hawthorn-adapted flies c. have been favored by a partial barrier to gene flow created because of preferences of apple- adapted flies for the odor of apples and the preference of hawthorn-adapted flies for the preference for hawthorns, plus the fact that the flies mate on or near their host fruit d. have been favored by the low fitness of hybrids of apple- and hawthorn-adapted flies, generated because the hybrids are not attracted to the odors of either apples or hawthorns e. all of the above are true

E

You are walking in an alfalfa field on the Davis campus. You notice that the plants harbor populations of the pea aphid. Healthy aphids are green, and feed either on the underside of the leaves or on the stems. You NEVER find healthy aphids on the upper surface of alfalfa leaves. On the upper surface of some leaves you do, however, find some aphids that are swollen and brown. Upon further inspection, you find that these aphids are dead or nearly dead, and inside their swollen bodies you find the immature stages of a parasitoid wasp. (A) Is the presence of swollen, brown aphids on the upper surfaces of alfalfa leaves an adaptation of the pea aphid? Explain your answer b. You collect live aphids and some of the nearly dead, brown aphids from the alfalfa plants and isolate DNA from their bodies. You find the DNA sequence associated with a particular bacterium (called Hamiltonella) in SOME of the live aphids, but in NONE of the swollen brown aphids? Could Hamiltonella be an obligate symbiont of the pea aphid? Explain your answer. c. How can you explain the different prevalences of Hamiltonella in the live versus the nearly dead aphids?

No. If the pea aphids found on the upper surface of the leaves are all dead or soon to be dead (due to parasitism) it is unlikely that this is a behavioral trait that enhances the fitness of the host aphid. Instead, it is likely to be a case where the parasitoid wasp has manipulated the host's behavior to enhance the parasitoid's fitness. (Note: This system is similar to a caterpillar that, when infected with a baculovirus, climbs to the top of plants and dies there. However, in the case of the baculovirus, it is clear that being high in the vegetation enhances pathogen transmission. In the case of the pea aphid, it is not clear how/why being on the upper surface of the leaf might enhance the fitness of the parasitoid. It may be that by moving out of the location where aphids normally feed, the risk that the parasitized aphid will be consumed by predators that normally eat aphids is reduced.) b. No, hamiltonella is not an obligate symbiont, which means that it needs the other organism to survive. If it was it would be in all of the aphids. c. Perhaphs the hamiltonella helps the aphids stay alive .

You are walking along the beach and you see a native plant whose flowers are being visited by a native bee. The flower is an obligate out-crosser (it cannot fertilize its ovules with its own pollen). You observe that the bee is collecting pollen and nectar from the open flower. As the bee exits the flower you note that it is extremely careful about incorporating every single pollen grain into a pollen ball (held on its hind legs). The bee then flies directly back to its nest, where it deposits the entire pollen ball into a chamber, where it will be used as food for its offspring. Further observations reveal that each bee in the population visits only a single flower during a single pollen-collecting trip from its nest. Is this an example of a mutualistic association between the bee and the flower? Explain your answer.

No. The current scenario is a description of a parasitic interaction, where the bee benefits and the plant suffers loss of gametes. Only if the bee actually moves pollen from one flower to another - not happening - this is not an example of mutralism

A bird eats the fruit of a plant species. The seeds are not digested and germinate in the bird's excrement at some distance from the parent plant. This is most likely an example of... a mutualistic interaction a trophic cascade sympatric speciation parasitism competition

a

Diversity of species is greater in the tropics because _____________ is/are greater in the tropics than in the temperate zone (choose the best answer). diversification rates productivity extinction rates disturbance b and d

a

The biomes with highest GPP and NPP on land have a) greatest moisture, highest temperature, and longest growing seasons. b) highest nutrient levels, but not greatest moisture, or longest growing seasons. c) lowest annual evapotranspiration among terrestrial biomes. d) greatest differences in available nutrients between edge and center of biome. e) All of the above.

a

The main problem with understanding how genes responsible for reproductive isolation could evolve 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.

a

Which of the following is necessary for a population to respond to natural selection? a) some individuals possess traits with high relative fitness b) all individuals possess traits with high fitness c) the population is very diverse genetically d) the population is large e) traits are determined by environmental effects

a

You carefully study populations of two very similar meadow mice, one from the Central Valley, the other from Napa County. You want to know whether the populations belong to the same species or to two different species. You could most confidently decide this if you could... a) show that the ranges of the two mice overlap without hybridization occurring. 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. show that the Napa Valley mice prefer Cabernet, but the Central Valley mice prefer Zinfandel.

a

The Lotka-Volterra model of predator-prey population dynamics predicts cycles of prey and predator population densities over time. This cycling is produced by a. a time lag between the build-up of the prey population and the subsequent build-up of the predator population b. continuous positive feedback influencing the growth rate of the prey and predator populations c. density-independent mortality of the prey population generated by the predators d. prey populations always lying directly on their zero-growth isoclines e. c and d are both true

a b is wrong because its a negative feedback loop c. density-idependent mortality is due to abiotic factors like weather d. no just no.. prey populations do not stay on the same plane e. no

Rare male advantage is sometimes seen in organisms. When it occurs, males with an uncommon phenotype are preferred as mates. The preferred type in one generation is not preferred a few generations later. What is happening here over the long-term? a) frequency-dependent selection b) sexual selection c) directional selection d) stabilizing selection e) divergent or disruptive selection

a Frequency-dependent selection occurs when the fitness of a genotype depends on its frequency.

Which process below creates different alleles for a gene? a) mutation b) natural selection c) hybridization d) sexual selection e) genetic drift

a because only mutation creates different alleles from nothing

s a result of road building, a formerly contiguous patch of tropical rain forest is now subdivided into smaller patches. The charismatic 8-striped purple newt lives in the forest, where it has long been among the most abundant species. The newt moves slowly and so cannot cross extensive areas of open ground that lack forest cover (e.g., a road) because it will dry out and die. Conservation biologists are interested in understanding the effect of all this road building on the newt, and have enlisted your services as a biological consultant. For the following list, state whether each would increase or decrease as a result of the road building, then briefly give a specific justification for your answer (no more than one sentence!). a.Risk of local newt extinction b. Levels of gene flow between patches of forest c. Potential for genetic drift to affect allelic frequencies d. Likelihood of a disease sweeping through the population and causing catastrophic mortality throughout the entire region E. The ability of the species to re-colonize a patch after a forest fire F. With climate change, the eastern half of the newt's range is predicted to become warmer and drier, the probability that newts could become locally adapted to the increasingly warmer and drier conditions predicted to occur in the Western portion of its range as a result of climate change G. If you wanted to reduce these impacts of roads, but still build the roads, what would be the most effective action to take?

a. Risk of local newt extinction Increase. Small, isolated populations are at greater risk of extinction. [Also acceptable to say some populations will decline due to lack of immigration] B. Levels of gene flow between patches of forest Decrease. The roads prevent migration of individuals between patches. C. Potential for genetic drift to affect allelic frequencies Increase. Populations are smaller. [Full credit is also earned if answered: no change, because the newt is common populations are still very large and genetic drift will be minimal] D. Likelihood of a disease sweeping through the population and causing catastrophic mortality throughout the entire region Decrease. Outbreaks will not spread between patches because there is no migration between patches [Also acceptable: no infected individuals from one patch will contact susceptible individuals in another patch] E. The ability of the species to re-colonize a patch after a forest fire Decrease. Dispersal is restricted by the roads, preventing recolonization [Also acceptable: immigration is decreased, the roads prevent newts from colonizing burned areas] F. With climate change, the eastern half of the newt's range is predicted to become warmer and drier, the probability that newts could become locally adapted to the increasingly warmer and drier conditions predicted to occur in the Western portion of its range as a result of climate change Increase. Local adaptation will be easier because roads restrict gene flow. [Also acceptable: Decrease because of the increased probability of exinction of populations (part A) or because genetic diversity will be smaller in small populations] G. If you wanted to reduce these impacts of roads, but still build the roads, what would be the most effective action to take? Build tunnels under the road [Also full credit for describing any sort of corridor or scheme (physically moving individuals] that allows newts to move across roads without drying out or getting run over by cars.

3. Two species of insect-feeding lizards colonize a group of three islands. Species 1 (solid line) lands on the first island and second island. Species 2 (dashed line) lands on the second and third islands. The islands are identical in every way that matter to the lizards. The following graphs depict population size of lizards on each island. Island 3 Island 2 Island 1 SPECIES 1 Population Size SPECIES 1 SPECIES 2 SPECIES 2 Time Time Time From these graphs you can conclude that... the first species is a superior competitor to the second. interspecific competition is less than intraspecific competition for both species. carrying capacity of species #2 is greater than that of species #1. the competition coefficient describing the effect of species #1 on species #2 > 1. the species are partitioning food resources.

b

In the graph below, in order to change the dashed curve into the solid curve you would need to... (pg 9 2008 test) Increase r, increase K Increase r, decrease K Decrease r, increase K Decrease r, decrease K Decrease N0

b

Speciation... a) always takes tens of millions of years. b) is a process by which populations of one species diverge genetically and produce two reproductively isolated lineages. c) can only occur when species are geographically separated. d) must pass through a stage where there is interspecific hybridization. e) is completed only when two different species can freely interbreed.

b

The competitive exclusion principle states that... species that compete with each other exclude each other. species that use the same resources in the same way cannot coexist. species that coexist experience greater interspecific than intraspecific competition. species that do not cooperate will go extinct. interference competition is stronger than exploitative competition.

b

Which of the following is NOT an example of a reproductive isolating mechanism? a) species-specific courtship rituals b) Hardy-Weinberg equilibrium c) gamete recognition d) hybrid breakdown e) all of the above are isolating mechanisms

b

The hooded crow lives in Western Europe and is grey with a black head and tail. The carrion crow lives in Eastern Europe and is all black. There is a narrow zone in central Europe where the two species meet and in this region some intermediate patterned crows have been found. What does this suggest is happening in central Europe? a bottleneck is forming a hybrid zone is forming a region of polyploidy is forming a pleiotropic character is evolving a new order of birds is evolving

b not bottleneck (or genetic bottleneck): a sharp reduction in the size of a population Polyploidy: cells and organisms are those containing more than two paired (homologous) sets of chromosomes. Pleiotropy: when one gene influences two or more seemingly unrelated phenotypic traits.

The Perdido Archipelago is a group of 10 islands, somewhere in the middle of the tropical Pacific Ocean. A species of laughing gull (a marine bird) exists in populations of about 1000 on each of the islands. There are two color morphs, a melanic (black) form and a white form. The gulls breed once a year. Every breeding season, 500 individuals disperse from each population to other islands in the archipelago and breed with residents when they arrive at their homes. Each of these 500 individuals is replaced by migrants from other islands. Which of the following statements is true? a) Inbreeding should lead to strong intersexual selection. b) Gene flow is sufficiently high to offset the effects of genetic drift in this example. c) The populations on each island are likely to diverge into new species over time. d) Genetic drift will very likely to cause the extinction of some island populations because of the increase in frequency of deleterious alleles. e) All of the above are true.  Feather color in these gulls is due to variation at the M-locus. Black-colored birds are either MM or Mm; white birds are mm. On each of the islands, assume that the gull population contains approximately 190 black-colored (melanic) individuals and 810 white individuals. Assuming Hardy-Weinberg equilibrium, what is the frequency of the M-allele in each population? a) 0.81 b) 0.19 c) 0.90 d) 0.10 e) 0.44 During a storm, two white male and two white female gulls are blown 1000 kilometers to an isolated island (Survivor Island) previously uninhabited by laughing gulls. They reproduce and found a new population. These gulls cannot disperse back to the source populations in the Perdido Archipelago. And, for many centuries, there is no additional migration from Perdido Archipelago populations to the population on Survivor Island. This newly established population has radically different color frequencies than the source population. This is most likely due to... a) mutation. b) disruptive selection. c) inbreeding. d) sexual selection. e) founder effects. 2000 years after the Survivor Island population was established, its members evolved mating displays that differ from those of the parent population. When a television producer from the Nature Channel introduces gulls from the original Perdido Archipelago population to the Survivor Island population, the two kinds of gulls find each other's mating behavior repellant. What type of reproductive isolating mechanism keeps the two populations of gulls from interbreeding? a) Vicariance b) Mechanical isolation c) Temporal isolation d) Behavioral isolation e) Hybrid sterility The example presented in #36 most likely represents __________ speciation. a) sympatric b) peripatric c) diversifying d) paraphyletic e) ecological

b then d then e then d then then b Allopatric (allo = other, patric = place) geographically isolated populations allopatric speciation Peripatric (peri = near, patric = place) a small population isolated at the edge of a larger population peripatric speciation Parapatric (para = beside, patric = place) a continuously distributed population parapatric speciation Sympatric (sym = same, patric = place) within the range of the ancestral population

Ecologists often prefer experimental studies over purely observational studies because a. experimentation produces a more natural setting for the data collection b. purely observational studies cannot produce definitive inferences about causality, whereas experimentation can c. experimentation can be performed without any manipulation of the environment, thereby avoiding any disturbance of the studied ecosystem d. a and b are both true e. a, b, and c are all true

b. A not true C irrelevant

Compare the following two ecosystems, both of which have EQUAL rates of primary productivity. The dominant primary producers in ecosystem #1 are woody plants (trees). The dominant herbivores are vertebrates (deer and hare). The dominant primary producers in ecosystem #2 are microscopic algae. Dominant herbivores are large crustacean zooplankton. Based on these data, which of the following statements is most likely to be true? The amount of energy at the carnivore trophic level will be higher in ecosystem #2 than ecosystem #1 Ecosystem #1 will have more omnivores than ecosystem #2 Ecosystem #1 will have higher ecological efficiency than ecosystem #2 There will be more trophic levels in ecosystem #1 than ecosystem #2 Ecosystem #1 will have a stronger trophic cascade than ecosystem #2

c

Oxygen was first added to the earth's atmosphere: a) by eukaryotic cells b) 4.6 million years ago c) by cyanobacterial cells d) 3.5 million years ago e) by green plants

c

The biological species concept is difficult or impossible to apply in which of the following circumstances? a) When there is inbreeding. b) In hermaphroditic species. c) Strictly asexually reproducing organisms. d) Species with sympatric distributions. e) a and d are both correct.

c

The difference between adaptation and acclimation is... Acclimation only refers to temperature; adaptation is more general. acclimation occurs over long time periods, while adaptation is quick. adaptations involve changes in the genetic composition of populations, whereas acclimation is not heritable. adaptations increase an organism's fitness more than acclimation. nothing, they are synonymous.

c

The intermediate disturbance hypothesis predicts that... diversity is greatest in the absence of disturbance. high disturbance results in intermediate diversity. low diversity occurs when disturbance is infrequent. high diversity results when competition is most intense. both B and C are correct.

c

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

Your new job at the Center for Disease Control has placed you in the Lyme Disease risk assessment unit. You know that the risk of humans contracting Lyme disease from ticks varies from year to year and is connected to the local food web. Gypsy moth caterpillars were introduced to America about 100 years ago and they feed voraciously on oak trees in the northeastern U.S. This resulted in almost complete defoliation of many trees. Given the following food web of the northeastern deciduous forest, and the likely relationship between removal of a tree's leaves and its reproductive success, you conclude that... lyme disease prevalence will be high in the years following a gypsy moth outbreak. adding fertilizer to Oak trees will reduce the likelihood of humans contracting Lyme disease. actions taken to eradicate the gypsy moth caterpillar could increase the prevalence of Lyme disease. Lyme disease risk and gypsy moth prevalence are uncorrelated because of multiple canceling indirect effects. Gypsy moth caterpillars control lyme disease by eating oak acorns.

c

he paradox of the plankton describes the problem of understanding how so many species can coexist on just a few resources. It can be resolved by... resource partitioning favoring the superior competitor. facilitation among species. rapidly changing environmental conditions that alter the competitive hierarchy. interspecific hybridization. the presence of a keystone species.

c

The Hardy-Weinberg equilibrium conditions require that population size be 'infinite' (or, more realistically, 'very large') because a.gene flow can create changes in allele frequencies in small populations b.mutation rates are expected to produce substantial changes in genotype frequencies in small populations c,genetic drift will change allele frequencies in small populations d. natural selection does not operate in very small populations e. random mating cannot occur in very small populations

c. small populations are especially sensitive to genetic drift Gene flow creates changes in allele frequences regardless of population size... reduces variance mutation rates do not make that big of changes natural selection and random mating still occur in small populations (albeit at a smaller scale)

Due to burning of fossil fuels, humans are adding a substantial amount of carbon to the environment as carbon dioxide. Which of the following is/are happening as a result of this? Oceans are becoming more acidic Permanent increases in plant growth rates Average surface air temperature of the Earth is increasing a and c None of the above

d

If one species is a superior competitor to another, the two might still coexist if... there is a tradeoff between competitive ability and resistance to predators there is a tradeoff between competitive ability and the ability to colonize disturbed patches predators prefer to eat the most abundant species a, b, and c are correct There is no way they can coexist

d

Increased temperature might increase the rate of evolutionary change because increased temperature leads to... increased mutation rates faster metabolism, leading to more rapid development and shorter generation times intermediate frequency of disturbance a and b only none of the above

d

Keystone species and foundation species are similar in that... both are very abundant both are always predators or herbivores both are usually sessile animals both have a strong effect on the species composition of a community both b and d are correct

d

Reducing the biological diversity of an ecosystem can result in... decreased primary productivity. increased variability in productivity or other critical ecosystem functions. increased likelihood of invasion by exotic species. a, b, and c are correct none of the above.

d

The most diverse terrestrial biological communities a) occur at the highest latitudes. b) are super organisms. c) are never exposed to succession. d) have the largest numbers of species. e) are drowned forests.

d

Which of the following events is ESSENTIAL to the process of speciation? a) genetic drift b) stabilizing selection c) pre-zygotic isolation d) restricted gene flow e) sympatry

d

You are an environmental consultant hired by a town adjacent to a small lake in the Sierras known for its clear waters due to a low standing biomass of algae. The figure below describes what you know about the current food web of the lake. The town is economically depressed, and residents have proposed two ideas for stimulating the local economy: (1) introduce northern Pike (a fish that only eats other fish) into the system to attract sportsfisherpeople (and their money) to the area and (2) harvest filter-feeding bivalves from the lake for food (they are quite a delicacy and fetch a hefty price). The town wants you to predict the consequences of each proposal for the their lake—in particular they are concerned about maintaining the clear water of the lake, and are not interested in any option that would decrease water clarity even if it would mean great short-term economic benefit. After careful study, you conclude that... adding pike will DECREASE water clarity by releasing herbivores from suppression. removing bivalves will have NO EFFECT on water clarity. adding nutrients from the bottom up will INCREASE water clarity. if townsfolk BOTH removed bivalves AND added Pike then they should be able to maintain water clarity in its present condition. removing bivalves OR adding pike would have similar effects on water clarity.

d

California salamanders of the genus Ensatina occur in several different forms. There is one form in northern California that splits into 3 or 4 forms on either side of the San Joaquin valley. The valley is too dry for salamanders, but salamanders from either side of the valley meet just inland from San Diego. When the two salamander populations meet near San Diego, they do not mate. All the other salamander populations mate with their neighbors. How do we describe this situation? a) it is parapatric speciation b) it is sympatric speciation c) is is allopatric speciation d) it is a ring species e) it is an example of sexual selection

d In parapatric speciation there is no specific extrinsic barrier to gene flow. The population is continuous, but nonetheless, the population does not mate randomly. ring species is a situation in which two populations which do not interbreed are living in the same region and connected by a geographic ring of populations that can interbreed sexual selection --intra (compete) or inter (fancy characteristics) --- natural selection arising through preference by one sex for certain characteristics in individuals of the other sex.

While hiking along a trail from the tip of a receding glacier in Alaska to a spruce forest 30 kilometers away, you move through patches of land that have been exposed for an increasing amount of time since succession began. You get the distinct impression that diversity increased throughout your hike and that highest diversity is found in the oldest, most undisturbed forests (late successional communities), rather than in those of intermediate time since disturbance as you might have predicted. This observation can best be explained by the fact that... rates of diversification are greater in late successional communities. early successional communities lack keystone predators. competitive exclusion is occurring in early successional communities, reducing the diversity there. nitrogen in the soil increases with time since the glaciers receded. you walked south, and you are observing the latitudinal gradient in species diversity.

d rates of diversification are not always greater in late successional keystone predators

You have done an experiment with a pair of species of zooplankton in a pond without any fish and without pollution. One of the zooplankton species is much smaller than the other and your preliminary work shows that they compete intensely and indirectly for phytoplankton. One year after the beginning of your experiment, which of the following scenarios is most likely? a) The large and small species of zooplankton are equally dense. b) The larger species is much rarer than the smaller species because small species can exist at equilibrium on lower densities of phytoplankton than large species. c) The pond is opaque green and thick with phytoplankton. d) The smaller species is much rarer than the larger species because the large species can exist at equilibrium on lower densities of phytoplankton than large species. e) The smaller zooplankton species is likely to drive the larger species extinct.

d????

As you hike down the Sierras from high elevation to the foothills you notice a pattern in which at high elevation one species of tree (a pine) always occurs right next to another (a fir), whereas at low elevation you observe that the pine and fir are never located near each other. This observation can best be explained by... hallucinations at high elevation. character displacement of the fir at low elevation. greater rainfall at higher elevation. increasing strength of competition with increasing elevation. decreasing strength of facilitation with decreasing elevation.

e

If a third species of lizard arrived on the second island described in Question 3, and the trajectories of populations of all three species after the arrival of species #3 (dotted line) were as depicted in the following graph (species #1 = solid line, species #2 = dashed line, species #3 = dotted line), you could conclude that: Species 3 does not compete with species #1 Species 3 is a superior competitor over both of the other species The competition coefficient relating the effect of species #3 on species #2 is > 1 The competition coefficient relating the effect of species #3 on species #1 is < 1 Both c and d are correct

e

Predation or parasitism might facilitate the co-existence of two potentially competing species a. by decreasing the populations of both competing species to such low levels that competition is weakened b. by selectively decreasing the population of the competitively inferior species c. by selectively decreasing the population of the competitively dominant species d. both a and b are true e. both a and c are true

e

Rana catesbiana and Rana silvestris are frogs. From the name, what do we know about Mus silvestris? a) it is a frog species b) it is in the same order as frogs c) it is in the same phylum as frogs d) it is in the same class as frogs e) it shares one descriptive feature with a frog species

e

Species diversity usually increases continuously with which of the following factor(s)? Productivity (resource availability) Disturbance Strength of interspecific competition a, b, and c None of the above

e

Which of the following is a characteristic of early successional species? Competitively dominant Well-defended against predators Usually unaffected by late successional species Always facilitate late successional species Short time to first reproduction

e

Which of the following is not a SIGNFICANT threat to species diversity on Earth? Invasive species Habitat destruction Overharvesting Climate change All are significant threats

e

Which of the following is an example of an indirect interspecific interaction? a.Moose killing wolves. b.Wolves killing coyotes. c.Cthamalus barnacles overgrowing Balanus barnacles. d.Wolves killing moose. e.Birds protecting plants by eating the herbivorous insects feeding upon the plants.

e interspecific interaction refers to when two unrelated species have certain types of interactions

The effect of pairwise interspecific interactions upon net per capita population growth can be summarized by "+" and "-" signs. Which of the following combinations of these signs is INCORRECT: a) Competition: - , - b) Amensalism: - , 0 c) Mutualism: + , + d) Predation and parasitism: + , - e) Commensalism: 0 , 0

e Commensalism is a relationship between two organisms where one receives a benefit or benefits from the other and the other is not affected by it. Amensalism refers to a relationship between two species in which one of the partners is inhibited, while the other is not affected in any significant way.

25. With respect to the phylogeny shown above, which of the following statements is TRUE: pg 10 2008 a) Species F, G, H, I, and J form a polyphyletic group. b) Species A, B, C, D, and E form a paraphyletic group. c) Species A, B, I and J form a monophyletic group. d) Species F, G, and H form a monophyletic group derived from the same common ancestor. e) Species C, D, and E form a monophyletic group. in the phylogeny shown above, what is the fewest number of speciation events that could have given rise to the clade that includes species A, B, C, D, and E? a) 4 b) 6 c) 8 d) 3 e) 11 With respect to the phylogeny shown above, which of the following species evolved (arose) most recently? a) Species A b) Species J c) Species F d) Species G e) Species B

e then a then b

A species of planktivorous fish was added to the pond in the previous question, and its population grew dense. This planktivore is unlike Alosa, and it eats both large and small zooplankton equally. One year after the addition of the planktivorous fish, which of the following scenarios is most likely? (Note, "opaque" is the opposite of clear). a) The pond changed from being green & opaque (with high concentrations of phytoplankton) to being clear. The large zooplankton species became much denser, and the small zooplankton species became sparse. b) The pond became opaque and noticeably greener. Phytoplankton densities increased measurably. The large zooplankton species, which was dense before the fish were added, became sparse. And, the small zooplankton species became much denser after the fish addition. c) No change in either water clarity or abundance of zooplankton. d) The pond became less clear and noticeably greener. The small zooplankton species, which was dense before the fish were added, became sparse. And, the large zooplankton species became much denser after the fish addition. e) The pond changed from being clear to green & opaque (with high concentrations of phytoplankton) to being clear. Densities of both zooplankton species decreased greatly.

e????

Soapberry bugs feed on the seeds inside fruit capsules using a proboscis or beak that they insert into fruits. The graph below shows the size distribution of fruits that are available to a population of soapberry bugs that has recently migrated to Davis. The bugs arrived from a location where the only seeds available were in fruits intermediate in size between those of balloon vines and golden rain trees. [4 pts. total] The curve on the graph below shows the distribution of beak sizes in a large founder population of soapberry bugs right after it became established in Davis. ON THIS GRAPH, DRAW A CURVE SHOWING HOW THIS DISTRIBUTION WILL HAVE CHANGED AFTER SEVERAL GENERATIONS OF BREEDING BY THE SOAPBERRY BUGS.

from something akin to a disruptive graph to something more like a stabilizing graph

Density dependent population growth f)has lower per capita birth or death rates, or both, as population increases. g) has lower values of per capita growth rate, ! as population increases. h) is caused by crowding, and or resource depletion, and or increasing per capita parasitism, predation, and/or disease as population increases. i) means slower per capita growth as population approaches K, the carrying capacity. j)all

j