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Lab 7 Homework Name: Calculate Average % time for treatments 1, 2, and 3

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Lab 7 Homework Name: Calculate Average % time for treatments 1, 2, and 3. We will not pool data for Treatment 4. Use your data and pooled data from the spreadsheet available on Canvas under Assignment 7. Use those results to answer the homework questions and for your graphs. Graph Treatments 1, 2, and 3. Do not graph treatment 4. A sample graph with imaginary data is shown below. Follow this example. 1) Describe the baseline mosquito time budget in the no-fish treatment (Treatment 1). 2) Describe the mosquito time budgets in the fish behind-partition (Treatment 2). 3) Do you have any quantitative evidence that mosquito larvae altered their time budget in the presence of the fish behind a partition (compare Treatment 1 to Treatment 2)? Briefly explain your reasoning. 4) Describe the mosquito time budget when fish were free to move about the tank (Treatment 3) 5) Do you have any quantitative evidence that mosquito larvae altered their time budget in the presence of the loose fish (Compare Treatment 1 to Treatment 3)? Briefly explain your reasoning. 6) Describe the mosquito time budget when cichlids were added (Treatment 4). 7) Do you have any quantitative evidence that mosquito larvae altered their time budget in the presence of the cichlids as compared to only Gambusia? Briefly explain your reasoning. 8) Gambusia have been introduced throughout much of the United States. In some locations Gambusia feeds on mosquito larvae as you observed in lab. However, in other places, Gambusia behaves as a true generalist predator. It is not always clear on which trophic level it will start to feed. It can eat mosquito larvae and other tiny aquatic herbivores, as well as invertebrate predators on the herbivores and small native fishes. Use the generalized food web for this system, shown in Figure 7-12, to answer the three questions below. Figure 7-12 a. When the introduction of Gambusia results in the sudden abundance of algae, called an algal bloom, on which food source is Gambusia likely to be concentrating? b. When the introduction of Gambusia results in a sudden increase in the abundance of mosquitoes, on which food source is Gambusia likely to be concentrating? c. How might the introduction of Gambusia lead to the extinction of native fish populations? Title: __________________________________________________ Title: __________________________________________________ Title: __________________________________________________ Title: __________________________________________________ Trophic Interactions in the Lab Note: There are two videos: one to provide context, go over the treatments and behaviors you will observe, and give you practice with data collection: https://youtu.be/zAHIpzbySV0 Use the second video (https://youtu.be/LxCHOVnccNc) for data collection to be used for the homework. Summary: In this week’s lab you will study the effect of a predator on prey behavior. You will be working with a freshwater system where the primary consumer are mosquito larvae (Figure 7-9), and the secondary and tertiary consumers are fish. Background Information on Mosquitoes There are several genera and many species of mosquitoes. You will study the aquatic larval form of the mosquito, Culex pipiens. Adult male mosquitoes feed on nectar or other substances but do not take blood meals. Female mosquitoes require a blood meal to gain protein for egg-production—these are the ones that bite you. Before egg-laying, a female collects sperm packets from one or more males and stores them. Sperm and eggs are combined inside the female reproductive tract, after which a female lays a raft of fertilized eggs that float on the surface of freshwater ponds, lakes, or streams. The eggs hatch, releasing swimming mosquito larvae. Larvae feed on algae and detritus in the water or on the bottom of shallow ponds, although there are a few predaceous species. Larvae go through several molts in the aquatic stage before they pupate and become flying adults. Larvae reach the adult stage in 7 to 17 days. One key feature of the larval stage is that it does not have gills—it is air-breathing and has a posterior breathing tube that it extends above the water’s surface (see Figure 7-9). And so they must breathe air to get their oxygen. In contrast, fish can use oxygen dissolved in the water. Did you know dragonfly larvae, a different type of insect, have gills in their rectal chamber? Animals can be so weird. Mosquito larvae float at the water’s surface with their breathing tube extended. In order to feed, they will move between the pond bottom, where food collects, and the pond surface, where they breathe. Feeding and breathing are both necessary, but how does a mosquito allocate its time? The advantage for having a breathing tube is these animals can live in water with very low levels of oxygen. But are there trade-offs with this respiratory strategy and feeding? Think about that as you do the lab. Figure 7-9 Breathing tube Predators of mosquitoes Culex pipiens is an opportunistic mosquito species that lays eggs in small containers, ponds, and shallow drainage ditches. To control mosquito population size and to reduce the spread of diseases transmitted by mosquitoes, predatory fish are often introduced to small bodies of water where females are likely to lay eggs. Predatory fish in the genus Gambusia (Figure 7-10) are members of a group of fish called the top minnows. Two species, Gambusia holbrooki and Gambusia affinis, are often introduced to shallow waters to help control mosquito populations; they are commonly called mosquito fishes. Gambusia holbrooki is native to the eastern United States but has been introduced throughout North America. Since the 1920s it has been added to drainage ditches, ponds, and even swimming pools in California. Gambusia can tolerate water temperatures between 33°F and 104°F. The fish is a generalist feeder capable of eating 100 to 500 mosquito larvae per day. Females reach lengths of about 7 cm, but males are smaller, typically less than 4 cm in length. Gambusia reproduces three to six times per summer with brood sizes ranging from 40 to 60 offspring. Their life span is two to three years. Figure 7-10 Cichlids (pronounced si-klud) are freshwater African and South American fish commonly found in aquarium stores. They are highly diverse, can be very pretty, and the subject of many evolutionary studies. For our purposes, the species we have are insectivores (insect eaters) and are a very active predator. Compared to the Gambusia, they are a more “aggressive” fish. We will use this fish for Treatment 4. Lab 7: Trophic Interactions The big question we are asking for this lab is: Does mosquito behavior change in the presence of a predator? To answer this question you will create a time budget of larval mosquitoes behavior. A time budget is a record of how an animal spends its time. Your mission is to determine how mosquito larvae allocate their time between different activities in the absence and presence of predators. You will be looking for a response to predation risk, but you should keep in mind that mosquitoes have an evolutionary history with fish predators and that their behaviors are the results of multiple generations of natural selection. They may behave as though predation were a possibility, even if predators are not present. On the other hand, they may not recognize a novel potential predator at all, if they have no evolutionary history with any similar organism. For this lab we will have you work as an individual then pool your data with data previously collected. Again, think about why do we keep pooling data in our labs. Creating Time Budgets You will estimate time budgets of mosquitoes in four experimental conditions: (1) fish absent; (2) fish (Gambusia) present but behind a partition (fish cannot access mosquitoes but they are visible to each other); (3) fish (Gambusia) released into the tank with the mosquito larvae (fish can now feed on mosquitoes), and (4) Gambusia and cichlids with mosquitoes. The video will show examples of the different treatment and behaviors you will keep track of. Treatment 1 will be used to determine baseline behavior of the mosquito larvae. What do mosquitoes do in the absence of a predator? Treatment 2: Do mosquitoes respond to visual cues? Treatment 3: Does mosquitoes behavior change when fish can access the mosquitoes? Treatment 4: Is there a difference in mosquito behavior in the presence of multiple predatory species? Here we can compare the behavior in Treatment 3 with Treatment 4. Collecting Data We have placed five mosquitoes in a 1gallon bucket for each treatment. This is our study arena. The mosquitoes feed on rabbit food, which is made from plant material. This has been ground into a fine powder and placed in each bucket where it then settles to the bottom. Time budgets will be estimated using the instantaneous scan sample method. For this method, you will keep track of all mosquitoes, recording the number of larvae doing each behavior at 30-second intervals. With the scan sample method, you are not concerned with what the mosquitoes are doing between each interval, just the behavior they are engaged in at each 30-second mark. We will have you observed the mosquitoes for 5 minutes for each treatment. There are four possible larval behaviors to record at every 30 second interval. These are described in the Intro video (https://youtu.be/zAHIpzbySV0) at the 3:10 mark. 1. Feeding on detritus that has settled on the bottom of the tank—if you see a larva at the bottom of the tank, assume it is feeding. 2. Hiding in the floating plant that has been added to the tank as a refuge. 3. Breathing if the larvae is floating at the water surface with the posterior tube extended, it is breathing; 4. Swimming, defined as actively moving through the water—some have described this as wriggling through the water as they are not efficient swimmers. One last metric to record: being eaten. This will be pertinent only for Treatments 3 and 4, but we do want you to track how many are eaten. You will observe each tank for 5 minutes, recording the number of larvae engaged in each activity at each 30-second intervals. You will collect data from this video: (https://youtu.be/LxCHOVnccNc). There will be a “Beep” to let you know when to count the number of mosquitoes doing each behavior. Data sheets are provided to help you record how many mosquitos are breathing, hiding, swimming, eating, or are being eaten. Place a tick mark (a vertical line) in the box for each activity, or activities, that you observe at the end of each 30second interval. Sum the number of tick marks in each activity column, sum all the columns to get the total, and then divide each column by the total to find the average percent time spent on each activity for your larva. We have a practice data collection video for you to help you get started before you collect real data. The practice observation begins at the 3:42 minute mark in Intro video. Time: Feeding Hiding Breathing Swimming Being Eaten Initial 0.5 m. 1.0 m. 1.5 m. 2.0 m. Sum Average Percent Time Total Sum To calculate an average time budget for the mosquitoes, first sum the number of tick marks in each activity column to determine the number of intervals spent in each behavior. Next, add all of these sums together to determine the total number of intervals observed. Enter this in the “total sum” box. Finally, divide each individual sum by the total sum to determine the average percent time spent in each activity. We describe this process in the video at the 6:05 minute mark in https://youtu.be/zAHIpzbySV0 You are welcome to begin collecting data. Start with Treatment 1. Record your data in the data sheets, calculate time budgets, then enter your data in the spreadsheet provided at the Learning Tree site. Why do you think we just don’t use your data for the analysis? Make 3 graphs, one for Treatments 1, 2, and 3 (we won’t graph Treatment 4). Plot the average percent time from all groups. Data analysis will be done as part of the homework. Again, use this video for data collection: https://youtu.be/LxCHOVnccNc Treatment 1 Time: Initial Feeding Hiding Breathing Swimming 0.5 m. 1.0 m. 1.5 m. 2.0 m. 2.5 m. 3.0 m. 3.5 m. 4.0 m. 4.5 m. 5.0 m. Total Sum Sum Average Percent Time Treatment 2 Time: Initial Feeding Hiding Breathing Swimming 0.5 m. 1.0 m. 1.5 m. 2.0 m. 2.5 m. 3.0 m. 3.5 m. 4.0 m. 4.5 m. 5.0 m. Total Sum Sum Average Percent Time Treatment 3 Time: Feeding Hiding Breathing Swimming Being Eaten Initial 0.5 m. 1.0 m. 1.5 m. 2.0 m. 2.5 m. 3.0 m. 3.5 m. 4.0 m. 4.5 m. 5.0 m. Total Sum Sum Average Percent Time Treatment 4: Time: Feeding Hiding Breathing Swimming Being Eaten Initial 0.5 m. 1.0 m. 1.5 m. 2.0 m. 2.5 m. 3.0 m. 3.5 m. 4.0 m. 4.5 m. 5.0 m. Total Sum Sum Average Percent Time Lab 7 Trophic Interactions Goals and Objectives At the end of this laboratory you should be able to: 1. Explain the terms primary producer, consumer, prey item, predator. 2. Give examples of how prey behavior influences predation rate. 3. Give examples of how predators influence prey behavior. 4. Explain the concept of a refuge in space, time, and size. 5. Explain how relative costs and benefits influence feeding time. 6. Explain why prey may have an inappropriate response to a novel predator 7. Describe a food web. 8. Describe a trophic cascade. 9. Analyze the relationship between number of trophic levels in a food web and population size of the primary producer. Pre-lab Introduction for Lab 7 Read and complete the pre-lab exercise before Monday 9 a.m. of lab week. Read the rest of the lab to get a general idea of what you will be doing. The energy for almost all life on earth comes from the sun. Photosynthetic organisms use this energy to combine (fix) carbon from the atmosphere (CO2) into organic compounds. This essential process, called primary production, occurs in autotrophic primary producers such as single-celled algae or multicellular plants. Primary producers are the members of a food web that produce an energy supply (food) for the rest of the web. Primary producers are eaten by primary consumers; an herbivorous insect is a primary consumer, as is a cow. Secondary consumers feed on primary consumers, and so a bird that eats insects is a secondary consumer. We organize these different groups into levels, called trophic levels, as illustrated in the Figure 7-1. Energy flows from one trophic level to the next, but the movement of energy can be hard to measure. Instead, biologists often record the consumption of biological tissue volume, called biomass, as organisms are eaten by other organisms. A collection of trophic levels connected by the flow of energy or biomass is called a food web. A simple food web is shown in Figure 7-1. The width of each box represents the relative biomass present at each level of the food web. The arrows indicate the flow of energy as each level consumes members of the level below it. This bland little diagram, while useful, fails to depict the dynamic processes within each box. Organisms within each level feed, reproduce, compete, and die as the populations they comprise evolve over time. These organisms not only interact with each other, but they interact with populations of other organisms both within and between trophic levels. As a result, populations of producers and consumers usually interact for multiple generations. This long-term interaction creates an opportunity for the Figure 7-1 populations to co-evolve. A plant species whose leaves are consumed by insects may evolve a morphological defense such as increased toughness, spines, or trichomes. In response, some of the herbivore species may evolve mouth parts that can handle spines, whereas others may consume other species instead. In addition to morphological defenses, antipredator defenses can be chemical, developmental, or behavioral. Behavioral changes include altering the time of activity to a period where the predator is less active. For example, a plant species may not replace above-ground vegetation when herbivores are present. By dying back to its roots for some part of the year, it may be more likely to coexist with the herbivore population. The herbivore will have to diversify its diet if it is to survive. Effects of Predators on Individual Prey Behavior The behavior patterns of prey reflect a balance between the actions necessary for survival and the risks inherent in those actions. This is a trade-off. For example, an animal must feed, but searching for food will make it vulnerable to its own predators. The animal might balance this risk by hiding during some of the time it could be feeding, thus shortening the total time it has to feed. Decisions about whether to feed or hide from potential predators are extremely important for most organisms. Starvation is a frequent source of mortality in natural populations because food supplies are usually insufficient to support all the adults and offspring born in each generation. Juvenile organisms use nutrients for growth, but adults (sexually mature organisms) direct any energy beyond that needed for basic metabolism into reproduction. If an organism can reproduce sooner than other organisms in the population or leave more surviving offspring than the average for the population, its genes will increase in future generations (recall Lab 4). So higher feeding rates lead to greater potential fitness, if the organism survives to reproduce. The costs and benefits of feeding are easily outlined using a simple terrestrial food web example (Figure 7-2). In such food webs, the primary producers are usually green plants, the primary consumers are herbivorous insects such as grasshoppers or beetles, and the predators may be other insects or vertebrates (such as birds) to name just two. From the perspective of a grasshopper, food is often abundant. However, to feed, the grasshopper must climb onto the plant’s branches where it is more visible to bird predators than it would be if it simply sheltered at the base of the plant. Thus, the grasshopper incurs a potential cost, the risk of death, each time it feeds. Figure 7-2 How much time should a grasshopper spend feeding? If more food means more offspring but also greater predation risk, how might an organism achieve a balance between these factors? One possibility is to feed for the minimum possible time and to remain out of the predator’s reach for the rest of the time. If a prey animal moves into a place where a predator cannot go, biologists say it has a refuge. A beetle that lives between the spines on a plant, as shown in Figure 7-3, might have a refuge from a bird predator, as long as the spines are longer than the predator’s beak. The term “refuge” usually refers to a safe place, but it can have other meanings. If a prey animal spends part of its life in a stage or phase where the predator cannot eat it, biologists call this a refuge in time. An insect like a cicada, which spends its entire larval phase underground, has a refuge from bird predation as a juvenile. Figure 7-3 However, when an adult cicada emerges to mate, it is vulnerable to bird predators. Biologists have also identified a refuge in body size: a prey organism may grow too large to consume, or reach a size where it can defend itself from the predator. Refuge use is interesting because deciding when to leave a refuge requires a risk/benefit calculation. An organism must evaluate the potential benefits of feeding in comparison to the risk, or cost, of being eaten. An organism does not have to make a conscious calculation; rather any organism whose complete suite of behaviors allowed it to feed, to avoid predators, and to reproduce successfully will leave offspring that make correct decisions for the circumstances under which they evolved. Which calculations of refuge use result in high relative fitness? Experiments on a variety of animals have been used to answer this question. A particularly elegant set of experiments was done using tubeworms. You may have seen these on the fouling plates in lab last week. Did you notice that each tubeworm has a crown of tentacles that it extends to catch tiny particles in surrounding water? The tentacles are large and soft, so they attract predators (Figure 7-4). Predation can be avoided if a tubeworm stays entirely within its tube, but then it cannot feed. Tubeworms balance predation risk by extending their tentacles for Figure 7-4 short periods. They draw into their tubes if there is movement in the water around them, or if a shadow passes overhead. You may have seen this last week. Tubeworms use shadows or water movements as indicators that fish or other predators may be nearby. How long does a tubeworm stay in its tube after withdrawing? How would you decide when to feed again if you were hiding in a refuge? You might think that the hunger level of the worm would influence the length of time that it stayed in the refuge. Biologists that worms that had eaten less recently than others would come out of their tubes sooner, but experiments did not find an effect of previous feeding history. What they did find was somewhat surprising. Tubeworms weighed the cost of coming out of the tube against the potential benefit of feeding. Costs include any negative result of an action, so in this case, a cost might be being eaten. For tubeworms, remaining in the tube (refuge) in a food-rich environment has a greater cost than it would in a food-poor environment. This is because the worm will lose the opportunity to consume more food when hiding in a food-rich environment than it would when hiding in a food-poor environment. Researchers varied the food present in the water surrounding the tubeworms and then subjected the worms to simulated attacks. Worms that had been feeding in water with a relatively high food level before the attack returned to feeding more quickly than did worms from water with a relatively low food level. Worms in the high food environment were paying a higher price by staying in their tubes than worms in the low food environment. These worms abandoned the refuge more quickly than did worms paying a lower cost. The tubeworm example indicates that organisms are able to assess the potential costs and benefits of staying in a refuge, a form of risk assessment. For tubeworms, movements or shadows overhead are enough to trigger a retreat into the tube, but these are not always caused by predators. Therefore, many such retreats are likely to occur when predators are not present. Is it possible that some organisms are able to evaluate the risk of predation more precisely than tubeworms do? It may have occurred to you that any organism able to gain better information about the presence, or likely presence, of predators would have an advantage in terms of calculating the risk of leaving the refuge. Information on the frequency and predictability of predator presence could be very valuable. If predators are present in the prey habitat most of the time, then prey must be constantly vigilant. Vigilance refers to any case where animals survey their surroundings, usually by raising their heads, if they have heads. In most species, all members of a population share the responsibility for vigilance; however, in some species only one group member is vigilant at a time. This occurs in prairie dog colonies where one animal watches for predators and alerts the colony if a predator is spotted while other members feed. These animals have a well-developed social structure where group members are genetically related. An animal that watches for predators and warns of their approach pays a cost in terms of reduced feeding time because it cannot eat and watch at the same time. Additionally, by calling out to warn others, this animal may attract the predator’s attention and have a greater risk of being eaten. Pre-lab Questions—Record Your Answers on the Online Version 1. Explain why such warning behavior is likely to occur only in groups that are genetically related. 2. Do you think risk assessment would be a better strategy for a prey animal than frequent vigilance? Explain your reasoning. In the absence of warnings from conspecifics, prey have other ways of determining the presence of predators. Some prey use sound cues to detect the approach of predators. For example, moths respond to the echo-location calls from their bat predator; moths drop to the ground (a refuge) once they hear the second pulse from the bat. Scent can also provide cues to the presence of predators—you may have learned from nature programs that many terrestrial predators approach prey from a direction where the wind will not bring in their scent to alert the prey. Scent can also play a role in aquatic systems where chemical cues from the predator may be perceived by prey. Prey may also be able to detect that others of their species have been wounded or consumed by cueing on blood or body fluids in the water. 3. How would being able to detect damaged members of a prey species be beneficial to individual prey? 4. What other kinds of cues might be reliable indicators for predator presence? 5. Why might prey size influence response to a predator? Some prey for groups (aggregate in the presence of a predator. One benefit of aggregation may result from defensive action by the entire group, but another potential benefit lies in reducing the per-individual likelihood of death. Detailed studies of the behaviors of individual fish in schools show that fish are in constant motion. A fish on the outside of a school swims inward, leaving other fish on the edge. These new “edge” fish then move inward and the cycle repeats. 6. Explain how aggregation is likely to result in a greater likelihood of survival for schooling fish in the presence of a predator. 7. Explain why predators and prey with many generations of interaction are likely to have pronounced behavioral responses to each other. 8. How would you expect prey to respond to a predator they have never encountered before (a novel predator)? Explain your reasoning. Integrating Individual Behavior Across Trophic Levels In the previous section, you were asked to think about the behavior of individual predators and prey. How do combined behaviors of many individuals result in interactions among trophic levels of a food web? Recall the simple food web described previously, where birds feed on grasshoppers and grasshoppers feed on plants (Figure 7-5). 9. What is the predicted effect of bird presence on the survivorship or biomass of the plants? (Hint: if this question leaves you puzzled, it may help to think about feeding time. If there are no birds, would more or less plant tissue be eaten by grasshoppers?) 10. If you want to protect the plants from insect damage, should you encourage birds to forage on the plants, or put netting over the plants to keep birds out? Explain your reasoning. Figure 7-5 In answering questions 9 and 10, you likely discovered the concept of a trophic cascade. Insects affect plants directly, whereas birds affect plants indirectly, through their consumption of the insects. When predators indirectly benefit primary producers by controlling herbivore populations, thereby reducing the rate of feeding by herbivores, this is called a trophic cascade. In the food web in Figure 7-6, herbivorous insects are eaten by lizards and spiders. 11. Diet studies show that spiders consume small insects, whereas lizards consume larger insects and spiders. If this system is a trophic cascade, which part of the food web likely has the largest effect on plants? Explain your reasoning. Experiments have shown that removing lizards from the system leads to increased plant damage due to insects, but removing spiders has far less effect on the plants. Such removal experiments can be very helpful in understanding how a food web functions. Figure 7-6 12. The food web in Figure 7-7 depicts a four-level system. From your understanding of the effects of predators on prey, which of the fishes would you remove if you wanted to increase the survival of the population of single-celled plants? Explain your reasoning. How could you test your prediction? Kelp are large marine algae that often form underwater “forests.” These kelp forests are complex multilayered habitats that serve as home to a wide variety of marine invertebrates (animals without backbones) and vertebrates (animals with backbones). They are especially important to the survival of many populations of fishes. When a kelp forest has been removed, the resulting empty habitat is called an “urchin barren.” Figure 7-7 13. Examine the structure of the food web in Figure 7-8, and explain: a) why the empty habitat is called an “urchin barren,” and b) why urchin barrens are positively correlated with presence of killer whales. Figure 7-8 BIS 2B - Lab 7 Enter your data. Averages are Calculated Automatically Treatment 1: Mosquitos only Group Names Feeding Hiding Breathing Swimming Happy Group 0% 0% 100% 0% Funny Group 3% 0% 96% 1% Excited Group 8% 0% 91% 0% Thoughtful Group 0% 0% 100% 0% Cautious Group 4% 0% 96% 0% Group to be Named Later 7% 1% 90% 3% Total: 22% 1% 573% 4% Average Percent Time: 3.6% 0.2% 95.4% 0.7% YOUR DATA Treatment 2: Mosquito & Fish separated by a glass divider Feeding Hiding Breathing Swimming Group Names Happy Group 4% 4% 88% 5% Funny Group 1% 0% 95% 4% Excited Group 0% 0% 93% 6% Thoughtful Group 0% 0% 95% 5% Cautious Group 1% 0% 99% 0% Group to be Named Later 4% 0% 96% 0% Total: 10% 4% 566% 20% Average Percent Time: 2% 1% 94% 3% YOUR DATA Treatment 3: Mosquito & Fish together Group Names Feeding Hiding Breathing Swimming Happy Group Funny Group 0% 0% 58% 15% 37% 77% 3% 8% Excited Group 0% 0% 94% 4% Thoughtful Group 7% 1% 89% 3% Cautious Group 0% 58% 37% 3% 21% 12% 67% 0% Total: 28% 145% 401% 21% Average Percent Time: 5% 24% 67% 3% Group to be Named Later YOUR DATA Treatment 4: We won't pool data. Just use your results from your trial BIS 2B - Lab 7 Enter your data. Averages are Calculated Automatically Being Eaten 1% 0% 2% 0% 1% 0% 4% 1% ??2 15 Which of the phylogenetic trees below represent the same evolutionary relationships? Tree 1 Tree 2 Tree 3 A G B E ? F G B A A E B -C ? 0 ? O w ? ? F E O Tree 1 and Tree 3 Tree 1 and Tree 2 Tree 2 and Tree 3 All three represent the same relationships No two trees represent the same relationships ??3 15 Which of the following factors are associated with higher rates of speciation? (select all that apply) More specialization of diet Flower pollination by wind U Amating system with elaborate courtship and highly selective mating decisions The ability to efficiently travel long distances Being a vertebrate living in a terrestrial environment ??4 15 Two fish species, Species 1 and Species 2 live in the same lake at the same time and are competing for the same prey. Which of the following is/are a possible outcome of competition? Select all that apply Species 1 is better at obtaining prey than Species 2 and drives Species 2 to extinction in the habitat. Species 2 is better at obtaining prey than Species 1 and drives Species 1 to extinction in the habitat. Species 1 begins to forage for prey in the shallow portions of the lake, while Species 2 forages in the deeper parts of the lake, and both species persist in the habitat. Over time, Species 1 develops a mouth shape adapted for smaller prey individuals and Species 2 develops a mouth shape adapted to larger prey individuals, and both species persist in the habitat. ??? ???? lo larger prey is, dllU VULIT ??5 15 The figure below shows the beak size of three pairs of bird species that occur both allopatrically and sympatrically. Which species pair(s) show(s) evidence of character displacement when the two species come into contact with one another? Select all that apply. 15 15 15 Species 1 Species 20 Species 3 Species 4 o Species 50 Species 6 0 10 T T 0 0 0 Allopatry Sympatry Allopatry Sympatry Allopatry Sympatry Species 1 and 2 Species 3 and 4 Species 5 and 6 None of these pairs show evidence of character displacement ??6 15 The figure below shows population size oscillations for a fictional predator and its prey. Which of the statements below best describes what is happening in the time period marked by the gray box? prey predator density unt 1 2 3 4 5 6 7 8 time O When there are few predators, the prey population increases o As prey population size increases, predator population increases o As predator population size increases, the prey population decreases O When the prey population is small, predator abundance declines ??7 15 Within a population of sunflowers, a new individual has a novel dominant mutation that causes it to flower 4 months earlier than the rest of the population. That sunflower survives and successfully self-fertilizes, leading over time to a novel population that evolves larger leaves and smaller flowers. This new population does not interbreed with the original population, although they are found in the same areas. This is an example of_. Allopolyploid speciation Behavioral isolation Allopatric speciation Sympatric speciation O Adaptive radiation ??8 15 Which of the following would be considered an adaptive radiation? A new island forms and many different species from neighboring islands colonize it, filling the open niches A single bird species colonizes a new island and continues its same food source A bee species colonizes a new island, then diversifies quickly into many species each specialize on different local flower species O When two species of lizards colonize a new island, one adapts to living in the tops of trees while the other adapts to living on twigs All of the above ??9 15 Which reproductive barrier is most likely to prevent interbreeding between a polyploid species and its diploid sister species? Behavioral isolation: the two species will not recognize each other as mates Gametic isolation: sperm and egg with different chromosome numbers cannot complete fertilization O Hybrid infertility: differences in chromosome numbers will result in infertile hybrids Mechanical isolation: differences in reproductive structures will prevent interbreeding Temporal isolation: the two species will not reproduce at the same time of year ?? 10 15 In the Lotka-Volterra equations for predator (P) and prey (V) population sizes, shown below, what term represents the carrying capacity for each species? = dV=rV - PVP dt dP dt cpVP – d,P P and V dP and dy p and c O PVP and dpP O Carrying capacity is not represented in the Lotka-Volterra equations ?? 11 15 In the phylogenetic tree below, which group(s) are monophyletic? (select all that apply) Group 1 Group 2 Group 3 ? Group 1 Group 2 Group 3 None of these groups are monophyletic