Select all that apply. ____3. When threatened, a stickleback can simultaneously flare out its pair of pelvic spines and three dorsal spines, making it difficult for predators to swallow them. Trunk/ground. It takes energy and resources for a stickleback to develop spines. Probably not, since the environment has changed so much in the 10 million years since that ancient lake existed. Which is true? Explain why it has been so hard to find rocks more than 4 billion years old at Earth's surface. 2. They can always produce fertile offspring. When you compare the results you obtained for Bear Paw Lake and Coyote Lake to the results Dr. Bell obtained in the same two lakes, you may find your numbers to be slightly different. Which of the following is an explanation for why the stickleback is a model organism for studying evolution? One lake you will study is Bear Paw Lake. 2004. The plates also make stickleback fish difficult to eat. researchers found that mice genetically engineered to lack the function of the Pitx1 gene did not develop complete hind limbs. 10. controls the development of the pelvis and . One lake represents the control population and the other population is the one we can compare to the control. (Students may also mention that in lakes with different types of predators, such as dragonfly larvae, the pelvic spines actually make stickleback easier to . One reason that pelvis and spine loss may occur is because some freshwater populations live in low calcium environments where building a pelvis may be metabolically costly, and are preyed upon by insects that can grasp onto spines, rather than by fish that can be deterred by the spines. A line graph is the only type of graph with both dependent and independent variables. It is found in the coding region of the Pitx1 gene. differential resource exploitation The ancestral marine population of stickleback must have lacked pelvic spines. Convergent evolution is said to have occurred if the mouse species on two islands with similar habitats are found to have similar characteristics even though they originated from different species that did not have these characteristics. Specific ecological niches The study of fossil stickleback offers the advantage of studying evolutionary rates across geologic time scales, but only living stickleback lend themselves to DNA analysis. They acquired new characteristics by mating with fish that lived in these lakes. One of the functions of pelvic spines in the ocean is to protect stickleback from larger fish predators. 2. a change in a developmental gene or in its regulation that altered the spatial organization of body parts. Most stickleback fish living in the ocean sport heavy armor in the form of bony plates and spines projecting from the back and pelvis. Investigation - Stickleback Evolution (HHMI) - Google Docs To compare the trait in stickleback populations living in two potentially different environments. paedomorphosis the evolution of cellular respiration, which used oxygen to help harvest energy from organic molecules. Why do some stickleback populations lack pelvic spines? Researchers examined mating calls of closely related tree frogs in South America. To have a larger number of specimens to score, increasing the accuracy of results. Gene flow between the two populations is extensive. Based on what you have learned so far about threespine stickleback fish, which of the following statements is most accurate: Why? Hybrids have poor survival and reproduction and thus produce few viable offspring with members of either parent species. Because fish don't need hind limbs to walk, many populations of fish evolved to lack pelvic spines. From this observation, They contain more than two haploid sets of chromosomes. ), The atmosphere of early Earth probably contained no O2 until the emergence of organisms that, used water as an electron source for photosynthesis Various explanations for the loss of spines have been suggested including lack of predator pressure and reduced levels of calcium. Major morphological changes in the hindfin skeletons . have strong pre-zygotic barriers Why do some stickleback populations lack pelvic spines? Using only these facts, perform the following operations. transcription Experimentally induced autotetraploidy and allotetraploidy in two Japanese pond frogs. 12. Hybrids have poor survival and reproduction and thus produce few viable offspring with members of either parent species. Why? The gene remains intact, but the location of its expression changesconveying a new phenotype without losing existing capabilities.). transcription Stickleback populations swam to freshwater lakes to spawn and stayed because there were no predators. The production of sterile mules by interbreeding between female horses (mares) and male donkeys (jacks) is an example of _____. Freshwater fish have evolved different types of protective armor to keep them safe from predators. 5. Interactive Video: Evolving Switches, Evolving Bodies: HHMI BioInteractive 9. Make a prediction about what would happen in an isolated lake with few predators if humans introduced predatory fish like trout. Some strands of RNA replicate more often and with more mutations. This means that, in this ancient lake, the frequency of stickleback with pelvic spines decreased over time. In lakes where there are no predatory fish, there is no advantage to having pelvic spines. The evolution of different ecomorphs on the Caribbean islands is an example of stabilizing selection. Polyploidy an area where members of two closely related species intermingle, but gene flow is prevented by prezygotic barriers That means those with a complete pelvis were more likely to survive, reproduce, and pass on their genes to the next generation. If you conducted the analysis portion of Experiment 2, you calculated the rate at which the percentage of fish with a complete pelvis decreased in that ancient lake. Which of the following statements about reinforcement is true? ____3. This suggests that pelvic spines imposed a selective disadvantage compared to the reduced or absent phenotypes, which means that there probably were no large predatory fish in the lake. Chapter 25 TEST Flashcards | Quizlet Use a bar graph to graph your data. A hybrid zone is properly defined as _____. prezygotic isolating mechanisms are in place especially important in the evolution of island species 1. Adaptive radiation The skeleton of three-spine stickleback, including pelvic spines and associated pelvic girdle, is reduced to varying extents in different populations [1]. The genetic relatedness of ecomorphs was determined by comparing their nuclear DNA sequences. Geographical isolation 3. Is the following statement true or false? What would you expect if you compare the calls of the two species in sympatry vs. in allopatry? Shaded bars represent those with a right bias. Which statement below best describes what happened to the stickleback population in the ancient lake that is now the Truckee Formation? Panel A of the figure shows SNP genotyping . Frog Lake and Bear Paw Lake are two lakes with very similar stickleback populations. HS-LS4-1, HS-LS4-2, HS-LS4-4, HS-LS3-1; SEP2, SEP4, SEP5, EVO-1.H, EVO-1.J, EVO-1.N, IST-1.J; SP1, SP2, SP4, The Making of the Fittest: Evolving Switches, Evolving Bodies, Schooling Behavior of Stickleback Fish from Different Habitats, Using Genetic Crosses to Analyze a Stickleback Trait, Using Genetic Evidence to Identify Ivory Poaching Hotspots, Genetic Origin of Variation in Human Skin Color, Effects of Natural Selection on Finch Beak Size, Mimicry in a Diverse Community of Arthropods, Lactase Persistence: Evidence for Selection, The Making of the Fittest: Natural Selection and Adaptation. In lakes with dragonfly larvae, pelvic spines can be disadvantageous, allowing the predatory larvae to grab the fish. Genetic drift occurred in the two populations. Click on the link at the top of the page to go to the "overview," then click on the interactive fish. Explain your reasoning. PDF Stickleback Spines Phenomenal Image Educator Materials True or false? The correct answer is "+prefsArray[190]+". right side. The scientists used these data to estimate the locations of deletion mutations in each population. sexual selection hybrids have lower fitness than either parent population The populations will be able to interbreed even though they are different species. 6. The results from Bear Paw Lake (BP) and Coyote Lake (Co) stickleback obtained in this experiment of the virtual lab are completely different from those presented in the graph for these populations. The tetraploids would be reproductively isolated from both parent species. This page is a draft and is under active development. Week 7 Lab - Stickleback fish lab - Stickleback - How do spines protect Allopatry Because fish don't need hind limbs to walk, many populations of fish evolved to lack pelvic spines. 1. reinforcement Dr. Bell's study did not examine fish from these two lakes. By analyzing so many fish, you have a greater chance of making errors. You can't. If the same morphological changes occur in the fossil record as in living populations, we might deduce that the genetic mechanism discovered in the living populations might be responsible for the changes observed in fossils. The island sinks and the population of birds that lived on the island returns to its original habitat. The motion of continental plates over time The correct answer is "+prefsArray[190]+". The reduced pelvic phenotypes have never been observed in marine and sea-run populations; the pelvic spines protect marine and sea-run sticklebacks from larger fish that prey on them in the ocean. Male frogs give calls that attract female frogs to approach and mate. 5. This suggests that similar molecular mechanisms may have been responsible for pelvic reduction in fossil and modern stickleback populations. In layers 1 and 2 (the oldest layers), most fossil stickleback have a complete pelvis, which means they had pelvic spines. unit cell. translation, Which of these indicates an enhancer region (what Dr. Kingsley called a "switch" in the regulation of the Pitx1 gene in threespine sticklebacks)? If the same morphological changes occur in the fossil record as in living populations, we might deduce that the genetic mechanism discovered in the living populations might be responsible for the changes observed in fossils. If you are returning to continue the interactive video, select "Resume." The food webs that characterize organisms in Bear Paw Lake and Frog Lake are virtually identical. Reinforcement is also called dispersive selection. Each rock layer represents sediment that was deposited year after year, and today the layers are stacked one on top of the other. if (prefsArray[119] == "0") { Why? In lakes with dragonfly larvae, pelvic spines can be disadvantageous, allowing the predatory larvae to grab the fish. How did ancestral populations of ocean-dwelling fish come to live in freshwater lakes? Based on the example discussed in Figures 24.11 and 24.15, the most likely explanation for the recent decline in cichlid species diversity in Lake Victoria (other than predation by introduced Nile perch), is _____. The tetraploids would be reproductively isolated from both parent species. Which organisms are not examples of an adaptive radiation? The two parent species would interbreed and fuse into one species. disruptive selection Longer or shorter spines: Reciprocal trait evolution in stickleback via Genetic evidence reveals the precise molecular mechanism responsible for the change in pelvic structures in stickleback populations. When different people conduct the same experiment, the results are going to be different. The population of fish with pelvic spines that arrived in the lake at time B evolved a reduced pelvis over time (beginning at time C). Dorsal spine evolution in threespine sticklebacks via a splicing change Studying modern stickleback populations gives us insight into the selection pressures acting on the stickleback pelvis. The population size of stickleback fish dropped dramatically, leaving only a few survivors, all of which have the absent pelvic phenotype. Crown By the end of the studied period (time D) there was an approximately equal number of sticklebacks with and without spines. In Experiment 1, it was appropriate to graph the data using a bar graph because you were comparing traits in two populations at the same snapshot in time. Modifications to those traits are usually made in small, incremental steps, and new inventions are rare. Which of the following has been shown to cause speciation most rapidly? Explain your answer. The loss of the pelvic spines is similar to the loss of which body parts in other four-legged vertebrates? ), A genetic change that caused a certain Hox gene to be expressed along the tip of a vertebrate limb bud instead of farther back helped make possible the evolution of the tetrapod limb. 2. The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. ), Applications and Investigations In Earth Science, Dennis G. Tasa, Edward J. Tarbuck, Frederick K. Lutgens, Latin America- How events of the past shaped. In seawater, pelvic spines help fish swim faster, but not in freshwater. translation, What name is given to the process in which the information encoded in a strand of mRNA is used to construct a protein? 6. mass extinction Why are random samples used rather than the entire population? The largest unit within which gene flow can readily occur is _____. When sea-run stickleback colonized freshwater lakes, some of the populations changed dramatically. Estimate Avogadro's number to four significant figures. Therefore, any change seen in the fossil record can be seen again in current evolutionary processes, provided that the selective pressures acting on the various populations are different. Flies were about as likely to mate with flies from different starch-adapted populations as with flies from their own starch-adapted population. 3. Over many generations the pelvic structures in Bear Paw Lake stickleback have remained the same, and the stickleback in Frog Lake have gained their pelvic spines. Conspecifics, True or false? All the sticklebacks from Frog Lake should have a complete pelvis. Why did Kingsley and his team cross marine and freshwater sticklebacks? The populations will not be able to interbreed because they are different species. Natural selection favored individuals that were more fit in the new environment. In this virtual lab, why did you compare pelvic structures of stickleback populations from two different lakes? What might be a reasonable explanation for the difference? Most fish could not be scored one way or another because a bias was not apparent. Some freshwater sticklebacks, however, either partially or completely lack a pelvis. ), "tinkering" with existing structures the appearance of a new species in the same geographical area as the parent population Name the part of the chloroplast where the Calvin cycle takes place. : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Investigation:_Earthworm" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Investigation:_Gene_Switches_in_Stickleback_Fish" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Investigation:_Phylogenetic_Trees" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Investigation_-_Proteins_Sequences:_Are_Bats_Birds?" Nondisjunction event during meiosis genetic drift, The appearance of an evolutionary novelty promotes _____. In 1990, Dr. Michael Bell and colleagues examined 210 fish from Bear Paw Lake and 192 fish from Frog Lake. This is still a sufficient sample size in either lake to statistically detect whether there is a difference between the numbers of fish with left bias and right bias. statement: Left-biased pelvic asymmetry appears to be a signature of the loss of function of the Pitx1 gene. Summarize what happened to the fish in Loberg Lake, include an explanation for WHY it happened. A line graph is the only type of graph that can include time as one of the variables. adaptive radiation, The different finch species found on the Galpagos Islands probably arose as a result of _____. hybridization Select all that apply. their chromosomes are no longer homologous enough to permit meiosis. The pelvic spines make it hard for large predators to swallow stickleback fish. gliding An annotated version of the article is also available from Science in the Classroom. As they adapted to life in fresh water, all stickleback populations living in lakes in Alaska underwent exactly the same evolutionary changes. In lakes where there are no large predatory fish, there is no advantage to having pelvic spines. Adaptive radiation occurs within a single lineage. Why? Click on Experiment 1 to read the objective. 16. if (prefsArray[192] == prefsArray[189]) { These new arrivals _____. How does continental drift affect living organisms? After you have scored all of the Bear Paw Lake fish, indicate the number that were: Absent _____ Reduced _____ Complete _____. The upper side is kept at 25C and the other sides are kept at 0C. tend to retard adaptation to the new food plants. 14. Mammals and reptiles in the post-dinosaur age. These results should be in general agreement with the results you graphed in Part 3 of this experiment. Why do some stickleback populations lack pelvic spines? Thus, over many generations the A. It occurred in a similar DNA region in freshwater stickleback populations all over the world. What did researchers discover about the genetic mutation causing the loss of pelvic spines? It occurred in a similar DNA region in freshwater stickleback populations all over the world. Why do some stickleback populations lack pelvic spines? All three answers are correct. B Which is true? document.write("--"); Some freshwater stickleback populations have reduced armor or none at all. In lakes where there are no large predatory fish, there is no advantage to having pelvic spines. Why do some stickleback populations lack pelvic spines? 11. Describe the location of the stickleback spine. Activators J. Exp. gene flow To decipher the changes at the origin of these . Based on this knowledge and your findings in this exercise, would you agree or disagree with the following Yellow-bellied toads and fire-bellied toads are two different species. A population of birds colonizes an area in which the insects upon which they feed live inside trees. The presence of pelvic spines, like many physical features, is determined by genetics. Watch the video about pelvic reduction in freshwater stickleback. Which of the following statements is supported by the data from the control group matings? The evolution of pelvic reduction seen in the fossil record is different from the phenomenon occurring in the lakes in Alaska today. More advantageous traits in a particular environment allow individuals with those traits to have more offspring; as a result their heritable traits become more common in succeeding generations of the population. The lake in Nevada was originally populated by stickleback with pelvic spines, but large predatory fishes outcompeted these stickleback for food, which almost drove the stickleback population to extinction. 1. Random sampling is the only way to collect fish when using traps. document.write("--"); Each of the other lakes has more fish with a left bias, as indicated by the higher unshaded bar compared to the shaded bar. Gene flow Watch the video about stickleback fish armor. In areas of sympatry, reinforcement is expected to occur. Measuring three to 10 centimetres long, stickleback fish originated in the ocean but began populating freshwater lakes and streams following the last ice age.
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