hybrids have lower fitness than either parent population C. Which of the following statements about the evolution of Anolis lizards in the Caribbean islands is true? List at least two reasons. The isolated population is exposed to different selection pressures than the ancestral population. 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. These populations swam to freshwater lakes to spawn and then never returned to the ocean because there were fewer predators in lakes. They don't actually live exclusively in fresh water; they only live in freshwater at certain stages in their lives. An annotated version of the article is also available from Science in the Classroom. ), Hox genes are thought to play an important role in the development of different morphologies because, they provide positional information in the embryo For example, the presence of pelvic spines is correlated with the presence of large predatory fish, which suggests that stickleback use the pelvic spines for defense against predatory fish. Initially, very few fossil stickleback sampled had the complete pelvic phenotype, but in the following 15,000 years, the frequency of this phenotype in the population increased significantly. Trunk/ground. 5. Watch the video about pelvic reduction in freshwater stickleback. The loss of the pelvic spines is similar to the loss of which body parts in other four-legged vertebrates? The Educator Materials document includes a captioned figure, background information, graph interpretation, and discussion questions. Which of the following statements about adaptive radiation is correct? The pelvic spines are homologous to legs in four-legged animals. 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. The physical splitting of a habitat, A change in allele frequencies caused by random events. Which of the following statements about reinforcement is true? 12. Investigation - Stickleback Evolution (HHMI) - Google Docs flight What happened to these fish as they adapted to living exclusively in freshwater? Because fish don't need hind limbs to walk, many populations of fish evolved to lack pelvic spines. To have a larger number of specimens to score, increasing the accuracy of results. Chapter 15 Flashcards | Quizlet Which of the following statements might be a plausible conclusion for these findings? artificial selection A line graph is the only type of graph that can include time as one of the variables. In Coyote Lake, most fish with reduced pelvises have a vestige that is larger on the left than on the right, whereas most fish in Bear Paw Lake do not show any bias. In this virtual lab, why did you compare pelvic structures of stickleback populations from two different lakes? 3. The same adaptation - a lack of pelvic spines in freshwater stickleback - occurred 10 million years ago. A flood that separates a population of frogs onto opposite sides of a lake is an example of a vicariance event that may result in allopatric speciation. One lake represents the control population and the other population is the one we can compare to the control. The mice without a The evolution of the swim bladder from lungs of an ancestral fish is an example of, are found in the deepest strata All three answers are correct. To find the location of the gene(s) causing the difference between stickleback populations with and without spines. the appearance of a new species in the same geographical area as the parent population Phylogeny The production of sterile mules by interbreeding between female horses (mares) and male donkeys (jacks) is an example of _____. Journal of Herpetology 38(3):381-92.) Sympatric speciation is _____. In this population, having pelvic spines seemed to provide a selective advantage to stickleback fish. Mutations occur at random in a population causing populations to change over time as those mutations are inherited from one generation to the next. 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. Some freshwater stickleback populations have reduced armor or none at all. 2. the evolution of reproductive isolation It is found in a regulatory region (a "switch") upstream of the coding region of the Pitx1 gene. Panel A of the figure shows SNP genotyping . Geographical isolation 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. All the sticklebacks from Frog Lake should have a complete pelvis. Sticklebacks developed traits that made them better adapted to fresh water and, as a result, they moved to a freshwater environment. Which of the following is a definition of the process of natural selection? When different people conduct the same experiment, the results are going to be different. Investigation - Stickleback Evolution (HHMI) - Google Docs Calls would be about the same in both areas. What was the main selective pressure behind the evolution of different Anolis lizard species in the Caribbean? Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. ), prokaryotic Gene flow between the two populations is extensive. a change in a developmental gene or in its regulation that altered the spatial organization of body parts. Microevolution, Mass extinctions create conditions that promote _____. About twice a year, one or two more birds from the neighboring island arrive. Why do some stickleback populations lack pelvic spines? Adaptive radiation occurs within a single lineage. Because fish don't need hind limbs to walk, many populations of fish evolved to lack pelvic spines. The phylogeny of ecomorphs on a given island reveals that adaptive radiation has taken place. A crown ecomorph living on one island is always the same species as a crown ecomorph living on a neighboring island. How do multiple lines of evidence (from the field, the fossil record, and molecular genetics) work together to illustrate stickleback evolution? Marine (top) have a large pelvic hindfin that has been lost in some populations that have evolved in different freshwater locations (bottom). In this virtual lab, why did you compare pelvic structures of stickleback populations from two different lakes? B. document.write("

Correct! Your answer: " +prefsArray[195]+". Honeycreeper songbirds of the Hawaiian islands The molecular mechanisms underlying major phenotypic changes that have evolved repeatedly in nature are generally unknown. right side. Dorsal spine and anal spine lengths map to chromosome 4. 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. Yellow-bellied toads and fire-bellied toads are two different species. RNA processing Dorsal spine evolution in threespine sticklebacks via a splicing change 14. "); Thus, in the first three lakes (abbreviated O, L, and CV), fish with right-biased pelvic reduction are more numerous. Because stickleback in Bear Paw Lake lack pelvic spines, we can infer that over time, the sea-run stickleback that founded this population evolved a reduced pelvis. the process by which most animal species have evolved 8. A. Stickleback populations have evolved recently and repeatedly in postglacial lakes. on their underside surface. Which do you think is the best view (lateral or ventral) for determining the type of pelvis? Studying modern stickleback populations gives us insight into the selection pressures acting on the stickleback pelvis. Adaptive radiation Adaptive radiation occurs within a single lineage. Give an example of sampling bias. Analysis of fossil stickleback shows us that threespine stickleback living millions of years ago looked strikingly different from those living today. To compare the Pitx1 protein-coding sequence from fish with and without pelvises. 5. Toads mate only with their own kind in order to avoid producing unhealthy hybrid young. Describe how genotyping techniques can be used to identify genes associated with certain traits. Most stickleback fish living in the ocean sport heavy armor in the form of bony plates and spines projecting from the back and pelvis. The unshaded bars represent stickleback with a larger vestige on the left. Adaptive radiation occurs in the presence of competitors. Random sampling is the only way to collect fish when using traps. transcription Competitors The fossil data show a pattern of evolution over long stretches of time. It occurred in a similar DNA region in freshwater stickleback populations all over the world. This page is a draft and is under active development. 6. Chapter 25 TEST Flashcards | Quizlet To test whether Pitx1 was involved in the formation of pelvic spines. The tetraploids would be selected against. In contrast, the pelvises in stickleback from Frog Lake still look like those of sea-run stickleback, and thus, we can infer that this trait was retained. document.write("--"); } else { Various explanations for the loss of spines have been suggested including lack of predator pressure and reduced levels of calcium. Why did Kingsley and his team cross marine and freshwater sticklebacks? Gene flow between the two populations is extensive. Panel B shows the sources of each population. Some stickleback populations that swam to freshwater lakes to spawn stayed because there were no predators at the end of the last ice age. the ocean, and/or that the cost of producing spines is much greater in Bear Paw Lake than it is in the ocean. Most or all fish in Bear Paw Lake and Coyote Lake have a pelvic vestige that is larger on the left than on the right (i.e., left-biased pelvic asymmetry). Theoretically, the production of sterile mules by interbreeding between female horses (mares) and male donkeys (jacks) should. Since the new environments were so similar to their old environments, their traits changed. "); In stickleback, the pelvic fin consists of one fin ray and a large, serrated, locking pelvic spine that articulates with an underlying pelvis and can be raised and lowered as a defense against predators . Why was it appropriate to use a line graph to summarize the results from this experiment? Because fish don't need hind limbs to walk, many populations of fish evolved to lack pelvic spines. Which of the following statements is supported by the data from the control group matings? gliding Stickleback in Frog Lake will lose their pelvic spines before the next ice age. Some strands of RNA replicate more often and with more mutations.

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