Wildlife Analyzing Genetic Evidence

CSI Wildlife: Analyzing Genetic Evidence INTRODUCTION This worksheet walks through Case One and Case Two of the CSI Wildlife Click & Learn, except for the Frequency Primer section at the end of Case One. A separate document, entitled “Frequency Primer,” may be used for that section. In this Click & Learn, you will analyze genetic evidence to solve two cases of elephant poaching based on real events. PROCEDURE As you go through the Click & Learn, follow the instructions below and answer the questions in the space provided. CSI Wildlife Introduction Read the introduction and watch the opening video. 1. What is a keystone species? A keystone species is a species which if removed would cause the decline of an ecosystem. 2. Dr. Wasser states that approximately 50,000 African elephants are killed each year. According to the video, it is estimated that there are around 470,000 African elephants. If these numbers are correct, approximately what percentage of African elephants are killed each year? Show your work. 50,000 divided by 470,000 would mean 10.6% of African elephants are killed each year. 3. In one or two sentences, summarize Dr. Wasser’s research and how it is being used to conserve elephants. Dr. Wasser's research is being used to deduce the areas where elephant ivory comes from using DNA testing and then having law enforcement focus on those areas. Case One Watch the video and read the introduction on the first slide (“The Crime Scene”). 4. Explain the goal of the case. The goal of the case is to identify the origin of the ivory to better protect against future poachers. 5. Look at the map on the screen. List the region or countries the majority of African elephants inhabit. African elephants primarily inhabit the Democrtic Republic of the Congo and close surrounding areas. CS CSII W Wildlif ildlif ildlifee: Ana naly ly lyzi zi zing ng Geneti eneticc Evi vidence dence Go to the next slide (“How DNA Profiling Works”) and read through the Background section. 6. Look at the gel on the screen. What do the bands on the gel represent? The bands on the gel represent the DNA profile. 7. DNA profiling is also called DNA fingerprinting. A common misconception about DNA fingerprinting is that the analysis has to do with actual fingerprints. Explain one similarity and one difference between a human being’s pattern of bands on an electrophoresis gel and a human fingerprint. A humans DNA fingerprinting and actual fingerprint are both unique to a single individual however fingerprints are a very visible trait whereas DNA fingerprinting is requires special equipment to see. Read through the Technique section. 8. A scientist makes primers specific to a particular STR fragment. These primers are then used to amplify the STR fragment from 10 different elephants. Would you expect the fragments to be the same size in all the elephants? Explain your answer. Due to the ten different elephants having unique DNA to each individual elephant the fragments would not all be the same 9. What is the relationship between the size of a DNA fragment and the distance it migrates in the gel? the longer fragments travel shorter distances making the relationship between size and distance inverse. Run the gel on the screen by pressing the Start button. 10. Which elephant (left or right) has both the largest and smallest fragments? right 11. Approximately what sizes (in bp) are the largest and smallest fragments? 190 bp largest, 63 bp smallest Read through the Application section. 12. Look at the gel on the screen. For Marker C, are the two elephants shown homozygous or heterozygous? How do you know? Heterozygous because two different bands appear on the gel. 13. Why do you think scientists use multiple markers to identify individual elephants? Using more markers means less chance of similarities. CS CSII W Wildlif ildlif ildlifee: Ana naly ly lyzi zi zing ng Geneti eneticc Evi vidence dence Answer the questions in the Review section. 14. Show how you calculated the number of base pairs in the 10-repeat unit. 10x4=40+9=49 bp Go to the next slide (“Finding a Match”) and answer the question, then watch the video on the “Case Solved” slide. 15. Name two properties of a good marker and explain why good markers are important. Two properties of a good marker is high variabiklity and ability to amplify, this allows clear genetic representation to show exactly what the Dna came from. Case Two Watch the video and read the introduction on the first slide (“The Crime Scene”). 16. In Case One, you were looking for a match with an individual elephant. How does Case Two differ from Case One? Case two, you are looking for a region with the multiple types of elephants the tusks came from. Go to the next slide (“Building a Reference Map”). Read through the Background, Technique, and Applications sections. 17. For the gel in the Applications section, why does the lane for the ivory sample contain only two bands while the other lanes (A and B) have multiple bands? The ivory sample is of individual elephants whereas lane A and B is the composition of all alelles from each population. 18. If an ivory sample has two alleles that are also found in a population sample, does that tell you with certainty that the ivory sample came from that population? Explain your answer. No, it narrows down which population the elephants with that ivory would be near. Answer the questions in the Review section. 19. If the scientist had collected 20 dung samples, would you expect more bands, fewer bands, or the same number of bands on the gel? Explain your answer. You would get more bands in the gel because more samples would provide more fragments. CS CSII W Wildlif ildlif ildlifee: Ana naly ly lyzi zi zing ng Geneti eneticc Evi vidence dence Go to the next slide (“Finding a Location”). Answer the questions until you reach the Eliminating North, East, or South section. 20. The three populations that were chosen for further analysis are geographically distant from one another. Why does this approach make more sense than choosing three populations that are geographically close to one another? This makes more sense because it allows for a larger area to be studied and eliminates larger areas when studying the DNA therefore the scientist's can deduce which area is more likely to be near a sample. 21. In the “Eliminating North, East, or South” section, which population did you eliminate, and which marker(s) helped you make this choice? I eieminated the forest elephants because the allele samples where only present among the savana elephant population. 22. In the next section, which population did you eliminate, and which marker(s) helped you make this choice? I eliminated the north population because it did not have some of the alleles present in the bands. Read through the last slide of Case Two (“Case Solved”). 23. By analyzing many more markers and all the populations, Dr. Wasser linked these seized ivory tusks to which country? East Africa Ivory Trade Watch the video and read through the final slide (“Stopping Illegal Poaching”). 24. Name two reasons elephant populations are threatened. Elephant populations are threatened due to habitat destruction and ivory poaching both of which are cause by human destruction. 25. The introduction to the Click & Learn mentioned that elephants are a keystone species. Based on your knowledge of this term, explain in your own words why it is important to the ecosystems of Africa to save the elephant populations. African elephants need saved because without them being around to dig watering holes and trappling dense areas, many other species could not survive the habitat in Africa.