Could you please use POPULUS to answer these questions? Please answer it from your observation, do not use google to answer it.

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Nuzrq1997U

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Wilkes University

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Hi there,

Could you please use POPULUS to answer these questions? POPULUS is a free application that graph two compete species. The link to download POPULUS provide in this page. Please answer it from your observation, do not use google to answer it. However, you can use google to understand some definition.

Some steps help you to know how to start on POPULUS:

At the main menu in Populus, choose "Multi-Species Interactions". On the multi-species interactions menu choose "Lotka-Volterra Competition". This will get you into the model that we will use this week. In case you need a refresher about the material, the Help Menu in Populus opens a pdf file that reviews ecological concepts and processes modeled by the program.

The Lotka-Volterra model of competition is a simple extension of the logistic model of intraspecific competition and population growth, with the added complications of equations for two (or more) species, and the addition of interspecific competition coefficients. In the two species case Populus designates the competition coefficients as a and b, where a is the effect of species 2 on species 1, and b is the effect of species 1 on species 2. Note that in the book the equivalent terminology for a is α 12 and for b is α 21. The remaining terminology (r, K, N) is the same as in the logistic model.

POPULUS linke:

https://cbs.umn.edu/populus/download-populus

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HW Exercise: Competition and the Lotka Volterra Equation Green sunfish and bluegill competition: You have both green sunfish (Lepomis cyanellus) and bluegill (L. macrochirus) available for stocking in a 10 ha impoundment. These two species compete to some degree; pertinent population data are: Green sunfish Bluegill K1 = 600 K2 = 600 r1 = 0.10 r2 = 0.10 a12 = 1.50 a21 = 0.90 1. Is there some level of competition between these 2 species? How do you know? 2. Would you classify these species as weak, moderate, or strong competitors? Think about population density. 3. Which species appears to be the stronger competitor? Why? 4. What would the phase-plane diagram look like for this situation? 5. What outcome would you predict if we started with 100 of each species? 6. How would we "test" if there is really competition between these 2 species? Note: You can save *.jpg files of your output graphs from POPULUS. In the 'Output' window, click on 'File' and then select 'Save output graph to file'. Save graphs that will help answer the following questions, and insert them into the word file with your answers where appropriate. 7. Use program POPULUS to simulate the population growth of 100 green sunfish growing alone (i.e., without bluegills present). Was the projected growth what you expected (i.e, logistic growth)? Did the population reach carrying capacity? If so, what was it and how many years did it take to reach K? 8. Use program POPULUS to simulate the population growth of 100 bluegill growing alone (i.e., without sunfish present). Was the projected growth what you expected (i.e, logistic growth)? Did the population reach carrying capacity? If so, what was it and how many years did it take to reach K? 9. If you initially stocked 100 sunfish and 100 bluegill, what is the projected population size of each species in 5 years? 10 years? 40 years? Was your predicted outcome (question #5) correct? Adapted from an exercise by Dr. Dave Oleyar, Department of Fish and Wildlife Resources, College of Natural Resources, University of Idaho HW Exercise: Competition and the Lotka Volterra Equation 10. Compare the population projections of each species when grown alone and together. How did "competition" affect the growth of each species? Was your guess about which species was the stronger competitor correct? 11. What would happen if you used the same initial population sizes but changed the following data: o Green sunfish: K1 = 600, r1=0.10, a12=1.45 o Bluegill: K2=700, r2=0.30, a21=0.95 Note: Be sure to look at both plot types (i.e., N vs t and N2 vs N1). And choose 'Run until steady' for your Termination conditions. 12. What would happen if we took the input parameters from question #11 and changed the initial population sizes to N1=10 and N2=100? 13. Are these projections realistic? Why or why not? (Hint: Think about the assumptions of the model). Submit your answers to these questions before class on Thursday, October 24 Adapted from an exercise by Dr. Dave Oleyar, Department of Fish and Wildlife Resources, College of Natural Resources, University of Idaho
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Explanation & Answer

Hey! I completed the questions! To be honest, I cannot answer Q2 with much of a certainty, since there is no initial population given to answer. If I had to make an explanation I'd say this:Since the intrinsic rate of increase is very low for both species, it means that the population density does not increase rapidly (since there is a very slow reproduction rate). Thus, the species would not compete for the space in the short term. So, it makes them weak competitors.If you want anything else, don't hesitate to ask me!

1) Since α12 ≥ 0 and α21 ≥ 0, of course there is a competition between the two species.
2) ???
3) Lepomis macrochirus is the stronger competitor, since its effect on Lepomis cyanellus is
greater than the the inverse (in other words, α12 > α21)
4) This will be the phase-plane graph:

5) The 2nd species would displace the other, since it would be , thus the 1 st would be extinct.
6) Something that could test the interspecies competition is increasing/decreasing the
population of each species and observe the response of the other species.

7) As seen from the graph, the increase was logistic and Species 1 did reach its carrying
capacity, 600, something that was expected since it does not have a competition. It took it
almost 65 years to reach its carrying capacity, as shown above.

8) As seen from the graph, the increase was logistic and Species 2 did reach its carrying
capacity, 600, something that was expected since it does not have a competition. It took it
also...


Anonymous
This is great! Exactly what I wanted.

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