Assignment 3

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University of North Texas *

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3160

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Statistics

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Jun 13, 2024

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Assignment 3 Name: ____Tony Espinal_______ Date: _________5/20/2024______________ For Assignment 3, I want you to work through four Donovan Modules that go over various methods for calculating population demography and PVA for plant and wildlife populations. These are population level estimates derived from scaling individual estimates and pooling the average across the population. This is an important distinction to keep in mind. Population level estimates do not apply to individuals, they apply to populations and provide us insight into the viability of the population, from which we can infer information on the stability and quality of the landscape that the species/population occupies. For this assignment, you will work through the modules and answer the question below. These questions are a summary of the questions from the Donovan Module. You need not answer all the questions from the Donovan modules, just the subset and summary questions below. They are organized by chapter below. Chapter 11 Q1.) What are the assumptions of the age-structured matrix model you have created in this exercise? No genetic age or sex structures as well as all individuals being reproductively active. Q2.) Based on Figure 5. Is the population Increasing, stable or decreasing –past a copy of Fog. 5. The populations increasing. Q3.) Based on Figure 7, at what point does the plot asymptote? This is the point at which a stable age distribution is reached. At this point the value of λ t is λ. What is λ? Paste Figure 7 here. The plot Asymptotes at 19 years; λ = 1.18

Chapter 12 Q1.) What are the assumptions of the age-structured matrix model you have created in this exercise? All individuals in population make the same contribution to population change without taking size, age, sex, stage or genetics into play. Q2.) What is λ? How would you describe the finite rate of population growth for this sea-turtle population, is it growing, stable, or declining? Declining λ= 0.95158 Q3.) What is the composition of the population (proportion of individuals that are hatchlings, small juveniles, large juveniles, subadults, and adults) when the population has reached a stable distribution? Set up the headings shown below. In the cell below the Hatchlings cell (cell I11) enter a formula (See Donovan Ch 11 Q2 for formula) to calculate the proportion of the total population in year 100 that consists of hatchlings (assuming λ t has stabilized by year 100). Enter formulae to compute the proportions of the remaining stage classes in cells below the other stage-class headings. The five proportions calculated should sum to 1, and give the stable stage distribution. I J K L M Hatchlings Small Juvs. Large Juvs Sub Adults Adults Q4.) One of the threats to the loggerhead sea turtle is accidental capture and drowning in shrimp trawls. One way to prevent this occurrence is to install escape hatches in shrimp trawl nets. These “turtle exclusion devices” (TEDS) can drastically reduce the mortality of larger turtles. The following matrix shows what might happen to the stage matrix if TEDS were widely installed in existing trawl nets:

If the initial abundance is 100,000 turtles, distributed among stages at 30,000 hatchlings, 50,000 small juveniles, 18,000 large juveniles, and 2,000 subadults, and 1 adult, how does the use of TEDS influence population dynamics? Provide a graph and discuss your answer in terms of population size, structure, and growth. Discuss how the use of TEDS affects the F and P parameters in the Lefkovitch matrix. TEDS increases fecundity of subadults and adults, while increasing the probability of survival in every life stage. Population increases yearly while age distribution stabilizes after 83 years

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Q5.) Compare and contrast the differences between stage-specific and age-specific matrix models. When might one be advantageous over the other? Stage specific matrix model is more for the life span of a individual rather than a specific age. Comparing ages are better for species with short life spans/species who change significantly when aging. In the case of people some age quicker than other skewing data. Stage is more useful in humans as you can find more similarity in them rather than looking at simply age. Chapter 13 Q.1) Interpret the reproductive values from your models from the standpoint of conservation of a game species whose populations are harvested and maintained at a high level, versus a pest species whose populations you would like to reduce or eliminate, versus a threatened species that is being reintroduced to an area. For each situation, which actions would you recommend based on your knowledge of reproductive values (e.g., which age class should be harvested; which age class should be reintroduced?) Does it matter how abundant each age class is when the population stabilizes? Game species are supposed to include death but when making guided efforts the numbers are actually lower as if they had chose to emigrate themselves. In order to maintain a consistant population we’d leave level 1 alone to grow and go through some cycles and begin harvest at level 2and even more at level 3 in order to prevent an influx of level 1’s every year. Pest species however can be harvested at all ages. There is no keystone level group, but if a drop in population is what is wanted then eliminating level 1 and 2’s will drastically drop there population by about half. Threatened species should be reintroduces at level 1 into the habitat in order to increase levls of survival as they are young and will have a full life of being able to reproduce ahead of them.

Q2.) Choose a species of interest to you (maybe e.g., your Green List Species). Conduct a Google Search to find life history data to parameterize either an age or stage specific (see Ch 14 for calculations if needed) Leslie matrix parameters to the best of your knowledge. What are λ and r? What is the long-term likelihood of persistence of the population? Paste appropriate graphs as needed to justify your explanations. As im already researching the dhole I figure this would be the perfect subject to research, the reproductivity of the dhole. With the survivorship data and avg number of pups per liter Fx=sxmx+1 For Sx theres a survival rate of .88 Mx is 3.75 since mothers have 7.5 pups per liter Fecundity is 4.3

Lambda never stabilizes yet trianually goes rfom 2.11 to 1.206 to 1.074. We were confused on the determination of R and hope the chart would suffice

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