LAB 8 Question Sheet answers

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LAB 8: Age Structure Part I – Assignment Template This is part 1 of the populations assignment. Part II will be completed next week. Read the Lab Manual Outline for Lab 8 on D2L!! ANSWER IN POINT FORM! Submit this to the Populations Assignment Folder on D2L. Preferably, this will be submitted before you leave lab. The deadline for Part I is November 11 th . • Submit this word document with questions completed. This document must include the answers, tables and graphs for full marks! POINT FORM ANSWERS! Dall Mountain Sheep 1. Using raw data for Dall sheep (Table 1) complete the life table calculations in excel. Paste the table below. Include a caption. Table 1: The life table for cohort of dall sheeps starting at age 0 until the population reach 0 (Insignificant value then) Date of spring census Age in years (x) No. of sheep alive (nx) l x (always 1000 at age 0) d x m x L x T x e x 1959 0 302.000 1000.000 198.675 0.199 900.662 7099.338 7.099 1960 1 242 801.325 9.934 0.012 796.358 6198.675 7.736 1961 2 239 791.391 13.245 0.017 784.768 5402.318 6.826 1962 3 235 778.146 9.934 0.013 773.179 4617.550 5.934 1963 4 232 768.212 29.801 0.039 753.311 3844.371 5.004 1964 5 223 738.411 46.358 0.063 715.232 3091.060 4.186 1965 6 209 692.053 46.358 0.067 668.874 2375.828 3.433 1966 7 195 645.695 69.536 0.108 610.927 1706.954 2.644 1967 8 174 576.159 132.450 0.230 509.934 1096.026 1.902 1968 9 134 443.709 188.742 0.425 349.338 586.093 1.321 1969 10 77 254.967 155.629 0.610 177.152 236.755 0.929 1970 11 30 99.338 92.715 0.933 52.980 59.603 0.600 1971 12 2 6.623 3.311 0.500 4.967 6.623 1.000 1972 13 1 3.311 3.311 1.000 1.656 1.656 0.500 1973 14 0 0.000 0.000 #DIV/0! 0.000 0.000 #DIV/0!

2. What is the life expectancy of Dall sheep at age 5 years (i.e. e x )? 738.411 3. Plot the survivorship curve with the age as the independent variable and # of animals ( l x ) as the dependent variable. Use excel with Log scale on the y-axis. Paste the graph directly below. Include a caption. Figure 1: Logarithmic scale of survivorship (y-axis) vs the age of the population of dall sheep on the x-axis (Year) 1.000 10.000 100.000 1000.000 0 2 4 6 8 10 12 14 16 Chart Title

4. What type of Survivorship Curve is exhibited bybthe Dall sheep? Its type one convex most death at old age a. Why? This curve suggests that mortality is low early in life, remains relatively constant during the lifespan of the organism, and then increases sharply at older ages. In the case of Dall sheep, their survival strategy involves protecting their young and ensuring their survival through parental care, resulting in a high probability of survival into old age. b. What other organisms exhibits this type of Survivorship Curve? Large type of mammals like elephants and human Herring Gulls 1. Using the life table for Herring gulls (Table 4), determine the following: Age in years (x) No. of Herring l x d x m x L x T x e x 0 308 1000 425.3 0.425 787.4 2308.6 2.31 1 177 574.7 185.1 0.322 482.2 1521.3 2.65 2 120 389.6 97.4 0.25 340.9 1039.1 2.67 3 90 292.2 64.9 0.222 259.8 698.2 2.39 4 70 227.3 71.4 0.314 191.6 438.5 1.93 5 48 155.9 61.7 0.395 125.1 246.9 1.58 6 29 94.2 45.5 0.482 71.5 121.8 1.29 7 15 48.7 22.7 0.466 37.4 50.4 1.03 8 8 26 26 1 13 13 0.5 2. What is the mortality rate of Herring gulls at age 4? 0.314 3. What is the life expectancy of a Herring gull? About 2.31 years 4. How many individuals actually died during the age interval 5 to 6? 5 5. Based on l x , how many died during the age interval 5 to 6? Based on the table it is 61.7

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6. Plot the survivorship curve. Paste the graph directly below. Include a caption. Figure 2: Logarithmic scale of survivorship (y-axis) against the age of the population of herring gulls on the x-axis (year). 7. What type of Survivorship Curve is exhibited by the Herring Gull? Its type 2 straight constant death rate. 1 10 100 1000 0 1 2 3 4 5 6 7 8 9 lx

8. Why? A type 11 survivorship curve for the Herring Gull indicates a constant death rate throughout its life. This suggests that the mortality rate for the Herring Gull remains relatively consistent, possibly due to a variety of environmental factors 9. What type of Survivorship Curve would you expect for fish? For fish, a type 111 survivorship curve would be expected. This type of curve reflects high mortality rates among the younger age groups, with relatively stable survivorship rates for those individuals that survive to adulthood. 10. Why ? Because of their high fertility (capacity to generate a large number of offspring) and minimal parental care, fish often display a type III survival curve. As a result of the vast number of children exposed to numerous threats in their environment, juvenile mortality rates are high. Hunter Harvested Moose 1. How do you think the wear class method compares with the cementum ring line method for accuracy and precision? Wear Class method: This method estimates the age of the moose based on observable wear patterns on the teeth. It is less time-consuming and easier to utilize than the cementum ring line approach. However, it may be less exact since factors other than age, including food and dental health, might impact wear patterns. Cementum Ring Line approach: This approach determines the age of the moose by analyzing cementum growth rings in the tooth. It can offer a more precise age calculation than the wear class technique, especially when the wear patterns are unreliable. It does, however, need specialized equipment and knowledge, and it may be time-consuming and labor-intensive. 2. What are some of the sources of error in each of the two methods? Errors in the wear class method can be caused by things such as changes in the moose's diet, dental health, and environmental condition. Errors in the cementum ring line method can be attributed to challenges in precisely counting the growth rings, particularly when the rings are not well defined or are masked by other variables. Inadequate sample preparation, staining, or imaging procedures can all have an impact on the visibility and interpretation of growth rings. 3. Using the hunter-harvested moose data, work up the n x and l x in the table below for a total number of moose, bulls only, and cows only. Paste the table below. Include a caption. Total # of moose:

# of cow moose: # of bull moose:

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4. Complete a life table for the total # of moose (not for bulls and cows). Paste the table below. Include a caption.

5. Plot the survivorship curve for the total number of moose. Paste the graph directly below. Include a caption.

Figure 3: Logarithmic scale of survivorship (y-axis) against the age of the total population of moose on the x-axis (year). 6. Plot the survivorship curves for bull and cow moose separately. Paste the graph directly below. Include a caption.

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Figure 4: Logarithmic scale of survivorship (y-axis) against the age of the population of cow moose on the x-axis (year).

Figure 5: Logarithmic scale of survivorship (y-axis) against the age of the population of bull moose on the x-axis (year). 7. What type of Survivorship Curve would you expect? All three curves for the moose show straight type curve. 8. Are data generated from hunter-harvested animals representative of the local moose population as a whole? a. Why? No, because the hunter-harvested data come only from moose that were killed as prey and not factoring all possible factors that affect life span of a moose or even life expectancy of an entire population of moose.