A lone alien, acting as ambassador for his kind, recently made a friendly trip t
ID: 51978 • Letter: A
Question
A lone alien, acting as ambassador for his kind, recently made a friendly trip to Earth. Naturally, a team of biogerontologists gathered some information from our new ET friend, outlined below. Using this data, write a ~1 page-long report including pertinent figures, contrasting the alien population to our own. Make sure to include: 1) a life-stage curve, 2) a life table with columns 1-4, 3) a survival curve (see note, pg 2), 4) information on intrinsic & extrinsic rates of aging (referencing data to support your claims) and 5) likely biological explanations for any phenomena that can be supported by observations or data given below. Ensure that all graphs have appropriate axis units and labels and are explained either in a figure legend or in the body of the report.
Observation report:
The alien culture experiences 5 distinct life stages, 4 larval stages followed by a reproductively-active adult stage. Larval stage 1 (L1) corresponds to approximate earth age 0-9 years, L2 to 10-24 years, L3 to 25-74 years, L4 to 75-124, and adult occurs from year 125 on. The reproductive period lasts for approximately 5 earth years. During this time, most females and hermaphrodites of the species give birth to 20-40 babies in one “litter.” The babies need only minimal weaning (a month or two in earth time) and then are self-reliant. See Table 1 for more information on deaths in each stage. Our alien friend says that a disease that affects only L2 stage individuals contributes 99% of the death toll seen during that stage. Other than that, our friend says that the population is very healthy.
Cell samples were taken from 5 separate tissues of the alien’s body (in L3 stage). Interestingly, every cell sampled was observed to have the ability to create any of the other types of cells upon each division. Upon questioning, the alien offered that while he doesn’t know much on the subject, he knows that all larval stages share similar types of cells, but upon molting into the adult life stage, their cells change dramatically.
Table 1.
Approx earth age interval
dx
0-1
150
1-4
104
5-9
42
10-14
14004
15-19
15843
20-24
18424
25-29
407
30-34
551
35-39
600
40-44
650
45-49
647
50-54
680
55-59
677
60-64
651
65-69
638
70-74
655
75-79
614
80-84
689
85-89
690
90-94
710
95-99
750
100-104
800
105-109
850
110-114
900
115-119
950
120-124
949
125-129
1000
130-134
15074
135-139
21301
Notes re: Problem 1:
When making your survival curve:
Create your life table including columns 1-4 in Excel or Google Sheets. When finished, email it to me! I will insert 1-2 columns of Excel math into your data. This information will convert your lx into sx (survival in percentage of lifespan) so that you can create your survival curve. Once you’ve generated your survival curve in Excel or Google Sheets, somehow indicate the mean and maximum lifespan of our aliens on the graph.
The entire report with graphs is worth 30 points.
Problem 1 Q1 (3 pts)
Using the mortality rate for the 25-29 age interval as your Initial Mortality Rate, fill in line for Alien in the table below. You’ll need to use your life table and survival curve for some of the information.
(hint 1: you don’t need a fancy equation like Equation 2.5 in your book, just use your life table and multiplication!)
(hint 2: just use the first time (chronologically speaking) the population reaches the doubled rate)
Species
IMR
MRDT (years)
Max lifespan (years)
Human
0.0002
8
120
Alien
Quail
0.07
1.2
5
Bat
0.36
3-8
11-25
P1.Q2. Based on the information in the table above, which species has the lowest rate of aging? (1 pt)
Humans
Aliens
Quails
Bats
Not enough information
P1.Q3. Which of the following of Hayflick’s big 6 of aging best explains why the disease the aliens experience during their L2 stage is indeed a disease, and not aging. (1 pt)
Aging occurs in every animal that reaches a fixed size in adulthood
Aging occurs only after sexual maturation
Aging increases the vulnerability to death in 100% of the animals in which it occurs
Aging occurs in both animate and inanimate objects
All of the above
P1.Q4. Based on your life-history table, and the information given in the observation report above, which of the following age groups would experience the lowest force of natural selection? (1 pt)
25-29
60-64
125-129
135-139
Both A and D
P1.Q5. Based on your life-history table, and the information given in the observation report above, which of the following age groups would experience the highest fitness and reproductive value?
25-29
60-64
125-129
135-139
C and D would have the same fitness and reproductive value
P1.Q6. Prior to the age you chose in P1.Q6, what is natural selection selecting most strongly for?
Survival to reproduction and maintenance of somatic cells
Survival to reproduction and maintenance of germ cells
Survival to senescence and maintenance of germ cells
Survival to senescence and maintenance of somatic cells
None of the above
Observation report:
The alien culture experiences 5 distinct life stages, 4 larval stages followed by a reproductively-active adult stage. Larval stage 1 (L1) corresponds to approximate earth age 0-9 years, L2 to 10-24 years, L3 to 25-74 years, L4 to 75-124, and adult occurs from year 125 on. The reproductive period lasts for approximately 5 earth years. During this time, most females and hermaphrodites of the species give birth to 20-40 babies in one “litter.” The babies need only minimal weaning (a month or two in earth time) and then are self-reliant. See Table 1 for more information on deaths in each stage. Our alien friend says that a disease that affects only L2 stage individuals contributes 99% of the death toll seen during that stage. Other than that, our friend says that the population is very healthy.
Cell samples were taken from 5 separate tissues of the alien’s body (in L3 stage). Interestingly, every cell sampled was observed to have the ability to create any of the other types of cells upon each division. Upon questioning, the alien offered that while he doesn’t know much on the subject, he knows that all larval stages share similar types of cells, but upon molting into the adult life stage, their cells change dramatically.
Explanation / Answer
1. The initial mortality rate of the alien population is very high. Compared to the life span, humans have lowest rate of aging.
2. Ageing increases the vulnerability to death in 100% of the animals in which it occurs
3. the age group of 60-64 experiences lowest force of natural selection
4. the age group 125 - 129 would have the highest fitness and reproductive value, as given in the observation report.
5. Survival to senescence and maintenance of germ cells
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