Name:_______________________________________ Student No.:___________________________
Here is the short list of equations you may need in completing this midterm.
B a
= B p
+ P/C
B i
/B s
= 1-P/

S = CA z log S = log C + z log A
P = 1 –

/c
P y
= (1-p e
) y
P n
= 1- (p e
) n
ˆ
H

3
V a
 m a
 e
 ra l a
 
 
1 e
 rx l m x
C =
 e -
 d
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Name:_______________________________________ Student No.:___________________________
Population Ecology 03-55-324
Midterm 2
November 17, 2011
There are a total of 90 marks on this exam.
Match the following terms from the left hand column with the appropriate definition from the right hand column. Enter the letter of the definition in the blank. Only one definition is correct.
1._
i __ rescue effect
2._
h __ sink population a.
pattern in which reproduction occurs by parthenogenesis for much of the year, but there is at least one generation of sexual reproduction each year
3._
4._
parthenogenesis
5._
6._
7._
j a g b
__ Preston log-normal m abundance distribution
__ cyclical
__ recruitment
__ determinate clutch
_ altricial b.
a clutch size that is fixed under most environmental conditions c.
a clutch size that is determined by environmental conditions, and thus varies from year to year d.
a relationship between a physical and a life history variable that has a slope

1 e.
a population in which the colonization (or migration) rate is so high among sub-populations that the population is not really subdivided f.
species that are very likely to disperse, can move long distances, and are thus early colonists, as well as the most likely to reach very isolated patches
8._
o __ bet hedging
9._
n
10._
11.
12._
q _ Levins
13._
15._
__ residual p e d reproductive value
_ indeterminate clutch metapopulation
_ patchy population
14._
f _ super tramp species
_ allometric relationship g.
addition of new individuals to a population by reproduction h.
a population that would continually decrease in size owing to high mortality, low reproduction, or both if it were not maintained by immigration from other populations i.
prevention of extinction of a local population by immigration of individuals from elsewhere j.
the distribution of frequencies of abundances of species typically observed for species from diverse communities k.
reproductive value for an individual that failed to reproduce in the current year l. local extinction and colonization to form new local populations by means of dispersal from other local populations m. in birds, hatched without down, eyes closed and dependent on the parents n. reproductive value evaluated for age x+1 o. a life history strategy observed in species living in an unpredictable environment such that reproduction can completely fail in some years.
Selection would strongly favor adult survivorship and repeated reproduction. p.a fixed number of eggs forming a completed clutch, but which may require the female to produce more than that number of eggs due to predation of eggs, loss of eggs accidentally, or loss of eggs by removal q.a metapopulation comprised entirely of populations occurring on isolated patches r. a strategy of reducing the risk of mortality or reproductive
failure in a variable environment by spreading one’s risk
over time and space s. there is no correct definition presented for this term
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Name:_______________________________________ Student No.:___________________________
16. According to the island-mainland model for metapopulation persistence, the probability of persistence is determined by: a. the difference between characteristic immigration and extinction rates b. the ratio of characteristic immigration and extinction rates c. the fraction of sites currently occupied d. the fraction of sites that are not currently occupied e. the metapopulation will not go extinct
19. The data gathered by Lack in studies of starlings indicated that the most vulnerable stage and highest mortality rate occurs at the time of: a. eggs being brooded by mature females b. hatchlings being raised in the nest c. fledglings leaving the nest d. overwintering e. there is no difference in vulnerability among these stages
17. According to the hypothesis of reproductive cost, which of the following is not reduced by increase in current reproduction? a. residual reproductive value b. litter size in future bouts of reproduction c. parental survivorship d. age of first reproduction,

, of offspring e. all are potentially reduced according to the hypothesis
18. Which of the following is important in explaining the ecological extinction of the
California condor during the 1980s? a. observed decrease in the age of first reproduction for the condor b. poaching of adult California condors by ranchers c. the abandonment of nests by adult condors when disturbed d. the low rate of egg production characteristic of the California condor e. all are important in explaining ecological extinction
20. More species are typically counted in small patches within a large, continuous ‘mainland’ than on isolated islands or patches of equal area. This is explained as due to: a. the habitat diversity in small ‘mainland’ patches b. the observation of transient species within those small ‘mainland’ patches that could not survive within those areas alone c. the abundance distribution of species in fragments of a ‘mainland d. differences in the slopes of species-area curves on mainlands and islands e. differences in the likelihoods of rescue in
‘mainland’ and island patches
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Name:_______________________________________ Student No.:___________________________
21. The survivorship schedule is plotted in the figure below for an iteroparous species. It has a litter size of 4 and an

= 1. Calculate the litter size of a semelparous species that would exactly balance the
“advantage of iteroparity”. Show your work.
(10)
1.0
Survivorship
0.5
0.1
1 Age 9
Two approaches: According to Charnov and Schaffer B a
= B p
+ P/C, B p
= 4, C = .5, and P can be calculated by the adult decline from .5 to .1 over 8 years, or .4/8. P is then 1-.05 or ~ .95.
B a
= 4 + .95/.5 = 4 + 1.9 = 5.9
The more complicated approach (which I don’t really expect anyone to use), goes back to life tables to calculate an r from l x
and m x
.
Age l x m x l x
m x xl x
m x
0 1
1 .5
0
4
2 .45 4
0 0
2 2
1.8 3.6
R
0
= 11
G = 44/11 = 4
r = ln(11)/4 = 2.397/4 = .599
3 .4 4
4 .35 4
1.6
1.4
4.8
5.6
5 .3 4 1.2 6
6 .25
4…
1… 6…
The semelparous species should have equal growth
22. Theory that has been developed around the “advantage of iteroparity” identifies various conditions that increase or decrease that advantage. For each of the following, discuss how the advantage of iteroparity changes with each of the following alterations in life history using graphs and/or text: (5 marks each) a. decreasing age of first reproduction,

- the advantage of iteroparity decreases. The semelparous species reproduces more frequently than when

was larger, and the iteroparous species, reproducing annually once it has reached age
 , gets fewer ‘extra’ chances to reproduce. b. a decrease in adult proportional survivorship, p x
– using Charnov and Schaffer’s formula, if
P decreases, the advantage of iteroparity decreases. The advantage, if

= 1 is P/C. If

> 1 the
‘advantage’ term is P/ 
. In either case a decrease in P decreases the advantage. c. increase in the litter or clutch size, b - the advantage of iteroparity decreases. With increasing litter size the difference between iteroparous and semelparous litters represents a smaller proportional increase for the semelparous species to ‘keep up’.
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Name:_______________________________________ Student No.:___________________________
23. Below is a map of North America. On it are marked locations where the clutch sizes of the yellow finch were measured. If the total range of clutch sizes observed was from 2 to 8 eggs per clutch, suggest for each of the marked locations what the likely mean clutch size observed was. For each explain, using one of the hypotheses you have studied (Lack’s, Cody’s or Ricklefs’) why that is the mean likely to be observed. (20 total, 5 for each location, ½ the marks for correct order of clutch size, ½ for explanation)
Central Northwest Territories
Connecticut
Texas tropical Mexico
Here are very concise explanations for each hypothesis at each location:
Tropical Mexico: Lack-lowest latitude means the shortest foraging day at the time of reproduction, as well as the highest yellow finch population, therefore lowest net intake to feed young. Cody-most tropical, therefore highest diversity of competitors and predators and the lowest potential allocation to reproduction versus maintenance and growth. Ricklefslowest seasonal difference in production of resources and high adult density mean less energy available to feed young at the time of reproduction. All predict smallest clutches here, probably 2-3 eggs/clutch.
Texas: Lack-somewhat longer foraging day during reproduction, with moderately high finch density, therefore slightly higher net intake to feed young. Cody-warm temperate climate with a moderately high diversity of competitors and predators, and therefore a moderate allocation to reproduction should occur. Ricklefs-some seasonal difference in productivity and a more moderate adult population density provides somewhat greater energy to feed young at the time of reproduction. All predict small clutches, but larger than in tropical
Mexico, say 3-4 eggs/clutch.
Connecticut: Lack-longer foraging day in late spring/early summer to feed young, therefore larger clutches. Cody-more maritime climate due to proximity of the ocean means greater stability and a somewhat smaller clutch than latitude alone might suggest. Moderate diversity of competitors and predators, along with climate, suggest a moderate clutch size.
Ricklefs-low winter population with a moderate excess of summer production suggest a
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Name:_______________________________________ Student No.:___________________________ larger clutch size, but less than maximum. Here you moght see a greater range of suggested clutch sizes, say 3-6.
Central Northwest Territories: Lack-longest foraging day at breeding time and the most condensed production due to the short growing season. Therefore the largest clutches among these sites. Cody-most continental climate with a very low diversity of competitors and predators suggests a large clutch. Ricklefs-lowest winter population (if any) and greatest excess production per adult at breeding time give suggestion of the largest clutches here.
Should result in estimates of 7-8 egg clutches.
24. It has been suggested that asynchronous metapopulations should have a much greater probability of persistence than those that are synchronous in dynamics. Explain why in 25 words or less, (5)
When populations grow asynchronously, a population which is increasing provides dispersers to colonize and rescue those that are declining. Regional extinction is then unlikely. When populations grow synchronously, all decline at the same time, there are few, if any, emigrants to colonize declining patches, and little likelihood of rescue. Local extinctions and regional extinction are then more likely.
25.
Tradeoffs between offspring size and number have been widely observed in both plant and animal reproduction. Choose one example discussed in lectures. Describe the evidence that a tradeoff between offspring size and number is occurring and the ecological/evolutionary explanation why the tradeoff is occurring. (10)
A number of examples were presented in class:
In goldenrods the relationship between size and number of propagules follows a regression with a slope insignificantly different from -1 across a broad range of environments from woods sites to old fields. This suggests a constant total biomass allocated to achenes (the propagules). Seed numbers are highest and size smallest where the intensity of competition is lowest (old fields), and the propagules are largest ands numbers smallest in oak woods, where competition for light and below ground resources would be greatest. Larger seeds are needed to successfully establish in very competitive environments.
Another example was European alpine charr. In Swedish lakes with low population density of adults (and thus low intraspecific competition) large broods of small eggs were produced. In lakes with high densities of adult charr (high intraspecific competition) small broods of larger eggs were produced. Brood size/egg size differences are logically an evolutionary adaptation to the intensity of competition.
A third example was Alberta whitefish. In one lake that lacked interspecific competitors and predators, the population size of whitefish increased dramatically, and with it intraspecific competition. Egg size increased by 10%. While the number of eggs produced increased with fish size, the slope of the relationship was low. In another lake, where whitefish density was lower, the allometric relationship between fish size and egg number had a much higher slope, and the volume of individual eggs was much lower.
The last example was of egg size and number across seasons in a group of Polish lakes in a calanoid copepod. They are cyclical parthenogens, and in spring the lake is basically recolonized from resting (ephippial) eggs. With low copepod density in spring, organisms produce more small eggs. As density increases into summer, the copepods in each lake produce fewer, larger eggs. The evolutionary explanation is once more the intensity of intraspecific competition among/within these populations.
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Name:_______________________________________ Student No.:___________________________
26. Life history theory is based on the principle that there is a cost of reproduction, but that cost has been difficult to demonstrate in either field or laboratory experiments. Design an experiment to test whether a cost of reproduction is evident in a population of pigeons your friend is raising in a pen on his roof. This is a thought experiment. Don’t worry about replication, statistical design, or details of the methods you would need to use to collect data. List two (or more) features of pigeon life history you would measure to find a cost of reproduction (4) . What are the predictions of life history theory with respect to relationships between these variables indicating a cost?
(8) What comparisons would you make to demonstrate cost from your measurements?
(8) .
The life history variables that can logically be measured and included in the experiment are:
Clutch size
Survivorship of the pigeon in subsequent periods
Size of future clutches
Condition (weight, perhaps) of adult pigeons before and after reproduction and next spring
Predictions of life history theory if there is a cost:
Negative correlations between current clutch size and either or both survivorship and future clutch size (together the residual reproductive value)
Negative correlation between clutch size and the comparative condition from before to after reproduction and/or to condition the following year
Comparisons you could make:
Keep track of individual pigeons according to their clutch sizes this year. Look at proportional survivorship p x or actual survivorship l x
into the next year. Is there a negative correlation between current clutch size and either of these measures of survivorship? Look at whether there is a negative correlation between this year’s clutch size and next year’s clutch size. Look at whether the condition of birds producing larger clutches this year is poorer than those producing smaller clutches.
Note that a correct answer requires only two life history features, then correctly drawing the relationship between them and suggesting what you would measure to test the character of that relationship.
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