ID#:___________________________________ Biology 372, Fall 2013 General Ecology with Jesse Brunner Name:________________________________ EXAM 2 17 October 2013 Read questions carefully before answering. If you need clarification, just raise your hand. For multiple choice and True/False questions, please circle the best answer. For short answers, please write clearly and concisely. There is no need to repeat the question in your answer, but please do write in full sentences and use proper grammar. Limit your answers to the space available. Where appropriate use diagrams to illustrate your answers. Remember, you are taking an ecology test, so use the appropriate mechanisms, rules of thumb, and always, always connect the logical dots for us. Calculators are allowed. Smart phones or other “smart” devices are not allowed. The exam will end at 10:20am. Potentially useful equations (a) N t = N 0 λt (b) λ = N t+1 N t = exp(r ) €
r = ln( λ) €
(c) dN
= rN dt
(d) ⎛ N ⎞
dN
= rN⎜1 − ⎟ ⎝ K ⎠
dt
(e) dP
= cP(1 − P) − eP
dt
(f) lx = n x /n 0
mx = bx /n x
(g) R0 = ∑ lx mx €
€
€
€
€
(h) (i) €
€
(j) T=
∑ xl m
x
x
R0 r = ln(R0 ) /T
⎛ N + α12 N 2 ⎞
dN1
= rN1⎜1 − 1
⎟,
dt
K1
⎝
⎠ ⎛ N + α 21N1 ⎞
dN 2
= rN 2 ⎜1 − 2
⎟
dt
K2
⎝
⎠
dN prey
= rN prey − aN prey N predators,
€ (k) dt
dN predators
= abN prey N predators − mN predators
dt
€
€ Q1: Which equation (above) best describes the growth of a bacterial infection in a newly infected, immunosupressed host (i.e., a host that does not have an immune response to fight back the infection)? (2pts) Page 1 of 9 Q2a: These two graphs (left) showing the number of eggs a frog lays (clutch size) against the mass of individual eggs illustrate which ecological principle? (2pts) a) Earlier reproduction leads to smaller clutches b) Smaller females have smaller eggs c) Females of both species invest in large eggs, which are more likely to survive d) Females trade-­‐off clutch size against the size of individual eggs Q2b: Based on these measurements of a female's investment in her eggs (from the same study), which species would you expect to live longer (the adults, all else being equal)? (2pts) a) Rana dalmatina b) Rana temporaria Q2c: On the axes below, draw what you think the survival curves would look like for R. dalmatina (solid line) and R. temporaria (dashed line). (4pts) Page 2 of 9 ID#:___________________________________ Q3a: In this figure from Arces & Smith, which panel(s) provide strong evidence of density-­‐
dependent reproduction in the Song Sparrows? (3pts) Q3b: What other aspect of the life history (not shown) might be density-­‐
dependent? (2pts) Q3c: What might be causing this density-­‐
dependence? (Provide one hypothesis) (2pts) Q3d: As you may recall, there are no important predators on Mandarte island, where Arces & Smith were studying these Song sparrows. What would happen to the sparrow population if bird-­‐ and egg-­‐eating snakes arrive on the island? (2pts) a) Very little; while some birds would be lost, the remaining individuals would have higher survival (and perhaps recruitment) b) The population would decline a great deal since reproductive output of these birds would decrease c) The population would fluctuate; predator-­‐prey interactions lead to cycles Q4: Naturalization refers to: (2pts) a) the arrival of an alien species in a new range b) the permanent establishment of an alien species in a new range c) the immigration of an alien species into a new locale d) the filling of a vacant niche in a new range by an alien species e) none of these. Page 3 of 9 Age
Use this life-­‐history table answer class in
years Number
the following questions. Show your (x)
alive
lx
work. 0
1000
1.00
1
950
0.95
Q5a: What is the average number of 2
900
0.90
female offspring that each female has in its life time? (3pts) 3
860
0.86
4
810
0.81
5
200
0.20
6
20
0.02
Q5b: What is the generation time of this population? (3pts) Q5c: What is the growth rate (r) of this population? (3pts) Q5d: Will this population grow, shrink, or stay the same? (2pts) Q5e: On these axes draw the survival curve. (Get the starting and ending values right and the general shape.) (4pts) Female
births
0
0
0
860
810
200
0
mx
0
0
0
1
1
1
0
lxmx
0
0
0
0.86
0.81
0.20
0
Page 4 of 9 xlxmx
0
0
0
2.57
3.26
1
0
ID#:___________________________________ Predation rate Q5f: What kind of organism might these data come from? What feature(s) of the life history make you think this? (4pts) Q6a: Which of the lines on this graph would best represent the functional response of a predator that could learn to hunt novel prey items, if they were worth the effort? (2pts) a b
!a!
Curve a Curve b Curve c c Density of novel prey Q6b: In one sentence, why do curves b and c saturate? (2pts) Q7: What lesson can we learn about predator-­‐prey dynamics from Huffacker's experiments with predator and prey mites on arrays of oranges? (2pts) a) Food quality is the essential to understanding the persistence of prey populations b) Having a dispersal advantage over the predator can keep prey metapopulations from going extinct c) Cycles are an inevitable consequence of predator-­‐prey systems with a single predator and single prey species Page 5 of 9 The circles in this picture represent discrete patches of habitat (e.g., ponds). Filled circles represent patches that are occupied (e.g., with the zooplankter, Daphnia pulex). Q8a: What is the value of P in this picture? (2pts) Q8b: If these discrete patches of habitat follow the classic metapopulation model, what would the pattern of patch occupancy look like if we came back in a decade and resurveyed the ponds? (Shade in the occupied patches/ponds in the picture to the right) (3pts) Q8c: Graph the rates of colonization and extinction on the graph, below, that would match the picture I gave you. (5 pts) Q8d: What would likely happen to the metapopulation if there were an outlet mall that split the habitat into four, unconnected groups? Why?(Continuing the example, Daphnia disperse between ponds by laying eggs on backswimmers, aquatic insects that occasionally fly between ponds. The mall would prevent backswimmers from flying from one side to the other.) (4 pts) Page 6 of 9 ID#:___________________________________ This graph shows the yield of Wheat (filled circles) and Kochia scoparia (filled triangles), a C4 weed, as well as their combined yield (open, upside down triangles) in a replacement series experiment. Q9a: Which species is more strongly affected by intraspecific competition? (2pts) a) Wheat b) Kochia c) Equally affected Other data from this experiment (not shown) suggest that cold-­‐adapted wheat can grow earlier in the year and shade the broad-­‐leafed plant, lowering its rates of photosynthesis and growth. The Kochia does, however, persist, and at warmer temperatures Kochia grows well. Q9b: Assuming the above results describe the competitive interactions of Wheat and Kochia: 1) Draw the zero growth isoclines for Wheat (X-­‐axis, solid line) and the Kochia (Y-­‐axis; dashed line). (4 pts) 2) Label the intersections of the axes with Kw, Kk, Kw/αwk, Kk/αkw (2pts) 3) Draw a circle around the carrying capacity of the wheat (2pt). 4) Draw an arrow to the density of Kochia that would be required to keep the wheat population from growing. (2pt) 5) Draw the path that these two species would take from the black dot to their eventual equilibrium. (4 pts). Kochia Wheat Page 7 of 9 Q10b: Now draw the realized niche of this barnacle if there were a very stronger competitor in the area with the same thermal tolerances, but that can withstand only small periods of desiccation. (dashed line) (2pts) Q10c: Draw on the graph where: (3pts) dN/dt > 0 dN/dt = 0 dN/dt < 0 short Time out of water long Q10a: Draw the fundamental niche of a barnacle that is able to withstand desiccation (long periods out of the water) and cold to moderately cool temperatures, but not warmer temperatures. (solid line) (3pts) cold Temperature hot Q10d: Will these two species likely coexist? Yes / No (2pts) Q11: Many species of plants and animals have large, synchronous reproductive events (e.g., oaks masting, 13 year cicadas emerging). Using your ecological understanding of predation dynamics and being as specific as possible, why does this reproductive strategy confer a fitness benefit (to the oaks and cicadas)? (4pts) Page 8 of 9 ID#:___________________________________ This graph shows the (idealized) densities of prey (solid line) and predator (dashed line) populations through time. Q12a: On the phase plane to the right, draw the isoclines of both species that you think could have produced these damped oscillations. (4pts) Q12b: What feature(s) or aspect(s) of predator or prey biology did you included in your isocline(s) to produce these damped oscillations? How do these achieve this outcome? (4pts) Q12c: Starting from the initial densities in the time-­‐series graph I provided above, draw the trajectories of the predator and prey populations, given your isoclines. (4pts) _________ / 100 pts Page 9 of 9