KEY

1.  In the field, when one factor is changed, others also frequently change along with it.

2.  Number of plants (biotic) in an area determines presence of oxygen (abiotic.)

3. b.
 

4. interspecific competition

5. b.

6.  You conduct a capture-recapture estimate of the population size of a species of crayfish in which you capture and mark an initial sample of 271 individuals, release these individuals, and then when you recapture, catch 42 marked crayfish and 218 unmarked crayfish.  Show how you would determine your population estimate, T, by using these numbers to fill in the following formula (NOTE: Donít calculate T, just put the numbers in to show how you would do it.)

 T = (271)(42+218)/42

7. too large

8.  systematic

9.  take more capture-recapture samples
 

10. population size is limited by the resource in shortest supply relative to needs

11. Both curves should be bell-shaped; the one labeled S should be much narrower than the one labeled E.

12. regulator

13.  suboptimal enzyme function in some environmental conditions

14.  endotherm

 15-16. Both should show a range where the line is flat, a large increase at the cold and and a slight increase at the warm end; the cold adapted form should have the flat range at a much lower temperature than the warm adapted species

17. acclimation

18. a.

19.  Degree to which ecological factors favor clumping of females so that one male can potentially defend several females

20. Fundamental niche

21. Realized niche

22.  biotic interactions

23.  a.

24.  One male would not be able to defend more than one female because of their large territories
 
 

25.  Statistical significance means that there is 5% chance or less that the observed trend is random.  In this case, because of small sample size, random error has a strong impact on the results and the tests have low statistical power.  You can conclude more strongly that SFB feed more deep in the lake because the low power makes it difficult to find a trend, but you found a significant one anyway, and significance means that the chance that the trend results from the random error that is present is very low.  You can not conclude that GFB do not feed more at one depth than another because low power makes it hard to find a trend, and since you did not find one you do not know if that means that there is really no trend or that random error was high enough, and power low enough, so that you were unable to find a real trend that is present.

26. It is important to look at five sites of each habitat rather than just one because if you only looked at one it would be possible that any difference you found was related to some other factor that differed between the specific sites you chose, not the habitat type; this is less likely when you replicate habitat types.  Random choice of sites for point counts decreases systematic error.  One systematic error that could be present is that dragonflies could be easier to observe in riparian and/or roadsite habitats than in woodlands; this could make you conclude that relative population sizes were larger in riparian and roadside habitats than woodlands even if they are not. (there are other errors that you could discuss)
 

27. Hypothesis 1. Individuals form schools because they benefit from the selfish herd phenomenon since if a predator encounters a school the chance of each individual being eaten is lower than if a predator encounters a single individual, so individuals are safer in schools.  The environment is predicted to differ in that the schooling fish should be subject to more predation than is the non-schooling fish, so that the non-schooling fish does not benefit from the selfish herd since predation is too low to be important.

Hypothesis 2.  Individuals form schools because they can use each other to find food.  The schooling fish should have clumped resources so that when one individual finds food others will benefit by coming to the same patch; the non-schooling fish should not have clumped resources so that it would not benefit individuals to go to the location where one individual has found food (they would get just as much, or more, food feeding on their own.)

(note: you could also consider other reasons predation can lead to group living.)

28. Two fish species are poikilotherms.  Explain what this means, and state the main cost to being poikilothermic rather than homeothermic.  One fish species has much larger body size than the other.  Suppose that the environmental temperature has been constant for a long time, and then there is a cold snap and it becomes much colder.  Which fish, the large or the small, will suffer the cost of poikilothermy more quickly in this situation?  Clearly explain why by fully explaining the impact of body size on heating/cooling and how this affects the cost to poikilothermy.

 
Poikilotherms allow their body temperature to change as the environmental temeprature changes.  The cost is suboptimal enzyme function since enzymes have specific temperatures at which they perform best.  The small fish will suffer the cost of poikilothermy more quickly because it has a higher surface area/volume ratio since, geometrically, modelling fish as spheres, surface area increases with the square of the radius and volume increases with the cube of the radius, so as you look at larger and larger fish they have relatively more and more volume compared to surface area.  Since heat is stored in the volume of the fish, but lost across the surface, higher SA/V ratios lead to faster loss of heat.