A mosquito species breeds in rain-filled tree holes scattered through a forest. Each tree hole is a separate population, and together they form a metapopulation. In a metapopulation, source populations are stable or growing populations that produce excess individuals that can disperse and colonize other patches, whereas sink populations are unstable populations that persist only because of immigration from elsewhere. The table below shows approximate characteristics for five representative tree holes.   Tree hole Population size Extinction probability (E) Colonization probability (C) A 80 0.10 0.40 B 25 0.50 0.60 C 100 0.05 0.10 D 10 0.80 0.70 E 40 0.30 0.20   A) Which two tree holes are most likely to act as source populations, and why? (3 pts)           B) Which two tree holes are most likely to act as sink populations, and what would happen to them if dispersal between holes stopped? (3 pts)  

Which of the following is a density-dependent limiting factor?

Which of the following correctly represents the hierarchy of ecological organization from smallest to largest?

Which example best illustrates a cost of group living?

Which outcome best describes a population maintained near carrying capacity by negative feedback?

Because tundra is defined by its high-latitude location, it cannot occur near the equator regardless of temperature.

On a rocky reef, a sea urchin population follows logistic growth, with per-capita growth rate of 0.4 and a carrying capacity 2000 individuals.   A) If the current population is N0 = 400, compute the number of new individuals added in the next year and the projected population size at N1. (A full credit answer will show any calculations) (6 pts)             B) Managers compare three possible urchin abundances after a cull: N = 200, N = 900, or N = 1600. At which abundance will the population add the most individuals next year under the logistic model? Briefly justify your choice. (2 pts)

Examine the relationship between water buffalo abundance and rainfall in the African Serengeti. What is the best explanation for why buffalo are only present above 500 mm rainfall?

Building on the Habronattus pyrrithrix jumping spider study, researchers now hypothesize that leg color intensity affects male survival by reducing predation, rather than influencing mating success. They design two treatments: Group 1: Males with leg color darkened using non-toxic paint. Group 2: Control males treated with a clear paint of the same chemical base. Spiders are then released into outdoor enclosures containing both females and predators.   A) Write the prediction being tested in this experiment. Identify both the predictor and response variables. (3 pts)   Prediction:       Predictor variable:   Response variable:   B) The paint used to darken legs can change heat absorption and thus body temperature, which could influence survival for reasons unrelated to predation. In one sentence, describe one practical way to control for the temperature effect in the study design. (1 pt)

What drives the rising and sinking of air in the Hadley cell between 0° and 30° latitude?