Exam 13: Population Dynamics Over Space and Time

Describe what is meant by delayed density dependence.

Which of the following is most likely to explain why Daphnia exhibits greater oscillations in population size than Bosmina?

When a population is small there is an abundance of resources for all individuals, so the per capita resource availability is high, thus leading to more rapid growth rates (as compared to larger populations). Why then are small populations more likely to go extinct compared to large populations?

A species of frog is found separated into many subpopulations living in ponds that are surrounded by agricultural fields. Sometimes one frog subpopulation goes extinct because of disease or environmental stochasticity. Frogs from other subpopulations will occasionally move across fields to recolonize ponds where subpopulations have gone extinct. This is an example of

Delayed density dependence

Explain the biological reason that higher intrinsic growth rates and longer delays lead to greater oscillations in population size.

Many species exhibit population cycles with peaks at regular intervals, such as peaks in population size that occur every 6 years. Explain why is it not likely that environmental variation is the underlying cause of these regular cycles. As part of your explanation, include a description of expected differences between changes in population size due to environmental variation and changes in population size due to density-dependent population regulation.

Which of the following is NOT a factor that determines whether a patch is likely to be occupied by a species?

Human activity can affect metapopulations. In the basic model of metapopulation dynamics, if humans improve the quality (and thus carrying capacity) of subpopulations, the probability of _____ and the proportion of occupied patches _____.