1) What is the difference in approach between the geometric growth equation and

Question

1) What is the difference in approach between the geometric growth equation and the exponential growth equation? (Ch. 12)

2) Why might a model that contains age structure better reflect the reality of population growth than a model that lacks age structure? (Ch. 12)

3) What is the difference between a stable population and a stable age distribution (Ch. 12)

4) What is the relationship between generation time and population growth? (Ch. 12)

5) What are the different causes of slow population growth at low population sizes versus high population sizes? (Ch. 12)

6) What evidence would you need to determine whether a population experiences negative density dependence or positive density dependence. (Ch. 12)

7) Explain why energy reserves can make a population experience delayed density dependence. (Ch. 13)

8) How does the age structure of a population inform us about population fluctuations over time? (Ch. 13)

9) Why does the probability of extinction due to stochastic processes decline as population size increases? Ch. 13)

10) Compare and contrast demographic stochasticity and environmental stochasticity? (Ch. 13)

11) Why is extinction less likely in models of stochastic extinction that include density dependence than in models that exclude density dependence? (Ch. 13)

12) If you were trying to save an endangered species that lived in a metapopulation, how might you try to increase the proportion of occupied sites? (Ch. 13)

Explanation / Answer

1. Geometric growth models species that reproduce at discrete times while exponential growth doesn't.

2. Differences in survival between different years is NOT accounted for in a model that considers age structure therefore it better reflect the reality of population growth

3.  A stationary population is a special example of a stable population with a zero growth rate, neither growing nor shrinking in size, and is equivalent to a life table population. however stable age distribution means the population will maintain the same age distribution.

4. In population biology and demography, the generation time is the average time between two consecutive generations in the lineages of a population. In human populations, the generation time typically ranges from 22 to 33 years. The annual percentage growth rate is simply the percent growth divided by N, the number of years.

5. When a society is small, population growth is slow because there are relatively few adults to procreate. But as the number of people grows over time, so does the number of adults. More and more procreation thus occurs every single generation, and population growth then soars in a virtual explosion.

6.

Competition among the individuals in a population is a very common mechanism of density dependence, caused by limited availability of a necessary commodity, usually a resource, or space (sites). The population responds with a drop in one or more vital rates, usually growth and survivorship, but also fecundity and recruitment. At low density, individuals do not interfere with each other, so that population growth is density-independent. As density increases in time, however, resources may become less available, each individual acquires less of the resource, and negative density dependence manifests itself. It becomes stronger if the population continues growing, at the lower growth rate.

Predation can have a similar negative density-dependent effect, as when at low density prey is left alone, but at high density it gets decimated down to a minimum (GUD, giving-up-density) or becomes extinct. The net result both in the case of competition and predation is that the growth of the population is unaffected at low density, but depressed at high density. In many cases this may lead to regulation of the population around a maximum density. In logistic models this is called the carrying capacity K of the environment (for the particular organism that is considered). Other negative density-dependent phenomena are infectuous desease and parasitism, which may cause outbreaks at high host population density.

7. Energy reserves makes population experience delayed density dependent because they enable the population .

8. It can show times of particular growth or decline in previous years.to survive above carrying capacity.

9. The probability of extinction due to stochastic processes declines as population size increases because

stochastic events have a proportionally smaller effect.

10. Demographic stochasticity results from chance independent events of individual mortality and reproduction, causing random fluctuations in population growth rate, primarily in small populations. Environmental stochasticity results from temporal fluctuations in mortality and reproductive rates of all individuals in a population in the same or similar fashion, causing population growth rate to fluctuate randomly in populations of all sizes

11. Extinction is less likely in models of stochastic extinction that include density dependence than in models that exclude density dependence beacuse in density dependent models, the growth rate at low populations is higher.

12. If you were trying to save an endangered species that lived in a metapopulation, you might try to increase the proportion of occupied patches by decreasing patch isolation.

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