Exam 27: Population Growth and Regulation

Parasites often kill their hosts, although they do not directly benefit from their hostsʹ death. Yet many ecologists believe that parasites may have beneficial effects on their host populations. Why?

During the winter of 1999, minimum temperatures did not get much below freezing in an Oregon pond, and the following summer, large mosquito populations were observed. In the winter of 2000, frost came early and most ponds were frozen for 3 months. The following summer, very small mosquito populations were observed. This is an example of

If a population of 100 birds increases to 120 birds in a year, what is the value of r?

Natural populations cannot exceed their carrying capacities.

Predation is considered to be a density-_________ factor that controls the size of the prey population.

In a stable population with neither immigration nor emigration, the RLF is 1.0 (one child per woman).

In the United States today, there is a trend toward women having their first child in their late 30s or early 40s. In contrast, a few decades ago, most women started having children in their early 20s. What effect would you expect this change to have on population growth in the United States? Would it have any effect if the number of children per woman remains the same? Explain.

-Which population represented on the graph has the highest biotic potential?

An ecologist is studying the painted turtle population in a small pond. At the beginning of the year, there are 100 individuals. Over the course of a year, 40 turtles are born and 60 die. There is no migration. What is the growth rate (r) of the painted turtle population?

Which tends to be more intense: intraspecific or interspecific competition? Why?

The_________ is made up of the entire Earth and all of the living organisms that inhabit it.

All the members of a species that live within an ecosystem form a(n) _________.

The sum of all factors (living and nonliving) that limit the ability of a population to grow is known as_________ .

In a constant-loss population, an organism has an equal risk of dying at any time during its life span.