Exam 54: Populations

Explain, in terms of the equations and in terms of resource availability, what happens in a population to cause it to change from exponential growth to logistic growth.

Zebra mussels were brought to North America from Europe and have spread rapidly through the Great Lakes and Mississippi River.Attaching themselves to boats, piers, and other hard surfaces, the adults feed on plankton, which clarifies the water but drastically decreases the food available for native mussels and fish.The clearer water promotes toxic algal blooms.Zebra mussels can breed in a wide range of temperatures.A zebra mussel lives five years and produces five million eggs, of which 100,000 reach adulthood.The offspring of a single mussel will produce half a billion adult offspring. All of the following contribute to the fact that zebra mussels have become major pests except

Two bird species, one an r-strategist and the other a K-strategist, are near extinction.Intense conservation efforts are undertaken, and both species begin to recover and increase in number.Which, if either, species should increase more quickly, and why?

Emigration and immigration are assumed to be equal in a population whose per capita growth is being estimated.However, if a population is experiencing more emigration than immigration, estimation of population size according to the equation r = b - d will cause the population size to be

A metapopulation of wood thrushes is found in an area of the Midwest.Individual thrush populations exist in forest patches interspersed with farm fields.Monitoring over several years showed several types of populations: I.Populations with negative birth rates that went extinct II)New populations that occasionally formed in previously bare patches III)Populations with positive birth rates that maintained population equilibrium Which of these types would be considered source populations, and which would be considered sink populations?

The fecundity of a population indicates

How will harvesting affect a population with density-dependent growth?

The number of individuals within a given area or volume is the

Refer to the table below, which shows hypothetical data for a cohort of robins. For the age class of 4 years, how many robins are alive?

When white pine seeds are blown by wind into an open field, young pine trees grow wherever the seeds land.As the pine trees get larger, they begin crowding each other and competing for space and light.Many pine trees die, and those that live are each located at a distance from their nearest neighbors.Which statement is the best description of the dispersion pattern of a white pine population over time?

In the two species of Lobelia from Mount Kenya discussed in the text, L.telekii, which lives on dry rocky slopes, is semelparous, produces many seeds, and has a short life span.L.keniensis, which lives in moist valleys, is iteroparous, produces fewer large seeds, and lives longer.The differences in these two species suggest that their

Ecologists measure population characteristics over several years in a metapopulation of insects.They find that, in Population A, birth rates exceed death rates.In Populations B and C, death rates exceed birth rates.The sizes of Populations A and C remain relatively stable, whereas Population B declines and eventually goes extinct.How could these three populations best be described?

In studying a tiny nematode worm, scientists found differences in egg number, egg size, and body mass when the worms were tested at two temperatures.At 12°C, but not at 24°C, the nematodes showed a negative correlation between egg size and egg number.At 24°C, they found a positive correlation between egg size and body mass.They also found genetic correlations for these traits, which varied in the same direction as temperature.What is the strongest conclusion that can be drawn about the contributions of environment and genetics to life history in these nematodes?

Compared to K-strategists, r-strategists are more adapted to what kind of environment?

Two populations are growing exponentially.At the end of one year, Population X has added 10 individuals and its final N_t = 1,010, while Population Y has added 100 individuals, and its final N_t = 10,100.What factor is likely different in the two populations?

North Pacific humpback whale populations declined dramatically due to hunting by humans.But when hunting was banned, the population grew from 1,400 whales in 1966 to almost 20,000 in 2006.This change was due to

Refer to the graph below. In the graph shown, what factor causes the difference in placement between the left and right growth curves?

The starting size of Population A is 1,000, and the starting size of Population B is 10,000.Both are growing at a rate of r = 1.00.Over a 10-year period, how will exponential growth affect these populations?

In the early twentieth century, a plant species was widely distributed in large grasslands across the Midwest.As agriculture advanced, the grasslands were fragmented, forming much smaller habitats.Because the plant's seeds were dispersed by wind, many of the smaller fragments were able to receive seeds from nearby fragments.The change in the spatial distribution of this species can be described in all of these ways except as a

Mountain sheep in Southern California are separated into small populations on different mountains within one range.Fenced highways bound two sides of these population areas.Of the small populations in this area, which would be considered part of a metapopulation?