To estimate the number of foxes m an area, a researcher conducted a mark-recapture survey. In the fast survey, he caught and marked 90 foxes. In his second survey a week later, he caught 120 foxes of which 40 were marked (recaptures). If you are told that the actual number of foxes in this area is 400, which of the following is a plausible explanation for the anomaly in the researcher's data? 

#Question id: 9210

#Section 2: Evolution

Overharvesting encourages extinction and is most likely to affect ________.

#Question id: 9211

#Section 2: Evolution

Of the following ecosystem types, which have been impacted the most by humans?

#Question id: 9212

#Section 2: Evolution

Burning fossil fuels releases oxides of sulfur and nitrogen. These air pollutants can be responsible for ________.

#Question id: 9213

#Section 2: Evolution

Suppose you attend a town meeting at which some experts tell the audience that they have performed a cost-benefit analysis of a proposed transit system that would probably reduce overall air pollution and fossil fuel consumption. The analysis, however, reveals that ticket prices will not cover the cost of operating the system when fuel, wages, and equipment are taken into account. As a biologist, you know that if ecosystem services had been included in the analysis, the experts might have arrived at a different answer. Why are ecosystem services rarely included in economic analyses?

#Question id: 9214

#Section 2: Evolution

Researchers have been studying a rare population of 87 voles in an isolated area. Ten voles from a larger population were added to this isolated population. Besides having ten additional animals, what benefits are there to importing individuals?

#Question id: 9216

#Section 2: Evolution

Which of the following criteria have to be met for a species to qualify as invasive?