USA Biology Olympiad (USABO) Practice Exam

What would most likely increase competition among voles in a given area?

1. Reduction of food supply

2. An increase in the reproduction rate of voles

3. Decrease in predator population

4. Expansion of habitat area

The correct answer is: An increase in the reproduction rate of voles

An increase in the reproduction rate of voles would most likely intensify competition among individuals within that population. When the birth rate rises, more voles inhabit a given area, which leads to a higher density of individuals competing for limited resources such as food, nesting sites, and mates. As the population grows, the demand for these resources escalates, thus heightening competition. In scenarios where food is reduced, this might lead to increased competition as well, but the primary factor here is the sheer number of voles present due to the rise in reproduction rates. Similarly, a decrease in predator populations could actually result in less competition, as it may allow for greater population stability without the pressures of predation, while expanding habitat area generally allows populations to disperse and utilize more resources, thus reducing competition.