The correct response is density independence. The leafhopper population was not regulated by density. The only thing that regulated the population was abiotic events, such as forest fires.

Species described as "r-strategist" have a survival strategy of producing large numbers of offspring, a short life expectancy, and typically smaller body sizes. Examples include mice, locusts, and frogs. These species survive by producing lots of offspring, since many individuals don't survive to adulthood.

R-selected individuals are characterized by the following: early age of sexual maturity, many lifetime reproductive events, large numbers of offspring per event, and minimal parenting. Many of the offspring of r-selected species will die before adulthood. On the other hand, K-selected individuals have only one or few offspring at once and invest larger amounts of time and energy into parenting to ensure survival. The rabbit is the only species listed whose life traits can be categorized as being r-selected.

The correct response is density dependence. Since the population growth rate is dependent on the size of the population, it is therefore regulated by density. This is the perfect example of a density dependent population.

The use of child laborers leads to higher birth rates. More children are needed to support families and households. Educating women also decreases birth rates. This is the reason why developing countries tend to have higher birth rates than developed countries. A lower average marriage age leads to an increase in birth rates. Religion can influence birth rates, either raising or lowering (generally it raises the birth rate).

Use the Rule of 72:

is rate of growth

is time (in years) it takes to double

By manipulating the equation to divide 72 by the given growth rate, you can find the number of years it takes for the population to double.

Elephants are large-bodied and give birth to only one offspring every few years, and mothers have a large role as caregivers to ensure the survival of their young. The other species listed here are r-selected species and have many offspring at a time. In some cases, r-selected species do not parent. In others, offspring mature very quickly and parents do not have to provide care for very long.

Corals are r-selected species, categorized by producing many offspring at once, which individually have low chances of survival, and short lifespans. Other r-strategists include rodents, insects, and other small-bodied, early-maturing animals. K-selected species produce few offspring and invest lots of parental care to ensure a higher chance of survival. Humans are an example of a K-selected species.

Species designated as K-strategists thrive through longevity and have a higher survival rate at birth, but produce far fewer offspring. Examples include elephants and whales. Consider an elephant; it may produce relatively few baby elephants, but these baby elephants each have the potential to live relatively long lives. On the other hand, contrast K-strategists like elephants with r-strategists like rats, locusts, and flies. These species are designated as r-strategists because in contrast, they produce numerous offspring, few of which may survive to adulthood, and each one of which reaches maturity quickly and lives a relatively short life. K-strategists in general spend more time than r-strategists caring for and raising their offspring; they have fewer offspring, so they put more care into ensuring the survival of each one. Contrast elephants with frogs to see this difference; elephants care for their young, while frogs lay their eggs and care for their offspring very little, if at all.

In terms of population trends, Nigeria can expect to see exponential growth in the following years for two reasons: Fertility rates are already quite high (e.g. a stable population is at births per female) and a large portion of the population is under the age of fifteen. Present fertility rates ensure current exponential growth, while a large proportion of the population reaching reproductive age ensures future population growth, especially if the fertility rate remains inflated.