Question

As song sparrow population density increases,

A. the average reproductive success of individual song sparrows tends to increase.

B. the average reproductive success of individual song sparrows tends to decrease.

C. the average reproductive success of individual song sparrows does not change.

D. the average reproductive success of individual song sparrows is unpredictable

Mosquitos have a life history that is near the extreme of

A. r-selection.

B. K-selection.

C. (both)

D. (neither)

During the early and middle twentieth century, there was

A. a sharp increase in human birth rate.

B. a sharp decrease in human death rate.

C. (both)

D. (neither)

Answer 1

1. Correct option is a. reproductive success tend to increase

Basically, density independant factors like climatic conditions (rainfall) affect reproduction of song sparrow, but studies suggest that population density didn't affect reproduction success.

It was observed that when population density was high, the survival of young

Another ingredient of song sparrow life history on Mandarte is their density dependent reproduction. When the population is high, the juvenile survival is very low, and vice versa. Thus, during population crashes on the island due to weather or other unknown causes, the population quickly recovered with high fecundity while population highs saw the likely effects of competition acting on the birds.

2. Correct option is a. r selection

These populations are determined by maximum reproductive capacity which tends to produce numerous small offsprings followed by exponential growth. They mature quickly which makes them capable of reproducing early i.e at young age and therefore have short life spans.

Kselection species produce large offsprings unlike r selected species which produces small offsprings and they produce offsprings in low number. They mature slowly and therefore they have long life span

So, mosquito has life history that is near or extreme of r slelection.

3. Correct option is c. Both (sharp increase in birth rate and decrease in death rate)

Basically, during 20th century what happened is because of infectious disease like influenza and degenerative disease like cancer, then because of world war II, there was tremendous death rates but because of improvement in health sector, death rates was decreased and following world war II there was increase in birth rates. This was called Baby boom. Basically, because of decrease in death rates and increase in birth rates, popultion increased.