The following population is comprised of 1,000 individuals. 400 individuals are juveniles (not yet reproducing), 500 are of reproductive age, while 100 are too old to reproduce. The sex ratio is 50:50 males to females. What is the effective population size?

a. 500

b. 1000

c. 400

d. 100

a. 500

Explanation:

The effective size of a given population is calculated by simply counting the total amount of organisms that actually are in conditions of reproduce and produce certain offspring in the next generation. In this particular case, althugh the population is formed by a total of 1000 individuals, only 500 organisms are capable of reproduce at that particular instant, and therefore contribute with offspring to the next generation.