LIFSCI 7B XL - Animation: Age structure copy & Life cycles and survivorship curves copy
Why are biologists interested in age structures of populations?
Because age structures provide information that allows the estimation of a population's potential for future growth
A survivorship curve plots the proportion of the original cohort that is alive at the end of each stage or time period. In the Lime Swallowtail butterfly scenario, the cohort we followed was the:
250 eggs that were laid
At which point stage are Lime Swallowtails least vulnerable to predation?
As larvae
At which stage in their lifecycle are Lime Swallowtails most vulnerable?
As pupae
According to the text book, demography is the study of the size structure and distribution of populations over time and includes changes in response to birth rates, aging, migration, and death rates at various times in the life cycle. In this Lime Swallowtail butterfly cohort, which of these factors were being followed most closely?
Death Rates
Which of the histograms above most likely represents a country with the highest population growth rate?
Histogram B
Above are three generalized age pyramid structures. Males are on the left in blue, females are on the right of the central line in red. Which histogram most likely represents a country with a declining population growth rate?
Histogram C
The expanding base of a population pyramid over time indicates which of the following?
The number of younger individuals in the population is increasing
Consider five human populations that differ demographically only in their age structures. The population that will grow the most in the next 30 years is the one with the greatest fraction of people in which age group(s):
The pre-reproductive age groups
In the Lime Swallowtail butterfly scenario, only 30 of the adults that hatched from pupae survived to reproduce. Given this, which of the following is not true?
Within this one generation, the total population of Lime Swallowtails increased by 300% (30 compared with 10).
