Question

Which of the following is correct for r-selected species?
A) Small number of progeny with small size
B) Small number of progeny with large size
C) Large number of progeny with small size
D) Large number of progeny with large size

Answer 1

Hint: r-selected species show semelparity (single reproduction), early reproduction, and rapid development.

Complete answer:
The concept of r-strategists and K-strategists provides a link between population dynamics and life history. Strongly variable and unpredictable environments lead to a highly fluctuating population density which preferably select for a high intrinsic growth rate ‘r’ which is achieved by a distinctive life-history strategy consisting of rapid development, a small body size, early reproduction, semelparity, and a short life span (usually with a life span of less than a year). Species showing this reproductive pattern overcome the massive loss of their offspring by producing so many unprotected young ones that a few will survive to reproduce many offspring to begin the cycle again. Species with these characteristics are called r-strategists. Algae, bacteria, rodents, annual plants (such as dandelions), and most insects are r-strategists. Such species tend to be opportunists. When conditions are favorable or when a disturbance opens up a new habitat or niche for invasion, as in the early stages of ecological succession, these species reproduce and disperse rapidly.

So, the correct answer is ‘Large number of progeny with small size’.

Note: - r-selected species are also called fugitive species or opportunistic species.
- Mac Arthur and Wilson designated the terms ‘r-selection’ and ‘k-selection’.
- All organisms must reach some compromise between the two extremes, no organism is completely r-selected or k-selected.