Why is there a trade-off between survivorship and fecundity?

A. Fitness trade-offs occur because fecundity is higher in young organisms and survivorship is higher in older organisms.

B. Resources such as time and energy are limited, so survivorship and fecundity cannot both be maximized simultaneously.

C. Life history is shaped by natural selection in a way that maximizes survivorship and fecundity.

D. Fecundity depends on survivorship. If survivorship is increasing, the fecundity also will be increasing.

B. Resources such as time and energy are limited, so survivorship and fecundity cannot both be maximized simultaneously.

Explanation:

Each species trade-off between the survival and the life history traits such as a number of offspring produced, parental care and frequency of reproduction. Both reproductive success (fecundity) and survival success cannot be maximized due to limited resources.

For instance, species such as mosquitoes spend minimum energy is parental care but produce a large number of relatively unprotected young ones when the growth conditions become favorable to ensure the continuity of the species. They cannot spend much time in acquiring reproductive maturity and post natal care due to a small period of favorable growth conditions. On the other hand, most of the mammals such as human beings spend their energy in pre - and postnatal care to their young ones.