Fecundity rate or reproductive rate quantifies the number of offspring an organism produces over time. It differs from fertility rate which refers to whether organisms can produce offspring at all. The fecundity rate takes into account how many offspring an individual could produce under ideal conditions and assumes that the individual’s reproductive cycle starts over again as soon as possible after production of the offspring.

In the animal world, there is an inverse relationship between fecundity rate the amount of care the parents give to their offspring. For example, marine invertebrates like jellyfish and sea stars have many offspring but provide little parental care. Mammals like humans, whales and bears have fewer offspring but spend a lot of time and energy caring for them. Another contrast in this example is that the offspring of mammals are virtually helpless and require more extensive care while those of marine invertebrates are much more self-sufficient at birth. The fecundity rate for plants is understood by studying their seeds. Coconut and chestnut trees have low fecundity rates because the few energy-rich seeds they produce have a good chance of survival. High fecundity plants like orchids produce many seeds that are low in energy, each with less chance of survival.

Eubalaena glacialis with calf
The image above shows a mother North Atlantic right whale, Eubalaena glacialis, and her calf. Mammals like whales have low fecundity rates and devote a lot of time to the care of their offspring.

References

  • OpenStax, Biology. OpenStax. May 20, 2013. http://cnx.org/content/col11448/latest/