Module 8 Lesson 5 - 1
Lesson 5 — Growth Patterns
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However, nine months of gestation are necessary to make an offspring, and if the mother is nursing, she may not ovulate for a few months after the birth. If we assume that she is capable of having one child each year for those 35 years, each woman has the potential to produce 35 offspring in her 80-year lifespan. However, this number does not consider many factors: multiple births, miscarriages, missed ovulations, malnutrition, maternal and/or child mortality, sterility, etc. However, it is still a very impressive figure.
With more than 7 billion people on the planet and approximately 50% of the population being female, you can see how human population could increase exponentially if conditions always were favourable! A glance at the human population graph may convince you it already has. However, humans typically do not produce 35 offspring, and they reproduce at a much slower rate than their biotic potential.
As impressive as the biotic potential of humans is, it pales in comparison to a typical female field mouse, which at one month is capable of breeding and having a litter of ten young after a gestation period of 20 days. A female field mouse is capable of breeding again 24 hours after her litter is delivered. Although the average life span of a field mouse is 5 months in the wild due to predation, the reproductive potential of a wild mouse is staggering: four months (120 days) of breeding with one litter of 10 pups every 20 days equals a potential to produce 60 offspring in her five-month lifespan. Achieving this potential is common. This is a startling reminder of how necessary predators such as coyotes, foxes, domestic cats, and possibly poisons such as warfarin are in controlling mouse populations.
By the end of this lesson, you should be able to answer these focusing questions:
- What are the types of population growth patterns?
- How do growth patterns illustrate these types of changes over time?
