94. A species whose life history strategies allow for high intrinsic rates of increase (r- strategist) will also exhibit the following EXCEPT
    (1) high tolerance for both environmental instability and low-quality resources.
    (2) short period of exponential population growth (r)
    (3) reproductive strategy that involves random mating, semelparity and little or no parental investment
    (4) survivorship that show density-dependent mortality, typically exhibiting Type l or 2
    survivorship curves.

Introduction

In ecology, r-strategists are species that maximize their reproductive output and thrive in unpredictable or rapidly changing environments. These species are known for their high intrinsic rates of increase (r), rapid population growth, and minimal investment in individual offspring. However, not every life history trait aligns with the r-strategy. Let’s identify which trait does not fit the r-strategist profile and why.

Defining r-Strategists

r-Strategists, or r-selected species, focus on rapid reproduction and dispersal. Their life history traits are shaped by environments where survival is uncertain, favoring strategies that ensure at least some offspring survive to adulthood.

Common Characteristics of r-Strategists

• High tolerance for environmental instability: Able to survive and reproduce in fluctuating or low-quality habitats.

• Short lifespan and early maturity: Quick to reproduce, often with many generations per year.

• Semelparity and little parental care: Many r-strategists reproduce once in a massive burst (semelparity) and provide little or no care to offspring.

• Random mating: Less selective in mate choice, maximizing reproductive opportunities.

• Short period of exponential population growth: Populations can boom quickly when conditions are favorable.

Evaluating the Options

Let’s review each statement in the context of r-strategists:

(1) High tolerance for both environmental instability and low-quality resources

• Typical of r-strategists.

• These species are well-adapted to unpredictable environments and can exploit poor-quality resources.

(2) Short period of exponential population growth (r)

• Typical of r-strategists.

• Their populations can increase rapidly for short periods when resources are available.

(3) Reproductive strategy that involves random mating, semelparity, and little or no parental investment

• Typical of r-strategists.

• These traits maximize offspring numbers and spread risk across many individuals.

(4) Survivorship that shows density-dependent mortality, typically exhibiting Type I or II survivorship curves

• NOT typical of r-strategists.

• r-strategists usually exhibit Type III survivorship curves, where most offspring die young, but a few survive to adulthood. Type I (high survival until old age, typical of humans) and Type II (constant mortality, typical of some birds) are more common in K-strategists.

• Density-dependent mortality and Type I/II curves are associated with stable populations and higher parental investment, which do not fit the r-strategy.

Survivorship Curves Explained

• Type I: Low mortality in early and middle life, high mortality in old age (e.g., humans, elephants).

• Type II: Constant mortality rate throughout life (e.g., many birds, some reptiles).

• Type III: High mortality early in life, with few survivors reaching adulthood (e.g., many insects, fish, and plants)—typical of r-strategists.

Conclusion

The life history trait NOT characteristic of r-strategists is:
Survivorship that shows density-dependent mortality, typically exhibiting Type I or II survivorship curves.

Correct answer:
(4) survivorship that show density-dependent mortality, typically exhibiting Type I or II survivorship curves.