84. Among the following which is not an characteristic feature of r-selected species?
    (1) Delayed Maturity (2) Large clutch size
    (3) Small size of offspring (4) semelperity

Introduction

In ecology, r-selected species are those that thrive in unpredictable or changing environments by reproducing rapidly and in large numbers. Their life-history traits are adapted for quick population growth rather than long-term stability. However, not every reproductive or developmental trait fits the r-selection profile. Let’s explore which feature among the options is not characteristic of r-selected species and why.

Core Features of r-Selected Species

r-Selected species are defined by several hallmark traits:

• Early Maturity: They reach reproductive age quickly to take advantage of fleeting resources.

• Large Clutch Size: They produce many offspring at once, maximizing the chance that some will survive.

• Small Offspring Size: Offspring are generally small, allowing parents to invest energy in quantity over quality.

• Semelparity: Many r-selected species reproduce once in a massive burst (semelparity), then die, although some can be iteroparous.

Analyzing the Options

(1) Delayed Maturity

• Not characteristic of r-selected species.

• r-Selected species are notable for early sexual maturity, not delayed. Early maturity allows them to reproduce quickly and often, which is essential in unstable environments.

(2) Large Clutch Size

• Characteristic of r-selected species.

• Producing many offspring in each reproductive event is a classic r-selection trait, increasing the probability of survival for at least some individuals.

(3) Small Size of Offspring

• Characteristic of r-selected species.

• Smaller offspring require less investment per individual, allowing for larger numbers and rapid population growth.

(4) Semelparity

• Characteristic of many r-selected species.

• Semelparity (one-time, massive reproductive event) is common among r-selected organisms, such as annual plants and many insects.

Why Delayed Maturity Is Not r-Selected

Delayed maturity is typically a feature of K-selected species, which invest more time and energy in growth, survival, and fewer, higher-quality offspring. These species are adapted to stable environments where competition is high and long-term survival strategies are favored.

Examples of r-Selected Species

• Insects: Mosquitoes, fruit flies, and aphids mature quickly and lay hundreds of eggs with little to no parental care.

• Annual Plants: Weeds and grasses germinate, grow, and reproduce all within a single season.

• Small Fish: Many small fish species mature rapidly and spawn in large numbers.

Quick Comparison Table

Conclusion

Delayed maturity is NOT a characteristic of r-selected species. Instead, r-selected species are defined by early maturity, large clutch sizes, small offspring, and often semelparity. Recognizing these differences is crucial for understanding population dynamics and species adaptation in changing environments.

Correct answer:
(1) Delayed Maturity