Which of the following is not a characteristic of r-selected species?

Question

Accepted Answer

The correct option is 2: Parental care

The concept of r-selected species (r-strategists) versus K-selected species (K-strategists) is a cornerstone of life history theory in ecology. The 'r' in r-selected species refers to the intrinsic rate of natural increase, meaning these organisms prioritize rapid growth and reproduction, which is an evolutionary adaptation to unpredictable, unstable, or disturbed environments. Because their habitat conditions are often harsh or temporary, the most successful strategy for r-strategists is to produce as many offspring as possible in a short period. This massive reproductive effort comes at a cost: minimal energy investment in each individual offspring, including post-natal care. Therefore, **parental care**—which is a major investment of time and energy aimed at maximizing the survival of *each* individual progeny—is the defining characteristic of K-selected species, such as mammals, birds, and large plants. An r-selected organism, such as a housefly, a bacterium, or an annual plant, commits its energy to sheer reproductive volume rather than nurturing a select few, making the absence of parental care a hallmark of this life strategy.

The incorrect option is 1: Produce large number of progenies

Producing a large number of progenies is, in fact, the central characteristic and namesake of the r-selected life strategy. Since these species occupy environments where resources fluctuate and mortality is extremely high and unpredictable, their evolutionary success depends on maximizing their intrinsic growth rate ($r$). By producing thousands or even millions of eggs, spores, or offspring, they ensure that statistically, at least a few will survive the initial environmental hazards to reproduce the next generation. This high reproductive output is a direct countermeasure to the high mortality rates they experience. This "big bang" approach to reproduction allows them to rapidly exploit favorable, but short-lived, resource pulses and is necessary for the population to persist.

The incorrect option is 3: Reproduce quickly

The ability to reproduce quickly is a critical feature that enables r-selected species to thrive in volatile environments. This is often achieved through early sexual maturity and a short generation time, allowing them to rapidly colonize a new habitat before it deteriorates or before K-selected competitors arrive. For example, pioneer species colonizing a freshly cleared area must reproduce quickly to complete their life cycle before the perennial plants and other established organisms take over. This characteristic of fast, continuous, and often semelparous (single reproductive effort) breeding ensures that population numbers rebound rapidly after catastrophic declines, which are common in their unstable habitats.

The incorrect option is 4: Low survival rate of progenies

A low survival rate of progenies is a direct and unavoidable consequence of the r-selected life strategy, thus making it a key characteristic. The limited resources of the parent are allocated to producing a high *quantity* of offspring, meaning there is minimal investment in the *quality* or protection of any single progeny. These numerous, small offspring are typically left to fend for themselves immediately, exposing them to high predation, harsh climate, and resource scarcity. On a survivorship curve, r-selected species exhibit a Type III pattern, where mortality is extremely high in the early stages of life, reinforcing that a low survival rate is expected and factored into their life history.