R-selected and K-selected strategies Knowledge-Based Download PDF

Questions

1. 1.

   In ecological succession, how do $r$-selected species and $K$-selected species typically differ in their colonization timing and community roles?

   • A) $r$-selected species act as rapid pioneer colonizers of disturbed sites, while $K$-selected species outcompete them to dominate mature climax communities.
   • B) $K$-selected species serve as initial colonizers due to high stress tolerance, while $r$-selected species dominate crowded climax communities.
   • C) $r$-selected species exclusively colonize mature ecosystems with dense canopies, while $K$-selected species colonize barren substrates.
   • D) $K$-selected species proliferate rapidly during initial disturbance, while $r$-selected species establish slowly to stabilize the soil.
2. 2.

   Which statement correctly describes how population size is primarily regulated in $r$-selected species compared to $K$-selected species?

   • A) $r$-selected populations are primarily regulated by density-dependent competition near carrying capacity, whereas $K$-selected populations are primarily controlled by catastrophic density-independent events.
   • B) $r$-selected populations are predominantly regulated by density-independent abiotic factors that cause boom-and-bust cycles, whereas $K$-selected populations are stabilized near carrying capacity primarily by density-dependent mechanisms.
   • C) Both $r$-selected and $K$-selected populations maintain stable equilibrium densities through equal reliance on density-dependent parental care and territorial defense.
   • D) $r$-selected populations are buffered against climatic extremes through negative density-dependent feedback, whereas $K$-selected populations undergo unpredictable population crashes driven solely by physical disturbances.
3. 3.

   Which survivorship curve is most characteristic of an $r$-selected species, and what mortality pattern does it represent?

   • A) Type I curve, representing high juvenile survival followed by rapid mortality in old age
   • B) Type II curve, representing a constant probability of mortality throughout all life stages
   • C) Type I curve, representing heavy early-stage mortality that levels off after reproductive maturity
   • D) Type III curve, representing extremely high juvenile mortality with increased survival for older individuals
4. 4.

   In population ecology, which environmental condition predominantly favors the evolution of an $r$-selected reproductive strategy rather than a $K$-selected strategy?

   • A) An unstable or frequently disturbed environment with abundant, unpredictable resources
   • B) A crowded, highly competitive habitat maintained near its carrying capacity
   • C) A climax community characterized by intense density-dependent competition
   • D) A predictable, stable environment where survivorship depends primarily on individual competitive ability
5. 5.

   Which life history characteristic is typically associated with $K$-selected species rather than $r$-selected species?

   • A) High fecundity with minimal parental investment
   • B) Rapid sexual maturation and short generation time
   • C) Extensive parental care and high juvenile survival
   • D) Population sizes that frequently fluctuate well below carrying capacity