Final answer:
r-selection strategy involves producing many offspring with little investment in each, suitable for unpredictable environments, while K-selection strategy involves producing fewer offspring with substantial investment, adapted to stable environments. r-strategists dominate in early successional stages, and K-strategists in later stages.
Step-by-step explanation:
Organisms that reproduce sexually often follow r-selection or K-selection strategies to maximize the survival of their offspring, dealing with the energetic limits of reproduction in different ways. The terms 'r-selected' and 'K-selected', while not absolute classifications, represent two ends of a continuum for life-history "strategies" employed by various species with regard to reproduction, care of young, and survival adaptations.
r-selected species typically produce a large number of offspring with relatively low investment in each individual. These species are usually found in unpredictable or changing environments, where their strategy is to maximize the chance of at least some of the offspring surviving. They tend to have quick growth, early maturity, and short lifespan. Examples include marine invertebrates like jellyfish and plants like dandelions.
In contrast, K-selected species thrive in stable, predictable environments and are characterized by a smaller number of offspring with significant investment in each. They often exist close to their carrying capacity, with populations that grow slowly, mature late, and have a longer lifespan. Elephants and oak trees are typical examples of K-selected species providing extensive parental care and resources to their few offspring.
In terms of ecological succession, r-strategists typically dominate early stages when environments are more variable and less competitive, while K-strategists tend to dominate in later stages where ecosystems have reached a stable equilibrium and competition for resources is intense.