Final answer:
r-selected species are opportunists due to their adaptability to unstable environments, characterized by producing many offspring with minimal parental care. This strategy reduces energy per offspring and increases the odds of survival amid fluctuating conditions.
Step-by-step explanation:
r-selected species are adapted to thrive in unstable and unpredictable environments. They tend to be opportunists because they produce a large number of small offspring, do not give long-term parental care, and have young that are relatively mature and self-sufficient at birth. The opportunistic nature of these species is manifested in the way dandelions, for example, produce many small wind-dispersed seeds to increase the likelihood that some will reach hospitable environments, despite many landing in places where they cannot survive.
Such reproductive strategy requires less energy investment per offspring when compared to K-selected species, which have fewer, larger offspring and invest heavily in parental care. By producing a high number of offspring and due to their lower energy demands for reproduction, r-selected species increase their chances of having at least some offspring survive in a changing environment, which is the essence of being opportunistic in the context of survival and reproduction.
r-selected species and K-selected species, although at opposite ends of a spectrum, both have limitations on the energy available for reproduction, which shapes their reproductive strategies and life history characteristics.