Final answer:
R-selected species thrive in unpredictable environments by rapidly producing many small offspring with little parental care, whereas K-selected species are suited for stable environments where they invest heavily in fewer, larger offspring with increased parental care.
Step-by-step explanation:
The main differences between r-selected and K-selected reproductive strategies are based on how species adapt to their environments and allocate resources for survival and reproduction. R-selected species are typically found in unstable and unpredictable environments, producing a large number of small offspring with minimal parental care, enabling them to spread rapidly, but with a lower survival rate for each individual. In contrast, K-selected species are adapted to stable and predictable environments, commonly producing fewer but larger offspring with more parental care, aiming for a higher survival rate per individual and populations that grow to be near their carrying capacity. For example, marine invertebrates such as jellyfish and plants like the dandelion are r-selected, producing many offspring that are relatively self-sufficient at birth. On the other hand, an example of a K-selected species would be elephants, which invest considerably in a small number of offspring with increased parental care. This is a continuum, and some species may exhibit a mix of these characteristics, but in general, these strategies represent two opposite ends of the reproductive spectrum.