R-selected and K-selected species represent two distinct reproductive strategies in ecology. R-selected species are characterized by high reproductive rates and low survival rates, while K-selected species exhibit low reproductive rates and high survival rates.

R-selected species, often referred to as opportunistic species, typically have short life spans and reproduce rapidly. They generate a large number of offspring but invest minimal resources in each individual, leading to low survival rates. These species are well adapted to unstable environments and frequently inhabit disturbed habitats. Common examples of r-selected species include insects, bacteria, and certain fish. For more information on how these species interact within their ecosystems, please refer to our notes.

In contrast, K-selected species, also known as equilibrium species, tend to have longer life spans and reproduce at a slower pace. They produce fewer offspring but allocate more resources to each one, resulting in higher survival rates. These species thrive in stable environments and are typically found in undisturbed habitats. Notable examples of K-selected species include elephants, whales, and humans. To gain a deeper understanding of how these species contribute to their ecosystems, explore our detailed notes.

The distinctions between r-selected and K-selected species go beyond their reproductive strategies. R-selected species generally exhibit smaller body sizes, shorter life spans, and faster growth rates. Conversely, K-selected species are characterized by larger body sizes, longer life spans, and slower growth rates. Additionally, r-selected species possess a greater tolerance for environmental stress and can rapidly colonize new habitats, while K-selected species are more sensitive to environmental changes and have a slower colonization rate. For insights into the ecological significance of these species, see our related notes.

A-Level Biology Tutor Summary: R-selected species reproduce quickly and in large numbers, yet they have low survival rates and short life spans, thriving in unstable environments. K-selected species reproduce more slowly and in smaller numbers, but they enjoy high survival rates and longer life spans, flourishing in stable environments. Examples of r-selected species include insects, while elephants are representative of K-selected species. These two groups differ significantly in body size, growth rates, and adaptability to environmental changes. For further insights into how diseases impact these species, please see our notes.