R and K selected species

R-selected and K-selected species are terms that biologists use to describe animals’ reproductive strategies. Either an animal produces a large number of offspring, and it is a numbers game for those offspring, or the animals have few offspring and invest a significant amount of time in those offspring. R-selected species are those that favor a large number of offspring. R-selected species include insects, amphibians, many fish, and reptiles. They tend to be smaller organisms, so the energy used to make each individual is low, and they live in unstable environments. They also have shorter lifespans and reach sexual maturity quickly. They have a type III survivorship pattern which means that earlier in life, more organisms will die than later on in their life. In these species, the number of offspring is crucial because it directly impacts the population size. Continue reading