British Sign Language Glossaries of Curriculum Terms

BSL Environmental Science Glossary - R-selected species definition

Definition: R-selected species usually reproduce just once in their lifetime and produce many offspring. We humans typically have just one child at a time, or maybe two (occasionally three or four) and that is because the environment that we live in is relatively safe and the chances of a child surviving into adulthood are high. Whereas for fish, water is a more dangerous environment which is why they produce so many offspring; they may lay hundreds and thousands of eggs, but many of them will perish and sometimes only a few eggs will hatch. The other difference (between K- and R-selected species) is that when we humans have a child, we nurture/look after our babies and care for our children as they grow up until they finally become independent. Fish are completely different; fish lay their eggs and then swim away - the eggs are just left until they hatch at which point these tiny fish are, in a very short space of time, independent. The difference is that humans (K-selected species) reproduce more than once in a lifetime and have fewer offspring; fish (R-selected species) reproduce just once in their lifetime and have many offspring.