The production of numerous small offspring followed by exponential population growth is the defining characteristic of R-selected species. R-strategists make an abundance of offspring in hopes that a few will make it. These organisms have a short lifespan, short maturation span, high young mortality rate, and produce a large amount of offspring. The population produces much offspring to survive in their unstable environment. Examples of r-strategists are weeds, mice, bacteria, insects, and fish.