Strategies of survival and reproduction differ between species, and are reinforced by their genetic makeup. Some species exhibit life history traits that are said to represent K-selection. These organisms are typically larger-bodied and longer-lived, existing in populations close to the carrying capacity (which is what “K” stands for) of their environment. Maturity and reproduction occur at an older age, and less offspring is produced; however, the mortality rate of progeny is significantly lower than those of r-selection. Many large, terrestrial vertebrates,such as the llama shown in the picture above, fit this model of selection.