Populations in Ecosystems Different species use different reproductive

Populations in Ecosystems • Different species use different reproductive strategies • Some species reach reproductive maturity very quickly and produce high volumes of offspring • These organisms tend to be small and have a short lifespan; individuals generally only reproduce once ▫ Ex: insects, dandelions

Populations in Ecosystems • Some species reach reproductive maturity more slowly and produce only a few offspring • These organisms tend to be longer-lived, and individuals will reproduce more than once in a lifetime • More care is invested in each offspring, and body sizes are generally larger ▫ Ex: whales, polar bears, humans

Predator and Prey o Predator and prey populations affect one another o As prey increases, the number of predators slowly increases o Eventually, the increase in predators will cause the prey population to “crash” o This decrease in prey will lead to a decrease in the predator population

Population Growth • Population sizes are not usually constant • Instead, they will increase and decrease in cycles • Limiting resource: a condition that can restrict a population’s growth ▫ Ex: amount of water will limit populations in the desert • Carrying Capacity: the number of organisms in a population that the environment can “carry” or handle

Population Growth o Some species increase population size rapidly until they reach carrying capacity o Others increase slowly and never cross carrying capacity o If a population overshoots carrying capacity, the population will crash o Once the population decreases, then individuals will have more resources, and the population will begin to grow again