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 Predator and prey populations affect one another As prey increases, the number of predators slowly increases Eventually, the increase in predators will cause the prey population to “crash” 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 Some species increase population size rapidly until they reach carrying capacity Others increase slowly and never cross carrying capacity If a population overshoots carrying capacity, the population will crash Once the population decreases, then individuals will have more resources, and the population will begin to grow again