Characteristics of Populations Spring 2018

Characteristics of Populations A group of organisms of the same species that live in the same area. Population density The number of individuals per unit area.

Characteristics of Populations To grow exponentially, a population Has to have abundant space and food Is well protected from predators and disease

Characteristics of Populations Exponential growth- Occurs when individuals of population reproduce at a constant rate J-shaped curve

Characteristics of Populations Logistic growth As resources become less available, the population growth rate slows or stops Carrying capacity The number of organisms of one species that can be supported in an environment S- shaped curve

Density-Dependent Limiting Factors Factors that are related to the density of a population: Competition Organisms compete for food, water, space, sunlight, and other essentials Predation Population control caused by predator-prey relationships Parasitism and disease Robs organisms of nourishment

Density-Independent Limiting Factors Effects of a population no matter what the size is. Unusual weather Drought Seasonal cycles El Nino Natural Disasters Volcanic eruptions, fires, floods Human activities Clear-cutting forests, damming rivers