5.2 Limits To Growth

Limiting Factors What factors determine carrying capacity?

Limiting Factors What factors determine carrying capacity? Limiting factors: available food and water, coemption for resources, predators and disease capacity of an environment for a species.

Limiting Factors A limiting factor is a factor that controls the growth of a population. There are several kinds of limiting factors. Some—such as competition, predation, parasitism, and disease—depend on population density. Others—including natural disasters and unusual weather—do not depend on population density.

Density-Dependent Limiting Factors Density-dependent limiting factors operate strongly only when population density—the number of organisms per unit area—reaches a certain level. These factors do not affect small, scattered populations as much. Density-dependent limiting factors include competition, predation, herbivory, parasitism, disease, and stress from overcrowding. Tends to affect a small number of populations at once, and they affect different populations in different ways.

Density-Independent Limiting Factors Density-independent limiting factors affect all populations in similar ways, regardless of population size and density. Unusual weather such as habitat destruction, hurricanes, droughts, or floods, and natural disasters such as wildfires, can act as density-independent limiting factors. Affect all populations about equally

What affects population size Density-Dependent Factor: limiting only when population is large Competition Predation Parasitism Disease Space Amount of Food Amount of Water Density-Independent Factor: affect population regardless of size Weather Natural disasters Seasonal cycles Human Influence

Which of the following is a limiting factor in a population of organisms? A. reproductive replacement B. life spans of the members C. fluctuations in atmospheric temperature D. availability of food

Answer: D. availability of food The availability of food is a limiting factor in a population of organisms. If there is not enough food, some of the organisms will die and the population will decrease in number.

When an environment has reached its carrying capacity for a certain population, which of the following is true?   A. Growth and immigration rate is equal to death and emigration rate. B. Growth and immigration rate is greater than death and emigration rate. C. Growth and immigration rate is less than death and emigration rate. D. Growth rate is exponential.

Answer: A. Growth and immigration rate is equal to death and emigration rate. Carrying capacity is the maximum population size of a species that can exist in a given environment given the resources.

Data on the immigration and emigration of a fish species would be most helpful in determining which of the following? A. biological magnification B. interspecies competition C. population of the species D. predator-prey relationships

Answer: C. population of the species Population size is determined by births, deaths, immigration and emigration.