LIMITS TO GROWTH

CARRYING CAPACITY

– The largest number of individuals or species that a given environment can support is the carrying capacity. Certain factors can limit population growth. If the population density of a species is higher than the environment’s carrying capacity, many individuals of the species may die. However, there are advantages to having a high population density. – Genetic diversity is one

CARRYING CAPACITY

LIMITS TO GROWTH Limiting factors – Limiting nutrients indicates an insufficient supply of a particular nutrient. – A limiting factor is a factor that causes population growth to decrease. – Limiting resource bases can also affect the long term survival of a species. An example is the panda which depends on bamboo for food. These forests, in China, have been cleared for timber and farmland therefore limiting the population growth of the panda.

LIMITS TO GROWTH Density-dependent factors – A limiting factor that depends on population size is called a density-dependent limiting factor. Only limiting when the population density-the number of organisms per unit area- reaches a certain level. – Density-dependent limiting factors include competition, predation, parasitism, and disease. – Competition Crowed populations cause organisms to compete for food, water, space, sunlight, and other essentials.

LIMITS TO GROWTH Competition can occur between members of different species. This type of competition is a major force behind evolutionary change. – When two species compete for the same resources, both species are under pressure to change in ways that decrease their competition. – They can even, over time, evolve to occupy separate niches. » No two species can occupy the same niche in the same place at the same time.

LIMITS TO GROWTH – Predation Populations in nature can be controlled by predation. The regulation of a population by predation takes place within a predator-prey relationship, which is one of the best known methods of population control.

PREDATOR-PREY GRAPH

LIMITS OF GROWTH – Parasitism and disease The parasite can severely weaken the host to the point of a disease state and, even, cause death. This can limit the growth of the organism.

LIMITS TO GROWTH Density-independent factors – Unusual weather, natural disasters, seasonal cycles, and certain human activities-such as damming rivers, and clear cutting forests- are all examples of density- independent limiting factors. – These can cause a drop in population size that can stay low forever or build up again. – Rainstorms, hurricanes, cold or hot temperatures affect the populations density. – Environments are always changing, and most populations can adapt to change.