Population dynamics

Exponential Growth Exponential growth of a population of organisms occurs when the # of organisms rises at an ever-increasing rate.

Population Growth of Houseflies 1 million 500,000 100 One year Population size

What are some things that prevent populations from growing exponentially?

Carrying Capacity The number of organisms that a particular environment can support over an indefinite period of time. Births will exceed deaths until carrying capacity is reached

Number of Yeast Cells Time (hours) Carrying capacity Carrying capacity

4 population growth graphs

Exponential vs. Logistic growth

Limiting factors Density-dependent Density-independent Predation

Limiting factors Density-dependent Have an increasing effect as population increases Ex. Disease, parasites, competition, crowding & stress Density-independent Affects all populations, regardless of their density Usually abiotic factors: ex. storms, floods, temp, fire Predation – keeps population size within limits (density-dependent)

Practice Intense heat wave Classify each of the following as either density-dependent or density-independent. Intense heat wave Large population of caterpillars infected with wasp larvae parasites Overpopulation of an organism Clear cutting of a forest to build a shopping center.

Exotics Species living in an area to which they are not native Can be introduced accidentally or on purpose Ex. Sika from Asia brought to South TX

How do you think introducing Sika into the population would affect the native population of deer?

Swamp Rats in California

https://www. mysanantonio https://www.mysanantonio.com/bayarea/article/nutria-should-we-eat-invasive-species-swamp-rats-12726054.php#photo-15020981