Section 1 Vocabulary (5): • population density, • population growth rate, • emigration, • immigration, • carrying capacity
SC.912.L.17.5: • Analyze how population size is determined by births, deaths, immigration, emigration, and limiting factors (biotic and abiotic), that determine carrying capacity
Populations • Groups of the same species, living in the same area, at the same time!
Population Characteristics • Population Density (92) • The number of organisms per unit area. • How many are in a given amount of space? • Notes: Population density is highest when resources are abundant and when body size is small
Patterns of population dispersion • Dispersion is the patters of spacing within an area. • Uniform • Clumped • Random • You can still calculate density!
Population Limiting Factors • Density independent factors: (94): • Any factor in the environment that does not depend on the number of members in the population per unit area. • Notes: usually are abiotic, includes natural phenomena and weather events like drought, floods, extreme heat or cold
Density dependent(95) • Any factor in the environment that depends on the number of members in a population per unit area. • Notes: usually biotic such as predation, disease, parasites, competition. Graphs of 2 populations often show a rise and fall in population size demonstrating the dependence on one another
Population Growth Rate(97) • How fast a population grows or increases in size. • Notes: Depends on factors such as • Density dependent , Density independent • Immigration, emigration
Emigration (97) • The number of individuals moving away from a population
Immigration (97) • The number of individuals moving into a population. • Notes Most of the time emigration rates = immigration rates. • Natality= number being born= increases • Mortality= number dying = decreases
No limits= exponential growth • Lots of food, lots of space, no competition, no predators …growth will go on and on…
Logistic Growth • Growth starts off the same way as exponential, with a lag phase, then grows rapidly, but reaches the carrying capacity. (k) and stops increasing when the number of births is less than the number of deaths or emigration exceeds immigration.
Carrying Capacity (K) (98) • The maximum number of individuals in a species that an environment can support for the long term. • Notes: limited by energy, water, oxygen, and nutrients available
1. What are the characteristics of populations? Density, distribution and growth rate
2. Why are populations with really low population densities less likely to survive than those with higher densities?
There are fewer of them to start off with so when some are lost, it is harder for the population to recover.
3. Name and describe the three types of population dispersion. • 1. Uniform: evenly dispersed • 2. Clumped: in groupings • 3. Random: no particular pattern
4. Food, water, and disease are examples of density-_dependent factors. • Therefore, weather and climate are examples of density-independent factors.
5. How does emigration affect a population? • InitiallyIt makes the population smaller due to the loss of organisms. Less competition, more resources could increase the birth rates and eventually allow the population to have a growth rate increase.
7. How does the carrying capacity affect the reproductive rates? If a population is below carrying capacity the reproductive rate will be high, if the population is at or above carrying capacity the reproductive rate will be low!
1. What things alter human population growth? Industry, resources, space, technology. • 2. Is there a carrying capacity for the earth for the human population? Yes, • Explain we have limited amounts of space and resources so there is a limit to the number of humans the earth can support.