Population Dynamics Life Science

Populations Change!  Population Dynamics is the study of why populations change and what causes them to change

 All living things need resources such as water, energy and living space.  Carrying Capacity- maximum number of individuals an ecosystem can support

Three stages of population change  Growth- population increases in size. Birth > Death.  Stability- the population does not increase the same  Decline- the population decreases in size Death > Birth

Patterns of Growth  Rapid growth- very sharp increase in the numbers of individuals in a population

 Gradual growth-

Darwin and his observations  All populations are able to grow rapidly  Populations tend to remain constant in size  There are limits to the natural resources  Within a given population there is genetic variation

Characteristics that define a population  Population size- the number of individuals in a population at a given time  This can be a result of a climate change, time of year, and availability of resources

 Population density- the measure of the number of individuals living in a certain space

 Low density

 High Density

Population Spacing Clumped-gather around resources in groups Uniform-evenly space themselves compete for resources Random-no regard to individuals, or resources

Age Structure  Age determines the amount on how much a population can grow  Post reproductive- organisms that can no longer reproduce  Reproductive- organisms capable of reproduction  Pre-reproductive- not yet able to reproduce

How can scientists predict population change?

Populations Respond to Pressures 8-2

Population Responding to Pressures  Population growth is limited  This is a result of many factors  Birth- numbers of births in a population  Death- numbers of deaths in a population  Immigration- movement of individuals out of a given area  Emigration- movement of individuals out of a population

Population Change = (birth + immigration)-(death + emigration)

Limiting Factors  Prevents the continuing growth of a population  Density – Dependent Factors  Density – Independent Factors

Density Dependent Factor  Competition  Disease  Parasitism  Predation

Density Independent Factors  Drought  Hurricanes  Tornados  Fires  Floods

Survival Strategies  Opportunists- species that reproduce rapidly and have a short life span

 Competitors- species with adaptations that allow them to remain near their carrying capacity for long periods of time