1. Populations

2. Populations = groups of individuals of the same species living in the same place
Individuals within a population:
occupy the same general area
rely on the same resources
influenced by the same environmental conditions

3. Population Dynamics Three Key Features of Populations Size Density
Dispersion
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

4. Three Key Features of Populations
Size: number of individuals in an area
Population Size Depends on 4 Factors:
Natality – number of births (increase population)
Mortality – number of deaths (decrease population)
Immigration – number of individuals moving into an area (increase population).
Emigration – number of individuals moving out of an area (decrease population).
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

5. Population Change Population size increases and decreases over time.
population change = (natality + immigration) – (mortality + emigration)

6. Population Limiting Factors
Density-dependent factors
Any factor in the environment that depends on the number of members in a population per unit area
Usually biotic (living) factors
These include
Predation
Disease
Parasites
Competition (for mates, resources)
Food shortage

7. Population Limiting Factors
Density-independent factors
Factors that limit population size, regardless of population density.
These are usually abiotic (non-living) factors
Natural weather events: Drought, flooding, extreme heat or cold, tornadoes, hurricanes, fires
Pesticides
Destruction of habitat
Pollution

8. Three Key Features of Populations
2. Density: measurement of population per unit area or unit volume
Pop. Density = # of individuals ÷ unit of space
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

9. Three Key Features of Populations
3. Dispersion: The pattern of spacing a population within an area
3 main types of dispersion
Clumped
Uniform
Random
The primary cause of dispersion is resource availability

10. Clumped Distribution Most common pattern in nature.
Result of unreliable resources.
Individuals of the population will clump around resources.
Also found among many animals to aid predation or fend off predators.

11. Uniform Distribution
Uniform Distribution = The tendency for populations to be found evenly distributed about their habitat.
Individuals use the resources found immediately around them, and spread out as to use all of the available resources
Happens because of interactions between individuals in the population.

12. Random Distribution Uncommon in nature.
Is the tendency for populations to be found randomly about their habitat.
This pattern occurs in the absence of strong attraction or repulsion from another individual.
Animals
Able to move about their habitat, so that at any given instance, they can be found anywhere about their environment.
Plants
Spores are randomly distributed by the wind
Usually have the ability to live anywhere in a given habitat.

13. Carrying Capacity
Carrying Capacity = the size of a population that can live indefinitely using the resources available where that population lives.

14. Factors that Affect Carrying Capacity
1. Materials and energy – populations are limited by the amount of usable energy from the sun and the supply of water, carbon, etc.

15. 2. Food chains – populations are limited by food supply and their predators.

16. 3. Competition – each species shares the same needs
3. Competition – each species shares the same needs. Competition for food, water, mates, space, etc. can limit population growth.
Intraspecific competition – among members of the same species
Interspecific competition – between different species

17. Density – species have differing needs for space
Density – species have differing needs for space. This determines an organism’s population density. Overcrowding can increase stress, promote disease, increase aggression, neglect of offspring, etc.
Death rates increase and birth rates decrease so that the population goes down.

18. Alien and Invasive Species
Alien species – a species that is accidentally or deliberately introduced into a new location
Invasive species – a species that can take over the habitat of native species

19. Deer: Predation of Starvation
Graphing Exercise

20. Human Population Growth
eo/the-magazine/the-magazine- latest/ngm-7billion/

21. World population density- 7 billion http://www. worldometers

23. Graphing Question (submit response)
Does the Human Population have a carrying capacity?