Population Ecology

Population Dynamics Population: all the individuals of a species that live together in an area Demography: the statistical study of populations, make predictions about how a population will change

Population Dynamics Three Key Features of Populations Size Density Dispersion (clumped, even/uniform, random)

Three Key Features of Populations 1. Size: number of individuals in an area

Growth Rate: Birth Rate (natality) - Death Rate (mortality) How many individuals are born vs. how many die Birth rate (b) − death rate (d) = rate of natural increase (r). Three Key Features of Populations

Immigration Emigration Natality Mortality Population Factors That Affect Future Population Growth

Three Key Features of Populations 2. Density: measurement of population per unit area or unit volume Formula: D= N Pop. Density = # of individuals ÷ unit of space S

1. Immigration- movement of individuals into a population 2. Emigration- movement of individuals out of a population 4 Factors that affect density

Three Key Features of Populations 3. Dispersion:describes their spacing relative to each other clumped even or uniform random

clumped even (uniform) random

Population Dispersion

Boom & Bust & Boom & Bust & Boom & Bust

Other factors that affect population growth Limiting factor- any biotic or abiotic factor that restricts the existence of organisms in a specific environment. –EX.- Amount of water Amount of food Temperature

Carrying Capacity- the maximum population size that can be supported by the available resources There can only be as many organisms as the environmental resources can support Other factors that affect population growth

Carrying Capacity Carrying Capacity (k) NumberNumber Time J-shaped curve (exponential growth) S-shaped curve (logistic growth)

Human Population Zero population growth: when birthrate equals the death rate Age structure: number of males and females in each of the three age groups

PRE-REPRODUCTIVE REPRODUCTIVE POST-REPRODUCTIVE

Population of a Stable Country

You decide!

Human Population Growth

Human population Demographic transition: A change in population from high birth and death rate to low birth and death rate.

What is biodiversity? Biodiversity- the variety of life in an area that is determined by number of different species in area Extinction- Entire species permanently disappears from the biosphere

What is biodiversity? Genetic diversity- variety of genes or inheritable characteristics that are present in a population

What is biodiversity? Species diversity- number of different species and how many of each species in biological community

What is biodiversity? Ecosystem diversity- variety of ecosystems that are present in the biosphere What abiotic factors would be different between Alaska and rainforest?

Why is biodiversity important? Economics Values – Direct- We depend on plants and animals for food – Indirect- healthy ecosystems help provide protection against floods and drought – Cost effective

Why is biodiversity important? Aesthetic value- the way something looks (beautiful) Scientific value- maintaining ecosystems and species

Threats to Biodiversity Background extinction- gradual process of species becoming extinct Mass extinction- an event in which a large percentage of all living species become extinct in a short period of time

Factors that threaten biodiversity Natural resources- all materials and organisms found in the biosphere What are some natural resources? Minerals Fossil fuels Nuclear fuels Plants Animals Soil Clean water Clean air Solar energy

Factors that threaten biodiversity Overexploitation- excessive use of species that have economic value At one time there use to be about 50 million bison but in 1889 there were less than 1000 left.

Factors that threaten biodiversity Habitat loss Destruction of habitat- clearing of rainforest Disruption of habitat- habitat not destroyed but can be disrupted

Factors that threaten biodiversity Habitat fragmentation- separation of an ecosystem into small pieces of land Edge effect- different environmental conditions that occur along boundaries of an ecosystem

Factors that threaten biodiversity Pollution Biological magnification- the increasing concentration of toxic substances in organisms as trophic levels increase up food chain/web

Pollution Acid pollution – Burning of fossil fuels Eutrophication- form of water pollution that destroys underwater habitats for fish and other species

Factors that threaten biodiversity Introduced species- nonnative species that are either intentionally or unintentionally transported to a new habitat Also known as invasive species

Conserving Biodiversity Why do you think it is important to try and conserve biodiversity?

Natural Resources Renewable resources- resources that are replaced by natural processes faster than they are consumed Nonrenewable resources- resources found on Earth in limited amount and take extremely long time to be replaced

Natural Resource Sustainable use- using resources at a rate in which they can be replaced or recycled while preserving the long-term environment

Protecting Biodiversity Protected areas – National parks – Wildlife reserves – Nature reserves – Yellowstone National Park -1872

Biodiversity hot spots Endemic species- species that are only found in that specific geographic area Corridors between habitat fragments- think of safe passages (bridges) for animals

Restoring Ecosystem Bioremediation- use of living organism, such as prokaryotes, fungi, or plants, to detoxify a polluted area Biological augmentation- adding natural predators to degraded ecosystem