# Ecology Populations and Communities What is Ecology Ecology

• Slides: 40

Ecology Populations and Communities

What is Ecology? Ecology: the study of interactions of organisms with other organisms and with the physical environment (word means "study of house")

What is a population? A population includes members of the same species living in the same area, they can interbreed.

What is a community? A community refers to all of the different populations in an area.

What is an ecosystem? the community plus the non-living factors Biotic (living) - animals and plants Abiotic (nonliving) - water, soil, air, temperature

Levels of ecological study

Biosphere: all the areas of the earth that supports life

BIOMES: a large naturally occurring community of flora and fauna occupying a major habitat, Types of biomes: Savanna / Grassland Rain Forest Temperate Forest Desert Arctic Tundra Coniferous Forest Aquatic (rivers, ponds, ocean, estuary, wetlands) Watch the Battle at Kruger

Demography = statistical study of population dynamics Population size (N) = total number of individuals Population density = the number of individuals in an area

How would you determine the population density? This scientist is using a QUADRAT marking off an area and counting the number of individuals in that area. This method is also called RANDOM SAMPLING. This method isn’t that useful with animals that can move. How could you measure the population density of deer?

Mark and Recapture This method involves marking a sample of captured animals and then releasing them. These animals are later recaptured and the number of animals marked are compared to recaptures that aren’t marked. Which technique (random sampling or mark and recapture) would be best at determining the size of the deer population?

Dispersion Patterns

Life Tables (Life History) Life tables divide the population into age groups and often sexes, and show long a member of that group is likely to live. Mortality = probability of an individual dying (life expectancy) For example, between ages three and four, 12 individuals die out of the 776 that were remaining from the original 1000 deer. This number is then multiplied by 1000 to get the mortality rate per thousand.

Mortality Rate Problem Farmer Finkes is has 200 sheep, which include 14 lambs born this season. When she goes out to the barn, she finds that 4 of the lambs have died and 1 mother sheep has died. What is the mortality rate of her sheep population?

Infant Mortality Rate (2010) What does this chart tell you?

Survivorship Curve probability of individuals surviving to a particular age -Late Loss (Type I) -Constant loss (Type II) -Early loss (Type III)

What type of strategy is shown here?

Environmental Limits to Growth Exponential Growth- J Curve Logistic Growth- S Curve

What happens if the carrying capacity is exceeded?

What kind of life history pattern do deer in Indiana have? What kind of survivorship curve would you expect within this population? How would this information help you determine a plan of action for dealing with the deer population?

What limits growth? Competition for resources: ● ● ● Food Water Space Oxygen Mates Interspecific & Intraspecific What is most likely limiting the growth of the deer population in Indiana?

Density Dependent Factors As a population becomes more dense, the greater the mortality rate (disease, competition, parasites), results in lower FECUNDITY (ability to produce many offspring) Density Independent Factors that cause death that aren’t related to density, ex natural disasters.

Life Histories: K-selected and R selected Exists close to carrying capacity (K), tend to have stable environments, care for young, long lifespans Have large number of offspring, not all survive

Human Population Growth

Age Structure Diagrams

Should countries aim for ZERO POPULATION GROWTH?

China's One Child Policy Russia's Day of Conception

Community Factors Composition: What organisms live there? Biodiversity: How many different kinds of organisms live there? How does having too many deer affect the composition and diversity of the Indiana forest? Consider effects on: - Other animals - Plants - Nonliving factors (soil)

Competitive Exclusion Principle No two species can occupy the same niche. One species will drive the other to extinction or resource partitioning occurs.

Mule deer are found in Western North America. What do you think would happen if you imported mule deer to Indiana? (Indiana and most eastern states contain white-tailed deer)

Some states have reintroduced top level predators to help control populations of deer and other large herbivores. What factors would need to be considered before introducing wolves to Indiana? Why would some people object to this plan?

Predator Prey Interactions

What is a keystone species? Keystone species maintain biodiversity and are often top predators. Examples: Sea Otters African Elephants Sea Star Wolves?

Sea Stars and Biodiversity How can you connect this scenario to competitive exclusion?

Use evidence-based reasoning to make a case for reintroducing wolves into Indiana. Or a case for NOT reintroducing them.