Ecology notes

What is ecology

The study of interactions between organisms and their evironment

Population Ecology

Population

Group of individuals that live in the area, can interbreed, and share the same gene pool

genetic adaptations occurs at the population level

Factors of an environment that impact organism interactions can either be

Biotic

any living component that affects another organism or shapes the ecosystem.

Abiotic

non-living chemical and physical parts of the environment that affect living organisms

population Distribution

how organisms are arranged within an area.

. .. . ... . . . .. . . . . Random

. . . . . . . . . . . . . . . Uniform--territoriality

... .... .. ... .. clumped

Population Density

Measure of how crowded a population is: N / A. Number divided by Area

Ex. 3km X 1 km = 3 km ^ 2 150 warblers / 3km ^2 50 warblers / km ^ 2

Can change by adding or removing individuals from a population

Population Growth

Determined by the following equation: change-N = (births - deaths) + (immigrants - emigrants)

positive growth rate = growing populations

negative growth rate = shrinking populations

Exponential growth

population increases every year

normally occurs only when small populations are introduced to an area with ideal environmental conditions

Rarely lasts long

Logistic Growth

Population grows at a constant rate until it reaches its carrying capacity

carrying capacity is the maximum population that an environment can support comfortably

Growth almost always slows and stops due to limiting factors

Limiting Factors: Determine Population size

Density-dependent:

Influence of factor changes with population density.

competition: food, mates, nesting sites

Predators, parasites, pathogens

Density-independent:

Influence of factor does not change with population density.

Does not matter how big population is, it will affect the population

Abiotic factors

non-living chemical and physical parts of the environment that affect living organisms

Community Ecology

Communities are made up of many populations and interactions

Ecological relationships form when two or more species live closely together for a prolonged period of time

Communities change over time depending on interactions between populations

Niche

To avoid competition, species will occupy different niches

niche is an organism's ecological role in the ecosystem

Habitat

method of obtaining energy

mating behaviors

interactions with other species

No two species can occupy the same niche and coexist

The species that uses the resource more efficiently has a slight reproductive advantage and will eliminate the competitor

competitive exclusion

fundamental vs. realized Niche

Fundamental = Want or need

realized = what they want after competition

Competition (-/- interaction)

Intraspecific Competition

Interspecific Competition

interference is actual physical competition - negative because of the use of energy

exploitation is taking the resources for themselves

Predation (+/- interaction)

positive for predator

negative for prey

Mutualism (+/+ interaction)

positive for both organisms

Ex. Bees get food, flower gets pollinated

Ex. Warthog and mongoose. Warthog gets ticks removed, mongoose gets rich protein through eating ticks

Parasitism (+/- interaction)

positive for parasite- gets to live in or on another organism

Negative for other living organism- parasite may pass disease to organism

Commensalism (+/0 interaction)

one benefits, the other does not care

barnacles and whales, barnacles do not harm and get a free ride

birds lay nest and offspring in tree, tree is not harmed and does not care

Co-Evolution

Two species exert selective pressure on one another and effect the other's evolution

predator- prey coevolution

host- parasite coevolution

flowers and pollinators

mutualism