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