2.1 - populations, species identification, interactions, carrying capacity

ecology

study of interactions between organisms and their biotic and abiotic environment

sphreres

• biosphere

  • parts of Earth with life existing

• atmosphere

  • air parts of Earth

• hydroshpere

  • water parts of Earth

• lithosphere

  • soil and earth parts

species

group of organisms that can interbreed and produce fertile offspring.

hybride

infertile offspring resulting from the crossbreeding of two different species or varieties.

keystone species

a species that has a disproportionately large effect on its environment relative to its abundance, playing a critical role in maintaining the structure of an ecological community.

impacts of keystone species

• population control

threats of removal a keystone species

• trophic cascade

• habitat changes

• biodiversity loss

population

the total number of individuals of a species living in a specific area or habitat, which are capable of inbreeding

hierarchical classification system

ranks↓ = organism number ↓ = simmilarity between them ↑

Binominal naming system

• name of genus (capital letter)

• name of species (small leter)

eg. Homo sapiens

tools for identifying species

• dichotomous key → based on characteristics

• comparison of specimens with reference to known samples and collections

• DNA surveys → based on protein analysis

• cladistics

• taxonomy → classifying and naming organisms

cladistics

the process of classifying organisms into clades based on evolutionary relationships and common ancestry.

cladistics structure

clade → group of species evolved from common ancestor (all alive and dead)

terminal branches → most recent species

node → history line from common ancestor to new species

root → most recent common ancestor of all present primates

biotic factors

living components of an ecosystem that affect species interactions in a community

• plants

• fungi

• animals

• bacteria

• etc

abiotic factors

non-living components of an ecosystem

• water

• temperature

• pH

• humidity

• etc

ecological niche

the role and position a species has in its environment, including its

• habitat

• resources

• interactions with other organisms.

fundamental niche

the broadest set of conditions under which a species can survive and reproduce, without the influence of competitors or predators.

realised niche

the actual conditions under which a species exists, influenced by competition and predation.

species interactions

• predation

  • one by other eaten

• herbivory

  • consumption of plants

• decomposers

  • feed on dead and decaying

  • recycle nutrients

• symbiosis

  • two species living in close relationship

• mutualism

  • both benefit

• commensalism

  • one benefit, other unaffected

• parasitism

  • one benefit, host harmed

• competition

  • struggle over limited resources

types of competition

• intra specific

  • same species

• inter specific

  • different species

competitive exclusive principle

two species competing for the same limited resource cannot coexist at constant population values.

• one will decline

• or both will narrow their niches

factors affecting population growth and decline

• birth rate decline/ incline

• limiting factors

  • density dependent

  • density independent

carrying capacity

the maximum number of individuals of a species that an area's resources can sustain indefinitely without significantly depleting or degrading those resources.

• exponential growth

• overshoot

• die back

• flutuations

*due to limiting factors

density dependent limiting factors

factors that affect a population only when it reaches certain density

*tend to be biotic

• competition

• disease

• parasitism

• predation

density independent limiting factors

control populations no matter what the density is

*tend to be abiotic

• sunlight

• temperature

• water and natural disasters

• human activities

J-shaped curve

• exponential population growth

• hasn’t yet reached carrying capacity

• population at its biotic potential

  • no limiting factors

S-shaped curve

• growth leveling off as it reaches carrying capacity

  • limiting factors slow the growth when it starts approaching