The study of the interactions that take place among organisms and their environment. Ecology. ENVIRONMENT – living and non-living components ABIOTIC – non-living component or physical factors as soil, rainfall, sunlight, temperatures BIOTIC – living component are other organisms .
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The study of the interactions that take place among organisms and their environment Ecology • ENVIRONMENT – living and non-living components • ABIOTIC – non-living component or physical factors as soil, rainfall, sunlight, temperatures • BIOTIC – living component are other organisms.
Biosphere • The part of Earth that supports life • Top portion of Earth's crust • All the waters that cover Earth's surface • Atmosphere that surrounds Earth.
Ecosystem • All the organisms living in an area and the nonliving features of their environment
Energy and organisms Organisms which can synthesise their own complex, energy rich, organic molecules from simple inorganic molecules (e.g. green plants synthesis sugars from CO2 and H2O) Autotrophs Heterotrophs Organisms who must obtain complex, energy rich, organic compounds form the bodies of other organisms (dead or alive)
Detritivores Heterotrophic organisms who ingest dead organic matter. (e.g. earthworms, woodlice, millipedes) Earth worm (Lumbricus terrestris)
Chanterelle (Cantherellus cibarius) Saprotrophs Heterotrophic organisms who secrete digestive enzymes onto dead organism matter and absorb the digested material. (e.g. fungi, bacteria)
Species A group of organisms that can breed to produce fully fertile offspring Population • All the organisms in an ecosystem that belong to the same species
The characteristics of populations are shaped by the interactions between individuals and their environment • Populations have size and geographical boundaries. • The density of a population is measured as the number of individuals per unit area. • The dispersion of a population is the pattern of spacing among individuals within the geographic boundaries.
Population Dynamics • Characteristics of Dynamics • Size • Density • Dispersal • Immigration • Emigration • Births • Deaths • Survivorship
Parameters that effect size or density of a population: Immigration Death Birth Population (N) Emigration The size of a population is determined by a balance between births, immigration, deaths and emigration
Introduction • Why do all populations eventually stop growing? • What environmental factors stop a population from growing? • The first step to answering these questions is to examine the effects of increased population density.
Density-Dependent Factors • limiting resources (e.g., food & shelter) • production of toxic wastes • infectious diseases • predation • stress • emigration
Density-Independent Factors • severe storms and flooding • sudden unpredictable severe cold spells • earthquakes and volcanoes • catastrophic meteorite impacts
Density-dependent factors increase their affect on a population as population density increases. • This is a type of negativefeedback. • Density-independent factorsare unrelated to populationdensity, and there is nofeedback to slow populationgrowth.
INTERACTIONS AMONG SPECIES • Interactions • Interspecific competition • Predation • Exploitation • Symbiosis
Types of Species Interactions • Neutral – two species do not interact • Mutualism – both benefit • Commensalism – one benefits, other neutral • Parasitism – one benefits, one harmed but not killed • Predation – one benefits, other killed
Community • All the populations in an ecosystem • Limiting Factors • Any abiotic or biotic factor that restricts the numbers, reproduction, or distribution of organisms.
Communities • Range of Tolerance • The limits within which an organism can exist.
Biodiversity • What is Biodiversity? The variety of life in an area that is determined by the number of different species in that area. • There are 2 main types: Genetic Diversity Species Diversity
Habitat • The place in which an organism lives • provides the kinds of food and shelter, the temperature, and the amount of moisture the organism needs to survive
The place of an organism in its environment NicheAn organism’s habitat + role + tolerance limits to all limiting factors THE COMPETITIVE EXCLUSION PRINCIPLE G.F. Gause (1934) If two species, with the same niche, coexist in the same ecosystem, then one will be excluded from the community due to intense competition
Niche The niche of a species consists of: • Its role in the ecosystem (herbivore, carnivore, producer etc) • Its tolerance limits (e.g. soil pH, humidity) • Its requirements for shelter, nesting sites etc, all varying through time
Species B Species A Separate niches No overlap of niches. So coexistence is possible
Species C Species B Overlapping niches Interspecific competition occurs where the niches overlap
Species C Species B Species C’ Species B’ Specialisation avoids competition Evolution by natural selection towards separate niches Specialisation into two separate niches
This niche is not big enough for the both of us! Species A Species D Very heavy competition leads to competitive exclusion One species must go
Isle of Wight Tourist Guide Example: Squirrels in Britain The Red Squirrel (Sciurus vulgaris) is native to Britain Its population has declined due to: • Competitive exclusion • Disease • Disappearance of hazel coppices and mature conifer forests in lowland Britain
Bananas in the Falklands The Alien The Grey Squirrel (Sciurus carolinensis)is an alien species Introduced to Britain in about 30 sites between 1876 and 1929 It has easily adapted to parks and gardens replacing the red squirrel
Competition • Competition caused by population growth affects many organisms, including humans • Limits population size
Intraspecific competition for food can also cause density-dependent behavior of populations. • Territoriality. • Predation.
Large blue butterfly (Maculinea arion) Feeding relationships • Predators & prey • Herbivory • Parasite & host • Mutualism • Competition
Food Chain • rose plant aphids beetle chameleon hawk • Producer • 1st order Consumer or Herbivore • 2nd order Consumer or 1st order Carnivore • 3rd order Consumer or 2nd order Carnivore • 4th order Consumer or 3rd order Carnivore • Decomposers – consume dead and decaying matter
Trophic levels • Each step in a food chain or a food web is called a trophic level. • Producers are the first trophic level • Consumers are the second, third, or higher trophic level • Each trophic level depends on the one below for energy