Ecology

1. 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.

2. 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.

4. Ecosystem • All the organisms living in an area and the nonliving features of their environment

6. 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)

7. Detritivores Heterotrophic organisms who ingest dead organic matter. (e.g. earthworms, woodlice, millipedes) Earth worm (Lumbricus terrestris)

8. Chanterelle (Cantherellus cibarius) Saprotrophs Heterotrophic organisms who secrete digestive enzymes onto dead organism matter and absorb the digested material. (e.g. fungi, bacteria)

9. 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

10. 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.

11. Population Dynamics • Characteristics of Dynamics • Size • Density • Dispersal • Immigration • Emigration • Births • Deaths • Survivorship

12. 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

13. 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.

14. Density-Dependent Factors • limiting resources (e.g., food & shelter) • production of toxic wastes • infectious diseases • predation • stress • emigration

15. Density-Independent Factors • severe storms and flooding • sudden unpredictable severe cold spells • earthquakes and volcanoes • catastrophic meteorite impacts

16. 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.

17. INTERACTIONS AMONG SPECIES • Interactions • Interspecific competition • Predation • Exploitation • Symbiosis

18. 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

19. Community • All the populations in an ecosystem • Limiting Factors • Any abiotic or biotic factor that restricts the numbers, reproduction, or distribution of organisms.

21. Communities • Range of Tolerance • The limits within which an organism can exist.

22. 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

23. 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

24. 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

25. 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

26. Species B Species A Separate niches No overlap of niches. So coexistence is possible

27. Species C Species B Overlapping niches Interspecific competition occurs where the niches overlap

28. Species C Species B Species C’ Species B’ Specialisation avoids competition Evolution by natural selection towards separate niches Specialisation into two separate niches

29. 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

30. 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

31. 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

32. Competition • Competition caused by population growth affects many organisms, including humans • Limits population size

33. Intraspecific competition for food can also cause density-dependent behavior of populations. • Territoriality. • Predation.

34. Large blue butterfly (Maculinea arion) Feeding relationships • Predators & prey • Herbivory • Parasite & host • Mutualism • Competition

35. 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

36. 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