BIOS1301 Lecture Notes - Lecture 5: Pioneer Species, Discrete Event Simulation, Ecological Niche
29 May 2018
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BIOS1301 – Ecology and Sustainability – Part 4
LEC 5: *Continued
Nitrogen Cycle
• DNA, RNA, amino acids and other organic molecules require nitrogen
• Plant growth - nitrogen is often the 'limiting nutrient'
Nitrogen pools:
• Atmosphere mainly N2 gas
• Oceans, lakes and rivers - large proportions of the world's N (dissolved inorganic and organic N
and in sediments)
• Soils - organic and inorganic
• No significant geological pool
Biological nitrogen fixation - change inorganic to organic (ammonia, nitrate)
• Mostly achieved by nitrogen fixing bacteria in soils and legumes
o Terrestrial: 1/3 non-symbiotic bacteria, 2/3 symbiotic bacteria
o Aquatic: cyanobacteria, bacteria in ocean vents (temp 92 degrees C)
• Cyanobacteria: autotrophic, heterocysts (specialised nitrogen fixing cells), large
blue-green algae blooms are problems in ecosystems.
LEC 6:
• What is an ecological niche?
• Abiotic and biotic factors
• Impacts on distribution and abundance
o Humans: land clearing, pollution, fragmentation (e.g. ski slopes causing a divide
between female and male possums, with predators waiting on the slope for
males to cross for breeding)
• Fossil record can give evolutionary history to explain the patterns of current species
LEC 7:
• Biodiversity in Australia
o Poorly understood (invertebrates, viruses, bacteria)
o Loosing species faster than we are understanding them
o High levels of endemism (91%) - species only found on Aus.
• Biogeography, evolution and changes in the Australian landscape
o Endemism is high due to long period of isolation of the continent
o Alfred Wallace - realised that continent drift has caused Aus. species to be
isolated and Aus. has only recently drifted close to Asia. - Wallace's line
(highlights distribution of species reflects past geological processes and
evolution)
LEC 8:
• Population, ecosystem dynamics, theory of succession, disturbance ecology,
patchiness
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Document Summary
Bios1301 ecology and sustainability part 4. Nitrogen cycle: dna, rna, amino acids and other organic molecules require nitrogen, plant growth - nitrogen is often the "limiting nutrient" Nitrogen pools: atmosphere mainly n2 gas, oceans, lakes and rivers - large proportions of the world"s n (dissolved inorganic and organic n and in sediments) Soils - organic and inorganic: no significant geological pool. Lec 6: what is an ecological niche, abiotic and biotic factors. Wallace"s line (highlights distribution of species reflects past geological processes and evolution) Case study 6: unequal power dynamics in science (abc background briefing 25/3/18: campaign giving women the strength to call out sexual harassment. Science: unequal power dynamics in research, professor terry speed, prime minister"s prize for science shown to have sexually harassed female co-worker. Policy: code of conduct - australian academy of science. Dynamic cycles of population: causes, predator-prey interactions, food resource limitation and excessive predation, predators reproduce more slowly than prey so they always lag behind.
