- Taxonomy: 3 domains, Binomial classification- hierarchy, defining species, phylogenetic relationships.
- Natural selection, speciation, evolution. How early humans evolved- role of bipedalism and anatomical adaptations.
- Risk of sex- sexual vs. asexual
- Definition, exponential growth, logistic cuve, other patterns observed in nature.
- Exponential: formulae (rN), human popln growth, starlings-N. America, Paramecium.
- Density-dependent limitation factors: competition, space, food, water, waste, disease, predators.
- Density-independent factors- hazards/extreme events e.g. Herons, UK- dip after some Winters
- S-shaped curve to carrying capacity (k). N=K- popln growth =0.
- Discontinous growth e.g. plants in temperate zones
- Examples- Flour beetles, Wildebeest, Willow tress-UK after introduction of Myxamatosis,
- MSY- over-exploitation of fish populations: passive vs modern drift nets, echo sounders, purse seine.
- No pattern? Skylarks, UK.- but gradual decline
- Boom-bust predator-prey cycle.
- All patterns (logistical/cyclical/random)- have an "r" value in growth model- useful for land managers.
- Habitat vs. ecological niche definitions
- Resource prey gradient graph and environmental gradient graph
- Principle of competitive exclusion
- Inter-specific and intra-specifc. resource exploitation.
- Red and grey squirrels - maybe not competition?
- Zonation of UK barnacles- Chthamalus vs. Semibalanus- definite competition-experiment.
- Fundamental v.s realised niche- edited resource prey gradient graph
- Example of niche differentiation- species of *** in Paridae- subtle but effective
- Niche dimension box graphs
- Character displacement - galapagos finches, mud snails on tidal flats (ventrosa vs. ulvae).
- Definition of predation. Define evolutionary fitness. Food chains + food webs
- True predators, grazers, parasites, parasitoids.
- How can we observe predation?- drag marks, prints, remains.
- Monophagous(specialists); Oligophagous (restricted range); Polyphagous (generalist)
- Specialist e.g. Lynx and snowshoe hare- unstable population cycles- 10 year oscillation cycles. Co-evolution- evolutionary arms race- selection pressures. Cost-benefit analysis. Searching/handling times vs. risk of starvation.
- Pied wagtails choosing fly size- 7mm= optimal size- most energy per unit effort/time.
- Prey switching- change searching image based on previous experience
- Generalists- Guam snakes, brown bears, red foxes, guppies, water bug.
Disease and parasitism:
- Definition of parasitism. Ectoparasites vs. Endoparasites. Effects= larger than predation.- Digenean flukes effect on mud snails compared to shorebirds.
- Vectors of disease. Energetic cost of disease on reproduction. e.g. Female western fence lizards, California- clutch sizes when infected with malaria.
- Energetic cost on chick mortality e.g. Mangrove finch chicks- anaemic due to parasitic larvae of Philornis downsi. Experiment- fumigated cotton balls- higher fledging success.; Cattle egret chicks- 24 ticks=fatal- blood loss and arbo-virus infection. - spraying nests with insecticide-lowered chick mortality,
- Vectors e.g. Harp seals spread virus when range was further south due to climate change- crossed species barrier- other seals. Zoonotic disease.
- Controlling disease- culling- fewer hosts- wipe out disease e.g. buffalo heardsin Yellowstone N.P. to stop spontaneous abortion due to bacterium brucellosis.
- Presence of other species either: more vectors or buffer species- cant be infected.
- Rabies- Lysavirus =zoonotic- also in humans. Mortality =highly cyclic.
- Co-evolution- if virus causes high mortality- fewer hosts- Myxamotosis- becoming less pathogenic over time. Although still hindering rabbit populations- grow when vaccine is administered.
Other interactions (not predation or competition):
- Symbiosis, commensalism, mutualism, neutral interactions
- Loose to tight mutualisms. examples: Pseudomyrmex ant + acacia plant (S…