| Ecology | The scientific study of the distribution and abundance of organisms; and their interactions that determine the distribution and abundance |
| Ecological systems from a hierarchy | From pops to communities to ecosystems to landscapes to biosphere. |
| Roots of ecology | Charles Darwin and Alfred Wallace. Theory pf evolution through natural selection and Theoretical foundation for ecological science |
| Pioneers in environmental science | Rachel Carson, Berta Flores and Wangari Maathai |
| Extinction | They are irreversible, one loss of species can lead to loss of others. Disrupt the food web. Species threatened: 40% Amphibians, 33% reefs, 33% mammals and 10% insects. |
| Main drivers of extinction | -Changes in land and sea use (3/4 land and 2/3 sea has been altered by us)
-Direct exploitation of organisms
-Climate change
-Pollution (plastic pollution10x more)
-Invasive species |
| Current problems | Habitat destruction, Biodiversity loss, Pollution, Climate change, Ocean acidification, Invasive species, Water crisis, Agriculture and food security, Ecosystem service loss |
| Natural selection | 1) There is a heritable variation in traits within pops of individuals 2) The environment cannot support unlimited pop sizes. 3) Advantageous traits, become more common. 4) changes the heritable characteristics of a pop over time |
| The modern synthesis | Combines natural selection with Mendelian genetics. NS acts of phenotype, which depends on the genotypic expression and the effect of environmental factors. |
| Organisms and their adaptations | Environment: Biotic and abiotic factors. Neo-Darwinism helps to explain how the adaptations evolved, understand the patterns of distribution and abundance. |
| Variations within pops | Environment is heterogenous: Patchiness and Gradients. Local adaptations: selection favours a specific characteristic in one location (eg the peppered moth). |
| Darwinian fitness | The average contribution to the gene pool of the next generation made by individuals of a specified phenotype or phenotype relative to other individuals. Usually measured as the no. of offspring. |
| Phenotypic plasticity | The ability of a single genotype to express itself in different ways in different environments.
RV=Current reproduction (CR) + Residual Reproductive Value (RRV).
PPV= organism's future reproduction through investment in growth and survival. |
| Reproductive isolation | Barriers to prevent hybridization and exchange of genetic material. Can be biological, genetic and geographical |
| Speciation | 1)Uniform species with large variable range
2)Pop is split into two sub-pops by geo barriers
3)Selection pressure takes place and the pops become genetically isolated
4a)Once barriers are removed they are no longer able to hybridize
4b)or hybrids have lower fitness, thus, selection pressure will act until hybridization not possible |
| Speciation is more complicated | Second contact might never occur: Allopatric speciation, island systems. Physical isolation may not be necessary : sympatric speciation |
| Island systems | Islands offer almost total geographic isolation. Later migrations meant further differentiation as species specialized in different food sources. |
| Spatial Ecology | Distribution: Geographic area where individuals of a species occur. Abundance: Numbers within a given area. |
| Study of Distributio | Basic understanding of factors that affect it. Predicting spread of invasive species. Essential for conservation of biodiversity. |
| Types that don't interbreed (3) - Orca whale | Resident: relatively fixed location in coastal waters
Transient: small groups
Offshore: Open water. |
| Metapopulations | Due to environmental heterogeneity, most populations are divided into subpopulations. Each occupies a patch of suitable habitat spatially separate from other subpopulations. The collective of local subpopulations is called a metapopulation. |
| What factors influence distribution and abundance (interact)? | Abiotic factors, Interactions with other organisms, ability to disperse to new areas, geographical barriers to dispersal, evolutionary/geographical history, continental drift. |
| Transplant experiment | Helps you determine whether the limitation on distribution of a species results from: inaccessibility of an area to the species, Unsuitable environmental conditions.
Move individuals of a species to an unoccupied area to determine if they can survive and reproduce
there. |
| Abundance | The No. of individuals in a defined geographic location. A function of: pop density and the area which the pop is distributed. Crude population density: number of individuals per unit area. |
| Patterns of spatial distribution | Random: If each individual’s position is independent of others. Uniform: negative interaction between individuals, usually competition. Aggregated: species may form social group, most common. |
| Generalization 1: climate and vegetation | Large temp differential reflects: Solar radiation coming in and distribution of water and land
Land and sea absorption is different. Intercepted solar radiation varies seasonally |
| Mean annual precipitation | Water holding capacity is higher at the tropics Earth rotation makes air capacities go south and north. Dry air descends 30 degrees latitude causing desserts. Between 30-60 degrees a second evaporation occurs. |
| Mean annual precipitation | The vegetation is considered a product of the area's climate. Its distribution is controlled by temp. and water. Classification of climate is allowed by the vegetation of a site. |
| Generalization 2: Rapoport’s rule | Geographic range sizes increase at higher latitudes. Range size is smaller in the tropics than polar regions. Supported for trees, fish, reptiles, some birds, mammals. Not all studies support it. |
| Rapaport’s rule: 1st explanation (Climate variability) | Climatic variability is greater at high latitudes. Obly broad range of tolerances organisms live there. |
| Rapaport’s rule: 2nd explanation (End of the last ice age) | When the glaciers retreated, only species with high dispersal capacity were able to repopulate northern areas. These species thus have large ranges. |
| Rapaport’s rule: 3rd explanation (lack of competition) | Fewer species live in polar regions. So levels of competition may be lower. Allows species to occupy
larger areas. (not tested) |
| Generalization 3: Hanski’s rule | Positive relationship between distribution and abundance. Abundant species have wide geographic ranges |
| Hanski’s rule: 3 explanations | 1) Ecological specialisation - species that exploit a wide range of resources become widespread and more common, generalists.
2) Sampling Model - Observed relationship is an artefact of sampling. Rare species are harder to find.
3) Local population - Pops consist of discrete patches. Individuals moves between habitats. Species with greater dispersal ability will occupy more patches. |
| Effects of conditions (Temp, humidity, salinity, ph etc.) | Affects the abundance and distribution. Organisms are adapted to them but they can also alter them |
| Effects of a range of environmental conditions on individual survival (S), growth (G) and reproduction (R) | Type I. Bell shaped curve, typical for response to temp and pH. Most fundamental.
Type II. A condition is lethal at high intensities.
Type III. Conditions are required by organisms at low concs but are toxic at high concs. |
| The temperature size rule for ectotherms | Phenotypic plastic response: organisms exposed to colder temps, reach maturity at larger size and grow slower. Growth rate and development rate are decoupled. |
| Heterotrophs categories | Generalists: polyphagous
Specialists: Monophagous or specialise is particular prey parts |
| The ecological niche | Conceptual summary of the conditions and resources that allow organisms to exist, reproduce and grow. It is multidimensional: 1 dimension - range of temp, 2 dimensions - eg shrimp survival in different temp and salinity, 3 dimensions - diagrammatic niche for aquatic organisms, pH, temp and food availability. |
| Fundamental niche | Niche in absence of competitors + predators |
| Realised niche | The more limited range of conditions and resources in the presence of competitors + predators |
| Bioindicators | Freshwater macro-invertebrates have different tolerances of low O2 levels. Their relative abundance can be used to indicate pollution caused by nutrient enrichment |
| Plant chemical defences | Constitutive and inducible. Thorns, tough hairs, sticky secretions and chemical compounds. Glucosinolates induced production increases in leaves when damaged. |
