Studied by 2 people
Ecology
The study of interrelationships between living organisms and their biotic (living) and abiotic (non-living) environment
Biosphere
The parts of earth where life exists
Atmosphere
The gases surrounding the planet
Hydrosphere
The water containing parts of Earth
Lithosphere
The underground parts of Earth
Species
A group of organisms that can interbreed and produce fertile offspring, and share the same characteristics
CITES
Convention on International Trade of Endangered Species
Liger
Offspring of a tiger and lion that is infertile, hence called a hybrid and not a specie.
Population
A group of organisms of the same species living in the same area at the same time, and which are capable of interbreeding
Classification
The identification system of organisms which allows for a prediction of characteristics.
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Hierarchal classification system
The higher ranks contain more organisms with less similarity between them and the lower ranks contain fewer organisms with more similarities.
Clades
The lines that are in the family of tree diagrams. Shows a group of species (from a taxonomic group) that evolved from a common ancestor.
Node
Where characteristics branch and species diverge
Root
Point prior to any divergence where the organisms share certain characteristics
Binomial nomenclature
Binomial naming system
Dichotomous keys
Quantitative and qualitative factors are considered (like number of legs, weight, height, etc.). Can be done in a graphical or written form - series of paired statements organised sequentially. Used to identify and organism.
Comparison of species with reference to collections by taxonomists
Comparing unknown specimens to those with similar characteristics that have been already identified and classified. Relies on the taxonomist’s expertise and quality of the reference collection.
Deoxyribonucleic acid (DNA) surveys
Analysing an organism’s DNA to determine its species. Compares the DNA sequence of the specimen with known sequences from a very large number of species, stored in large computer databases. Provides a precise and reliable identification, especially for closely related species.
Abiotic factors
Non-living physical factors that may influence an organism in an environment. Eg. Water level, humidity, temperature, salinity, soil mineral content, % of gases in the air, light, pollution, pH of soil.
Biotic factors
The living components of the environment that affect individuals. Eg. Parent material, parasites, predators, fungi, competitors, human activity, bacteria, plants, animals.
Ecological niche
the role or position a species occupies within an ecosystem, including all the biological, physical, and chemical factors it requires to survive, reproduce, and maintain a stable population.
Niche overlap
When two organisms occupy the same niche in the same habitat, they begin to compete
Carnivory
Predator-prey relationships
Mutualism (symbiosis)
Two species interacting with each other where both species benefit.
Commensalism
Two species interacting with each other and one species is benefiting while the other is unaffected.
Parasitism
Two species interacting while one species benefits and the host species (that the parasite lives on or off) is harmed.
Competition
The struggle between individuals or different populations for a limited source
Intra specific competition
Competition of individuals of the same species for limited sources.
resource strain = does not support unlimited population growth.
Reduced growth rate = slower population stabilisation
Niche partitioning = individuals specialise / adjust their ecological niches to minimise direct competition.
Niche selection = favouring traits that improve access to resources or enhance survival under competition.
Interspecific competition
When individuals of different species compete for the same limited resources (eg. Food, space, mates).
two different species require the same resources
Species directly interact
Species evolve or adjust to different resources or occupy different habitats to resolve competition: realised niche
Local extinction of weaker species
Species can coexists if they can occupy different ecological niches or if they evolve strategies that minimise direct competition.
Fundamental niche
The broadest range of habitats a species can occupy and the roles it can fulfil given the adaptations.
Realised niche
The actual mode of existence given competition with other species and its zone of tolerance
Competitive exclusion principle
If two species occupy the same niche, one will decline or both will narrow their niches to avoid overlap.
Tolerance of a species depends on?
The abiotic factors - that’s how the fundamental niche of an organism is formed.
Population growth and decline depends on
Birth rate, limiting factors: starvation/availability of food, disease, predation, hunting, natural disasters.
R-strategists
Species that focus on rapid reproduction and high growth rates.
• They typically produce many offspring but invest little energy or resources in each individual.
• Offspring are often small, grow quickly, and have a low survival rate.
• r-strategists are adapted to unstable or unpredictable environments where survival depends on quickly taking advantage of available resources.
• Examples: Bacteria, insects (e.g., flies), and some plants (e.g., dandelions).
Characteristics of r-strategists:
1. Short lifespan.
2. Early reproduction.
3. Small body size.
4. High population growth rate.
K strategies
Definition: Species that produce fewer offspring but invest heavily in their survival and development.
• They are adapted to stable environments, where competition for resources is significant, and long-term survival is key.
Characteristics:
1. Long lifespan.
2. Delayed reproduction.
3. Larger body size.
4. Low population growth rate.
5. High survival rate per offspring.
Examples: Elephants, whales, and humans.
Carrying capacity
The maximum number of individuals that an ecosystem can support sustainably
Density dependent factors
Affect the population only when it reaches a certain density, due to the many interactions that happen as the population size gets bigger.
Eg. Competition, disease, parasitism, predation = biotic factors
Waste building up
Often cause intraspecific competition
Density Independent factors
Control populations no matter what the density of the population is. Tend to be abiotic.
Eg, sunlight, temp, water & natural disasters, human activities.
J curve
Population growing at its biotic potential
exponential growth
Very steep
No limiting factors
S curve
Limiting factors slow the growth and the graph curves as it approaches the carrying capacity.
Non-motile organisms
Plants, lichens, mollusks, are often measured with quadrants and transects to measure percentage cover or percentage frequency.
Motile organisms
Organisms that can move. Eg. Fish, rabbits, insects, are often sampled through direct count and sampling
Random sampling
Involves selecting locations within the study area at random to count individuals.
Strength: reduces bias, as every part of the study area has an equal chance of being selected.
Limitations: might miss areas with particularly high or low population densities leading to inaccurate estimates.
Systematic sampling
Involves taking samples at regular intervals within the study area.
Strengths: When you need a straightforward method that ensures thorough and even coverage of the study area, and when the population is relatively uniform or randomly distributed without regular patterns.
Limitations: might introduce bias if the population has a pattern that coincides with the sampling interval, such as regular clustering.
Random sampling method
Randomly sample 5 quadrants - take the mean of the 5 quadrants. Multiply the mean by the area of the grid: 10 × 10 = 100
Transect sampling
Involves sampling along a line / path that runs through the study area.
Use when you need to study changes across an environmental gradient and to see how population abundance varies along a specific path or direction.
Line transect
Organisms found at the regular sample points are recorded.
Belt transect
Quadrants are placed at regular sample points and the abundance of the organisms within each other is recorded
Capture-mark-release = Lincoln index
Capture as many individuals as possible and mark them (without making them more visible to predators).
Release the captured individuals and allow time for reintegration with the population.
After some time, recapture as many individuals as possible.
Count how many individuals are marked and unmarked
Lincoln index → proportion of marked and unmarked individuals in the recapture = proportion within the whole population.
Pop. Size estimate = (n.o. Individuals caught and marked initially x total number of individuals recaptured) / number of marked individuals recaptured.
It assumes that there’s no migration into/out of the population and that there was complete mixing of marked and unmarked individuals.
Habitat
Natural environment in which a particular species lives, grows and thrives. Includes all physical, chemical and biological factors that support the existence of that species.
Ecosystem
A community of living organisms interacting with each other and their physical environment (like air, water and soil) forming a system where energy and nutrients cycle through.
Species
A group of organisms that can interbreed and produce fertile offspring, sharing common characteristics and genetic traits.
Population
A group of individuals of the same species living in a specific area, at the same time, capable of interbreeding and interacting with each other.
Community
A group of different species living and interacting in the same area, sharing resources and influencing each other’s survival and behaviour.
Keystone species
A specie that plays a critical role in maintaining the structure of the ecosystem in which they live.
Yellowstone wolves
Grey wolves were the apex predators in the Yellowstone park
Played a critical role in controlling populations of large herbivores: elk, deer, and moose, maintaining balance in the ecosystem by preventing overgrazing and helping to shape the structure of the entire landscape (river banks).
By keeping Elk numbers in check, wolves allowed vegetation such as willow and aspen to regenerate, which in turn benefited other species like bears and birds.
1900s - threat to live stock → aggressive government sponsored extermination campaigns.
1920s - extirpation (local extinction) of wolves from Yellowstone.
1973 - Endangered Species Act (ESA) provided legal protection for grey wolves, and by mid 1970s, wildlife biologists and conservationists bagan discussing the idea of reintroducing wolves to Yellowstone
6. 1980s-1990s: noticing the important role of wolves and planning the idea to reintroduce wolves into the Yellowstone park
1995: reintroduction of wolves to Yellowstone began as part of a broader effect to restore balance to the park’s ecosystem.
Controversy: balance between wildlife conservation and livestock protection continues to be a source of tension in the region.
Tipping point
The minimum amount of change within an ecosystem required that will destabilise it, causing it to reach a new equilibrium or steady state. (Irreversible change).
Planetary boundaries model
Defines a safe operating space for humanity in terms of 9 key environmental processes that are crucial for maintaining the stability of the Earth system. Exceeding the boundaries could lead to irreversible and catastrophic environmental changes:
novel entities
Climate change
Biosphere integrity
Land system change
Biochemical flows
Ocean acidification
Fresh water use
Atmospheric aerosol loading
Stratospheric ozone depletion
IUCN Red List
Monitoring population numbers.
Good luck
Part 1
