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Population
the number of individuals of the same species living in the same area at the same time.
Sample
Subset of the population used for data collection.
Advantage of Random Sample
Every item in the population has an equal chance of being selected.
Biased Sample
Sample not randomly selected, leading to skewed results.
Census
Data collected from every member of the population.
Advantages of Population
Accurate results as all members are included; all options
crude birth rate
number of live births per 1000 people in a population in a year
formula of CBR
total number of births/ total population *1000
Advantages of using Samples
Quicker and cheaper; less data to handle.
Disadvantages of Sample
Can lead to unreliable results if small or biased; may not be representative.
What is Random Sampling
Sampling method where points chosen randomly, often using random number generators; avoids researcher bias.
Systematic Sampling
Sampling points chosen in a regular pattern, prone to researcher bias if not done carefully.
Transect Sampling
Systematic sampling along a line to study species distribution relative to environmental changes.
what does Line Transect do
Record species touching a line at regular intervals.
Belt Transect
Place quadrats along a line at regular intervals to estimate abundance.
Quadrat
Square frame used for sampling non mobile organism
Percentage Cover of a species
Estimated area of a quadrat covered by a species.
what is Percentage Frequency
(Number of quadrat squares with species ÷ Total squares) × 100.
immigration rate formula
(number of immigrants / total population)*1000
Lincoln Index Formula
Population size = (M × N) ÷ R.
M
Number marked in the first sample.
N
Total individuals in the second sample.
R
Marked individuals recaptured in the second sample.
what are methodological limitations
Refers to the constraints in population size assessments due to factors like observer bias, equipment limitations, and animal behavior that affect the accuracy of capture-recapture studies.
factors affecting immigration
economic opportunities, political stability, social factors, environmental conditions
Sustainability
Refers to the ecosystem's ability to maintain balance and productivity over time.
crude death rate
number of deaths per 1000 people
crude death rate formula
total n of deaths/ population *1000
Inputs
Energy, nutrients, and water entering the ecosystem.
Outputs
Energy, nutrients, and waste leaving the ecosystem.
Ecosystem Flow Diagrams
Demonstrate the movement of energy and nutrients within ecosystems.
emigration rate
number of imigrants per 1000 people per year
emmigration rate formula
number of emigrants/ population *1000
Evidence of Sustainability
Some ecosystems have persisted for millions of years, indicating their resilience.
what is fertility rate
average number of children born to a woman over her lifetime, based on current asge specific fertility rates.
what is the impact of humans in the environment
Human activity can disrupt the stability of ecosystems, leading to tipping points.
Tipping Points
Critical thresholds where small changes trigger significant ecosystem shifts.
Deforestation
Clearing of trees for agriculture, logging, or urban development.
Impact on Climate of deforestation
Deforestation reduces water vapour generation, disrupting local and regional climate.
formula of total fertility rate
summation of age specific fertility rate * 5
life expectancy
average number of years a person is expected to live
Keystone Species
Organisms with a disproportionately large impact on ecosystem structure and function.
Role of Keystone Species
Regulate population sizes and maintain biodiversity.
Impact of Removal of keystone species
Removing keystone species can cause cascading effects and disrupt ecosystems.
doubling time
the number of years it takes for a population to double
doubling time formula
70/percentage growth rate
what is NIR
the rate of growth or depreciation of a population due to natural factors ( excluding migration )
Planetary Boundaries Model
Identifies nine key Earth system processes essential for a stable planet.
Biosphere Integrity
Refers to the overall health and diversity of life on Earth.
Natural increase rate (NIR) formula
(cbr-cdr)/10
What is the aim of Conservation Strategies
Aim to preserve ecosystem structure, function, and diversity.
what is habitat Conservation
Protecting natural habitats and mantaining ecosystem integrity.
what is the imprtance Species Conservation
Protecting endangered species is essential for biodiversity.
Sustainable Resource Management
the management of resources such a way that they can be replenished, avoidinf depletion
what are the 3 models of predicted growth
high fertity scenario: asumes high birth rates will continue leading to rapid population growth. medium fertility scenario: assumes a decline in ferility rate leading to a moderate population growth. low fertility rate assums that fetility rates will drop significantly leading to slower growth and decreased population
Positive Feedback
A process in which a change in a system amplifies further change, potentially destabilizing the system (e.g., deforestation reducing precipitation, leading to more forest loss).
Negative Feedback
A process that counteracts change, helping to maintain system stability (e.g., predator
Tipping Point
A critical threshold where small changes cause a system to shift to a new, often irreversible equilibrium (e.g., Amazon deforestation leading to savanna
what is classification
Classification is the process of organizing species based on their similarities and differences.
Hierarchical Classification System
The hierarchical classification system groups species in a hierarchy, where higher ranks have more organisms with less similarity, and lower ranks contain fewer organisms with more similarity.
Genus
A genus is a category in the classification hierarchy that includes species that are closely related and share common characteristics.
Binomial Nomenclature
Binomial nomenclature is a system of naming species using two parts: the genus name (capitalized) and the species name (not capitalized), written in italics or underlined.
What is DTM
The demographic transition model is a model that predicts the change in a population of a country from a pre industrial, to a post industrial
what are the direct policies implemented for population managent
anti natalist, pro natalist, immigration policies
what are the 5 stages of dtm
stage 1- pre industrial, stage 2- low income country, stage 3- midle income country stage 4- high income country, stage 5- high income country.
Dichotomous Keys
Dichotomous keys are tools that help identify organisms by providing a series of paired statements or questions with two possible answers.
strengths of the DTM
simple framework, broad applicability, predictive value.
Dichotomous keys may have limited scope, inaccuracies, and variability in organisms' characteristics, making them time
limitations of DTM
Eurocentric basis, assumes linear progression, overlooks external factors, stage 4 uncertainty, ignoring inequalities.
Biotic & Abiotic Factors
factors whose interactions make up an ecosystem
Biotic
Refers to the living components of an ecosystem
Abiotic
Refers to non living factors that influence ecosystem
Biotic Factors
The living, biological factors that influence ecosystems and the communities of organisms within them
Biotic Factors Definition
Interactions between organisms within a population or community
state the symbiotic relationships
Predation, Herbivory, Parasitism, Mutualism, Disease, Competition
What is the impact of new predators
Can unbalance ecosystems,
Competition
One species outcompetes another for resources, e.g., grey squirrels have outcompeted red squirrels in the UK
Abiotic Factors
Non living factors that affect the ecosystem
Examples of Abiotic Factors
Temperature, Sunlight, pH, Salinity, Dissolved oxygen, Soil texture, Moisture, Minerals, Wind, CO2 levels
Niche Concept
Each species has a distinct niche; two species cannot occupy the same niche without competition
Population Interactions
Populations interact in ecosystems through herbivory, predation, parasitism, mutualism, disease, and competition
Herbivory
organisms whose diet consists in eating plants
Importance of Predation
Predators lower prey populations, creating cycles in stable ecosystems
Parasitism
Parasites benefit from hosts but harm them, lowering host carrying capacity, e.g., fleas on mammals or the malaria parasite
Mutualism
Both species benefit,
Disease
Pathogens lower the carrying capacity of species
what is intraspecific and infraspecific competition
Intraspecific competition occurs within a species; interspecific competition occurs between different species.
Carrying Capacity
The maximum stable population size of a species that an ecosystem can support, determined by competition for limited resources.
what limits the population growth
Abiotic and biotic factors prevent all individuals from reproducing, ensuring population sizes remain limited at carrying capacity.
Human Population Exception
Humans have overcome many factors that limit population growth, allowing their population to dominate others.
Carrying Capacity Plateau
When population growth flattens on a graph, the carrying capacity is reached due to limiting environmental factors.
Competition for Resources
Higher population density leads to intense competition for food, water, and shelter, limiting population growth.
Benefits of Predation for increased population density
Increased population density raises the likelihood of predator encounters, regulating population size.
Exponential Growth Phase
(J Curve)
Crash Phase
At this point, if there has been a significant population overshoot (the population has increased far beyond the natural carrying capacity), there may be a sudden decrease in the population, known as a population crash
what is lag phase
refers to the initial stage in a population growth curve where the population size remains relatively stable or grows very slowly.
Exponential Growth Phase type of curve
(S Curve)
food chain
is a linear representation of the transfer of energy and nutrients in an ecosystem, illustrating the flow from one organism to another.
what are autotrophs
also known as producers, are organism that synthesise their own nutrients
what are heterothrophs
also known as consumers, are organisms that feed on other organisms.
