Topic 2- Ecology

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.

Limitations of Dichotomous Keys

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 DELETE

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.