Ecology

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. /

Homo sapiens

Homo sapiens is the species name for humans, with Homo being the genus and sapiens being the species. /

Canis Genus

The genus Canis includes several species of canids, such as Canis lupus (Grey wolf), Canis familiaris (Domestic dog), and Canis latrans (Coyote). /

Taxonomic Tools

Taxonomists use tools like reference collections, DNA surveys, and dichotomous keys to identify organisms. /

Identification by Reference Collections

Taxonomists compare unknown specimens with reference collections of known species to identify them. /

DNA Surveys

DNA surveys involve analyzing an organism's DNA and comparing it with known sequences in large computer databases for precise identification. /

Dichotomous Keys

Dichotomous keys are tools that help identify organisms by providing a series of paired statements or questions with two possible answers. /

Serengeti Dichotomous Key

An example of a dichotomous key for identifying species in the Serengeti ecosystem. /

Limitations of Dichotomous Keys

Dichotomous keys may have limited scope, inaccuracies, and variability in organisms' characteristics, making them time

Expertise for Dichotomous Keys

Dichotomous keys require some level of expertise and familiarity with the organisms to be used effectively./

Biotic & Abiotic Factors

Factors that determine the distribution of a population can be abiotic or biotic / Biotic

steady state

when the inputs and outputs are balanced in an ecosystem, allowing for stability in population sizes and resource availability.

Examples of Biotic Factors: Availability of food

More food increases survival and reproduction, e.g., rainforests have rich food supplies; deserts have fewer species due to poor food supply / New predators

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)

Worked Example: Red & Grey Squirrels

Grey squirrels introduced into a habitat led to a decrease in red squirrels due to competition for resources /

Negative Feedback

- A process that counteracts change, helping to maintain system stability (e.g., predator-prey relationships balancing population sizes)

Abiotic Factors

Non living factors in an ecosystem that influence living organisms, such as temperature, sunlight, water, and soil.

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-like conditions).

Abiotic Factor Effects: Temperature

Affects photosynthesis and metabolism / Sunlight

Ecological Niches

A niche describes the biotic and abiotic conditions and resources an organism depends on / Niche Concept

Population Interactions

Populations interact in ecosystems through herbivory, predation, parasitism, mutualism, disease, and competition / Herbivory

Parasitism

Parasites benefit from hosts but harm them, lowering host carrying capacity, e.g., fleas on mammals or the malaria parasite / Mutualism

Carrying Capacity

The maximum stable population size of a species that an ecosystem can support, determined by competition for limited resources. /

Population Growth Limitation

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. /

Density

dependent Factors

Competition for Resources

Higher population density leads to intense competition for food, water, and shelter, limiting population growth. /

Risk of Predation

Increased population density raises the likelihood of predator encounters, regulating population size. /

Pathogen Transmission

Dense populations facilitate disease spread, increasing mortality rates and controlling population size. /

Negative Feedback Mechanisms

Processes driven by density

J

Curve Growth

Lag Phase (J

Curve)

Exponential Growth Phase (J

Curve)

Crash Phase (J

Curve)

S

Curve Growth

Lag Phase (S

Curve)

Exponential Growth Phase (S

Curve)

Transitional Phase (S

Curve)

Plateau Phase (S

Curve)

Population

Entire set of items or individuals of interest. /

Sample

Subset of the population used for data collection. /

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/responses accounted for. /

Disadvantages of Population

Time

Advantages of Sample

Quicker and cheaper; less data to handle. /

Disadvantages of Sample

Can lead to unreliable results if small or biased; may not be representative. /

Random Sampling

Sampling 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. /

Line Transect

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

Percentage Cover

Estimated area of a quadrat covered by a species. /

Percentage Frequency

(Number of quadrat squares with species ÷ Total squares) × 100. /

Capture

Mark

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. /

Limitations of Capture

Mark

Ecosystem Functioning & Sustainability

Sustainability is a fundamental property of ecosystems. /

Sustainability

Refers to the ecosystem's ability to maintain balance and productivity over time. /

Self

Regulation

Balanced Inputs and Outputs

In a steady

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. /

Interconnectedness

Flow diagrams highlight the interconnectedness of biotic and abiotic factors. /

Tropical Rainforest Nutrient Flow

An ecosystem flow diagram showing a simplified form of the nutrient cycle in a tropical rainforest. /

Evidence of Sustainability

Some ecosystems have persisted for millions of years, indicating their resilience. /

Example of Sustainability

Tropical rainforests like the Amazon Rainforest show long

Human Impacts

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

Deforestation reduces water vapour generation, disrupting local and regional climate. /

Feedback Loop

Reduced precipitation leads to further forest loss, creating a positive feedback loop. /

New Equilibrium

Continued deforestation may lead to reduced biodiversity and altered climate patterns. /

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

Removing keystone species can cause cascading effects and disrupt ecosystems. /

Example: Purple Sea Stars

Control mussel populations, preventing ecosystem domination. /

Example: African Elephants

Shape savannah grasslands and promote habitat diversity. /

Human Impacts on Biosphere Integrity

Human activity has significantly impacted biodiversity and ecosystem health. /

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. /

Evidence of Damage

Accelerated extinction rates indicate severe disturbances to ecosystems. /

Conservation Strategies

Aim to preserve ecosystem structure, function, and diversity. /

Habitat Conservation

Protecting natural habitats maintains ecosystem integrity. /

Species Conservation

Protecting endangered species is essential for biodiversity. /

Sustainable Resource Management

Promotes responsible resource use without ecosystem degradation. /