Lesson Notes By Weeks and Term - Senior Secondary 2

TERM – 3^RD TERM

WEEK NINE

Class: Senior Secondary School 2

Age: 16 years

Duration: 40 minutes of 5 periods each

Date:

Subject: Biology

Topic: ECOLOGY OF POPULATION 1

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

1. Define succession
2. Identify the types of succession
3. Identify the characteristics of a stable community
4. Define overcrowding
5. Identify important factors affecting population space

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

NOTE

ECOLOGY OF POPULATION

Succession

In population ecology, succession specifically refers to the changes in species composition and population structure over time within a particular habitat or ecosystem. This concept is often applied to communities of plants, but it can also be extended to include animals.

Succession involves a sequence of changes in the species composition and structure of an ecological community over time. Initially, pioneer species colonize a bare area, and as conditions change, other species replace them. This process typically leads to an increase in species diversity and the overall complexity of the ecosystem.

Primary succession in an aquatic habitat

1. Primary Succession: Primary succession in an aquatic habitat typically begins with the colonization of a barren substrate, such as rock or sediment, by pioneer species. These could include algae, bacteria, and simple aquatic plants. As these organisms establish, they contribute organic matter and nutrients, gradually altering the habitat.

Factors like water quality, substrate characteristics, and external influences can influence the pace and direction of primary succession in aquatic environments.

2. Secondary Succession: Secondary succession refers to the process of ecological recovery that occurs in an area where a previous community has been disturbed or disrupted, but the soil or substrate remains intact. Unlike primary succession, which starts in a barren environment with no soil, secondary succession begins in an area with existing soil.

Examples of secondary succession include:

1. Abandoned Agricultural Fields: When agricultural land is left fallow, the original vegetation may start to re-establish, initiating secondary succession.
2. Forest Fires: After a forest fire, the soil is often still present, and plant life can regenerate from seeds or root systems of surviving vegetation.
3. Deforestation: Areas that have experienced deforestation may undergo secondary succession as vegetation gradually returns.
4. Abandoned Urban Areas: Vacant lots or abandoned urban areas can undergo secondary succession as plants reclaim the space.

Characteristics of a stable community

A stable community, also referred to as a climax community in ecological terms, exhibits several characteristics:

1. Biodiversity: A stable community tends to have a diverse array of species occupying various ecological niches, promoting balance and resilience.
2. Sustainable Population Levels: Species within the community maintain population levels that are in equilibrium with available resources, preventing overpopulation or depletion of resources.
3. Energy Flow and Nutrient Cycling: The community efficiently utilizes energy through food chains and cycles nutrients, contributing to a sustainable and balanced ecosystem.
4. Resilience to Disturbances: Stable communities can withstand certain disturbances, recovering and returning to their original state over time. This resilience is a key characteristic.
5. Successional Adaptations: If disturbances occur, stable communities may have mechanisms in place for secondary succession, allowing them to recover in an organized manner.
6. Limited Competitive Exclusion: Coexistence among species is facilitated by the absence of intense competition that could exclude certain species from the community.
7. Climax Vegetation: In terrestrial ecosystems, stable communities often display a specific and characteristic set of vegetation, which is known as climax vegetation.

Overcrowding

In ecology, overcrowding refers to a situation where a population of organisms exceeds the carrying capacity of its environment. This can have various ecological implications:

1. Resource Depletion: Overcrowded populations may exhaust essential resources such as food, water, and shelter more quickly than they can be replenished, leading to increased competition.
2. Increased Competition: With limited resources, individuals within an overcrowded population compete more intensely for access to these resources, which can affect growth rates, reproductive success, and overall fitness.
3. Stress and Disease Spread: Overcrowded conditions can elevate stress levels among individuals, making them more susceptible to diseases. Additionally, the close proximity facilitates the spread of diseases within the population.
4. Altered Behavior: Overcrowding may lead to changes in behavior, such as increased aggression, territorial disputes, or changes in migration patterns, as individuals attempt to cope with limited resources.
5. Population Decline: If the population surpasses the environment's carrying capacity for an extended period, it can lead to a decline in overall population size due to resource scarcity and increased mortality.
6. Impact on Ecosystem Dynamics: Overcrowding can have cascading effects on ecosystem dynamics, affecting the abundance and distribution of other species within the ecosystem.

Population density studies

Population density studies in ecology involve examining the number of individuals of a species within a defined area and understanding the interactions between population size and available resources. These studies are closely linked to the availability of resources, as population density is often influenced by the quantity and distribution of essential resources such as food, water, and shelter.  This relationship is crucial for several reasons:

1. Resource Management: Population density studies help in managing and preserving resources by providing insights into how populations utilize available food, water, and habitat.
2. Carrying Capacity: By monitoring population density in relation to available resources, scientists can estimate the carrying capacity of an ecosystem, which is the maximum population size it can sustain.
3. Conservation Planning: Understanding how population density responds to resource availability is essential for developing effective conservation strategies, ensuring the long-term survival of species.
4. Predicting Population Trends: Population density studies allow scientists to predict how populations might change over time in response to fluctuations in resource availability, climate, or other environmental factors.

Importance of Factors Affecting Population Space

Factors influencing population space, or the physical area a population occupies, have significant implications for ecosystem health and species survival:

1. Ecosystem Stability: Well-distributed population space contributes to the stability of ecosystems, preventing overuse of resources and minimizing the risk of population crashes.
2. Biodiversity: The availability of suitable space supports biodiversity by allowing various species to coexist, each occupying its unique ecological niche.
3. Disease Control: Optimal population space can reduce the spread of diseases within a population, as individuals are less likely to be in close proximity, limiting the transmission of pathogens.
4. Migration and Genetic Diversity: Factors affecting population space influence migration patterns, allowing for gene flow between populations. This contributes to genetic diversity, which is crucial for adaptability and long-term survival.
5. Sustainable Resource Use: Balancing population space with available resources promotes sustainable use of those resources, preventing depletion and ensuring the health of ecosystems.
6. Human-Wildlife Conflict Mitigation: Understanding and managing factors affecting population space are vital in minimizing conflicts between human activities and wildlife habitats, contributing to peaceful coexistence.

EVALUATION: 1. Define is succession

2. Identify the characteristics of a stable community
3. Define overcrowding
4. Identify the factors affecting population space

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively