Understanding Ecosystems

• Ecosystems comprise communities of living organisms like plants, animals, and microorganisms interacting with their physical surroundings.

Ecosystem Components

• Biotic factors encompass the living elements of an ecosystem, including plants, animals, and microorganisms.
• Abiotic factors include non-living elements like sunlight, temperature, water, nutrients, and soil.
• Interactions between biotic and abiotic components maintain a delicate ecosystem balance.
• Energy flow is generally unidirectional, moving from the sun to producers (plants), then to consumers (animals), and finally to decomposers (bacteria and fungi).
• Nutrient cycles, such as carbon, nitrogen, and water cycles, involve the continuous recycling of essential elements and compounds.

Types of Ecosystems

• Forests, grasslands, deserts, and tundra are examples of terrestrial ecosystems, each defined by specific climate, vegetation, and animal life.
• Aquatic ecosystems include freshwater environments like lakes, rivers, wetlands, plus marine environments like oceans, coral reefs, and estuaries.
• Ecosystems offer varied ecosystem services, including clean air/water, pollination, and climate regulation and support unique biodiversity.

Habitat Destruction

• Habitat destruction occurs when natural habitats can no longer support existing species, leading to biodiversity displacement or destruction.
• Major causes include deforestation, urbanization, agriculture, and mining.
• Fragmentation divides large habitats into smaller patches, reducing biodiversity and disrupting ecological processes.
• Habitat destruction is a primary cause of species extinction and the loss of ecosystem services.

Causes of Habitat Destruction

• Deforestation, driven by logging, agriculture, and urbanization, results in widespread habitat loss.
• Agricultural expansion converts natural habitats into farmland, reducing biodiversity.
• Urbanization replaces natural habitats with buildings, roads, and infrastructure, reducing wildlife space.
• Mining directly removes vegetation and pollutes areas, destroying habitats.
• Pollution from industrial, agricultural, and urban sources contaminates habitats.
• Climate change alters environmental conditions, shifting species distribution and habitat suitability.

Consequences of Habitat Destruction

• Habitat loss leads to biodiversity loss through species displacement or extinction.
• Disruption of ecosystem services, like pollination and water purification, results in environmental and economic consequences.
• Disturbed habitats face an increased risk of invasive species colonization.
• Simplified ecosystems are less resilient to environmental changes.

Succession

• Ecological succession refers to changes in an ecological community's species structure over time.
• Primary succession occurs in new environments, like volcanic rock, where no soil exists.
• Secondary succession occurs in disturbed areas where soil remains.
• Pioneer species are the first to colonize new or disturbed environments, often with adaptations to harsh conditions.
• A climax community is a stable, self-sustaining community representing the final stage of ecological succession.

Primary Succession

• Pioneer species, such as lichens and mosses, colonize rock and initiate soil formation.
• Decomposing pioneer species add organic matter which creates a more hospitable enviornment for other species.
• Small plants and grasses enrich the soil and create more complex habitats over time.
• Shrubs and trees subsequently colonize the area, developing a stable community like a forest.

Secondary Succession

• Soil containing seeds, roots, and nutrients allows rapid vegetation re-establishment after disturbances like fire or flood.
• Early successional species such as grasses colonize the disturbed area quickly.
• Shrubs and trees gradually replace these early colonizers to re-establish a stable community.
• Secondary succession typically occurs faster than primary succession due to existing soil.

Natural Selection

• Natural selection is a process where advantageous traits are more likely to be passed on to future generations.
• Variation in populations arises from genetic mutations and sexual reproduction.
• Individuals with adaptations survive and reproduce more, increasing the frequency of beneficial traits.
• Environmental factors act as selective pressures that favor some traits over others.
• Natural selection can lead to species evolution and population adaptation.

Mechanisms of Natural Selection

• Genetic variation is essential for natural selection.
• Adaptation is how populations become better suited to their environment.
• Differential survival and reproduction drives natural selection.
• Heritability allows for the accumulation of favorable traits over generations.

Examples of Natural Selection

• Peppered moths in industrial areas evolved darker colors to camouflage against soot-covered trees, enhancing survival.
• Antibiotic resistance emerged in bacteria due to antibiotic overuse, favoring resistant bacteria.
• Darwin's finches evolved different beak shapes to exploit different food sources.