🙀Philosophy of Biology Unit 9 – Ecology and Ecosystems

Key Concepts in Ecology

• Ecology studies the interactions between organisms and their environment at various levels of organization (individuals, populations, communities, ecosystems, biosphere)
• Abiotic factors are non-living components of an ecosystem that influence organisms (temperature, light, water, soil)
• Biotic factors are living components of an ecosystem that interact with each other (plants, animals, microorganisms)
  • Biotic interactions can be positive (mutualism), negative (competition, predation), or neutral (commensalism)
• Niche refers to an organism's role and position within an ecosystem, including its resource use and interactions
  • Fundamental niche is the full range of conditions and resources an organism can theoretically use
  • Realized niche is the actual niche an organism occupies, limited by biotic interactions and resource availability
• Habitat is the physical environment where an organism lives and includes both abiotic and biotic factors (coral reef, tropical rainforest)
• Ecological succession is the gradual process of change in species composition and community structure over time (primary succession on bare rock, secondary succession after disturbance)

Ecosystem Components and Interactions

• Ecosystems are composed of both biotic and abiotic components that interact with each other
• Primary producers (autotrophs) convert light or chemical energy into organic compounds through photosynthesis or chemosynthesis (plants, algae, some bacteria)
• Consumers (heterotrophs) obtain energy and nutrients by feeding on other organisms
  • Primary consumers (herbivores) feed on primary producers (rabbits, zooplankton)
  • Secondary consumers (carnivores) feed on primary consumers (hawks, sharks)
  • Tertiary consumers (top predators) feed on secondary consumers (lions, orcas)
• Decomposers (detritivores) break down dead organic matter and recycle nutrients back into the ecosystem (bacteria, fungi)
• Trophic levels represent the position of an organism in the food chain based on its feeding relationships (producers, primary consumers, secondary consumers)
• Food webs illustrate the complex feeding relationships and energy flow among organisms in an ecosystem (marine food web, terrestrial food web)

Energy Flow and Nutrient Cycles

• Energy flows through ecosystems in a unidirectional manner, from the sun to producers to consumers and eventually lost as heat
• Trophic efficiency is the percentage of energy transferred from one trophic level to the next, typically around 10%
  • This low efficiency limits the number of trophic levels in an ecosystem (usually 4-5)
• Biomass pyramids represent the amount of organic matter at each trophic level, with producers having the largest biomass
• Nutrients cycle through ecosystems in biogeochemical cycles, moving between biotic and abiotic components
  • Carbon cycle involves the exchange of carbon between the atmosphere, oceans, and living organisms (photosynthesis, respiration, decomposition)
  • Nitrogen cycle includes nitrogen fixation by bacteria, uptake by plants, and return to the atmosphere through denitrification
  • Phosphorus cycle is sedimentary, with phosphorus weathering from rocks, uptake by organisms, and eventual deposition in sediments
• Humans have significantly altered nutrient cycles through activities such as fossil fuel combustion and fertilizer use

Population Dynamics and Community Structure

• Populations are groups of individuals of the same species living in a particular area
• Population growth is influenced by birth rates, death rates, immigration, and emigration
  • Exponential growth occurs when populations increase by a constant percentage over time (bacteria in a petri dish)
  • Logistic growth occurs when population growth slows as it approaches the carrying capacity (deer in a forest)
• Carrying capacity is the maximum population size an environment can sustain given available resources
• Intraspecific competition occurs between individuals of the same species for limited resources (plants competing for light)
• Interspecific competition occurs between individuals of different species for shared resources (lions and hyenas competing for prey)
• Predation is an interaction where one organism (predator) feeds on another (prey), influencing population dynamics of both species
• Symbiosis is a close, long-term interaction between two species, which can be mutualistic (both benefit), commensalistic (one benefits, one unaffected), or parasitic (one benefits, one harmed)

Biodiversity and Ecosystem Functioning

• Biodiversity refers to the variety of life at all levels of organization, from genes to ecosystems
  • Species diversity is the number and relative abundance of different species in an area
  • Genetic diversity is the variety of genes within a species or population
  • Ecosystem diversity is the variety of ecosystems within a region
• Biodiversity is important for ecosystem functioning, stability, and resilience to disturbances
  • Higher diversity often leads to greater productivity, nutrient cycling, and resistance to invasive species
• Biodiversity provides numerous ecosystem services, such as pollination, pest control, and carbon sequestration
• Biodiversity hotspots are areas with high species richness and endemism that are threatened by habitat loss (tropical rainforests, coral reefs)
• Species-area relationship describes the increase in species richness with increasing area sampled, often used to estimate biodiversity loss due to habitat destruction
• Ecological redundancy suggests that some species may perform similar roles in an ecosystem, providing a buffer against species loss

Human Impact on Ecosystems

• Humans have significantly altered ecosystems through various activities, often leading to biodiversity loss and ecosystem degradation
• Habitat destruction is the primary cause of biodiversity loss, as it reduces available space and resources for species (deforestation, urbanization)
• Overexploitation of species through hunting, fishing, and harvesting can lead to population declines and extinctions (whales, elephants, rare plants)
• Invasive species, often introduced by humans, can outcompete native species and disrupt ecosystem balance (zebra mussels, kudzu)
• Pollution from human activities can harm organisms and alter ecosystem processes (oil spills, plastic waste, pesticides)
• Climate change, largely driven by human greenhouse gas emissions, is causing shifts in species ranges, phenology, and interactions (coral bleaching, earlier spring arrivals)
• Ecosystem management and conservation efforts aim to mitigate human impacts and protect biodiversity (protected areas, sustainable resource use, habitat restoration)

Philosophical Perspectives on Ecology

• Ecocentrism is an ethical stance that values ecosystems and all living beings, not just humans
  • It emphasizes the intrinsic value of nature and the importance of preserving ecological integrity
• Anthropocentrism is an ethical stance that places human needs and values at the center, often prioritizing human welfare over environmental concerns
• Environmental ethics considers the moral status of non-human entities and the ethical implications of human actions on the environment
  • It explores questions such as the rights of nature, the value of biodiversity, and the responsibilities of humans towards other species
• Ecological worldviews, such as deep ecology and ecofeminism, challenge dominant anthropocentric paradigms and advocate for a more harmonious relationship between humans and nature
• The concept of ecosystem services highlights the benefits humans derive from ecosystems, providing an anthropocentric argument for conservation
• The precautionary principle suggests that in the face of uncertainty, actions should be taken to prevent potential environmental harm
• Environmental justice examines the disproportionate impact of environmental degradation on marginalized communities and advocates for fair distribution of environmental benefits and burdens

Practical Applications and Case Studies

• Ecosystem-based management is an approach that considers the entire ecosystem, including humans, in decision-making and resource management (fisheries management, watershed protection)
• Ecological restoration aims to assist the recovery of degraded or destroyed ecosystems (wetland restoration, mine site rehabilitation)
  • It involves removing stressors, reintroducing native species, and monitoring ecosystem recovery
• Agroecology applies ecological principles to the design and management of sustainable agricultural systems (intercropping, biological pest control)
• Urban ecology studies the interactions between organisms and their environment in urban settings, informing sustainable city planning and green infrastructure (urban parks, green roofs)
• Bioremediation uses microorganisms to break down and remove pollutants from contaminated sites (oil spills, industrial waste)
• Climate change adaptation strategies in ecology aim to enhance the resilience of ecosystems and species to changing conditions (assisted migration, habitat connectivity)
• Ecological economics integrates ecological principles into economic analysis, recognizing the dependence of human well-being on ecosystem services (natural capital valuation, payment for ecosystem services)
• Case studies, such as the reintroduction of wolves in Yellowstone National Park or the restoration of the Everglades, provide real-world examples of ecological principles and management practices in action