Exam 2: Bio 150

Intro to Ecology

  • Definition and Scale of Different Ecological Fields of Study

    • Ecology is the scientific study of interactions between organisms and their environment at various levels, from individual organisms to global processes.

    • Key ecological fields include:

      • Organismal Ecology: Focuses on individual organisms and their physiological adaptations that allow them to thrive in their environments, including behavior, morphology, and life history traits.

      • Population Ecology: Examines populations of organisms, analyzing their dynamics, structure, and interactions within a community, including factors affecting population size, density, and growth patterns.

      • Community Ecology: Studies interactions between species in a community, investigating the roles and relationships among different species, including competition, predation, and symbiosis.

      • Ecosystem Ecology: Explores the flow of energy and cycling of nutrients through living (biotic) and non-living (abiotic) components of ecosystems, including food webs, decomposition, and nutrient dynamics.

      • Landscape Ecology: Looks at the spatial patterns of ecosystems and how they interact across landscapes, emphasizing the importance of landscape structure and heterogeneity for biodiversity.

      • Global Ecology: Considers ecological processes on a global scale, addressing issues like climate change, habitat loss, and the impact of human activities on ecosystems worldwide.

  • Types of Questions Asked in Ecology

    • What factors influence organism distribution and abundance, including climatic, biological, and anthropogenic influences?

    • How do species interact within communities, and what are the implications of these interactions for community dynamics and stability?

    • How does energy flow through ecosystems and what are the efficiencies of different trophic levels?

    • What are the effects of human activities such as pollution, deforestation, and urbanization on ecological processes and biodiversity?

Niche

  • Competition - The struggle between organisms for the same limited resources such as food, space, and mates.

    • Can be intra-specific (between individuals of the same species) or inter-specific (between individuals of different species), affecting community composition and species distribution.

Latitude and Longitude

  • Climate Zones - Defined by latitude, influencing temperature, precipitation patterns, and seasonal variability, which in turn affects biodiversity and species distributions.

    • Major climate zones include tropical (warm year-round), temperate (seasonal variations), and polar (cold with limited sunlight).

Population Ecology

  • Population Density and Distribution

    • Density: Refers to the number of individuals per unit area or volume, influencing competition and resource availability.

    • Distribution: Describes how individuals are spaced in a given area, which can be random, uniform, or clumped based on environmental factors and social behaviors.

  • Measuring Population Change

    • Techniques for studying population dynamics include direct observation, sampling methods (quadrats, transects), mark-recapture studies, and demographic analysis to track birth and death rates.

  • Patterns of Population Growth

    • Exponential Growth: Characterized by rapid population increase in the absence of limiting factors, often represented by the J-shaped curve.

    • Logistic Growth: When growth slows as resources become limited, leading to stabilization at a carrying capacity (K), represented by the S-shaped curve.

  • Limits of Population Growth

    • Factors limiting growth can be density-dependent (e.g., competition for resources, predation, disease) or density-independent (e.g., natural disasters, climate events).

  • Reproductive Strategies

    • Strategies include r-selected species (high reproductive rates, low parental investment) and K-selected species (low reproductive rates, high parental investment), influencing population dynamics and survival.

  • Demography

    • The statistical study of populations, focusing on metrics such as birth rates, death rates, age structure, and sex ratios, vital for understanding population trends and making predictions.

Community Ecology

  • Types of Species Interactions

    • Diverse interactions include mutualism (both species benefit), commensalism (one benefits, the other is unaffected), parasitism (one benefits at the expense of the other), competition, and predation, each shaping community structures.

  • Results of Competition

    • Competitive Exclusion Principle: One species outcompetes another for resources, leading to the latter's local extinction.

    • Character Displacement: Phenotypic differences are accentuated among competing species in regions where they overlap, reducing competition through niche differentiation.

  • Changing Environment Effects

    • Environmental changes such as climate shifts, habitat alteration, and anthropogenic influences can lead to shifts in community structure, species composition, and ecological dynamics.

Ecosystems

  • Energy and Matter Movement

    • Energy transfers through food chains and webs while matter cycles through biogeochemical cycles, critical for sustaining ecosystem functions.

  • Food Webs

    • Complex networks illustrating feeding relationships and energy transfer among organisms, highlighting keystone species' roles in maintaining ecological balance.

  • Limiting Nutrients

    • Nutrients such as nitrogen, phosphorus, and potassium that can limit productivity in ecosystems, influencing primary production and food web dynamics.

  • Primary Production and Trophic Levels

    • Gross Primary Production (GPP): The total amount of energy captured by photosynthesis.

    • Net Primary Production (NPP): GPP minus the energy utilized by plants for respiration, indicating the energy available for higher trophic levels.

  • Biomass Production Across Different Biomes

    • Varying levels of productivity across biomes influenced by climate, soil type, and water availability; understanding these differences is crucial for conservation efforts.

Biomes

  • Characteristics of Terrestrial and Aquatic Biomes

    • Terrestrial Biomes: Defined by climate, soil types, and dominant vegetation, major types include forests (tropical, temperate), grasslands (savannas, prairies), deserts (hot and cold), and tundra (arctic and alpine).

    • Aquatic Biomes: Include freshwater (lakes, rivers), marine (oceans, coral reefs), and estuarine systems, each with unique ecological characteristics and species adapted to their environments.

  • Species Distribution in Biomes

    • Species distributions are influenced by geographical barriers and local environmental conditions, leading to unique adaptations in different biomes.

Island Biogeography

  • Links Between Dispersal and Organism Traits

    • Dispersal mechanisms influence community dynamics; species with high dispersal ability may establish populations in new areas, impacting biodiversity and ecosystem stability.

  • Great American Biotic Interchange

    • The historical exchange of species between North and South America, resulting in significant changes in faunal diversity and competition among species.

  • Wallace’s Line

    • A biogeographical boundary separating species of Asian and Australian origin, illustrating the effects of geographical and environmental factors on species distributions.

  • Island Biogeography and Expectations

    • Theories suggest that larger and closer islands can support higher diversity, due to increased immigration and reduced extinction rates, critical for conservation decisions.

Succession and Community Change

  • Ecological Succession

    • Primary Succession: Occurs on newly formed or disturbed surfaces without soil, such as volcanic islands; involves pioneer species colonizing the habitat.

    • Secondary Succession: Follows disturbances that do not destroy soil, allowing vegetation to recover more quickly and create a new community structure.

  • Urban Ecology

    • Studies the effects of urbanization on biodiversity and ecological processes, addressing challenges such as habitat fragmentation and pollution.

  • Human Population in Urban vs. Rural Areas

    • An increasing percentage of the global population is living in urban centers, reshaping ecological dynamics and resource demands.

  • Resource Concentration in Urban Centers

    • Urban areas often concentrate resources due to infrastructure developments, impacting local ecosystems and biodiversity.

  • Urban Ecological Footprint

    • The environmental impact of urban lifestyles concerning resource consumption, waste production, and carbon footprints, emphasizing the need for sustainable practices.

  • Example of Ecosystem Service

    • Services provided by ecosystems, such as pollination, water purification, and carbon sequestration, that offer benefits to humanity and ecological integrity.

  • Combining Resource Areas with Waste Assimilation Areas

    • Strategies for integrating green infrastructure with urban waste systems to enhance sustainability and ecological resilience.

  • Rural to Urban Biodiversity Gradient

    • Documented changes in species richness and community composition as one transitions from rural to urban areas, reflecting species adaptability to urban environments.

  • Fragmented Habitats

    • Conservation strategies aim to connect isolated habitats, promoting biodiversity and facilitating species movement to mitigate the effects of habitat loss.

  • Evolutionary Effects on Species

    • Rapid evolution can occur in response to urbanization, often leading to changes in traits and behaviors that promote survival in altered environments.

Climate Change

  • CO2 and Climate Change Correlation

    • A strong correlation exists between rising CO2 levels and global temperature increases, influencing weather patterns and environmental phenomena.

  • Observations of Atmospheric CO2

    • Despite significant emissions, observed CO2 levels in the atmosphere are sometimes lower due to absorption by oceans and terrestrial vegetation, highlighting potential carbon sinks.

  • Temperature Patterns Over Past Few Hundred Years

    • Historical temperature records show fluctuations influenced by both natural variability and human activities, particularly fossil fuel combustion and land-use changes.

  • Effects of Changing Temperature on Weather

    • Climate change increases the frequency and intensity of extreme weather events, including droughts and floods, fundamentally altering ecosystems and affecting human communities.

  • Impacts on Communities Due to Climate Change

    • Changes in temperature and climate can disrupt species interactions, alter habitat ranges, and cause shifts in community composition, necessitating adaptation strategies for biodiversity conservation.