Ecology Notes PDF

**11/4/24 - Ecosystems** What is a Complex Dynamic System? - A complex dynamic system consists of many interconnected and interdependent elements that influence each other and evolve over time. - Examples include weather systems, economies, ecosystems, and biological networks. Ec...

**11/4/24 - Ecosystems** What is a Complex Dynamic System? - A complex dynamic system consists of many interconnected and interdependent elements that influence each other and evolve over time. - Examples include weather systems, economies, ecosystems, and biological networks. Ecosystems as Complex Dynamic Systems - Definition: Ecosystems are integrated systems of species coexisting in a particular place and time, along with their physical environment. - Dynamics arise from interactions among biological, chemical, and physical components. - 1st Principle of Ecosystem Dynamics: \"Everything is ultimately connected to everything else,\" indicating that ecosystem elements are interdependent. Understanding Complex Systems - Recognized as one of the greatest intellectual challenges of the 21st century due to the intricate nature of ecosystems. - Quote by Jeff Harvey, Science: Emphasizes the complexity of ecological systems and the importance of understanding them as whole systems. Meeting the Challenge of Understanding Ecosystems - Requires both reductionist and holistic approaches: - Reductionist Approach: Focuses on breaking down complex systems into smaller, simpler components for stepwise understanding. - Descartes on Reductionism: Advocates for reducing complex propositions into simpler parts as a scientific method. - Holistic Approach: Considers the system as a whole, focusing on interactions and emergent properties. - Emergent properties are unique to the system level and not predictable from individual parts. Factors Thinking (Reductionist Approach) - Focuses on specific factors affecting population cycles, such as: - Weather, Food, Predators, Parasites, Disease, Competitors, and Habitat. - Example: Ecologists study 4-year cycles in animal population abundance to understand the influence of these factors. Systems Thinking (Holistic Approach) - Reductionism is too simplistic - Examines how cycles in abundance and population dynamics are affected by the entire ecosystem\'s feedback loops. - Emphasizes understanding feedback: - Feedback: A process where a system's output affects its input, either amplifying (positive feedback) or diminishing (negative feedback) subsequent outputs. Daisy World - Developed by James Lovelock to support his Gaia Hypothesis. - Daisy World Simulation: An Earth-like planet with gradually increasing sunlight, where black daisies emerge as temperature rises. - Demonstrates how feedback from organisms (e.g., daisies affecting temperature) can regulate environmental conditions. Summary of Gaia Hypothesis - Proposed by James Lovelock in 1979. - Suggests the biosphere acts as a superorganism, self-regulating to maintain life-sustaining conditions. - Biosphere becomes homeostatic, sustained/modified by feedback from organisms that survive and prosper in specific environments Competition Definition of Competition - Occurs when organisms use or defend a limited resource, reducing its availability for others. - Population consequence: Coexisting species tend to have reduced abundance due to resource competition. - Types of competition - Interference: direct interaction between species - Exploitative: one species uses resources more efficiently than other species (limited resources, indirect) - Apparent: two species in the same habitat share a higher trophic level predator (results in more predators in the area) - Interspecific: different species - Intraspecific: same species Resource Partitioning - Mechanism by which similar species reduce competition by utilizing different resources. - Types of Partitioning: 1. Food Partitioning: Different species consume different types of food. 2. Space Partitioning: Species occupy distinct habitats or areas within a habitat. 1. Examples include Anolis lizards (food/space partitioning) and warbler species (microhabitat partitioning). 1. Time Partitioning: Species reproduce or are active at different times. - Niche expansion - Ex: removal of other species in a tree leads to the remaining species expanding its niche Co-Occurrence and Character Displacement - When species live together, they may undergo character displacement, where physical or behavioral traits evolve to reduce competition. - Adaptive Radiation: A rapid increase in species diversity, often due to organisms adapting to new ecological niches or \"adaptive zones.\" Competition in Laboratory Experiments Competitive Exclusion Principle - Developed by Gause through experiments with Paramecium species. - Competitive Exclusion Principle: Two species cannot coexist indefinitely if they occupy the same niche if 2+ species live in stable association, they must possess different ecological niches - Implications: - Key to understanding resource partitioning, species distribution and abundance, evolution, community structure, and diversity.**Bottom of Form** **10/31/24 -- Biodiversity, Productivity, and Population Ecology** Species Distribution Video - More diverse at the equator - Tropics older than temperate - Warmer, more water = more energy - More stable; less need for niche adaptations - Extreme competition drives evolution + speciation Latitudinal Gradients in Species Diversity - Biodiversity is influenced by latitude, showing a gradient with higher species diversity at lower latitudes (tropics) and lower diversity toward the poles. - Main Hypotheses for This Gradient: - Productivity Hypothesis: - More light, heat, and precipitation in tropical regions, which results in longer growing seasons. - Greater productivity in these regions promotes: - Increased specialization (species adapt to specific roles/niches). - Higher population sizes (more resources support larger numbers). - Larger geographic ranges for species. - Lower extinction rates and higher speciation rates (due to stable resources and habitats). - Stability Hypothesis: - Less variable tropical climates (less seasonal change and extreme weather). - Greater stability leads to: - Increased specialization (species can evolve more specific adaptations). - Larger geographic ranges (fewer disruptions to habitats). - Lower extinction rates and higher speciation rates (stable environment encourages diversification). Recap: The Biosphere and Earth's Climate Systems - Distribution of Moisture and Energy: - Atmospheric and oceanic energy flow determine climate, impacting major vegetation and animal communities in the biosphere. - Thermohaline currents help distribute heat, moderating Earth's temperature and supporting biodiversity. - Primary Energy Source: - The Sun's electromagnetic radiation (mainly 400-700 nm for photosynthesis) powers all life through energy capture by autotrophs. Definitions Related to Ecosystem Productivity - Standing Crop (SC): The amount of dry producer biomass at a given time in an ecosystem. - Gross Primary Production (GPP): Total carbon fixed by plants per unit area and time. - Net Primary Production (NPP): GPP minus the energy used by plants for respiration, representing the energy available to consumers. - Respiration: intake of oxygen/release of carbon dioxide NPP Video - Plants vs. climate change - More CO2, higher temperatures should benefit them - More droughts = less water for plants - Water is necessary for photosynthesis Oceanic and Terrestrial Productivity - Ocean NPP: - Highest where nutrient concentrations are high (e.g., continental margins due to upwelling). - Open oceans are nutrient-poor, leading to low NPP. - Terrestrial NPP: - Driven by sunlight, nutrient availability, temperature, and moisture. - Tropical regions and forests often have the highest terrestrial NPP. Carbon Balance and Global Ecosystem Productivity - Carbon Sources and Sinks: - Sources: Include fossil fuel combustion, forest fires, and respiration. - Sinks: Oceans, plants, and soil. - The balance between sources and sinks affects Earth's carbon cycle and climate. Remote Sensing - Measuring conditions on Earth with satellite images taken at different wavelengths - Assesses productivity - Chlorophyll absorbs in blue and red, reflects green - Images with high absorption of blue and red and high reflectance of green = high standing crops What is a Population? - Definition: A population is a group of individuals of the same species living together in the same place at the same time. - Scope: This includes all forms of life---plants, animals, and microorganisms. Population Ecology - The study of populations in relation to their environment, examining how biotic (living) and abiotic (non-living) factors affect population size, stability, and growth. Energy Flow in the Biosphere - Producers (like plants) are essential for life in the biosphere, providing the chemical energy that fuels all ecosystems. - Energy Transfer: Only a small percentage of energy transfers to the next trophic level, with most lost as heat, adhering to the Laws of Thermodynamics. - Energy Pyramids: Illustrate this energy flow, typically showing more energy at lower trophic levels and diminishing energy higher up, as seen in grassland ecosystems. Example of Population Behavior: Swarming Starlings in Rome (Murmuration) - Murmuration: A collective behavior seen in starling populations, where large flocks form intricate patterns in the sky as a population response. - Each track movements of 6 others; groups of 7 - Produces lots of excrement - Combatting: use of starling alarm calls to scare them - Swarm gains strength in numbers against predators - Rapid changes of direction - Difficult to get individual birds - Constantly splitting/reconnecting Species Diversity - Number of Species: Sir Robert May highlighted in 1998 that we lack knowledge of how many species exist globally, urging efforts to catalog species before they face extinction. - Named Species: Approximately 1.8 million species were identified by 2000, with ongoing efforts to increase this count. Population Growth and Extinction Patterns - Population Growth Patterns: - Exponential Growth: Shows a J-shaped curve, occurring under ideal conditions but unsustainable in nature due to resource limits. - Logistic Growth: Illustrates population growth leveling off as it approaches carrying capacity---the maximum population an environment can support. - Carrying Capacity: Determined by the availability of resources like food, habitat, water, and space. - Environmental Resistance: Refers to environmental factors (e.g., competition, nutrient limitations, predation) that restrict population growth. Stability and Instability in Populations - Population Stability: - Territorial Behavior: Helps maintain stability in species like tawny owls, where stable territories limit overpopulation. - Density-Dependent Factors: Population size may be regulated by factors like available space and territory, as seen in skuas. - Population Instability: - Populations like flour beetles experience fluctuating population sizes due to factors like nutrient limitations and biotic interactions. - Environmental Sensitivity: Populations, such as phytoplankton, are affected by abiotic conditions (e.g., temperature, nutrients, sunlight) and biotic pressures like grazing by zooplankton. Factors Influencing Population Size - Biotic Factors: - Food availability, habitat, and interactions such as predation, competition, parasitism, and disease. - Abiotic (Physical) Factors: - Light, nutrients, water, temperature, space, and pH all impact population growth and sustainability. **10/28/24 -- Ecology, Climate, and Biomes** Ecology - Ecology is the scientific study of interactions between organisms and their environment, affecting life's distribution, abundance, and evolution. - Human activity has increasingly affected and will continue to shape Earth\'s biosphere. Scientists - *Carl Linnaeus* viewed nature as interconnected, where every organism holds a unique role within a balanced system. - Economy of nature - *Charles Darwin* recognized that ecological dynamics like competition and predation are driving forces in evolution, with adaptations shaping populations and ecosystems. - Ecology and the Origin Foundational Definitions of Ecology - *Ernest Haeckel* coined "oekology" to describe nature's "economy," highlighting organisms\' relationships with their environment. - *Ellen Richards*, one of the earliest American advocates for sustainable environmental stewardship, contributed significantly to water quality and environmental chemistry. Video - Interdependence: species are dependent on other species for survival - Models (ecosphere): used to study interactions in a closed environment - Ecological levels of order - Ecosystems include all abiotic and biotic factors in a specific area - Community: different populations in an area (not abiotic factors) - Population: individuals of one species - Individual: one organism - Niche: job/role of organism in its environment - Generalists: variety of foods - Beneficial; less likely to go extinct - Specialists: few or one food(s) - Habitat: home of an organism Abiotic and Biotic Factors - Abiotic Factors: Climate (temperature, rainfall), energy sources, nutrient distribution, soil, wind, dissolved oxygen, salinity, currents, and tides. - Biotic Factors: Include the organisms within an ecosystem, competition for resources, predator-prey dynamics, and interspecies relationships. Ecosystems and Complexity - Ecosystems are dynamic systems of interacting species and environmental factors, characterized by constant change rather than equilibrium. - Food webs, though simplified in diagrams, represent complex, high-dimensional systems where biomass and species interactions are always in flux. Scale and Challenge in Ecology - Ecology involves large spatial and temporal scales. - A key 21st-century scientific challenge is to model ecological complexity to better predict biosphere dynamics. Biome Video - Biomes: general set of conditions - Grassland, tundra, rainforest, shrubland, taiga/coniferous forest, temperate deciduous forest, desert - Marine biomes Biosphere - The biosphere encompasses all regions where life exists, including Earth\'s hydrosphere, lithosphere, and atmosphere. - It is a dynamic system where elements interact and change over time, influenced by natural events and inter-sphere interactions. Distribution of Life and Climate's Role - Understanding climate\'s influence on life distribution helps scientists study interconnected Earth systems. - Climate patterns, such as those revealed by ocean currents, affect biome distribution and environmental conditions globally. Biomes - Biomes are the largest regional ecosystems with unique vegetation, animals, and microbes adapted to specific soil and climate. - The Whittaker Diagram categorizes biomes based on temperature and precipitation. Types of Biomes - Terrestrial Biomes: Desert, temperate forest, tropical seasonal forest, tundra, grassland, taiga. - Aquatic Biomes: Freshwater ecosystems (lakes, streams, wetlands) and marine zones (intertidal, estuary, oceanic, hydrothermal vents). Deep Ocean Biome Video - Hydrothermal vents discovered - Hot vents, spews nutrients - Life without sunlight - Chemosynthesis - Summary: - Sunlight is not a factor - Chemoautotrophic mechanism using sulfur compounds as an energy source to convert CO~2~ into organic food molecules for nutrition of hosts - Bacteria provide the nutrients for the other members of the community - These bacteria may be the most abundant biomass on the planet and they make the biome function by providing energy and fixing CO~2~ Ocean Currents and Climate - Major ocean currents, like the Gulf Stream, play crucial roles in regulating Earth's temperature and influencing regional climates. - Gulf Stream: Important for Europe, 10k km, very warm (heat pump) - Global circulation on rotating Earth splits atmosphere into 3 cells - Hadley cells- at equator - Polar cells- at poles, smallest cells - Ferrel cells- not temperature driven, goes in opposite direction than other 2 cell types - Water in constant motion in currents that influence regional climate. - Wind is responsible for surface currents. - Water circulates counter clockwise in southern hemisphere and clockwise in northern. - Coastal climates affected by water movement. - If cold water flowing near coast, winds approaching coast give off heat to the cold water and winds cool down. - Warm waters can give up heat to the prevailing winds. Seasons and Climate - Seasonal climatic effects are due to the tilt of the Earth. If no tilt, no seasons and day and night time are equal. - At summer solstice, north pole is oriented toward the sun and we have our longest day in the northern hemisphere. - At autumnal equinox (fall) and vernal equinox (spring) neither pole is oriented toward the sun and day time equals night. - The winter solstice is opposite of the summer solstice with the south pole getting greater light.