Population Ecology Review PDF

‭Comprehensive Review: Unit 3 - Population Ecology‬ ‭This review covers key concepts in population ecology, including species strategies, population growth‬ ‭dynamics, human population trends, and demographic transitions.‬ ‭3.1 Generalists vs. Specialists:‬ ‭‬ ‭Specialists: Species with narro...

‭Comprehensive Review: Unit 3 - Population Ecology‬ ‭This review covers key concepts in population ecology, including species strategies, population growth‬ ‭dynamics, human population trends, and demographic transitions.‬ ‭3.1 Generalists vs. Specialists:‬ ‭‬ ‭Specialists: Species with narrow niches, requiring specific habitats and diets. They thrive in‬ ‭stable environments but are vulnerable to environmental changes.‬ ‭‬ ‭‬ ‭Generalists: Species with broad niches, able to utilize a wide range of habitats and food sources.‬ ‭They are more adaptable to changing environments.‬ ‭‬ ‭3.2 r-selected vs. K-selected Species:‬ ‭These represent two ends of a reproductive strategy spectrum:‬ ‭Feature‬ ‭r-selected Species‬ ‭K-selected Species‬ ‭Size‬ ‭Small‬ ‭Large‬ ‭Offspring‬ ‭Many‬ ‭Few‬ ‭Parental Care‬ ‭Little to none‬ ‭High investment‬ ‭Maturity‬ ‭Fast‬ ‭Slow‬ ‭Lifespan‬ ‭Short‬ ‭Long‬  ‭Reproduction‬ ‭Often reproduce only once (semelparity) or‬ ‭Reproduce multiple times‬ ‭frequently‬ ‭(iteroparity)‬ ‭Environment‬ ‭Unstable, early succession‬ ‭Stable, late succession‬ ‭Competition‬ ‭Low‬ ‭High‬ ‭Biotic Potential‬ ‭High‬ ‭Low‬ ‭Export to Sheets‬ ‭‬ ‭Biotic Potential: The maximum reproductive rate under ideal conditions.‬ ‭‬ ‭‬ ‭Invasive Species: Typically r-selected, allowing them to rapidly colonize new environments.‬ ‭K-selected species are more vulnerable to competition from invasive species. Endangered‬ ‭species can be either r or K selected.‬ ‭‬ ‭3.3 Survivorship Curves:‬ ‭‬ ‭Definition: A graph showing the proportion of individuals in a cohort (group of the same age)‬ ‭surviving to each age.‬ ‭‬ ‭‬ ‭Types:‬ ‭○‬ ‭Type I: High survival rates early and middle life, followed by a rapid decline in later life‬ ‭(characteristic of K-selected species, e.g., humans).‬ ‭○‬ ‭Type II: Relatively constant mortality rate throughout life (some birds and reptiles).‬ ‭○‬ ‭○‬ ‭Type III: High mortality rate early in life, with a few surviving to old age (characteristic‬ ‭of r-selected species, e.g., insects, fish).‬ ‭○‬ ‭3.4 & 3.5 Carrying Capacity (K):‬  ‭‬ ‭Definition: The maximum number of individuals an environment can sustainably support‬ ‭given available resources.‬ ‭‬ ‭Overshoot: When a population exceeds carrying capacity.‬ ‭‬ ‭Dieback: A sharp decline in population size due to resource depletion following an overshoot.‬ ‭This can be caused by famine, disease, and increased competition.‬ ‭‬ ‭‬ ‭Resource Limitation: Population growth is limited by finite resources (food, water, space).‬ ‭Abundant resources lead to accelerated growth; shrinking resources lead to increased mortality,‬ ‭decreased reproduction, and population decline towards carrying capacity.‬ ‭‬ ‭3.6 Age Structure Diagrams:‬ ‭‬ ‭Definition: Graphical representation of the distribution of individuals across different age‬ ‭groups in a population.‬ ‭‬ ‭Interpretation:‬ ‭○‬ ‭Pyramid shape: Rapidly growing population (high proportion of young individuals).‬ ‭○‬ ‭○‬ ‭Column shape: Stable population (relatively even distribution across age groups).‬ ‭○‬ ‭○‬ ‭Inverted pyramid shape: Declining population (higher proportion of older‬ ‭individuals).‬ ‭3.7 Factors Affecting Total Fertility Rate (TFR):‬ ‭‬ ‭TFR: The average number of children a woman is expected to have in her lifetime.‬ ‭‬ ‭‬ ‭Influencing Factors:‬ ‭○‬ ‭Age at first childbirth.‬ ‭○‬ ‭Educational opportunities for women.‬ ‭○‬ ‭Access to family planning and contraception.‬ ‭○‬ ‭Government policies (e.g., pronatalist or antinatalist policies).‬ ‭‬ ‭Replacement Level Fertility: The TFR needed to maintain a stable population size‬ ‭(approximately 2.1 children per woman).‬ ‭‬ ‭Infant Mortality Rate (IMR): The number of deaths of infants under one year old per 1,000‬ ‭live births. Influenced by access to healthcare and nutrition.‬ ‭‬ ‭3.8 Human Population Growth and Decline:‬ ‭‬ ‭Influencing Factors:‬ ‭○‬ ‭Birth rates.‬ ‭○‬ ‭Death rates.‬ ‭○‬ ‭IMR.‬ ‭○‬ ‭Access to family planning.‬ ‭○‬ ‭Access to nutrition and healthcare.‬ ‭○‬ ‭Age at marriage.‬ ‭‬ ‭Limiting Factors:‬ ‭○‬ ‭Earth's carrying capacity.‬ ‭○‬ ‭Factors described by Malthusian theory (population growth will eventually outstrip‬ ‭resource availability).‬ ‭○‬ ‭‬ ‭Density-Dependent Factors: Factors whose impact varies with population density (e.g.,‬ ‭competition, predation, disease).‬ ‭‬ ‭‬ ‭Density-Independent Factors: Factors whose impact is independent of population density‬ ‭(e.g., natural disasters, weather events).‬ ‭‬ ‭‬ ‭Rule of 70: A method for estimating population doubling time: Doubling Time ≈ 70 /‬ ‭(Percentage Growth Rate).‬ ‭‬ ‭3.9 Demographic Transition:‬ ‭‬ ‭Definition: The shift from high birth and death rates to low birth and death rates as a country‬ ‭develops from a pre-industrial to an industrialized economy.‬ ‭‬ ‭‬ ‭Stages:‬ ‭○‬ ‭Stage 1 (Pre-industrial): High birth and death rates, stable population size.‬ ‭○‬ ‭Stage 2 (Transitional): Death rates decline due to improved sanitation and healthcare,‬ ‭birth rates remain high, rapid population growth.‬ ‭○‬ ‭Stage 3 (Industrial): Birth rates decline due to increased access to education,‬ ‭contraception, and changing social norms, population growth slows.‬ ‭○‬ ‭○‬ ‭Stage 4 (Post-industrial): Low birth and death rates, stable or declining population size.‬  ‭‬ ‭Developing Countries: Often characterized by high IMR and a larger proportion of children‬ ‭in the workforce.‬ ‭This comprehensive review covers the essential concepts of population ecology, providing a foundation‬ ‭for understanding population dynamics and human impacts on the environment.‬ ‭Comprehensive Review: Unit 4 - Earth Systems and Resources‬ ‭This review covers the key concepts of Earth systems and resources, focusing on geological processes,‬ ‭soil science, atmospheric science, watersheds, solar energy, and climate influences.‬ ‭4.1 Plate Tectonics and Geological Events:‬ ‭‬ ‭Plate Boundaries: The Earth's lithosphere is divided into tectonic plates that interact at their‬ ‭boundaries.‬ ‭○‬ ‭Convergent Boundaries: Plates collide, resulting in:‬ ‭‬ ‭Oceanic-Continental: Subduction of the oceanic plate, forming volcanic‬ ‭mountain ranges (e.g., Andes), trenches, and earthquakes.‬ ‭‬ ‭Oceanic-Oceanic: Subduction of the denser plate, forming volcanic island arcs‬ ‭(e.g., Japan), trenches, and earthquakes.‬ ‭‬ ‭Continental-Continental: Collision, forming large mountain ranges (e.g.,‬ ‭Himalayas) and earthquakes.‬ ‭○‬ ‭Divergent Boundaries: Plates move apart, resulting in:‬ ‭‬ ‭Seafloor spreading at mid-ocean ridges, creating new oceanic crust.‬ ‭‬ ‭Rift valleys on continents (e.g., East African Rift Valley).‬ ‭‬ ‭Volcanoes and earthquakes.‬ ‭○‬ ‭Transform Boundaries: Plates slide past each other horizontally, resulting in:‬ ‭‬ ‭Earthquakes (e.g., San Andreas Fault).‬ ‭‬ ‭Mapping: Maps depict plate boundaries, hotspots (areas of volcanic activity caused by mantle‬ ‭plumes), faults (fractures in the Earth's crust), volcanoes, and island arcs.‬ ‭‬ ‭Earthquakes: Occur when stress overcomes the friction of a fault, releasing stored energy in the‬ ‭form of seismic waves.‬ ‭4.2 Soil Characteristics and Formation:‬ ‭‬ ‭Formation: Soil forms from the weathering (physical and chemical breakdown) of parent‬ ‭material (rock), which is then transported and deposited.‬  ‭‬ ‭Soil Horizons: Distinct layers of soil, differentiated by their composition, texture, and organic‬ ‭matter content. Common horizons include:‬ ‭○‬ ‭O Horizon: Organic layer (humus).‬ ‭○‬ ‭A Horizon: Topsoil, rich in organic matter and minerals.‬ ‭○‬ ‭B Horizon: Subsoil, accumulation of minerals leached from above.‬ ‭○‬ ‭C Horizon: Weathered parent material.‬ ‭○‬ ‭R Horizon: Bedrock.‬ ‭‬ ‭Erosion: Soil can be eroded by wind and water, impacting soil fertility and water quality. Soil‬ ‭acts as a natural filter, purifying water as it percolates through the soil profile.‬ ‭4.3 Soil Types and Their Impact:‬ ‭‬ ‭Water Holding Capacity: Varies among soil types and influences land productivity. Clay soils‬ ‭have high water retention, while sandy soils have low retention.‬ ‭‬ ‭Particle Size and Composition: Affect soil properties:‬ ‭○‬ ‭Porosity: The amount of pore space in the soil.‬ ‭○‬ ‭Permeability: The ability of water to flow through the soil.‬ ‭○‬ ‭Productivity: The soil's ability to support plant growth.‬ ‭‬ ‭Soil Testing: Chemical, physical, and biological tests help determine nutrient content, pH, and‬ ‭other properties, guiding decisions on fertilization and irrigation.‬ ‭‬ ‭Soil Texture Triangle: A tool used to classify soil based on the percentages of sand, silt, and clay.‬ ‭4.4 Earth's Atmosphere:‬ ‭‬ ‭Composition: Primarily nitrogen (N2) and oxygen (O2), with trace amounts of other gases‬ ‭(e.g., argon, carbon dioxide).‬ ‭‬ ‭Layers (based on temperature gradients):‬ ‭○‬ ‭Troposphere: Lowest layer, where weather occurs.‬ ‭○‬ ‭Stratosphere: Contains the ozone layer, which absorbs UV radiation.‬ ‭○‬ ‭Mesosphere: Middle layer, where meteors burn up.‬ ‭○‬ ‭Thermosphere: High temperatures due to solar radiation absorption.‬ ‭○‬ ‭Exosphere: Outermost layer, transitioning into space.‬ ‭4.5 Atmospheric Circulation (Winds):‬ ‭‬ ‭Global Wind Patterns: Driven by:‬ ‭○‬ ‭Solar Insolation: Uneven distribution of solar radiation due to Earth's curvature.‬  ‭○‬ ‭Coriolis Effect: The deflection of moving objects (including air) due to Earth's‬ ‭rotation. This results in prevailing wind patterns like trade winds, westerlies, and polar‬ ‭easterlies.‬ ‭4.6 Watersheds:‬ ‭‬ ‭Definition: An area of land where all water drains to a common outlet (e.g., river, lake, ocean).‬ ‭‬ ‭Characteristics: Vary in size, length, slope, soil type, vegetation, and are separated by divides‬ ‭(ridges or high points).‬ ‭4.7 Solar Energy and Seasons:‬ ‭‬ ‭Solar Insolation: Incoming solar radiation, Earth's primary energy source. Varies with latitude‬ ‭and altitude.‬ ‭‬ ‭Angle of Incidence: The angle at which sunlight strikes the Earth's surface. The equator‬ ‭receives the most direct sunlight, while the poles receive the least.‬ ‭‬ ‭Seasons: Caused by Earth's axial tilt (approximately 23.5 degrees). This tilt causes variations in‬ ‭the length of daylight hours and the intensity of solar radiation throughout the year. Summer‬ ‭occurs in the hemisphere tilted towards the sun, while winter occurs in the hemisphere tilted‬ ‭away.‬ ‭4.8 Geographic Influences on Weather and Climate:‬ ‭‬ ‭Geographic Features: Influence weather and climate patterns.‬ ‭○‬ ‭Mountains: Create orographic lift (air forced to rise over mountains), leading to‬ ‭precipitation on the windward side and a rain shadow effect on the leeward side (dry‬ ‭side). Mountains are also generally cooler than surrounding lowlands.‬ ‭○‬ ‭Oceans: Moderate coastal climates due to their high heat capacity, absorbing and‬ ‭releasing heat slowly.‬ ‭‬ ‭Rain Shadow Effect: A dry area on the leeward side of a mountain range.‬ ‭4.9 El Niño and La Niña:‬ ‭‬ ‭El Niño-Southern Oscillation (ENSO): A periodic climate pattern involving changes in sea‬ ‭surface temperatures in the tropical Pacific Ocean.‬ ‭○‬ ‭El Niño: Warmer-than-average sea surface temperatures, leading to changes in global‬ ‭weather patterns, including increased rainfall in some areas and droughts in others.‬  ‭○‬ ‭La Niña: Colder-than-average sea surface temperatures, with opposite effects on global‬ ‭weather patterns compared to El Niño.‬ ‭This comprehensive review provides a detailed overview of the key concepts within Unit 4: Earth‬ ‭Systems and Resources. Understanding these interconnected systems is crucial for comprehending‬ ‭Earth's dynamic processes and their impact on the environment.‬