BISC 111
Week 10 Day 1: The Science of Ecology; Climate (Ch 18.1, Ch 19 Secs 19.1, 19.2)
Ecology vs. Environmentalism
Ecology: The study of interactions between organisms and their environment.
Environmentalism: A social and political movement focused on protecting the environment and advocating for sustainable practices.
Comparison: Ecology is a scientific discipline, while environmentalism is an activism-based movement.
Levels of Ecology
Organism: Individual living entity.
Population: A group of organisms of the same species living in the same area.
Community: Different species living together in a particular area.
Ecosystem: A community plus the abiotic environment (e.g., sunlight, soil, water).
Organism vs. Population: A population is a group of organisms of the same species, while a community includes multiple species interacting.
Biotic and Abiotic Factors
Biotic: Living components (e.g., plants, animals, bacteria).
Abiotic: Non-living components (e.g., water, air, temperature, minerals).
Example: Trees (biotic) provide shelter for birds (biotic), while sunlight (abiotic) supports photosynthesis in plants.
Community vs. Ecosystem
Community: The living organisms in a particular area.
Ecosystem: The community and the abiotic components (e.g., nutrients, climate, etc.).
Example: The Grove community is the collection of plant, animal, and microbial species. The Grove ecosystem includes those species and their interactions with the soil, air, and water.
Climate vs. Weather
Climate: Long-term patterns of temperature, precipitation, and other atmospheric conditions in a region.
Weather: Short-term atmospheric conditions.
Static Variables: Long-term, unchanging factors (e.g., latitude, elevation).
Dynamic Variables: Variable factors that change over time (e.g., ocean currents, seasonal winds).
Sunlight Variation and Temperature
Sunlight hits the equator directly, leading to more intense heating, while at higher latitudes (near the poles), sunlight is less direct, resulting in cooler temperatures.
Earth’s tilt causes seasonal temperature changes, with opposite seasons in the Northern and Southern Hemispheres.
Convection Cells and Climate Zones
Convection cells: Rising warm air at the equator creates zones of low pressure, while cool air sinks at 30° latitude, creating dry regions.
Distinct zones form based on latitude: Tropical near the equator, deserts around 30° N/S, temperate between 30° and 60° N/S.
Ocean Currents and Mountains
Ocean currents: Distribute heat, affecting coastal climates.
Mountains: Influence climate by blocking air masses, creating rain shadows (one side receives rainfall, while the other side is dry).
Week 10 Day 2: Biomes (Ch 19.3)
Ecosystem vs. Biome
Biome: Large geographical areas characterized by particular climates and ecosystems.
Ecosystem: A smaller, localized community of organisms interacting with their environment.
Two classes of biomes:
Terrestrial Biomes: Forests, deserts, tundras, etc.
Aquatic Biomes: Freshwater (lakes, rivers) and marine (oceans, coral reefs).
Fundamental Abiotic Factor of a Biome
The primary abiotic factor is climate, especially precipitation and temperature, which determine the types of organisms that can thrive in the biome.
Productivity and Primary Producers
Productivity: The rate at which energy is produced and stored in an ecosystem (primarily through photosynthesis).
Primary Producers: Plants, algae, and some bacteria that produce energy through photosynthesis.
Most Productive Biomes
Tropical rainforests and estuaries are the most productive biomes because of high levels of sunlight, water, and temperature.
Marine vs. Freshwater Biomes
Marine biomes include oceans, coral reefs, and estuaries.
Freshwater biomes include lakes, rivers, and wetlands.
Marine biomes have higher salinity, while freshwater biomes have low or no salt.
Week 11 Day 1: Population Ecology (Ch 18.1-18.5)
Defining Populations
Population: A group of individuals of the same species living in the same area.
Example: The human population of the U.S. vs. Mississippi: The U.S. is a larger population with diverse characteristics, while Mississippi has its own population size and specific dynamics.
Applying Population Ecology to Natural Resource Management
Population ecology helps design regulations to prevent overuse of resources by predicting growth and establishing sustainable harvest levels.
Population Features
Density: Number of individuals in a given area.
Dispersion: The pattern of distribution of individuals within a population (e.g., random, clumped, uniform).
Population Growth and Size
Factors affecting population size: Birth rates, death rates, immigration, and emigration.
Growth rate: How the population changes over time, typically represented as a percentage.
Age Structure Diagrams
Diagrams show the distribution of individuals in different age groups, helping predict future population trends (growth, stability, decline).
Life Tables and Survivorship Curves
A life table tracks survival and death rates within a population.
A survivorship curve shows the probability of surviving at different ages (Type I: low infant mortality, Type II: constant mortality, Type III: high early mortality).
Life History and Reproductive Strategies
r-strategy: Many offspring, little parental care (e.g., insects).
K-strategy: Fewer offspring, high parental care (e.g., humans).
Exponential vs. Logistic Growth
Exponential growth: Growth rate is constant, leading to a J-shaped curve.
Logistic growth: Growth slows as the population approaches the carrying capacity (K), resulting in an S-shaped curve.
Density-Dependent vs. Density-Independent Factors
Density-dependent: Factors whose impact increases with population size (e.g., disease, competition).
Density-independent: Factors that affect populations regardless of size (e.g., natural disasters).
Week 11 Day 2: Human Population Growth (Ch 18.6)
Human Population Growth
The human population has grown exponentially over the last 10,000 years, with a current population of approximately 8 billion.
This growth is due to technological, agricultural, and medical advances.
Differences in Growth Among Countries
Growth rates vary based on economic development, healthcare, education, and cultural factors. Developing countries often have higher birth rates.
Demographic Transition
Stage 1: High birth and death rates (pre-industrial).
Stage 2: Death rates drop (improvements in healthcare).
Stage 3: Birth rates drop (family planning, improved education).
Stage 4: Low birth and death rates (industrialized, stable population).
Birth and Death Rate Variation
In more developed countries, birth and death rates are low due to better healthcare and economic development, while in less developed countries, these rates tend to be higher.
Age Structure Diagrams for Predicting Growth
Expanding: A pyramid-shaped diagram with a large younger population.
Stable: Even distribution of age groups.
Declining: More elderly than young, leading to a shrinking population.
Human Growth Model and Carrying Capacity
The human population currently follows an exponential growth model but may approach carrying capacity, influenced by resource limitations and environmental impacts.
Ecological Footprint
An ecological footprint measures the environmental impact of a population. Wealthier, industrialized countries typically have larger footprints, while developing countries have smaller footprints.
Week 12 Day 1: Species Interactions within Communities (Ch 19.4)
Six kinds of interspecific interactions:
Competition: Two species compete for the same resources. Example: Lions and hyenas compete for prey.
Predation: One species hunts and kills another for food. Example: A wolf hunting a deer.
Herbivory: One species feeds on plants or algae. Example: A giraffe eating acacia leaves.
Mutualism: Both species benefit from the interaction. Example: Pollination by bees for flowers.
Commensalism: One species benefits, the other is neither helped nor harmed. Example: Barnacles attaching to a whale.
Amensalism: One species is harmed, the other is unaffected. Example: A tree shading and preventing grass from growing beneath it.
Consequences of each interaction:
Competition can reduce population sizes and biodiversity.
Predation can regulate prey populations and impact species evolution (e.g., through predator-prey cycles).
Herbivory can shape plant communities and influence plant evolution (e.g., through defensive traits).
Mutualism increases the fitness of both species, often leading to coevolution.
Commensalism can benefit one species without affecting the other significantly.
Amensalism may lead to the exclusion of less competitive species but does not affect the dominant species.
Competitive Exclusion vs. Resource Partitioning:
Competitive Exclusion: Two species cannot coexist if they are competing for the same resource, and one will drive the other extinct.
Resource Partitioning: Species divide the available resources in such a way that they can coexist by exploiting different parts of the environment or using the resource at different times.
Herbivory vs. Predation:
Herbivory involves feeding on plants or algae (not typically killing the organism), whereas predation involves killing and eating another animal.
Adaptations to avoid being eaten:
Camouflage: Hiding in plain sight, like a chameleon or stick insect.
Mimicry: Mimicking another species, like viceroy butterflies imitating the toxic monarch.
Defensive structures: Sharp spines, shells, or toxins, like porcupines or pufferfish.
Behavioral defenses: Fleeing or defensive postures, like the “playing dead” behavior of opossums.
Coevolution: When two species exert selective pressures on each other, leading to reciprocal adaptations. Example: The long-tongued bat and the agave flower have evolved together so that the bat can pollinate the flower while feeding on its nectar.
Keystone Predator:
A species whose impact on the ecosystem is disproportionately large compared to its biomass. Example: Sea otters control sea urchin populations, which in turn prevents overgrazing of kelp forests, maintaining biodiversity in the ecosystem.
Week 12 Day 2: Energy and Nutrient Transfer in Ecosystems (Ch 19.6-19.7)
Energy Flow vs. Nutrient Cycling:
Energy Flow is unidirectional; it enters ecosystems through sunlight and is lost as heat at each trophic level (second law of thermodynamics).
Nutrient Cycling involves the recycling of materials (like carbon, nitrogen, and water) within an ecosystem.
Food Web vs. Food Chain:
A food chain is a linear sequence of organisms through which energy and nutrients flow.
A food web represents a more complex, interconnected network of food chains.
Trophic Levels:
Producers (Primary Producers): Organisms that make their own food (e.g., plants).
Primary Consumers: Herbivores that eat producers (e.g., deer).
Secondary Consumers: Carnivores that eat herbivores (e.g., foxes).
Tertiary Consumers: Top predators (e.g., eagles).
Decomposers: Break down dead organic material (e.g., fungi, bacteria).
Consumers:
Primary Consumers: Herbivores.
Secondary Consumers: Carnivores that eat herbivores.
Tertiary Consumers: Apex predators.
Role of Decomposers:
Decomposers recycle nutrients back into the ecosystem, which is different from consumers who consume living organisms. Decomposers break down dead material into simpler forms usable by producers.
Productivity:
Gross Primary Productivity (GPP): Total energy captured by producers in an ecosystem.
Net Primary Productivity (NPP): Energy remaining after producers have used some energy for their own metabolism, available for consumption by herbivores and higher trophic levels.
Most Productive Biomes:
Tropical rainforests, coral reefs, and wetlands are among the most productive due to year-round warmth and abundant water.
Energy Limiting Food Chains/Webs:
Energy limits food chains because energy decreases with each trophic level. The "10% rule" suggests that only about 10% of the energy is transferred to the next trophic level.
Week 13 Day 1 (Ch 19.6, 19.5):
Biogeochemical Cycles (Water & Carbon):
Water Cycle: Involves reservoirs (oceans, glaciers, atmosphere) and transfer processes (precipitation, evaporation, transpiration).
Carbon Cycle: Carbon moves through the atmosphere, biosphere, oceans, and geosphere. Reservoirs include the atmosphere, plants, soil, and fossil fuels.
Water Pathway:
Water evaporates, condenses into clouds, and precipitates as rain. It enters terrestrial food chains through plants, is consumed by herbivores, and eventually reaches the ocean via runoff.
Carbon Pathway:
CO₂ enters the atmosphere, is absorbed by plants during photosynthesis, and transferred through food chains. Carbon is stored in biomass (plants/animals) and long-term in fossil fuels, soil, and oceans.
Primary vs. Secondary Succession:
Primary Succession: Occurs in a new area with no pre-existing soil (e.g., after a volcanic eruption). Begins with pioneer species like lichens, followed by grasses, shrubs, and eventually trees.
Secondary Succession: Occurs in an area where soil is intact (e.g., after a fire). It is faster than primary succession because the soil and some species remain.
Week 13 Day 2 (Ch 20.2-20.4):
Disturbance and Ecological Communities:
A disturbance is any event that disrupts the structure of a community (e.g., fire, hurricanes). It can promote biodiversity by allowing new species to colonize or by resetting succession.
Human Disturbance:
Habitat destruction and climate change are the two most severe disturbances threatening ecosystems.
Dead Zones:
Dead zones are areas in aquatic environments with low oxygen, often caused by excess nutrients (nitrogen and phosphorus) from agricultural runoff, leading to algal blooms that deplete oxygen.
Greenhouse Effect:
The greenhouse effect is the warming of Earth due to gases like CO₂ trapping heat. Human activities, like burning fossil fuels, increase CO₂ levels, enhancing this effect.
Carbon Pollution and Temperature:
Carbon pollution contributes to global warming by increasing the greenhouse effect, causing global temperatures to rise.
Surface Temperature, Water Cycle, and Climate Change:
Rising temperatures alter weather patterns, increase evaporation rates, and change precipitation patterns, leading to more extreme weather events (droughts, floods).
Deforestation and Climate Change:
Deforestation reduces carbon storage (less photosynthesis) and increases CO₂ in the atmosphere, contributing to climate change.
Climate Change and Coral Reefs:
Rising sea temperatures and ocean acidification from excess CO₂ threaten coral reefs, leading to coral bleaching and decreased biodiversity.
Week 14 Day 1 (Ch 20.1, 20.6): Threats to and Protections for Biodiversity
Three levels (scales) of biodiversity and reasons to conserve all:
Genetic diversity: Variability in genetic makeup within a species. It is important for the species' ability to adapt to environmental changes, resist diseases, and maintain healthy populations.
Species diversity: The variety of species within an ecosystem or across the planet. It ensures ecosystem stability, resilience, and the functioning of ecological processes like pollination and nutrient cycling.
Ecosystem diversity: The variety of ecosystems (e.g., forests, wetlands, coral reefs) on Earth. Conserving ecosystem diversity helps maintain ecosystem services like clean air, water, and carbon sequestration.
Reason to conserve all levels: Loss of any level of biodiversity can have cascading effects, compromising the stability and resilience of ecosystems, reducing our resources, and diminishing the potential for future scientific discoveries.
Endangered and vulnerable (threatened) species definitions:
Endangered species: Species that are at risk of extinction in the near future. According to international and national regulations (e.g., IUCN Red List, U.S. Endangered Species Act), these species face a very high risk of extinction in the wild.
Vulnerable (threatened) species: Species that are not yet endangered but are likely to become so in the near future due to factors such as population decline, habitat loss, or environmental changes.
Quantify how many species are endangered or threatened today:
According to the International Union for Conservation of Nature (IUCN) Red List, over 28,000 species are threatened with extinction, including more than 40% of amphibians, 25% of mammals, and 14% of birds.
Conservation biology definition:
Conservation biology is the scientific discipline focused on the preservation and management of biodiversity. It involves studying the threats to species, ecosystems, and genetic diversity, and developing strategies for conservation, such as creating protected areas, breeding programs, and sustainable management practices.
Value of protecting habitat to conserve biodiversity:
Habitat protection is crucial for preserving biodiversity because it ensures the survival of species and the stability of ecosystems. Without a suitable habitat, species cannot thrive, reproduce, or fulfill their ecological roles. Protected habitats help conserve entire ecosystems, supporting not only the species living within them but also the ecosystem services they provide (e.g., clean air, water, climate regulation).
Regulations and biotechnology used to save the bald eagle from extinction:
The Bald Eagle was saved from extinction through a combination of:
Regulations: The Endangered Species Act (ESA) of 1973 played a key role in protecting the bald eagle by banning hunting, habitat destruction, and the use of harmful pesticides like DDT.
Biotechnology: Efforts such as captive breeding programs, artificial nesting platforms, and the use of biotechnology to monitor eagle populations contributed to their recovery. The banning of DDT also helped restore eagle reproduction rates by eliminating the chemical's harmful effects on egg shells.
Week 14 Day 2 (Ch 20.1, 20.4): Small and Large Scale Ways to Limit Global Warming
Top two nations that emit the most greenhouse gases:
China and the United States are the two largest emitters of greenhouse gases globally. China leads in overall emissions, followed by the U.S. These two countries together are responsible for about 40% of global greenhouse gas emissions.
Two ways nations can cut greenhouse gas emissions:
Renewable energy transition: Shifting from fossil fuels to renewable energy sources like wind, solar, and hydroelectric power can significantly reduce greenhouse gas emissions.
Energy efficiency: Improving energy efficiency in industries, transportation, and buildings can lower energy consumption and associated emissions. This includes measures such as upgrading infrastructure, promoting energy-saving technologies, and reducing waste.
Why methane emissions are especially problematic:
Methane is a potent greenhouse gas, with a global warming potential 25 times greater than carbon dioxide over a 100-year period. Methane is released during the production and transport of coal, oil, and natural gas, as well as from livestock, rice paddies, and landfills. Its relatively short atmospheric lifetime (around 12 years) means that cutting methane emissions can lead to faster climate benefits than reducing carbon dioxide.
How individuals can contribute to a reduction in greenhouse gases:
Reduce energy use: Individuals can lower their carbon footprint by using energy-efficient appliances, turning off lights when not in use, and improving home insulation.
Transportation: Reducing car travel by using public transportation, carpooling, walking, biking, or driving energy-efficient vehicles can cut emissions.
Diet changes: Reducing meat consumption, particularly beef, can help lower methane emissions from livestock production.
Waste reduction: Minimizing waste, recycling, and composting reduces methane emissions from landfills.
Support policies: Individuals can advocate for policies that promote renewable energy, carbon pricing, and other environmental protections.