Bio Final Notes PDF

Page 1 of 9 I. Key Principles of Ecology 1. Populations evolve Populations change genetically over time in response to environmental pressures. 2. Populations co-evolve Interacting species in uence each other’s evo...

Page 1 of 9 I. Key Principles of Ecology 1. Populations evolve Populations change genetically over time in response to environmental pressures. 2. Populations co-evolve Interacting species in uence each other’s evolution (e.g., predator-prey relationships). 3. One true tree of life All species, living and extinct, share a single evolutionary history. 4. Populations uctuate in abundance Populations naturally rise and fall due to environmental or biological factors. 5. Populations cannot grow inde nitely Growth is limited by resources and environmental constraints. 6. Populations can be harvested sustainably With proper management, populations can provide long-term resources. 7. Communities are composed of interacting species Biodiversity and ecological interactions shape ecosystems. 8. Patterns in biodiversity are predictable Factors like climate and geography in uence diversity. 9. Extinctions are a part of history All populations eventually go extinct; extinctions shape biodiversity. 10. Communities are always changing Environmental changes drive community dynamics. 11. Nutrients cycle Essential for ecosystem health and sustainability. 12. Ecosystems provide services Ecosystems sustain life by providing air, water, and food. 13. Tragedy of the commons Overuse of shared resources leads to depletion. 14. Humans are cooperative by nature Cooperative behaviour is essential for survival and resource sharing. II. Darwin’s Contributions to Evolutionary Theory 1. Why is Darwin famous? Provided the mechanism of natural selection. Popularized “survival of the ttest” (though he didn’t coin the term). 2. Darwin’s theory of evolution: Organisms vary in traits, some of which are heritable. fl fl fi fi fl  Page 2 of 9 Populations over-reproduce, leading to competition. Differential survival and reproduction cause genetic changes over time. 3. Key concepts in Darwin’s theory: Natural Selection: Favors traits that increase reproductive success. Evolution: A change in genetic composition of a population over time. 4. Implications: Populations, not individuals, evolve. Local adaptation occurs in response to environmental changes. III. Co-evolution of Species 1. De nition: Species evolve in response to one another, creating reciprocal adaptations. 2. Examples: Predator-prey relationships. Human impacts on biodiversity (e.g., domestication, sheries). 3. Humans and co-evolution: Intentional: Agriculture, domestication. Unintentional: Antibiotic resistance, arti cial selection. 4. Lessons from history: Early human settlers caused extinctions due to lack of co-evolution with native species. Co-evolution fosters harmony with the environment. IV. One True Tree of Life 1. Metaphors for evolution: Tree of Life: Branches represent species and their relationships. Bush of Life: Evolution is not linear but highly branching. 2. Key ideas: Humans and chimps share a common ancestor but did not evolve from one another. Evolutionary classi cation links all species through ancestry. 3. Misconceptions about evolution: No “progress” or ranking of species in evolutionary theory. Humans are not at the top of the evolutionary ladder. 4. Implications: All species are equal in ecological and evolutionary terms. Indigenous philosophies emphasize mutual respect for all forms of life. fi fi fi fi Page 3 of 9 V. Populations Fluctuate in Abundance 1. Extinction is inevitable: All populations face a nonzero chance of extinction. Small and isolated populations are more vulnerable. 2. Population size and extinction risk: Minimum Viable Population (MVP): The smallest size for a population to survive long-term. 3. Metapopulations: Populations linked by migration. Sources: Produce excess individuals. Sinks: Depend on incoming individuals to persist. 4. Conservation priorities: Focus on preserving sources and meta-population structures. VI. Additional Topics 1. Braiding Sweetgrass & Indigeneity: Reciprocity with the land leads to a deeper connection. Living as if future generations matter is key to sustainability. 2. Biophilia: Humans have an innate tendency to connect with nature. 2d Key Terms to Know: Natural Selection Evolution Local Adaptation Co-evolution Tree of Life Extinction Risk Tragedy of the Commons Biophilia Populations and Growth Models Populations cannot grow indefinitely; limited by resources and energy availability. 2 Theoretical Growth Models: Exponential: Rapid, unsustainable growth. Logistic: Stabilizes at carrying capacity (maximum population an environment can support). 3 Ways to Slow Population Growth: [specific methods not provided]. Case Study: Humans: Page 4 of 9 Humans are thriving but face challenges in managing growth. Demographic transition (DT) is slowly addressing overpopulation issues. Energy and Diversity in Ecosystems Energy Limits: The available energy determines ecosystem richness and diversity. Net Primary Productivity (NPP): Higher NPP supports more individuals and species. Diversity Types: Alpha Diversity: Diversity within a single area or ecosystem. Beta Diversity: Species differences between habitats. Gamma Diversity: Overall diversity across multiple ecosystems in a region. Climate and Diversity Climate Harshness Hypothesis: Higher latitudes support fewer species due to harsher conditions. Climate Stability Hypothesis: Stable tropical climates support higher species diversity compared to variable temperate regions. Historical/Evolutionary Hypotheses 1. Historical Perturbation Hypothesis: Low species richness at higher latitudes due to historical disturbances (e.g., glaciation). 2. Evolutionary Rate Hypothesis: Faster evolutionary rates in the tropics lead to higher speciation and diversity. Area Effects on Species Diversity Species-Area Relationship: Larger areas support more species. Formula: , where: = species number, = area, and are constants. Island Biogeography Theory: Species diversity on islands depends on the balance between immigration and extinction rates. Influencing Factors: Immigration: Decreases as species accumulate. Extinction: Increases with competition and limited resources. Distance to Source: Closer islands receive more immigrants. Island Size: Larger islands have lower extinction rates. Equilibrium: Point where immigration rate equals extinction rate. Community Ecology and Sustainability Biological Community: Populations of different species interacting in an area. Key Interactions: Predation: Predators regulate prey populations. Competition: Species compete for limited resources. Page 5 of 9 Mutualism: Beneficial relationships between species. Community Sustainability: Harvesting affects multiple species in a community. Sustainable harvesting requires considering community-wide impacts. Ecological Niches Competitive Exclusion Principle: No two species can coexist using the same limiting resource or occupying the same niche. Ecological Niche: A species’ role in its environment, including resource use. Example: Darwin’s finches occupy different foraging niches. Species Distribution and Invasive Species Species Distribution Factors: Habitat availability, evolutionary history, and barriers to movement. Example: Polar bears live in Arctic habitats suited for hunting seals on pack ice. Invasive Species: 10% Rule: 10% of introduced species establish; 1% become invasive. Impacts: Outcompete native species, economic damage, and habitat alteration. Example: Rabbits in Australia caused widespread extinction of endemic species. Management: Protect critical habitats for endangered species. Use the precautionary principle when moving species to new regions. Sustainability and Ecology Levels Sustainable Practices: Harvest sustainably (take less than Maximum Sustainable Yield). Evaluate community-wide impacts. Levels of Ecology: Global > Landscape > Ecosystem > Community > Population > Organismal. Key Terms Summary Carrying Capacity: Maximum population an environment can support. MSY (Maximum Sustainable Yield): Maximum harvest without depleting resources. Niche: Role of a species in its ecosystem. Equilibrium Diversity (): Balance of immigration and extinction rates in island ecosystems. I. Patterns of Biodiversity Page 6 of 9 1. Biodiversity Distribution: Unevenly distributed across the planet. Energy limits: Richness correlates with net primary productivity (more energy → more individuals → more species). 2. Extinction Rates: Increase as diversity rises due to competition, predation, and parasitism reducing population sizes. II. Sustainable Harvesting 1. Concept: Take the “interest” (growth) while preserving the “capital” (population size). Examples: Early human practices like hunting mammoths or gathering medicinal plants. 2. Models of Population Growth: Exponential Growth: Growth remains constant; harvest must remain below surplus growth. Logistic Growth: Growth slows as it approaches carrying capacity (K). Maximum Sustainable Yield (MSY): Harvesting at K/2 ensures sustainability. 3. Challenges: Overexploitation (e.g., buffalo population collapse). Mismanagement and ignoring ecological limits. III. Indigenous Knowledge & Active Management 1. Fire as a Tool: Indigenous practices like controlled burns promoted biodiversity and provided materials like birch. 2. Active Management: Necessary for top predators, grazing, and fire. Laissez-faire approaches often reduce biodiversity. IV. Energy Flows and Dissipates 1. 2nd Law of Thermodynamics: Usable energy decreases; entropy increases. Energy dissipates as heat (earth as an open system). 2. Ecological Implications: Carnivores require more space → higher extinction risks. Eating lower on the food chain reduces ecological footprints. V. Nutrient Cycles 1. First Law of Thermodynamics: Page 7 of 9 Energy flows; nutrients cycle (e.g., carbon, nitrogen, phosphorus). 2. Human Impact: Imbalances from pollution and non-biodegradable materials. Solutions for nutrient issues (e.g., acid rain reduction via low-sulfur coal). 3. Carbon Cycle: Climate change from burning fossil fuels. Ocean acidification due to carbonic acid formation. VI. Ecosystem Services 1. Examples: Pollination, climate regulation, water supply, nutrient cycling. 2. Economic Value: Ecosystems subsidize the economy by providing essential services. 3. Sustainability: Live within natural limits; take only “interest.” VII. Tragedy of the Commons (TOC) 1. Concept: Public resources are overused when individual benefits > shared costs. “Freedom in a commons brings ruin to all.” 2. Solutions: Regulation (laws, taxes). Privatization (sometimes effective). 3. Critiques: Hardin’s pessimism overstated; examples of sustainable common resource use exist. VIII. Cooperation and Mutualism 1. Evolutionary Basis: Cooperation is as significant as competition. Examples: Mutualism between species. 2. Encouraging Cooperation: Strategies like kin selection, reciprocity, and repeated interactions. 3. Prisoner’s Dilemma: Explains individual vs. collective tension. Solutions include punishment, incentives, and structural changes to encourage cooperation. Key Highlights 1. Biodiversity: Energy drives species richness; human management often required. 2. Sustainability: Page 8 of 9 Harvest below growth rates to preserve ecosystems. 3. Nutrient and Energy Flow: Energy dissipates; nutrients recycle. Reducing human impact is vital. 4. Ecosystem Services: ; Support human wealth and economy; maintaining them ensures sustainability. 5. TOC and Cooperation: Address collective action problems with rules, incentives, and local solutions. KEY TERMS AND QUESTIONS TO ALSO FOCUS ON= WHY ARE CARNIVORES RARER? carnivores are rarer because they are at the top of the food chain and require large areas to hunt and find enough food. Since they depend on herbivores and smaller predators for sustenance, their populations are smaller. Additionally, many large carnivores have experienced population declines and reduced ranges over the past 200 years. ENERGY FLOWS AND DISSIPATES= energy flows through an ecosystem as it moves from the sun to plants then to animals that eat them and so on.At each step, most of the energy is lost at heat, so less energy is available as you go up the food chain. MAIN TERMS OF POPULATION EVOLVE CHAPTER= Darwin’s theory, natural selection acts on individuals within populations, populations as the unit of evolution, local adaptation of populations within species, be cautious when moving/stocking individuals from one population into another, preserving local populations of domestic species is important-seed banks & genetically discrete and significant populations get protection under the species at risk act NATURAL SELECTION= is the process where organisms with traits that make them better adapted to their environment are more likely to survive and reproduce. Over time, these beneficial traits become more common in the population. EX: giraffes with longer necks could reach food other couldn’t so they survived and passed on their genes leading to longer necks overtime. DEFINITIONS= 1. Natural Selection: The process through which traits that enhance reproductive success become more common in a population over time. 2. Co-evolution: A reciprocal evolutionary process where two or more species in uence each other's adaptations. fl Page 9 of 9 3. Tree of Life: A metaphor describing evolutionary relationships among species, represented as branching from common ancestors. 4. Carrying Capacity: The maximum population size an environment can sustain based on available resources. 5. Biophilia: The innate human tendency to seek connections with nature and other forms of life. 6. Tragedy of the Commons: A situation where shared resources are overused and depleted because individual bene ts outweigh shared costs. 7. Maximum Sustainable Yield (MSY): The largest amount of a resource that can be harvested sustainably without depleting the resource base. 8. Species-Area Relationship: A principle stating that larger areas tend to support more species due to greater habitat diversity. 9. Ecological Niche: The role and position of a species within its environment, including its use of resources and interactions with other organisms. 10. Extinction Risk: The likelihood of a species becoming extinct, in uenced by factors like population size and habitat conditions. fi fl