Ecology Week 7: Communities and Interactions

Week 7: Introduction to Ecology and Communities

• Ecology basics cover interactions between biotic and abiotic factors, building complexity step-by-step.
• Foundational concepts include understanding evolution's role in interpreting current ecological patterns
• Conditions and resources such as climate, temperature, and precipitation shape ecosystems.
• Progression in ecosystems: individuals to populations (same species) to interactions among populations.
• Communities focus on interactions among multiple species in various environments.
• Lab activities at Laurel Creek involved fieldwork to explore riparian systems.
• Lab work parallels lectures, using sampling species in water systems to enhance learning.

Ecological Communities Example: Arctic System

• Artic ecosystems have simple communities due to extreme cold climates, short growing seasons, limited moisture and sunlight.
• Low species diversity restricts interactions.
• Snowshoe hares are keystone species, interacting with predators like lynx and wolves and plants (primary producers).

Transition to More Complex Systems

• Tropical and temperate ecosystems are more diverse, leading to complex food webs and species interactions.
• Focus shifts from intraspecific to interspecific interactions (among species within a region).

Island Biogeography

• Island biogeography models predict species richness based on immigration and extinction rates.
• Species richness depends on immigration (arrival of new species) and extinction (loss of existing species).
• X-axis represents species numbers (not time).
• Y-axis represents rates of change in species numbers.
• Immigration is high when an area has no species and decreases as species richness increases due to competition and resource limits.
• Extinction is low when species numbers are few and increases with increased competition.
• Equilibrium Point represents where immigration and extinction rates intersect.

Field Study: Mangrove Islands Experiment

• Researchers (MacArthur and Wilson) conducted experiments on mangrove islands.
• Covered islands with tarps and killed the fauna.
• Observed species recolonization over time.
• Findings show species richness initially increases, then levels off near pre-experiment levels.
• Larger islands support more species due to resources and niches.
• Islands closer to the mainland have higher immigration rates.
• Species richness is influenced by proximity to mainland and island size. Smaller islands face higher extinction risk and fewer species.
• Students used plastic animals to simulate species migration.

Week 7 Pt 2: Metapopulations

• Metapopulation: A collection of populations across habitat patches with individuals migrating between them.
• Larger, connected populations act as sources of dispersal.
• Smaller, isolated populations are more vulnerable to extinction and often act as sinks.
• Theory builds on island biogeography, emphasizing patch size and isolation.
• Empirical research (Ilkka Hanski's work with silver-studded blue butterflies) provided data.
• Applications in conservation strategies include connectivity corridors, forest bird planning, habitat patch management in fragmented landscapes.

Week 7 Pt 3: Disturbance Ecology and Succession

• Disturbance: Temporary changes in environmental conditions (fires, insect outbreaks, windstorms) causing significant ecosystem shifts.
• Key characteristic: Extent—size of the disturbed area.
• Primary Succession: Lifeless areas with no prior biological influence (e.g., volcanic lava fields, retreating glaciers).
• Secondary Succession: Areas with remnants of prior ecosystems and seed banks (e.g., post-fire recovery).
• Climax Communities are stable, self-replicating ecosystems (e.g., Maple-Beech forests, sagebrush ecosystems).
• Case study examples: Silver-studded blue butterflies (metapopulation ecology) and Mount St. Helens eruption (primary succession).

Week 8: Biodiversity Basics

• Biodiversity: Variety of life on Earth, including genetic, species, and ecosystem diversity.
• Importance of maintaining biodiversity for healthy, functional ecosystems.
• Theory of Biogeography explains species richness and diversity patterns across regions.
• Quantifying biodiversity uses tools like the Shannon Diversity Index.
• Predictors of biodiversity include climate, habitat, and ecosystem variables.
• Global Biodiversity Patterns: Biodiversity varies based on latitude, climate, and resources.
• Ecosystems like North American tallgrass prairies are endangered due to human activities.

Week 8 Pt 2: Biodiveristy Insights

• Species Richness: Number of unique species within an area.
• Global Biodiversity Trends: Declines in biodiversity are severe, across terrestrial, freshwater, and marine ecosystems.

Week 9: Levels of Biodiversity & Conservation Challenges

• Levels of biodiversity include genetic, species, and ecosystem diversity and functional diversity (importance for evolution).
• Threats and challenges to biodiversity include loss of ecosystems and unknown species numbers.
• Historical context and research focus on biodiversity is relatively new (e.g., research in Panama).
• Ecologists study biodiversity at multiple scales to understand its role in evolutionary and ecological processes.

Week 9 Pt 2: Biodiversity Insights, Threats & Challenges

• Threats to biodiversity include habitat loss, invasive species, and overexploitation.
• Drivers include climate change, pollution, and disease.
• Conservation challenges include lack of knowledge about less-studied taxa, limited data from biodiversity hotspots, ecosystem services' monetary value, and other interesting insights (beetle races in Panama).
• Conservation challenges also include the dominance of beetle species in Earth's biodiversity, the importance of metrics like the Shannon index to assess species diversity considering species richness and abundance.

Week 10: Global Cycles and Biodiversity

• Global cycles (carbon, phosphorus, and nitrogen) are fundamental to ecosystem function and are altered by human activities leading to significant ecological impacts.
• Planetary boundaries define limits to Earth systems stability, focusing on novel entities (e.g., synthetic chemicals).
• Discussion of how exceeding planetary boundaries might impact various ecosystems.
• Examples of exceeded boundaries include biogeochemical flows and climate change (due to high CO2 levels).
• Historical examples include ozone depletion.

Week 10 Pt 2: Nutrient Cycles

• Phosphorus: Essential nutrient for life, and exists in rocks, soil, water, and organisms.
• Excess phosphorus from fertilizers and detergents leads to eutrophication, affecting aquatic ecosystems.
• Human impacts on the phosphorus cycle include pollution from agriculture and urban runoff in areas like the Great Lakes.
• Carbon Cycle: A key figure (Charles David Keeling) is a pioneer in measuring atmospheric CO2 levels.
• Carbon cycle connects to climate change by regulating CO2 levels. Anthropogenic (human-caused) CO2 emissions drive climate change.
• Monitoring (long-term data) from the Mauna Loa Observatory shows steadily rising CO2 levels. Seasonal and regional variation in NPP influences the trend.

Week 10 Pt 3: Greenhouse Gases and Their Effects

• CO2 exerts a warming effect due to abundance and long atmospheric residence time.
• Oceans absorb CO2, but warming reduces their absorption capacity, impacting marine life.
• Methane (CH4) is a potent greenhouse gas, with sources including wetlands, agriculture, and permafrost thawing.
• Feedback loops amplify warming, for example, melting sea ice reducing reflection and accelerating further melting (positive feedback).
• Negative feedback loops counteract changes but have less impact in the current climate system. Climate impacts and adaptation includes societal concerns.
• Public perception often views climate change as an existential threat, creating anxiety among younger populations.

Week 10 Pt 4: Biodiversity, Climate, and Change

• Historical trends in climate, emphasizing that humans have thrived in various climates.
• Infrastructure challenges from sea-level rise and extreme weather events, and the role of media in exaggerating risks.
• Global carbon footprint, highlighting the need for global solutions rather than local ones, which may impact the overall global climate change issue.
• Transitioning to cleaner energy (renewable, natural gas) may yield climate benefits compared to using coal or wood.
• Solutions should balance emissions reductions with society's needs, e.g., poverty alleviation.
• Dietary and infrastructure adjustments such as adopting lower-impact diets, ranching over farming where possible, and climate-adaptive infrastructure can help mitigate negative impacts.

Week 10 Pt 5: Global Considerations and Solutions

• Climate change is complex; oversimplified solutions are not ideal.
• Broad, informed strategies are needed to navigate the trade-offs and challenges in addressing the issue(s) of climate change and global warming.
• Discussions of proposed solutions includes renewable energy (solar and wind), nuclear energy, carbon taxes, and innovation.
• Global efforts, like the Paris Agreement, highlight the need for increased global cooperation and broader solutions, emphasizing the need to avoid framing the problem as a political issue divided by opposing ideologies rather than accepting the problem as a shared global challenge.

Explore the basics of ecology, focusing on the interactions between biotic and abiotic factors. This quiz delves into the structure and dynamics of ecological communities, including Arctic systems and their unique characteristics. Understand how conditions like climate and resources influence these intricate relationships.