ECCB 205 - Fall 2025 Exam 2 Study Notes

ECCB 205 - Fall 2025 Exam 2 Guide

General Exam Preparation Tips

• Review Materials: Use online quizzes (4–7), Simutext questions (including both “graded” and “non-graded” questions), iClicker questions, lecture slides, and personal notes as applicable.

• Focus: Understand the concepts demonstrated by examples or case studies rather than memorizing exact details or numbers.

• Provided Formulas: Equations for Population Growth Models and Lotka-Volterra models will be provided during the exam, but familiarity with variable meanings is essential.

Population Growth and Regulation

• Growth Models:

  • Continuous vs. Discrete Models: Different methods for modeling population growth based on time intervals.

  • Geometric Growth (lambda): A model represented by the formula $N(t) = N<em>0 imes ext{lambda}^t$ where $N(t)$ is the population size at time $t$, and $N</em>0$ is the initial population size.

  • Exponential Growth: Understand the relationship between lambda and intrinsic growth rate $r$:

  • $r = ext{ln}( ext{lambda})$; where $r$ is the per capita growth rate.

  • Logistic Growth: Characterized by carrying capacity $K$. The instantaneous growth rate changes with population size and can be calculated.

  • Instantaneous growth rate $dN/dt = rN imes (1 - N/K)$.

• Age Structure: Recognize pyramid shape in population graphs indicative of growth rates.

• Density Dependence:

  • Density Independence: Factors affecting growth that do not rely on population density.

  • Negative Density Dependence: As population increases, per-capita growth rate decreases due to resource limitation.

  • Positive Density Dependence (Allee Effect): Per capita growth can increase with population size due to social or cooperative benefits.

• Note: Doubling time does not need to be memorized for the exam.

Life Histories (Not covered in Simutext)

• Life History Traits: Traits that influence an organism's schedule of reproduction and survival.

• Resource Allocation Trade-offs: Basic concept for understanding life histories, indicating how organisms allocate resources to growth, reproduction, and survival.

• Variation in Life Histories: Varies along a slow-fast continuum (r vs. K strategists).

  • Example: Trinidadian guppies - Understanding general concepts rather than specific details.

Competition

• Resource Definition: Understanding what constitutes a resource in the context of competition.

• Niche Concept:

  • Realized vs. Fundamental Niche: The fundamental niche is the full potential range of conditions and resources, while the realized niche is where the species actually exists due to competition and limiting factors.

• Types of Competition:

  • Intra-specific Competition: Competition among individuals of the same species.

  • Inter-specific Competition: Competition between different species.

• Competitive Exclusion Principle: Two species competing for the same limiting resource cannot coexist at constant population values.

• Abiotic Factors: Influence the outcomes of competition, exemplified by longleaf pine's role.

• Disturbances: Affect competition outcomes, explained through examples (e.g., longleaf pine).

• Predation and Herbivory: Impacted by competition, exemplified by toads and newts (remembering concept, not specifics).

• Types of Competition:

  • Exploitative Competition: Indirect competition, where organisms compete for shared resources.

  • Interference Competition: Direct competition for resources.

• Other Forms of Competition:

  • Preemption: Occupation of resources before competitors can.

  • Territoriality: Defense of a territory by an organism.

  • Allelopathy: Influence of one plant's growth on another through chemical means.

  • Apparent Competition: Occurs indirectly when two species share a predator.

Consumer-Resource Interaction (Exploitation)

• Parasites:

  • Ecto vs. Endoparasites: Differences outline advantages/disadvantages of living on or in hosts.

• Defenses Against Herbivory: Four strategies:

  • Chemical Defenses: Production of toxic substances.

  • Mechanical Defenses: Structures that deter herbivores (e.g., thorns).

  • Nutritional Defenses: Qualitative/quantitative reductions in nutritional value.

  • Tolerance: Ability to withstand damage without serious impact on growth/fitness.

• Animal Defenses Against Predation: Types include:

  • Chemical, Physical, Aposematism (warning coloration), Batesian and Müllerian mimicry, Crypsis (camouflage), Behavioral, Structural.

• Trade-offs in Defense: Understand how different defenses come with costs, illustrated by nicotine and ladybug alkaloid examples; be equipped to interpret related problems.

• Lotka-Volterra Model: Understand the model for predator-prey dynamics:

  • Characteristics of population growth for both predators and prey: predator populations typically lag behind prey.

• Modeling Types: Stochastic (involving randomness) vs. Deterministic (predictable outcomes).

Evolutionary Arms Race

• Red Queen Hypothesis: The necessity for organisms to constantly adapt to survive, driven by coevolution.

• Sexual vs. Asexual Reproduction: Sexual reproduction is often more costly due to the energy and risk involved.

• Recombination: Genetic process during sexual reproduction enhancing variability.

• Coevolution: Requires reciprocal adaptations between interacting species. Differences between diffuse (guild) vs specific coevolution should be noted.

Symbiosis and Mutualism

• Transmission Types: Difference between vertical and horizontal transmission in symbiotic relationships.

• Symbiotic Relationships: Understand definitions and roles of commensalism, mutualism, and the term symbiont.

• Endosymbiosis: Interaction where one organism lives within another, referred to as the endosymbiont.

• Generalists vs. Specialists: Understanding characteristics of mutualisms based on partners’ requirements.

• Types of Mutualisms: Differentiate by types of benefits provided.

• Drosophila-Spiroplasma Case Study: Understand mutualistic interactions without memorizing numerical data; focus on patterns and graph interpretation.

• Specific Mutualism Examples:

  • Ants/Acacia Tree: Provide mutual protection.

  • Plants/Endophytic Fungi: Advocate for mutual nutrient exchange.

  • Plants/Mycorrhizal Fungi: Roots enhanced by fungi for nutrient uptake.

  • Plants (Legumes)/Rhizobium Bacteria: Nitrogen fixation partnerships.

  • Termites/Protozoa: Digestive assistance in gut.

  • Yucca Moth/Yucca Plant: Mutualism for pollination and nourishment.

  • Corals/Zooxanthellae: Understand coral bleaching and its causes.

Climate Change

• Temperature-Performance Relationship: Understand how temperature affects biological performance across scales, from enzymes to species.

• Graph Interpretation: Ability to interpret graphs depicting temperature-performance relationships (e.g., enzyme activity, growth rate, locomotion) and their variability with temperature.

• Ectotherm vs. Endotherm: Differences in response to temperature changes.

• Climate Forcings: Distinguish between natural and anthropogenic factors affecting climate.

• Uncertainty in Projections: Understand sources of uncertainty in climate warming projections.

• Milankovitch Cycles: Forces responsible for glacial-interglacial periods.

• Climate Change Evidence: Attribution of recent climate changes to human activities, distinguishing patterns across different global areas (high vs. mid-latitudes, ocean vs. land).

• Evidence Types: Differentiate between direct and indirect climate change evidence using proxies and instrumental records.

• Key Terms:

  • Anomaly: Deviations from the norm in climate data.

  • Indices of Change: Common metrics for measuring climate change.

• Air Capacity & Temperature: Water vapor holding capacity based on temperature changes.

• Temperature Change Trends:

  • General patterns of temperature change over the past ~150 years (no exact values).

  • Patterns of minimum Arctic sea ice area since ~1980.

  • Global mean sea level trends since ~1880; understand thermal expansion's role.

• Keeling Curve: Understanding the trend, average of pre-industrial levels at 278 ppm versus present levels over 400 ppm.

• Isotope Signatures: Recognizing evidence of temperature change through ice core analysis, without memorizing specific isotopes.

• Tree Rings: Evidence from tree rings documenting temperature changes in the Northern hemisphere (not exact values).

• Hockey Stick Graph: General trends observed; distinguishing between instrumental and proxy record contributions.

• Greenhouse Gases: Know the four main gases and understand the greenhouse effect:

  • Short vs. Long Wave Radiation dynamics.

• Albedo Effects: Understanding light reflectivity changes impacting climate.

• Thresholds and Tipping Points: Basic concept without detailed examples.

• Feedback Mechanisms: Understand positive and negative feedback effects on climate systems.

• Biological Consequences of Climate Change:

  • Direct vs. indirect impacts on ecosystems and species.

• Coral Reefs and CO2: Understand how elevated CO2 levels lead to ocean acidification, affecting coral reefs and shell-building invertebrates without needing chemical formulas.

• Phenology: Ability to interpret graphs showing seasonal changes for organisms based on various cues (e.g., temperature, photoperiod).

• Trophic Mismatches: Understanding ecological timing mismatches due to climate change.

• Biological Responses: Understanding limits and impacts of biological responses to climate change.

• Note: Excluded are concepts like signal-to-noise, ozone effects, climate velocity, etc.