General Biology II: Final Exam Study Guide – Fungi, Animal Diversity, Ecology, and Ecosystems

Lecture 15: Fungi

Fungal Phylogeny and Characteristics

Fungi are a diverse kingdom of eukaryotic organisms that play essential roles in ecosystems as decomposers, symbionts, and pathogens. Understanding their placement in the tree of life and their unique features is fundamental in biology.

• Phylogenetic Placement: Fungi are more closely related to animals than to plants, sharing a common ancestor with animals in the Opisthokonta clade.

• Synapomorphies: Key shared traits include chitin in cell walls, absorptive heterotrophy, and the production of spores.

• Fungal Morphology: Fungi exhibit structures such as hyphae (filamentous cells), mycelium (network of hyphae), and specialized forms like mycorrhizae (symbiotic associations with plant roots), saprophytes (decomposers), and parasites.

• Generalized Fungal Life Cycle: Most fungi have a life cycle that includes both sexual and asexual reproduction, with spore formation as a key feature.

• Fungal Movement: Fungi do not move actively; instead, their spores are dispersed by wind, water, or animals.

Example: Mycorrhizal fungi form mutualistic relationships with plant roots, enhancing nutrient uptake for the plant and receiving carbohydrates in return.

Lectures 16-17: Animal Diversity

Animal Synapomorphies and Body Plans

Animals are a monophyletic group characterized by specific shared traits and diverse body plans. Understanding these features helps in classifying and studying animal diversity.

• Shared Traits: Multicellularity, heterotrophy, lack of cell walls, and unique tissues (e.g., nervous and muscle tissue).

• Animal Body Plans: Animals exhibit various body plans, including radial and bilateral symmetry, segmentation, and the presence or absence of a coelom (body cavity).

• Major Animal Clades: Key clades include Porifera (sponges), Cnidaria (jellyfish, corals), Protostomes (arthropods, mollusks), and Deuterostomes (echinoderms, chordates).

• Cambrian Explosion: A period (~541 million years ago) marked by rapid diversification of animal body plans and the appearance of most major animal groups.

• Vertebrate Evolution: Major milestones include the development of jaws, limbs, and adaptations for terrestrial life.

Example: The transition from aquatic to terrestrial environments in vertebrates required adaptations such as lungs and limbs.

Lecture 18-19: Behavioral Ecology

Animal Behavior and Its Evolutionary Basis

Behavioral ecology examines how animal behavior is shaped by ecological and evolutionary pressures, focusing on survival and reproductive success.

• Proximate vs. Ultimate Causes: Proximate causes explain how behaviors occur (mechanisms), while ultimate causes explain why behaviors have evolved (adaptive value).

• Innate vs. Learned Behaviors: Innate behaviors are genetically programmed, while learned behaviors are acquired through experience.

• Types of Learning: Includes habituation, imprinting, classical conditioning, and operant conditioning.

• Mating Systems: Monogamy, polygamy (polygyny, polyandry), and promiscuity differ in parental investment and sexual selection.

• Sexual Selection: Selection for traits that increase mating success, often leading to sexual dimorphism.

Example: In birds, elaborate courtship displays are often a result of sexual selection.

Lecture 20: Intro to Ecology

Levels of Organization and Ecological Patterns

Ecology studies the interactions between organisms and their environment, organized into hierarchical levels and patterns.

• Levels of Organization: Individual, population, community, ecosystem, biome, and biosphere.

• Ecological Patterns: Distribution and abundance of organisms, influenced by biotic and abiotic factors.

• Ecological Processes: Include energy flow, nutrient cycling, and population dynamics.

• Spatial and Temporal Scales: Ecological phenomena can occur at various scales, from local to global and from short-term to long-term.

• Climatic and Regional Factors: Climate, weather, and disturbances (e.g., fires, storms) shape ecological communities.

• Biomes: Large ecological regions defined by climate, vegetation, and animal life (e.g., tundra, rainforest).

Example: The rain shadow effect creates dry areas on the leeward side of mountains, influencing biome distribution.

Lecture 21-22: Population Ecology

Population Dynamics and Regulation

Population ecology focuses on the factors that affect population size, growth, and structure over time.

• Population vs. Species: A population is a group of individuals of the same species in a given area.

• Population Growth Models: Exponential growth ($N_t = N_0 e^{rt}$) and logistic growth ($N_t = \frac{K N_0 e^{rt}}{K + N_0 (e^{rt} - 1)}$), where $K$ is carrying capacity.

• Life Tables and Survivorship Curves: Tools to study age-specific survival and reproduction.

• r- and K-selection: r-selected species produce many offspring with low survival; K-selected species produce fewer offspring with higher survival.

• Density-Dependent and Density-Independent Factors: Density-dependent factors (e.g., competition, disease) regulate population size; density-independent factors (e.g., weather) affect populations regardless of size.

Example: A population of deer may be regulated by food availability (density-dependent) and harsh winters (density-independent).

Lecture 23-24: Community Ecology

Species Interactions and Community Structure

Community ecology examines how species interact and how these interactions shape community composition and dynamics.

• Species Interactions: Include competition, predation, herbivory, parasitism, mutualism, commensalism, and amensalism.

• Ecological Niches: The role and position a species has in its environment; fundamental niche (potential) vs. realized niche (actual).

• Food Webs: Complex networks of feeding relationships; energy flows from primary producers to consumers and decomposers.

• Succession: The process of change in species composition over time, including primary (on new substrates) and secondary (after disturbance) succession.

• Species Richness and Diversity: Influenced by factors such as disturbance, area, and proximity to other communities.

Example: After a forest fire, secondary succession leads to the gradual return of plant and animal species.

Table: Types of Species Interactions

Interaction	Effect on Species 1	Effect on Species 2	Example
Competition	-	-	Two plants competing for sunlight
Predation	+	-	Wolf preying on deer
Herbivory	+	-	Caterpillar eating leaves
Parasitism	+	-	Tapeworm in mammal intestine
Mutualism	+	+	Bees pollinating flowers
Commensalism	+	0	Barnacles on whales
Amensalism	-	0	Tree shading out grass

Lecture 25-27: Ecosystems Ecology

Cycles of Matter, Productivity, and Biodiversity

Ecosystem ecology explores the flow of energy and cycling of matter, as well as the importance of biodiversity and the impact of human activities.

• Cycles of Matter: The water, carbon, nitrogen, and phosphorus cycles are essential for ecosystem function.

• Net Primary Productivity (NPP): The rate at which plants convert solar energy into biomass, minus the energy used in respiration.

• Biogeochemical Cycles: Each cycle involves reservoirs (e.g., atmosphere, soil, water) and processes (e.g., photosynthesis, decomposition).

• Biodiversity: The variety of life at genetic, species, and ecosystem levels; provides ecosystem services and resilience.

• Threats to Biodiversity: Habitat loss, invasive species, overexploitation, and climate change are major threats.

• Mitigation: Conservation efforts, sustainable resource use, and restoration ecology can help protect biodiversity.

Example: Deforestation reduces biodiversity and disrupts the carbon cycle, contributing to climate change.

Table: Major Biogeochemical Cycles

Cycle	Main Reservoirs	Key Processes	Biological Importance
Water	Oceans, atmosphere, lakes, rivers	Evaporation, precipitation, transpiration	Essential for all life processes
Carbon	Atmosphere, fossil fuels, biomass	Photosynthesis, respiration, combustion	Basis of organic molecules
Nitrogen	Atmosphere, soil, organisms	Nitrogen fixation, nitrification, denitrification	Component of proteins and nucleic acids
Phosphorus	Rocks, soil, water	Weathering, uptake by plants, decomposition	Component of DNA, RNA, ATP

Additional info: These notes expand on the study guide questions by providing definitions, examples, and context for each major topic, suitable for exam preparation in a General Biology II course.