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 to biology.

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

• Synapomorphies: Shared derived traits of fungi include chitin in cell walls, absorptive heterotrophy, and the production of spores.

• Fungal Morphology: Fungi exhibit structures such as hyphae (filamentous cells), mycelium (networks of hyphae), and specialized forms for symbiosis (e.g., mycorrhizae) and parasitism.

• 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 via flagella (except some chytrids); instead, they grow by extending hyphae.

Example: Mycorrhizal fungi form mutualistic relationships with plant roots, enhancing nutrient uptake.

Lectures 16-17: Animal Diversity

Animal Synapomorphies and Body Plans

Animals are a monophyletic group characterized by unique features and diverse body plans. Understanding these traits and evolutionary milestones is key to studying animal diversity.

• Shared Traits: Animals are multicellular, heterotrophic, lack cell walls, and have specialized tissues (except sponges).

• Animal Body Plans: Body plans differ in symmetry (radial vs. bilateral), number of tissue layers (diploblastic vs. triploblastic), and presence of a coelom.

• Major Animal Clades: Key clades include Porifera (sponges), Cnidaria (jellyfish, corals), and Bilateria (most other animals).

• Cambrian Explosion: A period (~541 million years ago) marked by rapid diversification of animal body plans.

• Chordate Evolution: Chordates are defined by features such as a notochord, dorsal nerve cord, pharyngeal slits, and post-anal tail.

• Vertebrate Adaptations: Key adaptations include jaws, limbs, amniotic eggs, and endothermy.

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

Lectures 18-19: Behavioral Ecology

Animal Behavior and Evolutionary Explanations

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

• Tinbergen's Four Questions: Proximate (mechanism, development) and ultimate (function, evolution) explanations for behavior.

• Innate vs. Learned Behavior: Innate behaviors are genetically programmed; learned behaviors are acquired through experience.

• Types of Learning: Includes habituation, imprinting, associative learning, and social learning.

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

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

Example: Bird song learning is a form of social learning influenced by both genetics and environment.

Lecture 20: Introduction 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, biosphere.

• Ecological Patterns: Distribution and abundance of organisms, spatial and temporal variation.

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

• Climatic and Regional Factors: Climate, weather, and geographic features influence ecological patterns.

• Biomes: Large ecological zones defined by climate and dominant vegetation.

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

Lectures 21-22: Population Ecology

Population Dynamics and Growth Models

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-Dependence: Population growth rates are regulated by density-dependent (e.g., competition) and density-independent (e.g., weather) factors.

Example: Human populations have shifted from high birth and death rates to low birth and death rates (demographic transition).

Lectures 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: Competition, predation, herbivory, parasitism, mutualism, commensalism.

• Fundamental vs. Realized Niche: The fundamental niche is the full range of conditions a species can occupy; the realized niche is where it actually exists due to interactions.

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

• Succession: The process of change in species composition over time, including primary and secondary succession.

• Species Richness and Diversity: Influenced by disturbance, area, and environmental heterogeneity.

Example: After a forest fire (secondary succession), pioneer species colonize the area, followed by a sequence of other species.

Table: Types of Species Interactions

Interaction	Effect on Species 1	Effect on Species 2	Example
Competition	-	-	Plants competing for sunlight
Predation	+	-	Wolf eating deer
Herbivory	+	-	Caterpillar eating leaves
Parasitism	+	-	Tapeworm in mammal
Mutualism	+	+	Bees pollinating flowers
Commensalism	+	0	Barnacles on whales

Lectures 25-27: Ecosystems Ecology

Cycles of Matter, Energy Flow, and Biodiversity

Ecosystem ecology studies the flow of energy and cycling of matter through living and nonliving components, as well as the importance of biodiversity.

• Cycles of Matter: Key cycles include the water, carbon, nitrogen, and phosphorus cycles.

• 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; essential for ecosystem resilience and function.

• Threats to Biodiversity: Habitat loss, invasive species, overexploitation, pollution, and climate change.

• Mitigation: Conservation efforts include protected areas, restoration, sustainable resource use, and policy measures.

Example: Deforestation reduces carbon sequestration, contributing to climate change and loss of biodiversity.

Table: Major Biogeochemical Cycles

Cycle	Main Reservoir	Key Processes	Human Impact
Water	Oceans	Evaporation, precipitation, runoff	Water pollution, altered flow
Carbon	Atmosphere, biomass	Photosynthesis, respiration, combustion	Fossil fuel burning, deforestation
Nitrogen	Atmosphere	Nitrogen fixation, nitrification, denitrification	Fertilizer use, pollution
Phosphorus	Rocks, soil	Weathering, uptake by plants	Fertilizer runoff, eutrophication

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