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

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Lecture 15: Fungi

Fungal Phylogeny and Traits

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 characteristics 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 chitinous 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 like mycorrhizae (symbiotic associations with plant roots) and haustoria (parasitic structures).
Generalized Fungal Life Cycle: Most fungi have a life cycle that includes both sexual and asexual reproduction, with haploid, dikaryotic, and diploid stages.
Fungal Movement: Fungi do not move via flagella (except some chytrids); instead, they grow by extending hyphae.
Example: Rhizopus (bread mold) demonstrates a typical fungal life cycle with both sporangia (asexual) and zygospores (sexual).

Lectures 16-17: Animal Diversity

Animal Synapomorphies and Body Plans

Animals are multicellular, heterotrophic organisms with specialized tissues. Their diversity is reflected in their body plans and evolutionary history.

Animal Synapomorphies: Key traits include multicellularity, lack of cell walls, nervous and muscle tissue, and development from a blastula.
Current Animal Phylogeny: Animals are divided into major clades such as Porifera (sponges), Cnidaria (jellyfish, corals), and Bilateria (bilaterally symmetrical animals).
Body Plans: Animals differ in symmetry (radial vs. bilateral), number of tissue layers (diploblastic vs. triploblastic), and presence of a coelom (body cavity).
Major Milestones: The Cambrian explosion (~541 million years ago) marked a rapid diversification of animal body plans.
Chordate Evolution: Chordates are defined by traits such as a notochord, dorsal nerve cord, pharyngeal slits, and post-anal tail. Vertebrates are a subclade with a backbone.
Key Adaptations: Adaptations in vertebrates include jaws, lungs, limbs, and amniotic eggs, facilitating life on land.
Animal Clades: Major clades include Chordata, Arthropoda, Mollusca, and Echinodermata.
Example: Amphibians represent a transitional group between aquatic and terrestrial vertebrates.

Lectures 18-19: Behavioral Ecology

Behavioral Questions and Learning

Behavioral ecology examines how animal behavior is shaped by ecological and evolutionary pressures.

Four Questions of Tinbergen: 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: Traits that increase reproductive success may evolve even if they reduce survival (e.g., peacock's tail).
Example: Optimal foraging theory predicts how animals maximize energy intake per unit time.

Lecture 20: Intro to Ecology

Levels of Organization and Ecological Patterns

Ecology studies the interactions between organisms and their environment at multiple levels.

Levels of Organization: Individual, population, community, ecosystem, biome, biosphere.
Ecological Patterns and Processes: Patterns include species distributions and abundance; processes include predation, competition, and nutrient cycling.
Spatial and Temporal Scales: Ecological phenomena can occur at local, regional, or global scales and over varying time frames.
Abiotic and Biotic Factors: Abiotic (non-living) factors include climate and soil; biotic (living) factors include interactions among organisms.
Climograms: Graphs that plot temperature and precipitation to predict biome types.
Example: Rainfall and temperature patterns determine whether a region is a desert, grassland, or forest.

Lectures 21-22: Population Ecology

Population Dynamics and Growth Models

Population ecology focuses on the factors that affect population size, structure, and dynamics 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 () occurs under ideal conditions; logistic growth () includes carrying capacity (K).
Life Tables and Survivorship Curves: Used to analyze age-specific survival and mortality rates.
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 Independent Factors: Density-dependent factors (e.g., competition, disease) intensify as population increases; density-independent factors (e.g., weather) affect populations regardless of size.
Example: Human population growth has shifted from exponential to logistic in some regions due to resource limitations.

Community Ecology

Species Interactions and Community Structure

Communities are shaped by interactions among species and by patterns of species diversity and abundance.

Species Interactions: Include competition, predation, herbivory, parasitism, mutualism, commensalism, and amensalism.
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 biotic interactions.
Ecological Succession: The process by which community composition changes 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.
Food Webs: Depict the complex feeding relationships among species in a community.
Example: Keystone species have a disproportionate effect on community structure (e.g., sea otters in kelp forests).

Table: Types of Species Interactions

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

Lectures 25-27: Ecosystems Ecology

Cycles of Matter, Energy Flow, and Biodiversity

Ecosystem ecology examines the flow of energy and cycling of matter through living and nonliving components of the environment.

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; important for ecosystem resilience and function.
Major Threats to Biodiversity: Habitat destruction, invasive species, overexploitation, and climate change.
Mitigation: Conservation strategies include protected areas, restoration ecology, and sustainable resource management.
Example: Deforestation reduces carbon sequestration and threatens tropical biodiversity.

Table: Major Biogeochemical Cycles

Cycle	Main Reservoirs	Key Processes
Water	Oceans, atmosphere, lakes, rivers	Evaporation, precipitation, transpiration
Carbon	Atmosphere, fossil fuels, biomass	Photosynthesis, respiration, combustion
Nitrogen	Atmosphere, soil, organisms	Nitrogen fixation, nitrification, denitrification
Phosphorus	Rocks, soil, water	Weathering, uptake by plants, sedimentation

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