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.

• Fungal 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) and mycelium (networks of hyphae). Specialized structures include mycorrhizae (symbiotic associations with plant roots), spores (reproductive cells), and fruiting bodies (e.g., mushrooms).

• 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 chytrids); instead, they grow toward resources by extending hyphae.

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

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.

• Shared Traits: Animals share traits such as multicellularity, lack of cell walls, nervous and muscle tissue, and development from a blastula.

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

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

• Cambrian Explosion: The Cambrian explosion (~541 million years ago) was a period of rapid diversification of animal body plans.

• Vertebrate Evolution: Key adaptations in vertebrates include the development of a backbone, jaws, lungs, and limbs for terrestrial life.

Example: Chordates are defined by the presence of a notochord, dorsal nerve cord, pharyngeal slits, and post-anal tail at some stage of development.

Lectures 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 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: Types include monogamy, polygyny, and polyandry, each with different implications for sexual selection and parental investment.

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

Example: Optimal foraging theory predicts that animals will maximize energy gained per unit time spent foraging.

Lecture 20: Intro to Ecology

Levels of Organization and Ecological Patterns

Ecology is the study of interactions among organisms and their environment, organized into hierarchical levels.

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

• Ecological Patterns and Processes: Patterns include species distribution and abundance; processes include energy flow and nutrient cycling.

• Scales: Ecological phenomena occur at spatial (local to global) and temporal (short to long-term) scales.

• Abiotic and Biotic Factors: Abiotic factors (e.g., climate, soil) and biotic factors (e.g., competition, predation) influence ecological patterns.

• Climographs: Graphs that plot temperature and precipitation to predict biome types.

Example: A climograph can help determine whether a region is a tropical rainforest or a desert based on its climate data.

Lectures 21-22: Population Ecology

Population Dynamics and Growth Models

Population ecology focuses on the factors that affect population size, density, 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: Includes exponential and logistic growth models.

• Exponential Growth Equation:

$\frac{dN}{dt} = rN$

• Logistic Growth Equation:

$\frac{dN}{dt} = rN \left(1 - \frac{N}{K}\right)$

• Life History Strategies: r-selected species produce many offspring with low survival; K-selected species produce fewer offspring with higher survival.

• Density-Dependent vs. Density-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: A population of deer may grow rapidly when resources are abundant (exponential growth), but growth slows as resources become limited (logistic growth).

Community Ecology

Species Interactions and Community Structure

Communities are composed of interacting populations of different species. The nature of these interactions shapes community structure and dynamics.

• Species Interactions: Types 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.

• Food Webs: Diagrams that show the feeding relationships among organisms in a community.

• Succession: The process by which community composition changes over time, including primary and secondary succession.

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

Example: After a forest fire (disturbance), secondary succession occurs as plants and animals recolonize the area.

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 ecosystems.

• 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 chemical energy, minus the energy used in respiration.

$\text{NPP} = \text{GPP} - R$

• Biogeochemical Cycles: Each cycle involves reservoirs (storage) and processes (movement between reservoirs).

• Biodiversity: The variety of life at genetic, species, and ecosystem levels. Major threats include habitat loss, invasive species, overexploitation, and climate change.

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

Table: Comparison of r-Selected and K-Selected Species

Characteristic	r-Selected Species	K-Selected Species
Reproductive Rate	High	Low
Offspring Number	Many	Few
Parental Care	Little or none	Extensive
Survivorship Curve	Type III (high juvenile mortality)	Type I or II (low juvenile mortality)
Population Stability	Variable, often below carrying capacity	Stable, near carrying capacity

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