BI223 Final Exam Study Guide: Fungi, Animal Diversity, Behavioral Ecology, and Ecology

Fungi

Fungi in the Tree of Life

Fungi are a diverse group of eukaryotic organisms that are classified within the supergroup Opisthokonta, which also includes animals and some protists. Their evolutionary relationships are important for understanding their biology and ecological roles.

• Placement: Fungi are more closely related to animals than to plants, sharing a common ancestor within Opisthokonta.

• Synapomorphies with Opisthokonts: Shared traits include the presence of a single posterior flagellum in ancestral forms, chitin in cell walls, and storage of glycogen.

Fungal Morphology and Function

Fungi exhibit a range of morphologies that support their ecological roles as decomposers (saprobes), mutualists (mycorrhizae), and parasites.

• Hyphae: Thread-like structures that form a mycelium, increasing surface area for absorption.

• Mycorrhizae: Symbiotic associations with plant roots, enhancing nutrient uptake.

• Saprobes: Decompose dead organic matter, recycling nutrients.

• Parasites: Extract nutrients from living hosts, sometimes causing disease.

Generalized Fungal Life Cycle

Fungi have complex life cycles that often include both sexual and asexual reproduction.

• Plasmogamy: Fusion of cytoplasm from two parent mycelia.

• Karyogamy: Fusion of nuclei, resulting in a diploid zygote.

• Meiosis: Produces haploid spores that disperse and germinate.

• Asexual reproduction: Many fungi also reproduce by mitotic production of spores.

Fungi and the Colonization of Land

Fungi played a key role in the movement of plants onto land by forming mycorrhizal associations, which facilitated nutrient uptake in early terrestrial environments.

• Mycorrhizal fungi: Enhanced water and mineral absorption for early plants.

• Soil formation: Fungal decomposition contributed to soil development.

Animal Diversity

Shared Traits of Animals

Animals are multicellular, heterotrophic eukaryotes with specialized tissues and developmental patterns.

• Synapomorphies: Multicellularity, lack of cell walls, nervous and muscle tissue, development from a blastula.

Animal Phylogeny and Body Plans

Current animal phylogeny is based on molecular and morphological data, grouping animals by body plan, development, and tissue layers.

• Body plans: Symmetry (radial vs. bilateral), presence of tissues (diploblastic vs. triploblastic), body cavities (acoelomate, pseudocoelomate, coelomate).

• Major lineages: Invertebrates (e.g., arthropods, mollusks) and chordates (including vertebrates).

Cambrian Explosion and Animal Evolution

The Cambrian explosion (~541 million years ago) was a period of rapid diversification of animal body plans and the origin of most major animal groups.

• Milestones: Evolution of hard parts, complex body plans, and predation.

Origin and Evolution of Vertebrates

Vertebrates evolved from chordate ancestors, developing key adaptations for life on land.

• Key adaptations: Vertebral column, jaws, lungs, limbs, amniotic egg.

• Amniotes: Adaptations include the amniotic egg, impermeable skin, and rib ventilation.

Evolution of Animal Clades

Major animal clades evolved in a specific order, with shared traits defining each group.

• Order of evolution: Multicellularity → tissues → bilateral symmetry → coelom → segmentation → vertebral column → jaws → limbs → amniotic egg.

Behavioral Ecology

Tinbergen’s Four Questions

Niko Tinbergen proposed four questions to understand animal behavior, distinguishing between proximate and ultimate causes.

• Proximate explanations: Mechanisms and development (how a behavior occurs).

• Ultimate explanations: Evolutionary history and adaptive value (why a behavior occurs).

Innate vs. Learned Behaviors

Behaviors can be classified as innate (genetically programmed) or learned (acquired through experience).

• Innate behaviors: Fixed action patterns, reflexes, orientation, and kinesis/taxis.

• Learned behaviors: Habituation, imprinting, associative learning, observational learning, and insight.

Types of Innate Behaviors

• Fixed action pattern: Unchangeable sequence triggered by a stimulus (e.g., goose rolling egg).

• Reflex: Automatic response to a stimulus (e.g., knee-jerk).

• Orientation: Movement in response to environmental cues.

• Kinesis/Taxis: Random or directed movement in response to stimuli.

Types of Learning

• Habituation: Decreased response to repeated stimulus.

• Imprinting: Rapid learning during a sensitive period (e.g., ducklings following mother).

• Associative learning: Linking two stimuli (classical and operant conditioning).

• Observational learning: Learning by watching others.

• Insight: Problem-solving without trial-and-error.

Optimal Foraging Model

The optimal foraging model predicts how animals maximize energy intake while minimizing costs.

• Equation: $E_{net} = E_{gain} - (E_{search} + E_{handling})$

• Application: Explains food choice and foraging strategies.

Mating Systems and Sexual Selection

• Mating systems: Monogamy, polygyny, polyandry; differ in parental investment and reproductive strategies.

• Sexual selection: Leads to traits that increase mating success, affecting fitness.

Intro to Ecology

Levels of Organization

Ecology studies organisms at multiple levels, from individuals to the biosphere.

• Levels: Organism, population, community, ecosystem, landscape, biosphere.

Ecological Patterns and Processes

• Patterns: Observable distributions (e.g., species richness, abundance).

• Processes: Mechanisms causing patterns (e.g., competition, predation).

Climate and Biomes

• Climate: Long-term patterns of temperature and precipitation.

• Weather: Short-term atmospheric conditions.

• Global/regional factors: Latitude, altitude, ocean currents, rainshadow effect.

• Climograph: Graph showing temperature and precipitation, used to identify biomes.

Population Ecology

Population vs. Species

• Population: Group of individuals of the same species in a given area.

• Species: All individuals capable of interbreeding.

Population Data Interpretation

• Dispersion: Clumped, uniform, or random distribution.

• Life tables: Summarize survival and reproductive rates.

• Survivorship curves: Type I, II, III patterns.

Population Growth Models

• Exponential growth: $\frac{dN}{dt} = rN$

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

• Carrying capacity (K): Maximum population size environment can support.

Life History Strategies

• K-selection: Stable environments, few offspring, high parental care.

• r-selection: Unstable environments, many offspring, low parental care.

Population Regulation

• Density-dependent: Factors intensify as population increases (e.g., competition, disease).

• Density-independent: Affect population regardless of size (e.g., weather, disasters).

Community Ecology

Niches and Species Interactions

• Fundamental niche: Full range of conditions a species can use.

• Realized niche: Actual conditions used due to competition.

• Resource partitioning: Division of resources to reduce competition.

• Competitive exclusion: One species outcompetes another.

Types of Species Interactions

Interaction	Effect on Species 1	Effect on Species 2	Example
Predation	+	-	Wolf and deer
Herbivory	+	-	Caterpillar and leaf
Parasitism	+	-	Tapeworm in mammal
Mutualism	+	+	Bees and flowers
Commensalism	+	0	Barnacles on whale
Amensalism	-	0	Algae shading out other plants

Trophic Levels and Energy Transfer

• Trophic efficiency: Percentage of energy transferred from one trophic level to the next (typically ~10%).

• Energy calculation: $E_{n+1} = E_n \times \text{Trophic Efficiency}$

Food Webs and Trophic Cascades

• Food web: Network of feeding relationships.

• Trophic cascade: Changes at one trophic level affect others.

Community Structure and Succession

• Primary succession: Colonization of new habitats (e.g., after volcanic eruption).

• Secondary succession: Recovery after disturbance (e.g., fire).

• Disturbance: Events that change community structure (e.g., storms, fires).

• Species richness: Influenced by area, habitat diversity, time, location, proximity to other populations.

Island Equilibrium Model and Species-Area Curves

• Island equilibrium model: Predicts species number based on immigration and extinction rates.

• Species-area curve: $S = cA^z$ (where S = number of species, A = area, c and z are constants).

Ecosystem Ecology and Global Change

Cycles of Matter and Energy

• Energy: Flows through ecosystems, lost as heat.

• Matter: Cycles between biotic and abiotic components (e.g., carbon, nitrogen cycles).

Net Primary Production (NPP)

• Definition: Amount of energy captured by producers minus energy used in respiration.

• Equation: $NPP = GPP - R$ (GPP = gross primary production, R = respiration)

• Limiting factors: Light, nutrients, water (varies by biome).

Biogeochemical Cycles

• Water cycle: Evaporation, condensation, precipitation, runoff.

• Carbon cycle: Photosynthesis, respiration, decomposition, fossil fuels.

• Nitrogen cycle: Nitrogen fixation, nitrification, assimilation, denitrification.

• Phosphorus cycle: Weathering of rocks, uptake by organisms, return via decomposition.

Biodiversity and Conservation

• Value of biodiversity: Ecosystem services, genetic resources, cultural value.

• Major threats: Habitat loss, invasive species, overexploitation, pollution, climate change.

• Mitigation: Protected areas, restoration, sustainable practices, policy changes.

Greenhouse Effect and Global Change

• Mechanism: Greenhouse gases trap heat in the atmosphere.

• Evidence: Rising CO2 levels, global temperature increase, melting ice.

• Impacts: Shifts in species distributions, altered ecosystem function.