Comprehensive Study Guide: Ecology, Evolution, and Diversity

Introduction to Ecology

Definition and Branches of Ecology

Ecology is the scientific study of interactions between organisms and their environment. It encompasses various levels of biological organization, each with specific focus areas:

• Global Ecology: Examines the biosphere and global processes affecting life on Earth.

• Landscape Ecology: Studies the interactions between ecosystems within a particular area.

• Ecosystem Ecology: Focuses on energy flow and nutrient cycling among organisms and their environment.

• Community Ecology: Investigates interactions among species living in the same area.

• Population Ecology: Analyzes factors affecting population size and composition.

• Organismal Ecology: Explores how individual organisms adapt to their environment.

Example: Population ecology might study how food availability affects the growth of a rabbit population.

Microclimate vs. Macroclimate

• Microclimate: Local atmospheric conditions that differ from the surrounding area (e.g., shade under a tree).

• Macroclimate: Large-scale climate patterns, such as those affecting entire regions or biomes (e.g., desert vs. tropical rainforest).

Seasons and Prevailing Winds

• Seasons result from Earth's tilt and orbit around the sun, causing varying sunlight intensity throughout the year.

• Prevailing Winds are large-scale wind patterns driven by Earth's rotation and uneven heating.

Biomes and Climate Variables

• Biome: A major ecological community type defined by dominant vegetation and climate.

• Key Climate Variables: Temperature and precipitation are the most important factors determining biome type.

Population Ecology

Population Concepts

• Population: A group of individuals of the same species living in a specific area.

• Population Size Determinants: Births, deaths, immigration, and emigration.

• Dispersion: The pattern of spacing among individuals within a population (clumped, uniform, random).

• Population Density: Number of individuals per unit area or volume.

• Demographics: Statistical study of populations, including structure and growth.

Types of Dispersion

• Clumped: Individuals aggregate in patches (e.g., schools of fish).

• Uniform: Evenly spaced due to territoriality or competition (e.g., penguins nesting).

• Random: Unpredictable spacing (e.g., dandelions dispersed by wind).

Life Tables and Survivorship Curves

• Life Table: Summarizes survival and reproductive rates of individuals in age groups.

• Cohort: A group of individuals of the same age tracked over time.

• Survivorship Curve: Graph showing the number of survivors at each age. Three idealized types:

  • Type I: High survival early, steep decline at old age (e.g., humans).

  • Type II: Constant death rate (e.g., birds).

  • Type III: High mortality early, survivors live long (e.g., oysters).

Population Growth Models

• Exponential Growth: Population increases under ideal conditions, forming a J-shaped curve.

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

• Logistic Growth: Population growth slows as it approaches carrying capacity (K), forming an S-shaped curve.

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

• Carrying Capacity (K): Maximum population size an environment can sustain.

r- and K-Selection Strategies

• r-Selection: Favors high reproductive rates in unstable environments (e.g., insects).

• K-Selection: Favors competitive ability and efficiency in stable environments (e.g., elephants).

Predator-Prey Dynamics

• Predator-prey interactions can cause cyclical population changes ("boom-bust" cycles), as seen in the lynx-hare relationship.

Community Ecology

Community and Interactions

• Community: All populations of different species living and interacting in an area.

• Types of Interactions:

  • Competition (-/-): Both species are harmed by shared resource use.

  • Predation (+/-): Predator benefits, prey is harmed.

  • Herbivory (+/-): Herbivore benefits, plant is harmed.

  • Mutualism (+/+): Both species benefit.

  • Commensalism (+/0): One benefits, other unaffected.

  • Parasitism (+/-): Parasite benefits, host is harmed.

Competition and Niche

• Competition: Occurs when species vie for the same resource.

• Types: Interspecific (between species) and intraspecific (within species).

• Competitive Exclusion Principle: Two species competing for the same resource cannot coexist indefinitely.

• Ecological Niche: The sum of a species' use of biotic and abiotic resources.

Predation and Adaptations

• Predator Adaptations: Claws, speed, camouflage.

• Prey Adaptations: Camouflage, toxins, warning coloration.

• Aposematic Colouration: Bright warning colors indicating toxicity.

• Batesian Mimicry: Harmless species mimics harmful one.

• Müllerian Mimicry: Two harmful species resemble each other.

Herbivory and Adaptations

• Herbivory: Animals eat plants; plants may develop thorns, toxins, or tough leaves as defenses.

Symbiosis and Types

• Symbiosis: Close, long-term interaction between species.

• Types: Mutualism, commensalism, parasitism, and (Additional info: sometimes amensalism or facilitation).

• Parasitism: Parasite benefits at host's expense.

• Facultative Mutualism: Both benefit but can survive alone (e.g., ants and aphids).

• Obligate Mutualism: Both require the relationship to survive (e.g., lichens).

• Commensalism: One benefits, other unaffected (e.g., barnacles on whales).

Community Diversity and Structure

• Species Richness: Number of different species in a community.

• Relative Abundance: Proportion of each species.

• Importance: Greater diversity increases stability and productivity.

Trophic Structure and Food Webs

• Food Chain: Linear sequence of energy transfer.

• Food Web: Interconnected food chains.

• Major Players:

  • Producers/Autotrophs: Make their own food (e.g., plants).

  • Herbivores (Primary Consumers): Eat producers.

  • Predators (Secondary/Tertiary Consumers): Eat other consumers.

  • Detritivores: Consume dead organic matter.

Key Species and Disturbance

• Dominant Species: Most abundant or highest biomass.

• Keystone Species: Exert strong control on community structure (e.g., sea otters).

• Foundation Species: Cause physical changes in environment (e.g., beavers).

• Disturbance: Events that change communities (e.g., fire, storms); important for maintaining diversity.

Succession

• Primary Succession: Begins in lifeless areas (e.g., after lava flow).

• Secondary Succession: Occurs where soil remains after disturbance (e.g., after fire).

• Principle: Autotrophs colonize, alter soil, enabling other species to follow.

• Disturbance and Biodiversity: Moderate disturbance promotes highest diversity.

Invasive Species

• Invasive Species: Non-native species that spread rapidly and disrupt communities due to lack of natural predators or competitors.

Invertebrates, Chordates, and Mammals

Body Plans and Key Terms

• Body Plan: General structure, symmetry, and organization of an organism.

• Key Terms: Open/closed circulatory system, hermaphrodite, molting, metamorphosis, segmentation, suspension feeders, sessile, hydrostatic skeleton, cuticle, mantle, radula, valve, exoskeleton/endoskeleton, notochord, vertebrate, pharyngeal slits, swim bladder/lungs, tetrapod, amniotic eggs, oral disk, exposed vs. covered gills, jaws, ray vs. lobe finned, ectothermic/endothermic, placenta, opposable thumb, bipedalism, lactation.

Classification and Differences

• Invertebrates vs. Chordates: Invertebrates lack a backbone; chordates have a notochord.

• Mammals: Have hair, mammary glands, and (usually) live birth.

• Primates: Opposable thumbs, large brains, forward-facing eyes.

• Hominins: Bipedalism, reduced jaw, larger brain compared to other primates.

Viruses and Bacteria

Characteristics and Differences

• Viruses: Non-living, require host cells to reproduce, consist of genetic material and protein coat.

• Bacteria: Prokaryotic, living cells, reproduce by binary fission, have cell walls.

Key Terms

• Flagella, fimbriae, endospores, cell wall, capsules, glycoprotein membrane, bioremediation, binary fission, extremophiles, heterotroph, autotroph.

Bacteria vs. Archaea

• Similarities: Both are prokaryotes, lack nucleus, reproduce by binary fission.

• Differences: Cell wall composition, membrane lipids, some archaea are extremophiles.

Phylogenetics

Phylogenetic Trees and Binomial Nomenclature

• Phylogenetic Tree: Diagram showing evolutionary relationships.

• Latin Binomial: Two-part scientific name (Genus species), italicized, genus capitalized, species lowercase (e.g., Homo sapiens).

Protists

Characteristics and Examples

• Euglenozoans: Flagellated, some photosynthetic (e.g., Euglena).

• Dinoflagellates: Two flagella, some cause "red tides."

• Ciliates: Move with cilia (e.g., Paramecium).

• Diatoms: Silica cell walls, important phytoplankton.

• Brown, Green, Red Algae: Multicellular, photosynthetic, differ in pigments and habitats.

• Amoebozoans: Move with pseudopodia (e.g., amoebas).

• Forams and Radiolarians: Have shells (tests), important in marine environments.

Endosymbiont Theory

• Explains origin of mitochondria and chloroplasts from engulfed prokaryotes.

Plants and Fungi/Lichens

Plant Characteristics and Classification

• Common Characteristics: Multicellular, photosynthetic, cell walls of cellulose.

• Vascular vs. Non-vascular: Vascular plants have specialized tissues (xylem, phloem); non-vascular do not (e.g., mosses).

• Bryophytes: Non-vascular (e.g., mosses).

• Ferns: Vascular, seedless.

• Gymnosperms: Vascular, seeds not in fruit (e.g., pines).

• Angiosperms: Vascular, seeds in fruit (flowering plants).

• Monocots vs. Eudicots: Differ in seed leaves, leaf veins, flower parts.

Fungi and Lichens

• Fungi: Heterotrophic, cell walls of chitin, reproduce by spores.

• Main Groups: Basidiomycetes, ascomycetes, zygomycetes, chytrids.

• Lichen: Symbiotic association between fungus and photosynthetic partner (alga or cyanobacterium).

Evolution and Speciation

Key Terms and Concepts

• Fossils: Preserved remains of ancient life.

• Radiometric Dating: Determines age of rocks/fossils using decay of isotopes.

• Lamarckism: Early theory of evolution by acquired traits (disproven).

• Descent with Modification: Darwin's idea of evolution by natural selection.

• Natural Selection: Differential survival and reproduction due to heritable traits.

• Artificial Selection: Human-driven selection of traits.

• Adaptation: Trait increasing fitness in environment.

• Biogeography: Study of species distribution.

• Homologous Structures: Similar due to shared ancestry.

• Analogous Structures: Similar function, different ancestry.

• Vestigial Structures: Reduced, nonfunctional remnants of ancestors.

• Gene Pool: All alleles in a population.

• Allele: Variant of a gene.

• Mutation: Change in DNA sequence.

• Microevolution: Change in allele frequencies within a population.

• Genetic Drift: Random changes in allele frequencies.

• Gene Flow: Movement of alleles between populations.

• Bottleneck Effect: Population size reduction causes loss of genetic diversity.

• Founder Effect: New population started by few individuals.

• Types of Selection: Stabilizing, directional, disruptive, balancing.

• Sexual Dimorphism: Differences between sexes.

• Sexual Selection: Selection for traits increasing mating success.

• Speciation: Formation of new species.

• Macroevolution: Broad patterns of evolutionary change.

• Continental Drift & Plate Tectonics: Movement of Earth's plates affects evolution.

• Mass Extinction: Large-scale loss of species.

• Adaptive Radiation: Rapid diversification into new niches.

• Pangea: Ancient supercontinent.

• Biological Species Concept: Species are groups of interbreeding populations.

• Reproductive Isolation: Barriers preventing gene flow.

• Prezygotic Barriers: Prevent mating/fertilization (habitat, temporal, behavioral, mechanical, gametic isolation).

• Postzygotic Barriers: Prevent hybrid viability/fertility.

• Allopatric Speciation: Speciation by geographic isolation.

• Sympatric Speciation: Speciation without geographic isolation.

• Abiogenesis: Origin of life from non-living matter.

• Stromatolites: Layered structures formed by cyanobacteria, evidence of early life.