BIOL 1407 EXAM 2 REVIEW

Vocabulary flashcards summarizing key evolutionary, ecological, and origin-of-life concepts from the lecture notes.

Precambrian

The vast span of Earth’s history before the Phanerozoic; dominated by prokaryotes, first eukaryotes, and earliest simple animals.

Paleozoic Era

Geologic era marked by the first plants and vertebrates, including fish, amphibians, and reptiles.

Mesozoic Era

Era featuring the first birds, flowering plants, mammals, and extensive reptile diversification (dinosaurs).

Cenozoic Era

Current era characterized by major diversification of mammals, birds, and flowering plants.

Macroevolution

Evolutionary change above the species level, such as the origin of new taxonomic groups.

Gradualism

Evolutionary model proposing slow, steady accumulation of mutations; challenged by fossil evidence of rapid radiations.

Evolutionary bursts

Episodes of rapid macroevolution producing many new forms in a short time.

Punctuated equilibrium

Model proposing long periods of stasis interrupted by rapid speciation, often in small, isolated populations.

Adaptive radiation

Rapid diversification when organisms enter new habitats or after mass extinctions; lacks detailed genetic mechanism.

Allopatric speciation

Formation of new species due to geographic isolation blocking gene flow.

Sympatric speciation

Speciation without geographic isolation, often via microhabitat use or polyploidy.

Inbreeding

Mating between closely related individuals, increasing homozygosity and potential genetic problems.

Hydrothermal vent hypothesis

Idea that life’s chemistry began in mineral-rich, super-heated seafloor vents; salt water hinders vesicle formation.

Warm pond hypothesis

Suggests life started in small terrestrial pools that cycled between wet and dry; UV radiation poses a problem.

Meteorite hypothesis

Proposes key organic molecules (or life) arrived on meteorites; still requires further complexity on Earth.

Panspermia

Speculation that life arrived from space, merely shifting the origin question elsewhere.

RNA world hypothesis

Proposes RNA was the first genetic material because it can store info and catalyze reactions.

Ribozyme

RNA molecule with enzyme-like catalytic activity.

Four stages of abiogenesis

1) Simple organics form 2) Complex organics assemble 3) Molecules are packaged 4) Systems self-replicate.

Endosymbiont theory

Mitochondria and chloroplasts originated as free prokaryotes engulfed by early eukaryotes.

Ardipithecus

Early hominid showing partial bipedalism yet still adept at tree climbing.

Australopithecus

Fully upright hominid with larger brain; used simple tools.

Homo habilis

“Handy man”; early human that crafted specialized meat-cutting tools.

Homo erectus

Hominid with larger brain; likely controlled fire and dispersed widely from Africa.

Homo neanderthalensis

Large-brained hominid using crude tech, possible rituals, and art; interbred with H. sapiens.

Homo sapiens

Modern humans noted for advanced language, technology, and problem solving.

Out-of-Africa hypothesis

Model stating modern humans originated in Africa and later spread worldwide.

mtDNA (mitochondrial DNA)

Maternal lineage DNA used to trace human ancestry to a single woman ~200,000 years ago.

Desert biome

Dry biome with sparse rainfall, succulents, and high temperature variability.

Tropical rainforest biome

Warm, wet year-round biome with the planet’s highest biodiversity.

Savannah biome

Seasonally dry grassland with scattered trees and large grazing mammals.

Prairie / Grassland biome

Temperate grassland with few trees and diverse herbivores; similar to savannah but cooler.

Taiga biome

Coniferous forest with long cold winters; many animals migrate or hibernate.

Tundra biome

Treeless region with permafrost, shrubs, and mosses; extremely cold.

Deciduous forest biome

Temperate forest of broad-leaf trees with seasonal rainfall and temperatures.

Marsh

Grass-dominated wetland with high biodiversity.

Swamp

Tree-dominated wetland with high biodiversity.

Bog

Moss-dominated, acidic, often cold wetland.

Aquatic photic zone

Sunlit upper layer of water where most marine and freshwater life exists.

Thermocline

Steep temperature gradient separating warm surface water from cold deep water.

Turnover (lake)

Seasonal mixing of lake layers that redistributes nutrients and oxygen.

Producer

Photosynthetic organism forming the base and bulk of ecosystem biomass.

Population density

Number of individuals per unit area or volume.

Immigration

Movement of individuals into a population.

Emigration

Movement of individuals out of a population.

Boom-and-bust cycle

Repeated pattern of rapid population growth followed by sharp decline.

Life expectancy

Average lifespan of individuals in a given region.

Ecological footprint

Amount of resources an individual or population consumes from the environment.

Altricial young

Offspring requiring extensive parental care; often associated with monogamy.

Precocial young

Offspring relatively independent at birth; often associated with polygamy.

Random distribution

Spatial pattern where individuals are spread unpredictably due to evenly available resources.

Clumped distribution

Individuals aggregated in patches where resources are uneven or social behavior groups them.

Uniform distribution

Even spacing of individuals, often from competition or territoriality at high densities.

Exponential growth

Population increase at a constant rate assuming unlimited resources.

Logistic growth

S-shaped growth that slows as a population approaches carrying capacity.

Carrying capacity

Maximum population size an environment can sustain long-term.

Density-dependent factor

Regulator whose effect strengthens with population density (e.g., disease, competition).

Type I survivorship

Curve where most individuals live to old age; high parental investment.

Type II survivorship

Curve with constant death rate across all ages.

Type III survivorship

Curve with high juvenile mortality and low parental care; many offspring.

Competition (-,-)

Interaction where species vie for the same resources, harming both.

Mutualism (+,+)

Interaction benefiting both participating species.

Commensalism (+,0)

Interaction benefiting one species while the other is unaffected.

Parasitism (+,-)

Relationship where one organism benefits and the host is harmed.

Predation (+,-)

One species (predator) kills and eats another (prey).

Keystone species

Low-abundance species that exerts strong control on community structure.

Ecological succession

Orderly community change over time from pioneer species to climax community.

Intermediate disturbance hypothesis

Moderate disturbance promotes highest biodiversity by preventing dominance.

Competitive exclusion principle

No two species can occupy identical niches indefinitely; one will outcompete the other.

10% rule

Only about 10 % of energy transfers to the next trophic level.

Mechanical defense

Physical structures (e.g., spines) that protect prey from predators.

Chemical defense

Toxins or noxious chemicals used by prey to deter predators.

Aposematic coloration

Bright warning colors advertising toxicity or danger.

Cryptic coloration

Camouflage allowing organisms to blend with surroundings.

Batesian mimicry

Harmless species mimics harmful one for protection.

Müllerian mimicry

Two or more harmful species share similar warning signals, reinforcing predator avoidance.

Vector (disease)

Organism that transmits pathogens from one host to another.

Zoonotic disease

Infection that spreads from animals to humans.

Emerging disease

New or rapidly increasing infection in a population.