Evolution, Ecology & Microbiology – Lecture Vocabulary

Comprehensive vocabulary flashcards covering evolution, ecology, species interactions, climate, biomes, prokaryote biology, and pathogenic mechanisms from the lecture notes.

Evolution

Heritable change in biological populations across successive generations.

Universal Common Ancestor

Hypothetical single organism from which all life descended ~3.8 billion years ago.

Charles Darwin

Naturalist who proposed evolution by natural selection in 1859.

On the Origin of Species

Darwin’s 1859 book outlining evidence for evolution and natural selection.

Natural Selection

Process in which individuals with favorable traits leave more offspring in a given environment.

Fitness

An organism’s reproductive success relative to others in the population.

Variation

Genetic differences among individuals of a population.

Evidence of Evolution

Data from biogeography, fossils, anatomy, molecular biology, and experiments supporting evolutionary change.

Biogeography

Study of geographic distribution of species (e.g., marsupials in Australia).

Fossil Record

Chronological collection of fossils in sedimentary layers showing evolutionary change.

Radiometric Dating

Technique for determining the age of rocks or fossils using radioactive isotopes.

Structural Adaptation

Physical feature that enhances survival, such as mimicry or camouflage.

Mimicry

Resemblance of one species to another for protection or other advantage.

Camouflage

Coloration or form that allows an organism to blend into its surroundings.

Homologous Structures

Anatomical features with common evolutionary origin but diverse functions.

Analogous Structures

Similar functions but independent evolutionary origins (convergent traits).

Vestigial Organ

Reduced structure with little or no modern function (e.g., whale hind limbs).

Genetic Drift

Random change in allele frequencies, strongest in small populations.

Bottleneck Effect

Genetic drift caused by drastic reduction in population size due to disaster.

Founder Effect

Genetic drift in a new colony started by a few individuals.

Gene Flow

Movement of alleles between populations via migration of individuals or gametes.

Mutation

Heritable change in DNA sequence creating new alleles.

Non-random Mating

Mate choice based on traits rather than chance, altering allele frequencies.

Directional Selection

Natural selection favoring one extreme phenotype.

Stabilizing Selection

Selection favoring intermediate phenotypes and reducing variation.

Disruptive Selection

Selection favoring both extreme phenotypes over intermediates.

Sexual Selection

Natural selection stemming from competition for mates.

Sexual Dimorphism

Distinct difference in appearance between males and females of a species.

Artificial Selection

Human-directed breeding of organisms possessing desired traits.

Reproductive Barrier

Biological feature that prevents interbreeding between species.

Pre-zygotic Barrier

Reproductive isolation occurring before fertilization (e.g., habitat isolation).

Post-zygotic Barrier

Isolation after fertilization leading to inviable or sterile hybrids.

Temporal Isolation

Pre-zygotic barrier in which species breed at different times.

Habitat Isolation

Pre-zygotic barrier arising from occupation of different environments.

Behavioral Isolation

Pre-zygotic barrier involving differences in courtship signals.

Mechanical Isolation

Pre-zygotic barrier due to incompatible reproductive structures.

Gametic Isolation

Pre-zygotic barrier where gametes fail to fuse or survive.

Hybrid Inviability

Post-zygotic barrier in which hybrid embryos fail to develop properly.

Hybrid Sterility

Post-zygotic barrier producing healthy but infertile hybrids.

Hybrid Breakdown

Post-zygotic barrier where F2 or later hybrids are weak or sterile.

Allopatric Speciation

Formation of new species after geographic separation.

Adaptive Radiation

Rapid diversification of a lineage into multiple species adapted to different niches.

Convergent Evolution

Independent evolution of similar traits in unrelated lineages living in similar environments.

Coevolution

Reciprocal evolutionary change in interacting species.

Population (Genetics)

Group of individuals of the same species sharing a gene pool.

Gene Pool

Total collection of alleles in a population at one time.

Population (Ecology)

Interbreeding individuals of a species living in the same area.

Community

All interacting populations occupying the same area.

Ecosystem

Community plus its abiotic environment.

Carrying Capacity (K)

Maximum population size an environment can sustain long-term.

Exponential Growth

J-shaped population growth under unlimited resources.

Logistic Growth

Population growth that levels off as it approaches carrying capacity (S-curve).

Density

Number of individuals per unit area or volume.

Dispersion

Pattern of spacing among individuals within an area.

Clumped Dispersion

Aggregated distribution often reflecting patchy resources.

Uniform Dispersion

Even spacing often due to territoriality or competition.

Random Dispersion

Unpredictable spacing where individuals act independently.

Demography

Statistical study of population birth, death, and growth rates.

Life Table

Age-specific summary of survival and reproductive rates.

Survivorship Curve

Graph showing proportion of a cohort surviving at each age.

Type I Curve

Low early mortality; most deaths late in life (e.g., humans).

Type II Curve

Constant death rate across ages (e.g., squirrels).

Type III Curve

High early mortality; survivors live long (e.g., oysters).

Density-Dependent Factor

Limiting factor whose impact increases with population density (e.g., disease).

Density-Independent Factor

Limiting factor unaffected by population density (e.g., hurricane).

Age Structure

Relative numbers of individuals in each age class of a population.

Mutualism

Interaction where both species benefit.

Commensalism

Interaction benefiting one species with little or no effect on the other.

Exploitation

Relationship where one species benefits and the other is harmed (e.g., predation).

Herbivore

Consumer that eats plants or plant parts.

Predator

Organism that kills and eats other animals.

Parasite

Consumer living on or in a host, harming it.

Induced Defenses

Plant defensive responses activated by herbivore attack.

Warning Coloration

Bright colors advertising toxicity or defense to predators.

Niche

Sum of a species’ use of abiotic and biotic resources.

Fundamental Niche

Entire set of resources a species could use without competition.

Realized Niche

Resources a species actually uses in presence of competitors.

Competitive Exclusion

Theory stating no two species can occupy identical niches indefinitely.

Interference Competition

Direct interactions preventing others from accessing resources.

Exploitative Competition

Indirect competition through shared use of limited resources.

Niche Partitioning

Differentiation of niches that allows similar species to coexist.

Character Displacement

Divergence of traits in sympatric species due to competition.

Keystone Species

Species with disproportionate influence on community structure relative to abundance.

Food Chain

Linear sequence of energy transfer via consumption.

Food Web

Network of interconnected food chains showing energy flow.

Producer

Autotroph that synthesizes organic matter from inorganic sources.

Primary Consumer

Herbivore feeding on producers.

Secondary Consumer

Carnivore feeding on primary consumers.

Tertiary Consumer

Predator that eats secondary consumers.

Succession

Sequential change in species composition of a community over time.

Primary Succession

Succession on newly formed or exposed substrates lacking soil.

Secondary Succession

Succession occurring after disturbance in an area with existing soil.

Disturbance

Event that alters community structure by removing organisms or changing resources.

Biome

Large ecological region defined by climate and dominant vegetation.

Chaparral

Shrubland biome with dry summers, wet winters, fire-adapted plants.

Tropical Rainforest

Warm, high-rainfall biome with highest species diversity.

Savanna

Tropical grassland with scattered trees and seasonal rainfall.

Desert

Biome characterized by very low precipitation and extreme temperatures.

Rain Shadow Effect

Dry area on lee side of a mountain due to descending dry air.

Convection Cell

Large-scale pattern of atmospheric circulation driving wind and rainfall.