Genes, Evolution, and Speciation – Lecture Review

These vocabulary flashcards summarize key terms and definitions from the lecture notes on scientific methods, genetics, microevolution, and macroevolution to aid exam preparation.

Scientific Method

A systematic process of observation, hypothesis formation, experimentation, and conclusion used to investigate natural phenomena.

Control (Experimental)

An unchanged standard in an experiment that allows comparison and validates results.

Sample Size

The number of observations or replicates; larger sizes increase statistical reliability.

Scientific Theory

A broad, well-supported explanation of natural events, developed after repeated testing and evidence gathering.

Mutation

Any heritable change in DNA sequence that creates genetic variation.

Point Mutation

A single-nucleotide change that can alter an amino acid in a protein.

Gene Expression

The process by which information from a gene is transcribed and translated into a functional product.

Chromosomal Mutation

Large-scale DNA change involving segments of chromosomes, such as duplications, deletions, or rearrangements.

Transposable Element

A DNA segment that can move within the genome, potentially disrupting genes.

Exon Shuffling

Recombination that mixes coding regions (exons) of different genes, creating new proteins.

Gene Fusion/Deletion

Chromosomal events that join genes together or remove them, altering gene function.

James Hutton

Geologist who proposed gradualism—earth’s features result from slow, continuous processes.

Charles Lyell

Author of ‘Principles of Geology’; championed uniformitarianism, influencing Darwin.

Jean-Baptiste Lamarck

Suggested inheritance of acquired traits; emphasized adaptation though mechanism was incorrect.

Charles Darwin

Naturalist who formulated the theory of evolution by natural selection.

Adaptation

An inherited trait that increases an organism’s reproductive success in a specific environment.

Natural Selection

Process where individuals with advantageous traits reproduce more, shifting allele frequencies.

Artificial Selection

Human-driven breeding that selects for desirable traits in organisms.

Darwin’s Observations

1) Variability exists within populations; 2) More offspring are produced than survive.

Darwin’s Inferences

Individuals with favorable traits have higher survival and reproduction, leading to accumulation of those traits.

Alfred Russel Wallace

Co-developer of the theory of evolution by natural selection, whose independent work on biogeography and beetle distribution prompted Darwin to publish 'On the Origin of Species'.Wallace is also known for proposing the concept of natural selection alongside Charles Darwin, emphasizing the role of geographic distribution in species evolution.

Direct Observation Evidence

Real-time evolutionary change measured in living populations, e.g., bacteria.

Antibiotic Resistance

Bacterial ability to survive drugs, often evolving via mutations and selection.

Horizontal Gene Transfer

Movement of genes between organisms without reproduction, common in bacteria.

Homology

Similarity due to shared ancestry (e.g., vertebrate forelimbs).

Analogous Trait

Similarity due to convergent evolution, not common ancestry (e.g., bird vs insect wings).

Convergent Evolution

Independent evolution of similar features in distinct lineages facing similar pressures.

Vestigial Trait

A reduced or change in use of a structure inherited from ancestors (e.g., human tailbone).

Fossil Record

Preserved remains that document past life and evolutionary transitions.

Biogeography

Study of geographic distribution of species, supporting common descent.

Allele

Alternate form of a gene found at the same locus on homologous chromosomes.

Genotype

The specific allelic composition of an individual for a given gene or set of genes.

Phenotype

Observable traits resulting from genotype and environmental interaction.

Microevolution

The process of small-scale evolutionary changes within a population, often involving minor shifts in allele frequencies over time.

Hardy–Weinberg Equilibrium

Ideal state where allele frequencies remain constant across generations in a non-evolving population.

Hardy–Weinberg Conditions

No mutation, random mating, large population, no migration, and no selection.

Directional Selection

Selection that favors one extreme phenotype, shifting the population mean.

Disruptive Selection

Selection that favors both extremes over intermediate phenotypes.

Stabilizing Selection

Selection that favors intermediate variants and reduces extremes.

Bottleneck Effect

Sharp reduction in population size that randomly alters allele frequencies.

Founder Effect

Genetic drift when a few individuals start a new population with limited diversity.

Heterozygote Advantage

Heterozygous individuals have higher fitness than either homozygote (e.g., sickle-cell trait).

Frequency-Dependent Selection

Fitness of a phenotype depends on its frequency in the population.

Biological Species Concept

Defines species as groups of interbreeding natural populations reproductively isolated from others; limited for fossils/asexuals.

Macroevolution

The large-scale evolution that occurs over long time periods, resulting in the emergence of new species and higher taxonomic groups.

Allopatric Speciation

Formation of new species via geographic isolation, common on islands or fragmented habitats.

Sympatric Speciation

Speciation within the same geographic area, often via polyploidy, sexual selection, or habitat shift.

Polyploidy

Genome duplication creating reproductive isolation, frequent in plants.

Habitat Differentiation

Subpopulations exploit different ecological niches within the same area, reducing gene flow.

Prezygotic Barrier

Reproductive barrier preventing fertilization (e.g., temporal or mechanical isolation).

Habitat Isolation

A prezygotic reproductive barrier where species live in different habitats and do not encounter each other to mate.

Temporal Isolation

A prezygotic reproductive barrier where species breed at different times of day or year, preventing mating.

Behavioral Isolation

A prezygotic reproductive barrier where species have different mating behaviors or rituals, leading to a lack of mating between them.

Mechanical Isolation

A prezygotic reproductive barrier where differences in reproductive structures or mechanisms prevent successful mating.

Gametic Isolation

A prezygotic reproductive barrier where the eggs and sperm of different species are incompatible, preventing fertilization.

Postzygotic Barrier

Barrier after fertilization that reduces hybrid viability or fertility.

Reduced Hybrid Viability

A postzygotic reproductive barrier where hybrid offspring do not develop properly or are frail, leading to lower survival rates.

Reduced Hybrid Fertility

A postzygotic reproductive barrier where hybrid offspring are sterile or have reduced fertility, preventing them from producing viable offspring.

Hybrid Breakdown

A postzygotic reproductive barrier where first-generation hybrids are fertile, but their subsequent generations are inviable or sterile.

Reinforcement

Strengthening of reproductive barriers; hybrids have lower fitness, populations diverge further.

Fusion

Weakening of reproductive barriers; gene flow causes two populations to merge.

Stability (Hybrid Zone)

Hybrids persist because they are fit in the contact zone, maintaining separate parental species.