Printable reference
Plain-language glossary
A compact vocabulary for checking causal claims. Print this page or keep it open during book-club discussion.
Foundations
- AdaptationAn inherited feature shaped by selection because it improved reproduction in past environments; not a synonym for all evolution.
- AlleleOne version of a gene or DNA location.
- Genotype and phenotypeGenotype is inherited genetic information; phenotype is the resulting observable trait built through development and environment.
- Mutation and recombinationMutation creates new DNA changes; recombination reshuffles inherited versions into new combinations.
Forces and accounting
- EvolutionChange in inherited population or lineage characteristics across generations—not an individual’s development.
- Natural selectionSystematic frequency change caused by inherited variants differing in reproductive contribution in a stated environment.
- FitnessRelative expected contribution to future generations in a context; not strength, worth, or survival alone.
- Genetic driftChance frequency change from finite sampling; stronger in smaller effective populations.
- Effective population size (Nₑ)The idealized size producing the observed strength of drift; often smaller than census size.
- Gene flowMovement of inherited variants among populations; hybridization and introgression are important routes.
- Nearly neutralA variant whose selection effect is weak enough relative to Nₑ that drift strongly influences its fate.
Development and inheritance
- Developmental biasDevelopment makes some phenotypic variants more likely or viable than others, changing the variation supplied.
- Phenotypic plasticityOne genotype produces different phenotypes in different environments.
- Genetic accommodationSelection changes the inherited regulation or sensitivity of a phenotype initially affected by environment.
- Epigenetic inheritanceTransmission of regulatory state not explained by DNA-sequence change; mechanism, taxon, controls, and persistence must be specified.
- Niche constructionOrganisms modify environments in ways that feed back on selection.
- Ecological inheritanceDescendants encounter persistent environmental modifications produced by ancestors.
Histories and levels
- IntrogressionDNA enters a population after hybridization with a diverged population or species.
- Horizontal gene transfer (HGT)Genetic material moves other than parent-to-offspring; especially consequential in microbes.
- Incomplete lineage sortingAncestral variants persist through rapid splits and sort differently, making gene trees disagree with a species tree.
- PangenomeA representation of shared and variable sequence across many members of a species, often graph-based.
- Multilevel selectionPartitioning selection within and between nested units such as cells, organisms, or groups.
- Major transitionFormerly independent units become a higher-level reproductive individual while internal conflict is controlled.
- HolobiontA host plus associated microbes as an ecological unit; not automatically one Darwinian individual.
Claim-checking card
- What varies?
- How does it get transmitted?
- Whose reproductive contribution differs?
- What roles do chance, migration, development, and history play?
- What observation would distinguish this story from alternatives?
Language swaps
PURPOSE → HISTORY“Evolved in order to…”Try: “Variants causing X left more descendants under Y.”
ESSENCE → CONTEXT“The fittest animal…”Try: “The phenotype with higher expected reproduction in this environment…”
NEED → SUPPLY“The environment caused the useful mutation…”Try: “Variation arose; the environment changed its reproductive consequences.”
SLOGAN → MECHANISM“For the good of the species…”Try: “Measure within- and between-group reproduction, assortment, and transmission.”