Foundations

Evolution concerns inherited change across generations.

Heritable variation can change through differences in reproductive contribution.

Chance can change allele frequencies independently of an adaptive advantage.

Evolutionary relationships describe descent from shared ancestors.

Species boundaries depend on the organisms and the question being investigated.

Reduced reproductive exchange can permit populations to diverge into lineages.

Evolutionary trees are hypotheses inferred from comparative evidence.

Shared ancestry and independent similarity are different explanations.

For an autosomal diploid two-allele locus, random union of gametes with frequencies p and q gives genotype proportions p², 2pq and q².

The neutral diploid Wright–Fisher model samples 2N gene copies independently from the previous generation.

In a specified population model, narrow-sense heritability is the ratio of additive genetic variance to phenotypic variance.

Likelihood phylogenetics compares how probable an aligned sequence dataset is under candidate trees, branch lengths and substitution models.

Magnification enlarges an image; resolution determines whether adjacent structures can be distinguished.

PCR repeatedly separates template DNA, anneals sequence-directed primers and extends them with a suitable DNA polymerase.

Molecular cloning inserts a selected DNA fragment into a replicating vector for propagation or study.

Sanger sequencing detects terminated DNA products produced when extension incorporates a nucleotide lacking the required 3′ hydroxyl.

SDS-PAGE uses denaturing detergent treatment to separate suitable proteins primarily by apparent size.

A biological experiment tests a stated hypothesis using measured outcomes and comparisons that address alternative explanations.

Mutation transfers allele copies between states.

If migrants form a specified fraction of a population's allele pool, the post-migration allele frequency is a weighted average of resident and migrant frequencies.

Recurrent mutation can replenish a deleterious allele that purifying selection removes.

In the ideal neutral diploid population, a new single-copy allele has eventual fixation probability 1/(2N).

Under equal constant lineage-specific substitution rates, the expected substitutions separating two descendant lineages accumulate over both branches since their common ancestor.

Mitochondrial and plastid ancestry is supported by bacterial affinities in molecular machinery and genes, organelle reproduction and transfer of many organelle-derived genes into nuclear genomes.

Mosses, liverworts and hornworts illustrate gametophyte-dominant land-plant life cycles.

Lycophytes and fern-related lineages have vascular sporophytes and life cycles that produce gametophytes through spores.

Gene lineages need not coalesce at a population or species split.

Species traits can be correlated because related lineages share evolutionary history.

The D statistic compares two discordant allele-sharing patterns in an ordered four-sample test.

A local alignment score is evaluated against an explicit random-sequence null and search space.