Inspect a real fruit fly reconstruction, choose inherited copies, exchange chromosome segments and test why a probability does not promise an exact family. Follow linked markers from parent to gamete to offspring.
Current gene identity, chromosome arm 2L and pigmentation-related biology.
Curated Drosophila record. The historical symbol b is retained on teaching cards to match the historical cross; modern name Adc is taught alongside it.
Together/split marker arrangements, female 83%/17% example and male no-crossover comparison.
A Critique of the Theory of Evolution, Figure 66 and accompanying text. Public domain in the US. Historical quantitative example retained; obsolete historical molecular explanations are not reused as modern fact.
Original recent and reciprocal F2 adult counts, with viability considered.
The Linkage of Two Factors in Drosophila That Are Not Sex-Linked, printed page 177. Counts are transcribed as source observations and kept separate from generated simulations.
Temperature-associated expression differences in the measured adult sample context.
Genes 10(7):498, Figure 1 and Table 3. CC BY 4.0 figure retained in full. Three biological replicates; technical repetitions are not independent biological samples. ZI/ZK label conflict disclosed.
Prepared female micro-CT reconstruction and a detailed fly simulation model.
Nature Methods, source Methods. The paper has separate copyright; no restricted paper figure is copied. The geometry is reused under its repository license.
Source-owned meshes, assembly transforms and Apache 2.0 license.
Pinned commit; 65 mesh parts and 334,525 triangles retained. Public provenance records hashes, scale and coordinate conversion. Authored colors and inspection pose are identified separately.
This is a selected historical fruit-fly marker model. It is not a human appearance predictor, genetic report, clinical interpretation or full-genome model.
The genotype-to-class mapping is specified for the chosen recessive variants. Other alleles and developmental contexts can have other effects. Recessive does not mean weak, uncommon or inferior.
The 17% recombinant fraction is a historical example, not a universal gene-pair rate. The independent-marker branch is an explicit counterfactual that removes linkage; it does not relocate the genes.
The selected exchange is a schematic between nonsister chromatids. It conserves tracked copies but omits DNA chemistry, full meiosis, additional chromosomes, mutation, gene conversion, nondisjunction and crossover-position modeling.
Simulations assume equal segregation, gamete success and observation, with no differential survival. The actual adult counts remain separate from these assumptions and are never edited to fit a target ratio.
The real fly is a prepared female micro-CT-derived research reconstruction. Source assembly pose, subsequent transforms and our materials do not measure a living posture, pigment variation or predicted mutant wing shape.
The 2019 expression figure measures pooled adult vg mRNA at two temperatures, not wing length or a continuous response curve. The ZI/ZK source-label conflict remains unresolved; only unambiguous SU and FR male ratios are tabulated.
Local interactions use invented marker choices and seeded simulations. No family history, genetic information, biological sample or personal phenotype is requested. No narration or provider request is triggered automatically.
Alleles, genotypes and phenotypes: An allele is a version at a genetic locus. A genotype describes the inherited copies being tracked; a phenotype is an observed characteristic. Neither two markers nor a single outward feature specifies a whole organism. Dominance is a relationship between selected alleles and a measured trait in a context, not a measure of strength, quality or frequency.
A source example of linkage: Morgan’s 1916 example assigns 17% total recombinant combinations to this female-fly cross. For a together-phase parent, the four canonical pairs (+,+), (+,vg), (b,+), (b,vg) receive probabilities 83/200, 17/200, 17/200 and 83/200. Split phase reverses which pairs are common. Each individual variant still has probability 1/2.
One event and an ensemble are different: One selected nonsister exchange makes two recombinant chromatids among four. That count does not establish that 17% of cells undergo the illustrated event. The historical fraction is a separate ensemble description. Our model does not derive a crossover frequency from marker spacing or draw multiple exchanges, gene conversion or every meiotic product.
The organism matters: Standard Drosophila melanogaster male meiosis lacks the usual meiotic crossing over. Our male comparison therefore supplies only the two parental marker combinations, with probability 1/2 each. This is a species-specific comparison, not a rule about human fathers or all male animals. The tester remains fixed when the modeled parent changes.
A transparent random experiment: The seeded testcross uses one uniform pseudorandom draw per offspring and exact integer probability weights summing to 200. A generated run stores its phase, mode, seed and sample size. Later control changes prepare a new run without reinterpreting the saved results. The expected count N × p can be fractional; observed simulated counts are integers.
Adult counts can include survival effects: Morgan and Lynch’s 1912 recent-cross F2 count lists 1,081 reference-wing and 280 vestigial-wing adults; the reciprocal-cross F2 lists 1,213 and 273. These are preserved source observations, not generated data. An adult sample can be affected by viability and observation as well as the inherited combinations. The original investigators considered viability.
Genes act in a developmental context: FlyBase now names the historical body-color b gene Adc, on chromosome arm 2L. The vg gene lies on 2R and contributes, with other factors, to wing and haltere identity. The schematic does not convert arm-local sequence coordinates into a distance or apply the same phenotype mapping to every possible allele.
Expression is not anatomy: Voigt and colleagues measured normalized vg mRNA in pooled adult samples at 17 °C and 28 °C. Their reported adult-male ratios are 1.76 for Sweden and 2.28 for France. Those are expression ratios, not wing-size multipliers or individual forecasts. The source has an unresolved ZI/ZK population-label mismatch; the affected ratios are not assigned here.
What has been checked
Analytical reference cases, conservation or transition invariants, finite drawing commands, bounded setup parsing, discovery and route integrity are checked automatically. These checks do not establish anatomical fidelity, learner outcomes or browser/device compatibility. Independent subject review, learner trials, comprehensive accessibility review and browser video encoding checks remain pending.
Each source supports the associated claim. Sources do not certify this implementation or its visuals.
About the cover illustration
NeuroMechFly micro-CT-derived female Drosophila reconstruction, 65 original source parts. Apache 2.0 geometry; Brytalearn materials and inspection camera. Source assembly pose; not a genetically predicted offspring.