This example visualizes meiosis by modeling chromosome sets with genes and their alleles, demonstrating crossover at specified loci. The code constructs a pea plant organism with chromosomes containing genes like podColor and seedColor, then duplicates and swaps alleles past a crossover point. It renders the resulting chromatids as red rectangles using D3 v6’s data join (`selectAll().data().join()`) and SVG text for allele labels positioned by locus. The drawing functions `draw_chrom` and helper `dupChrom` handle the layout and mutation logic.