Germline ecology: Managed herds, tolerated flocks, and pest control.

The article focuses on the evolutionary dynamics and intranuclear ecology of multicopy sequences—such as mitochondrial DNA (mtDNA), ribosomal DNA (rDNA), transposable elements (TEs), satellite DNA, and centromeric repeats—within germline cells. It describes how these sequences evolve adaptations to increase their copy number and transmission, often engaging in conflicts with the single-copy "conjugal genome" that manages their activity to preserve organismal fitness. Key mechanisms include selective breeding of mitochondrial herds via germline bottlenecks and intracellular quality control, concerted evolution maintaining rDNA homogeneity, and the birth-and-death dynamics of TEs that balance transposition benefits against organismal costs. The article also explores how germline architecture influences genome size through opportunities for transposition and discusses the implications of multicopy sequence dynamics for reproductive medicine, particularly in oocyte quality and early embryonic development.