Genetic Mechanisms of Reproductive Isolation in Drosophila Systems

Reproductive isolation in Drosophila involves a suite of genetic mechanisms that operate at sequential stages to prevent gene flow and facilitate speciation. Premating barriers arise through divergence in courtship behaviours, pheromone profiles and mechanical incompatibilities that reduce heterospecific mating. When mating occurs, postmating prezygotic barriers—such as defective sperm storage, mismatches in seminal proteins and failures in sperm-egg recognition—further impede fertilisation. Postzygotic isolation commonly manifests as hybrid inviability or sterility, disproportionately affecting the heterogametic (XY) sex, a pattern known as Haldane’s rule. At the molecular level, Dobzhansky–Muller incompatibilities underpin these outcomes: lineage-specific allelic changes interact epistatically to disrupt development, gametogenesis or fertility in hybrids. A pronounced large X effect, in which X-linked loci contribute disproportionately to hybrid sterility, highlights the rapid evolution and hemizygosity of sex chromosomes. Additionally, genetic conflicts—for example between selfish elements in heterochromatin and host suppressors—drive adaptive divergence of incompatibility genes. High-resolution mapping and transcriptomic analyses have revealed that both coding sequences and regulatory elements, including satellite repeats and transposable elements, can act as barrier loci. Gene flow between diverging lineages, combined with selection and chromosomal rearrangements, shapes a polygenic architecture of reproductive isolation. Together, these findings illustrate how intertwined genetic, epigenetic and chromosomal processes generate and maintain species boundaries in Drosophila.

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Genetic Mechanisms of Reproductive Isolation in Drosophila Systems publication trend

The graph below shows the total number of articles in genetic mechanisms of reproductive isolation in drosophila systems across all publications each year (not limited to Nature Index journals).

Technical terms

Haldane’s rule: Preferential sterility or inviability of the heterogametic sex in interspecific hybrids.

Dobzhansky–Muller incompatibility: Epistatic interactions between alleles that have diverged in separate lineages, causing hybrid dysfunction.

Large X effect: Disproportionate impact of X-linked genes on hybrid sterility or inviability relative to autosomal genes.

Epistasis: Non-additive interactions between genes that influence the expression of complex traits.

Postmating prezygotic isolation: Barriers that act after copulation but before zygote formation, such as sperm-female tract incompatibilities.

References

1. Identification and genetic analysis of a pervasive ‘needle-eye’ sperm phenotype in Drosophila sterile hybrid males. Proceedings of the Royal Society B (2024).
2. Hybrid Sterility, Genetic Conflict and Complex Speciation: Lessons From the Drosophila simulans Clade Species. Frontiers in Genetics (2021).
3. Multiple Genes Cause Postmating Prezygotic Reproductive Isolation in the Drosophila virilis Group. G3: Genes, Genomes, Genetics (2016).
4. High-Resolution Genome-Wide Dissection of the Two Rules of Speciation in Drosophila. PLOS Biology (2007).
5. The Hmr and Lhr Hybrid Incompatibility Genes Suppress a Broad Range of Heterochromatic Repeats. PLOS Genetics (2014).