Population Genetics and Hermaphroditic Reproductive Strategies in Vertebrates

Vertebrate hermaphroditism represents a rare but illuminating natural experiment in the interplay between mating system and genetic diversity. In populations where individuals possess both male and female gonadal tissues, reproduction may occur by self-fertilisation, outcrossing, or a mixture of both. These strategies profoundly influence effective population size, allele frequency dynamics and levels of homozygosity. Selfing accelerates the uncovering of recessive mutations and can reduce genetic variation, while occasional outcrossing mitigates inbreeding depression and replenishes diversity. Studies of model species such as the mangrove killifish have elucidated how mating systems shape genome architecture, from the distribution of recombination along chromosomes to the activity of mobile genetic elements. Insights derived from population genetic theory and empirical data extend to broader questions of adaptation, hybridisation and the maintenance of reproductive polymorphisms. Understanding hermaphroditic strategies in a vertebrate context informs conservation of threatened taxa, experimental design in developmental genetics and the evolutionary mechanisms by which genomes respond to ecological challenges.

Research from Nature Portfolio

High-resolution genome assembly of a self-fertilising hermaphroditic killifish has revealed an unexpected diversity and fine-scale distribution of transposable elements. These mobile DNA sequences contribute to recombination hotspots and may act as reservoirs of genetic variation in a lineage otherwise prone to homozygosity. The work highlights the role of transposable elements in buffering diversity loss associated with selfing and suggests a genomic mechanism by which such vertebrates adapt to fluctuating environments.

Population Genetics and Hermaphroditic Reproductive Strategies in Vertebrates publication trend

The graph below shows the total number of articles in population genetics and hermaphroditic reproductive strategies in vertebrates across all publications each year (not limited to Nature Index journals).

Technical terms

Hermaphroditism: possession of both male and female reproductive organs within a single individual.

Self-fertilisation: fusion of gametes produced by the same individual, leading to inbreeding.

Androdioecy: coexistence of hermaphroditic and male phenotypes within a population.

Transposable element: mobile DNA sequence capable of relocating within the genome.

Hybrid zone: geographic area where genetically distinct populations or species interbreed.

Epigenetics: heritable changes in gene expression not attributable to DNA-sequence variation.

Single-nucleotide polymorphism (SNP): variation at a single base position in the DNA sequence among individuals.

Inbreeding depression: reduced biological fitness resulting from increased homozygosity of deleterious alleles.

References

1. A Genetic Map for the Only Self-Fertilizing Vertebrate. G3: Genes, Genomes, Genetics (2016).
2. Diversity, distribution, and significance of transposable elements in the genome of the only selfing hermaphroditic vertebrate Kryptolebias marmoratus. Scientific Reports (2017).
3. Against the Odds: Hybrid Zones between Mangrove Killifish Species with Different Mating Systems. Genes (2021).
4. Additive and non-additive epigenetic signatures of natural hybridization between fish species with different mating systems. Epigenetics (2022).
5. Evolutionary game in an androdioecious population: Coupling of outcrossing and male production. Journal of Theoretical Biology (2021).