Population Genetics of Freshwater Aquatic Species

Population genetics of freshwater aquatic species examines the distribution of genetic variation within and among populations inhabiting rivers, lakes and wetlands. It integrates concepts of gene flow, genetic drift, selection and mutation to understand how demographic processes and environmental factors shape genetic structure. Modern molecular tools, including microsatellite markers, single-nucleotide polymorphisms (SNPs) and restriction-site associated DNA sequencing (RADseq), enable high-resolution analyses of population connectivity, effective population size and adaptive variation. Insights into heterozygosity, allelic richness and inbreeding coefficients inform on the resilience of populations facing habitat fragmentation, pollution, climate change and exploitation. In dendritic freshwater landscapes, barriers such as dams and weirs can restrict dispersal and promote genetic divergence even over short distances. Conversely, restoration measures and managed translocations can enhance gene flow and mitigate loss of genetic diversity. A robust understanding of neutral and adaptive genetic variation underpins conservation strategies, guides captive-breeding and stocking programmes, and predicts evolutionary responses to environmental change. By linking spatial genomics with ecological and hydrological data, researchers can forecast population vulnerability, prioritise conservation units and support sustainable management of globally important aquatic resources.

Research from Nature Portfolio

Recent studies have characterised the genetic structure and conservation status of an endangered riverine fish in East Asia. Using 21 microsatellite markers across nine populations, researchers revealed moderate to high allelic richness and heterozygosity alongside evidence of historical and recent bottlenecks. Genetic differentiation separated one basin from others, with limited gene flow except for a restored stream population. Inbreeding indices highlighted populations at risk, and chromosomal structuring suggested two major genetic clusters. These findings underpin targeted conservation actions, emphasising the need for gene exchange among fragmented populations and continual monitoring of genetic health in restoration programmes.

Population Genetics of Freshwater Aquatic Species publication trend

The graph below shows the total number of articles in population genetics of freshwater aquatic species across all publications each year (not limited to Nature Index journals).

Technical terms

Allelic richness: A measure of the number of alleles per locus within a population, reflecting genetic diversity.

Effective population size (Ne): The size of an idealised population that would experience genetic drift at the same rate as the observed population.

Gene flow: The movement of genes or alleles between populations through dispersal or migration.

Genetic drift: Stochastic fluctuations in allele frequencies due to random sampling effects, particularly in small populations.

Heterozygosity: The proportion of individuals in a population that carry two different alleles at a locus, indicating genetic variability.

Microsatellite markers: Short tandem repeats in DNA sequences used to assess genetic variation and population structure.

Population structure: The organisation of genetic variation into subgroups, often driven by limited dispersal or environmental barriers.

References

1. Population structure and genetic diversity of the endangered fish black shinner Pseudopungtungia nigra (Cyprinidae) in Korea: a wild and restoration population. Scientific Reports (2023).
2. Genetic Structure and Diversity of Hatchery and Wild Populations of Yellow Catfish Tachysurus fulvidraco (Siluriformes: Bagridae) from Korea. International Journal of Molecular Sciences (2024).
3. Macroecological predictors of evolutionary and plastic potential do not apply at microgeographic scales for a freshwater cladoceran under climate change. Evolution Letters (2023).