Invertebrate population genetics across Earth's largest habitat: The deep-sea floor

Area of Science:

• Marine Biology
• Population Genetics
• Deep-Sea Ecology

Background:

• The deep sea, Earth's largest habitat, remains understudied regarding invertebrate population genetics.
• Only 77 studies (115 species) exist for non-chemosynthetic deep-sea floor ecosystems below 200m.
• Existing research reveals genetic diversity comparable to shallow-water species.

Purpose of the Study:

• To review and synthesize existing population genetic studies of deep-sea invertebrates.
• To identify patterns in genetic diversity, connectivity, and population structure.
• To highlight research gaps and limitations in current deep-sea genetic research.

Main Methods:

• Systematic review and synthesis of 77 published population genetic studies.
• Analysis of species distribution, geographic scope, and depth range of studies.
• Examination of genetic markers used and inferred demographic processes.

Main Results:

• Deep-sea invertebrates show genetic diversity similar to shallow-water species.
• Widespread connectivity (100s-1,000s km) observed at similar depths.
• Population structure detected at smaller scales (100s-1,000s m) linked to adaptation or physical barriers.
• Research is heavily biased towards the Atlantic and megafauna, neglecting meiofauna and other key groups.
• Most studies use single-locus mitochondrial DNA, indicating non-neutrality and potential demographic instability.

Conclusions:

• Deep-sea invertebrate populations exhibit complex connectivity patterns influenced by both large-scale oceanographic and small-scale environmental factors.
• The current body of research is insufficient to make broad ecological inferences about the deep sea.
• Future research should expand geographic and taxonomic scope, utilize diverse genetic markers, and investigate underrepresented taxa and deep-sea regions.