Molecular Taxonomy and Phylogenetics of Copepod Diversity

Copepods, the most abundant metazoan zooplankters, underpin aquatic food webs and drive biogeochemical cycles in marine and freshwater environments. Traditional morphology-based classification has long struggled with high levels of shape plasticity and the existence of cryptic or sibling species. Over the past decade, molecular taxonomy has transformed our capacity to delimit species through standardised genetic markers—most notably mitochondrial cytochrome c oxidase subunit I—and has revealed previously undetected diversity across all major clades. Concurrently, phylogenetic methods that integrate multiple loci and genome-wide data are refining our understanding of evolutionary relationships among orders and families, resolving long-standing debates on monophyly and interordinal branching patterns. Advanced approaches such as DNA barcoding, environmental metabarcoding and phylogenomics now permit rapid species identification, community profiling and robust inference of copepod origins, radiations and biogeographic histories. These developments carry global significance: molecular inventories inform assessments of ecosystem health, guide conservation of vulnerable habitats and improve predictive models of planktonic responses to climate change. The synthesis of taxonomy and phylogenetics also facilitates discovery of novel lineages with potential applications in biotechnology, pollution monitoring and fisheries management. Together, these tools are building a comprehensive molecular framework for copepod diversity that bridges systematic biology, ecology and environmental monitoring on a planetary scale.

Research from Nature Portfolio

Recent studies have combined DNA barcoding and mass spectrometry to expose hidden diversity within benthic copepods. Assessment of mitochondrial COI sequences alongside MALDI-TOF mass spectra from North Sea harpacticoids uncovered over 19 % novel lineages and multiple molecular operational taxonomic units previously masked by morphological uniformity. Concordant delimitation by both methods confirmed ten cryptic species complexes and demonstrated that routine environmental surveys may underestimate true species richness by a third or more. This integrative strategy has highlighted the power of coupling high-throughput barcoding with proteomic profiling to accelerate biodiversity assessments in well-studied regions and promises similar revelations when applied to other copepod groups worldwide.

Molecular Taxonomy and Phylogenetics of Copepod Diversity publication trend

The graph below shows the total number of articles in molecular taxonomy and phylogenetics of copepod diversity across all publications each year (not limited to Nature Index journals).

Technical terms

DNA barcoding: Use of a standard gene region, typically COI, to identify and discriminate species based on sequence variation.

Cryptic species: Distinct evolutionary lineages that are morphologically similar and traditionally treated as a single species.

COI (cytochrome c oxidase subunit I): A mitochondrial gene commonly employed as a molecular marker for animal species identification.

MALDI-TOF MS: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, a proteomic technique used here to fingerprint species-specific peptide patterns.

Phylogenomics: Reconstruction of evolutionary relationships using genome-scale datasets, often comprising hundreds to thousands of loci.

Molecular operational taxonomic unit (MOTU): A cluster of sequences that is treated as a proxy for species in biodiversity analyses.

References

1. Revealing higher than expected diversity of Harpacticoida (Crustacea:Copepoda) in the North Sea using MALDI-TOF MS and molecular barcoding. Scientific Reports (2019).
2. A synthesis tree of the Copepoda: integrating phylogenetic and taxonomic data reveals multiple origins of parasitism. PeerJ (2021).
3. Phylogenomic analysis of Copepoda (Arthropoda, Crustacea) reveals unexpected similarities with earlier proposed morphological phylogenies. BMC Ecology and Evolution (2017).
4. Mediterranean and Black Sea Monstrilloid Copepods (Copepoda: Monstrilloida): Rediscovering the Diversity of Transient Zooplankters. Water (2021).