DNA barcodes reveal extensive hidden diversity in polychaetes questioning cosmopolitan distributions and calling for comprehensive taxonomic revision
Marcos AL Teixeira1,2, Arne Nygren3,4, Ascensão Ravara5, Filipe O Costa1,2*
1 CBMA, Centre of Molecular and Environmental Biology, Departamento de Biologia, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal
2 Institute of Science and Innovation for Bio-sustainability (IB-S), Universidade do Minho, Portugal
3 Sjofartmuseet Akvariet, Goteborg, Sweden
4 Institutionen for marina vetenskaper, Goteborgs Universitet, Goteborg, Sweden
5 CESAM, Departamento de Biologia, Universidade de Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
*Corresponding author: [email protected]
- Polychaeta (Annelida) is one of the most prominent bioindicator groups among the marine benthic invertebrates1.
- The main goal was finding and describing new cryptic lineages from already recognized or still unknown species complexes and gaining insights into the prevalence of cryptic species among presumed cosmopolitan polychaetes.
- Cryptic complexes examined: Eumida sanguinea, Eulalia clavigera, Trypanosylis zebra and Platynereis dumerilii.
- Original DNA barcodes from 192 specimens obtained using published protocols2, supplemented with 97 BOLD and GenBank published sequences.
- Area: Mediterranean Sea and NE Atlantic.
- Maximum Likelihood phenogram with best fit model (Fig.1), using MEGA software.
- Four different MOTU clustering algorithms applied: BIN, ABGD, bPTP and GYMC to form a consensus MOTU performed in the respective web interfaces.
- Mean interspecific distances (ISD) were calculated using Kimura-2-parameter distance (K2P) in MEGA software.
- One additional MOTU, present only in the Great Britain, recorded within the large Eumida sanguinea complex, comprising 9 different described morphospecies (15.5% mean distance).
- Five additional MOTUs within the Eulalia viridis/clavigera complex with 17.9% mean distance, including one of them exclusive to the Madeira island.
- Seven MOTUs within Trypanosyllis zebra (22.1% mean distance), three of which from the Mediterranean.
- Four MOTUs within Platynereis dumerilii with 17.4% mean distance and comprising two lineages endemic to Portugal with an unusual low nucleotide COI divergence when compared between each other and against Platynereis massiliensis (4 to 5%), an already described species from this complex.
- Up to 29 cryptic lineages hidden within only four cryptic complexes.
- Considerable hidden diversity within the presumed cosmopolitan species. Geographic ranges of the cryptic lineages is only a fraction of the whole cryptic complex, hence more vulnerable and under higher risk from a conservation perspective3.
- Molecular data for the study of cryptic species can contribute to the DNA barcode reference library for polychaetes, and be used in high-throughput sequencing technologies for biomonitoring programmes or other relevant ecological researches.
1 Nygren A (2014) Cryptic polychaete diversity: a review. Zoologica Scripta, 43, 172–183. DOI: 10.1111/zsc.12044;
2 Lobo J et al. (2016) Starting a DNA barcode reference library for shallow water polychaetes from the southern European Atlantic coast. Molecular Ecology Resources 16, 298-313. DOI: 10.1111/1755-0998.12441;
3 Hutchings P & Kupriyanova E (2018) Cosmopolitan polychaetes – fact or fiction? Personal and historical perspectives. Invertebrate Systematics, 32, 1–9. DOI: 10.1071/IS17035.
This study was supported by the project The NextSea (NORTE-01-0145-FEDER-000032), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). Marcos AL Teixeira benefited from an FCT fellowship: SFRH/BD/131527/2017.