Closely related dinoflagellate species in vastly different habitats–an example of a marine–freshwater transition

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Abstract

Phytoplankton are present in a large variety of aquatic environments, ranging from small freshwater ponds to the oceans. Typically, freshwater and marine species are not closely related, indicating an ancient divergence and that salinity poses a strong dispersal barrier. Here we reveal a common recent origin of two dinoflagellates that are well adapted to different habitats. Gymnodinium baicalense inhabits the geologically old freshwater Lake Baikal, which is located in the middle of the Eurasian continent. Gymnodinium corollarium, on the other hand, is a brackish water species from the Baltic Sea. Both species form blooms under ice during the spring. We generated 10 DNA sequences from these species. The partial 28S rRNA gene from G. baicalense and the partial 18S rRNA gene and internal transcribed spacer-2 (ITS2) from G. corollarium were sequenced for the first time. A more detailed description of G. baicalense, which was previously known only from light microscopy observations, is also provided. In the laboratory we demonstrated that G. baicalense is strictly adapted to fresh water, while G. corollarium had a wide salinity tolerance. However, the two species have almost identical morphology, identical SSU rRNA gene sequences, and only small differences in the LSU rRNA gene and ITS2. We infer a common ancestor, which was a species from the Arctic region with a tolerance to a range of salinities. Our data support the scenario that the under-ice phytoplankton community in Lake Baikal has been formed recently, even though the lake is the oldest in the world.

Detaljer

Författare
Enheter & grupper
Externa organisationer
  • Limnological Institute, Siberian Branch of the Russian Academy of Sciences
  • University of Copenhagen
Forskningsområden

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Evolutionsbiologi

Nyckelord

Originalspråkengelska
TidskriftEuropean Journal of Phycology
StatusE-pub ahead of print - 2020 maj 18
PublikationskategoriForskning
Peer review utfördJa