Genetic diversity of Microsporidia in the circulatory system of endemic amphipods from different locations and depths of ancient Lake Baikal.

Mariya Dimova,Anton Gurkov,Renat Adelshin,Ekaterina Madyarova,Maxim Timofeyev,Yulia Lubyaga,Elizaveta Kondrateva,Polina Drozdova

doi:10.7717/peerj.5329

Abstract

Endemic amphipods (Amphipoda, Crustacea) of the most ancient and large freshwater Lake Baikal (Siberia, Russia) are a highly diverse group comprising >15% of all known species of continental amphipods. The extensive endemic biodiversity of Baikal amphipods provides the unique opportunity to study interactions and possible coevolution of this group and their parasites, such as Microsporidia. In this study, we investigated microsporidian diversity in the circulatory system of 22 endemic species of amphipods inhabiting littoral, sublittoral and deep-water zones in all three basins of Lake Baikal. Using molecular genetic techniques, we found microsporidian DNA in two littoral (Eulimnogammarus verrucosus, Eulimnogammarus cyaneus), two littoral/sublittoral (Pallasea cancellus, Eulimnogammarus marituji) and two sublittoral/deep-water (Acanthogammarus lappaceus longispinus, Acanthogammarus victorii maculosus) endemic species. Twenty sequences of the small subunit ribosomal (SSU) rDNA were obtained from the haemolymph of the six endemic amphipod species sampled from 0–60 m depths at the Southern Lake Baikal’s basin (only the Western shore) and at the Central Baikal. They form clusters with similarity to Enterocytospora, Cucumispora, Dictyocoela, and several unassigned Microsporidia sequences, respectively. Our sequence data show similarity to previously identified microsporidian DNA from inhabitants of both Lake Baikal and other water reservoirs. The results of our study suggest that the genetic diversity of Microsporidia in haemolymph of endemic amphipods from Lake Baikal does not correlate with host species, geographic location or depth factors but is homogeneously diverse.

Highlights

Lake Baikal is the deepest (1,643 m) and oldest lake in the world (25–30 million years); it is the largest reservoir of clean fresh water, containing approximately 20% of the available world’s liquid fresh water (Martens, 1997; Yoshii, 1999)
We screened the haemolymph of 22 species (Table S1) of endemic amphipods from Lake Baikal and found microsporidian DNA in two littoral (E. verrucosus, E. cyaneus), two littoral/sublittoral (P. cancellus, E. marituji) and two sublittoral/deep-water species (A. lappaceus longispinus, A. victorii maculosus)
Twenty nucleotide sequences of small subunit ribosomal (SSU) rDNA belonging to the Cucumispora, Dictyocoela, Enterocytospora-like groups and unassigned Microsporidia were obtained from the haemolymph of the six endemic amphipod species sampled from depths of 0–60 m at Southern Lake Baikal’s basin and at Central Baikal (Table S2)

Summary

Introduction

Lake Baikal is the deepest (1,643 m) and oldest lake in the world (25–30 million years); it is the largest (by volume: 23,000 km3) reservoir of clean fresh water, containing approximately 20% of the available world’s liquid fresh water (Martens, 1997; Yoshii, 1999). How to cite this article Dimova et al (2018), Genetic diversity of Microsporidia in the circulatory system of endemic amphipods from different locations and depths of ancient Lake Baikal. As a unique ecosystem with exceptionally high degrees of biological diversity and endemism, Lake Baikal was designated a UNESCO World Heritage Site. 2,595 animal species from Lake Baikal have been described, approximately 80% of which are endemic (Timoshkin, 2001)

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