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Genetic variability of charophyte algae in the Baltic Sea area

Nowak, Petra, Schubert, Hendrik
Botanica marina 2019 v.62 no.1 pp. 75-82
Chara, Lamprothamnium, Tolypella, algae, ancestry, euryhaline species, genetic variation, habitats, parthenogenesis, phytogeography, population size, salinity, salt tolerance, Baltic Sea, Europe
The Baltic Sea, a young habitat in geological terms, is characterised by strong climatic and salinity gradients that determine species distribution and trigger adaptation processes. The aim here was to test the hypothesis that Baltic Sea charophytes which originate from large freshwater populations exhibit a higher genetic variability than euryhaline charophyte species, restricted to a small number of brackish-marine populations. For this, genetic variability of euryhaline, mesohaline and halotolerant freshwater charophytes with different distribution patterns and population sizes were analysed. Euryhaline Lamprothamnium papulosum, restricted to a few and small populations in the Baltic Sea, showed a complete lack of genetic variability. Also euryhaline Tolypella with large and widely distributed populations displayed only low genetic variability. On the other hand, mesohaline Chara canescens, one of the most common charophytes in the Baltic Sea, exhibited comparatively high genetic variability, in spite of its parthenogenetic mode of reproduction. Halotolerant Chara baltica, originating from freshwater ancestors with a huge number of populations all over Europe, showed a rather restricted genetic variability, indicating a habitat filter acting prior to colonisation of brackish habitats.