Phylogenetic relationships of aquatic and terrestrialTetradesmus
Of the 25 known species in the green algal genus Tetradesmus,five were described from terrestrial habitats (Lewis & Flechtner 2005, Mikhailyuk et al. 2019, Terlova & Lewis 2019). Strain UTEX 72 was confirmed as a strain of T. obliquus in the present study.As shown in our study (Fig. 1) and in Terlova & Lewis (2019), not all terrestrial taxa are reconstructed as closest sister taxa, with aquaticT. “raciborskii ” sharing a common ancestor with terrestrialT. bajacalifornicus . The other aquatic taxa T. obliquusand T. distendus were further separated from the first group by intervening terrestrial taxa. This result supports habitat switches within the genus, although the direction of these are not testable in the present study (Fig. 1). However, given the contrasting habitats ofTetradesmus species, we tested the hypothesis of distinct responses to desiccation and rehydration by the aquatic and the terrestrial congeners.