The origin and early diversification of the Ulvophyceae likely took place in the lateNeoproterozoic,[7][8] though may have taken place earlier, in the Mesoproterozoic.[9] Although most contemporary ulvophytes are marine macroalgae (seaweeds),ancestral ulvophytes may have been freshwater, unicellular green algae. Molecular phylogenetic evidence suggests that macroscopic growth was achieved independently in the various major lineages of Ulvophyceae (Ulvales-Ulotrichales,Trentepohliales,Cladophorales,Bryopsidales andDasycladales).[8] The earliest known representative is thecladophoralesProterocladus antiquus from theMesoproterozoic-Neoproterozoic boundary in North China.[10]
Current hypothesis on relationships among the main clades of Ulvophyceae[11][12] are shown below.
^Stewart KD, Mattox KR (April 1978). "Structural evolution in the flagellated cells of green algae and land plants".Bio Systems.10 (1–2):145–152.doi:10.1016/0303-2647(78)90036-9.PMID656563.
^abGuiry MD, Guiry GM (2007)."Class: Ulvophyceae taxonomy browser". AlgaeBase version 4.2 World-wide electronic publication, National University of Ireland, Galway. Retrieved2023-06-17.
^Graham LE, Graham JM, Wilcox LW (2009).Algae (2nd ed.). San Francisco, CA: Benjamin Cummings (Pearson).
^Verbruggen H, Ashworth M, LoDuca ST, Vlaeminck C, Cocquyt E, Sauvage T, et al. (March 2009). "A multi-locus time-calibrated phylogeny of the siphonous green algae".Molecular Phylogenetics and Evolution.50 (3):642–653.doi:10.1016/j.ympev.2008.12.018.PMID19141323.
^Škaloud P, Kalina T, Nemjová K, De Clerck O, Leliaert F (February 2013). "Morphology and Phylogenetic Position of the Freshwater Green Microalgae Chlorochytrium (Chlorophyceae) and Scotinosphaera (Scotinosphaerales, ord. nov., Ulvophyceae)".Journal of Phycology.49 (1):115–129.doi:10.1111/jpy.12021.PMID27008394.S2CID7359581.
