Light capture and pigment diversity in marine and freshwater cryptophytes.

Abstract

Phenotypic traits associated with light capture andphylogenetic relationships were characterized in 34 strains of diversely pigmented marine and freshwater cryptophytes. Nuclear SSU and partial LSU rDNA sequence data from 33 of these strains plus an additional 66 strains produced aconcatenated rooted maximum likelihood tree that classified the strains into 7 distinct clades. Molecular and phenotypic datatogether support: (i) the reclassification of Cryptomonas irregularis NIES 698 tothe genus Rhodomonas, (ii) revision of phycobiliprotein (PBP) diversity within the genus Hemiselmis to include cryptophyte phycocyanin (Cr-PC) 569, (iii) the inclusion of previously unidentified strain CCMP 2293 into the genus Falcomonas, even though it contains cryptophyte phycoerythrin 545 (Cr-PE 545), and (iv) the inclusion of previously unidentified strain CCMP 3175, which contains Cr-PE 545, in aclade with PC-containing Chroomonas species. Adiscriminant analysis-based model of group membership correctly predicted 70.6% of the clades using three traits: PBP concentration · cell-1 , the wavelength of PBP maximal absorption, and habitat. Non-PBP pigments (alloxanthin, chl-a, chl-c2 , α-carotene) did not contribute significantly to group classification, indicating the potential plasticity of these pigments and the evolutionary conservation of the PBPs. Pigment data showed evidence of trade-offs in investments in PBPs vs. chlorophylls (a +c2 ).