Premium
CHARACIOCHLORIS AND CHARACIOSIPHON FORM A SISTER GROUP TO THE “ DUNALIELLA ” LINEAGE
Author(s) -
Buchheim J.A.
Publication year - 2000
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1046/j.1529-8817.1999.00001-23.x
Subject(s) - biology , sister group , thallus , phylogenetic tree , lineage (genetic) , dunaliella , botany , clade , taxon , algae , phylogenetics , ecology , evolutionary biology , zoology , gene , genetics
The freshwater green algal genera, Characiochloris and Characiosiphon , are distinctive taxa for which no clear consensus exists regarding phylogenetic placement. Characiochloris is an epiphytic unicell that exhibits multiple (>2), scattered contractile vacuoles throughout the cytoplasm of the vegetative cell. Although Characiochloris has been placed in the Tetrasporales by most systematists, the uncertain status of this green algal order raises questions regarding the position of Characiochloris. Characiosiphon , a coenocytic freshwater organism, has been linked to another freshwater coenocyte, Protosiphon. However, multiple chloroplasts, greater thallus size, and a strictly aquatic life history for Characiosiphon have led to comparisons with caulerpalean ulvophytes. Phylogenetic analysis of 18S and 26S rDNA data was undertaken to test hypotheses of relationship for Characiochloris and Characiosiphon. Results from molecular phylogenetic analyses strongly support a sister relationship for Characiochloris and Characiosiphon. In addition, the Characiochloris / Characiosiphon clade is resolved as a sister group to the “ Dunaliella ” lineage of the Chlamydomonadales that includes Ascochloris, Chlorogonium, Dunaliella, Haematococcus, Protosiphon and Spongiochloris. These results further support the hypothesis that the “ Dunaliella ” clade includes the majority of taxa that exhibit multiple contractile vacuoles. Moreover, these results support an interpretation of the Characiosiphon coenocyte as a modified zoosporangium.