Light Antennas in phototactic algae.

A broad overview of the diversity of living dinoflagellates is presented in a hypothetical evolutionary context. Ultrastructural, and some physiological information is included. Five principal organizational types: prorocentroid, dinophysoid, gonyaulacoid, peridinioid and gymnodinoid, are taken to represent lineages, and the developments within each summarized. Thecal evolution is discussed partly with the aid of a model developed to determine probable plate homologies in the gonyaulacoids and peridinioids. Both primitive and highly specialized features are drawn attention to, particularly with regard to the nucleus and ocelli. The parallelism between the latter and metazoan eyes is extraordinary, considering that the dinoflagellate organelles are made of subcellular components. The roles of various types of cysts within the lifecycle of dinoflagellates are discussed. The compatibility of the hypothetical events proposed here with the fossil record is briefly considered, and some indications of the phyletic position of dinoflagellates are reviewed. The conclusions summarize the principal developments that appear to have arisen within the group. The relative primitiveness of the desmokonts is affirmed. A new combination, Plectodinium miniatum (Kofoid and Swezy) comb. nov. is proposed, as well as the recognition of a new order, the Gonyaulacales ord. nov.

On dinoflagellate evolution

Publisher Summary Mitosis is defined as all those types of nuclear division that produce two, or rarely more, daughter nuclei, each containing a chromosome complement approximately similar to that of the original nucleus. The greatest range of variations by which mitosis is accomplished, occurs in the protistan and fungal kingdoms, some members of which are probably most similar to the ancestors of higher plants and animals. The variations in the higher organisms are secondarily derived from the division patterns of typical plants and animals. This chapter discusses the characteristics and evolution of mitosis. The efficiency of mitosis consists of two basic components; the frequency with which each daughter nucleus receives the necessary complete genome complement (genetic efficiency) and the amount of energy and materials expended in the synthesis and operation of the mitotic apparatus. The chapter also discusses the use of mitosis as a phylogenetic marker. It is applicable to all eukaryotic cells and thus is valuable across boundaries where other structures are absent on one side and present in various forms on the other side.

B. T. Bibby

Papers

The Prorocentrales (Dinophyceae): I. A comparative account of fine structure in the genera Prorocentrum and Exuviaella