Book contents
- Frontmatter
- Contents
- Preface to the first edition
- Part 1 Introduction
- Part II The prokaryotic algae
- Part III Evolution of the chloroplast
- 3 Glaucophyta
- 4 Rhodophyta
- 5 Chlorophyta
- Part IV Evolution of one membrane of chloroplast endoplasmic reticulum
- Part V Evolution of two membranes of chloroplast endoplasmic reticulum and the Chlorarachniophyta
- Glossary
- Index
4 - Rhodophyta
- Frontmatter
- Contents
- Preface to the first edition
- Part 1 Introduction
- Part II The prokaryotic algae
- Part III Evolution of the chloroplast
- 3 Glaucophyta
- 4 Rhodophyta
- 5 Chlorophyta
- Part IV Evolution of one membrane of chloroplast endoplasmic reticulum
- Part V Evolution of two membranes of chloroplast endoplasmic reticulum and the Chlorarachniophyta
- Glossary
- Index
Summary
RHODOPHYCEAE
The Rhodophyceae, or red algae, comprise the only class in the division Rhodophyta. The Rhodophyceae are probably one of the oldest groups of eukaryotic algae. The red algae are most likely directly descended from a cyanome in the Glaucophyta (see Chapter 3). It is likely that the first red alga evolved into an ecological niche that was unoccupied by cyanobacteria, the only extant photosynthetic alga that evolved oxygen. This ecological niche would have been in waters with a pH less than 5, which, for some unknown reason, cyanobacteria are not able to inhabit (Brock, 1973). Indeed, modern phylogenetic studies utilizing nucleic-acid sequencing have shown that Cyanidium, an alga that lives in acidic waters, is probably the oldest extant red alga (Oliveira and Bhattacharya, 2000).
The Rhodophyceae lack flagellated cells, have chlorophyll a, phycobiliproteins, floridean starch as a storage product, and thylakoids occurring singly in the chloroplast.
A majority of the sea weeds are red algae, and there are more Rhodophyceae (about 4000 species) than all of the other major seaweed groups combined. Although marine red algae occur at all latitudes, there is a marked shift in their abundance from the equator to colder seas. There are few species in polar and subpolar regions where brown and green algae predominate, but in temperate and tropical regions they far outnumber these groups. The average size of the plants also differs according to geographical region.
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- Phycology , pp. 89 - 138Publisher: Cambridge University PressPrint publication year: 2008
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