DIVERSITY OF LIFE

DESCRIPTION OF THE KINGDOM ALVEOLATAE (CAVALIER-SMITH 1993)

EUKARYA>CHROMALVEOLATA>ALVEOLATAE
Alveolatae (al-vee-o-LA-tee) is made of a Latin root (alveolus) that means little cavity or bag.  The reference is to the bag-like structures beneath the cell membrane  

INTRODUCTION TO THE ALVEOLATAE

Taylor (1999) described the "Alveolata" as a member of the crown eukaryotes and a sister to the Heterokontae.  More recently, Baldauf (2003a) summarized molecular and ultrastructural information to condense the eukaryotes into eight supergroups, one of which was the alveolates.  Her summary both confirmed the natural status of the alveolates and dismissed the concept of the crown eukaryotes as an artifact of single gene comparisons.   Harper et al. (2005) used a 6-protein phylogeny of eukaryote taxa and provided strong evidence that they are part of a larger clade (alveolates+heterokonts) and have a weak association with the cryptomonad+haptomonad clade (Hacrobia).  Keeling (2004) also suggested the same relationship in a supergroup called the chromalveolates [formalized to Chromalveolata].

The alveolates are now seen as an organization of three well-defined and seemingly disparate phyla: Dinoflagellata, Ciliata, and Apicomplexata.  The connection between the dinoflagellates and the ciliates was first proposed by Taylor (1976).  The association of the apicomplexan sporozoans with the others and the coherence of the group were confirmed by Gajadhar et al. (1991).  Patterson (1999) said that the main synapomorphy [and the one that Cavalier-Smith (1993) used to name the group] for the group is the occurrence of alveoli or membranous sacs that lie beneath the plasmalemma.  The alveoli form a layer beneath the cell membrane that is broken only by extrusosomes (e.g. trichocysts).  Their flagella (or cilia), when present,  usually come in pairs, one of which has a cross-striated root. 

Notable differences between the phyla of this system and Margulis and Schwartz (1998) include the union of their phyla Dinomastigota (Pr-7), Ciliata (Pr-8), and Apicomplexa (Pr-9) into a separate kingdom.  Margulis and Schwartz (1998) also show the derivation of the Plants and the Chlorophyta (Pr-28) from the alveolate line, a view that we cannot support. 

 

 

FIGURE 1. Topology of the alveolates within the higher taxa of the Chromalveolata as given by Baldauf (2003), Keeling (2004), and Harper et al. (2005).  The basal position of the ciliates and the sister relationship between apicomplexans and dinoflagellates have been confirmed. 

 

 

PHYLA OF THE KINGDOM ALVEOLATAE

 

 

DINOFLAGELLATA (Bütschli 1885)
CILIOPHORA (Doflein 1901)
APICOMPLEXA (Levine 1970)

 

 
FURTHER READING:

DISCOVERY OF THE DOMAINS OF LIFE

INTRODUCTION TO THE DOMAIN EUKARYA

 

LITERATURE CITED

Baldauf, S. L. 2003a. The deep roots of eukaryotes. Science. 300 (5626): 1701-1703.

Bütschli, O. 1883–1887. Protozoa. Abtheilung II. Mastigophora. In: Bronn, H. G., ed. Klassen und Ordungen des Thier-Reichs. C. F. Winter, Leipzig . 1: 6171097.

Cavalier-Smith, T. 1993. Kingdom protozoa and its 18 Phyla. Microbiological Reviews. 57: 953-994.

Doflein, F. 1901. Die Protozoen als Parasiten und Krankheitsrreger nach Biologischen Gesichtspunkten Dargestellt. Verlag von Gustav Fischer. Jena.

Gajadhar, A. A., W. C. Marquardt, R. Hall, J. Gunderson, E. V. A. Carmona, and M. L. Sogin. 1991. Ribosomal RNA sequences of Sarcocystis muris, Theileria annulata, and Crypthecodinium cohnii reveal evolutionary relationships among apicomplexans, dinoflagellates, and ciliates. Molecular and Biochemical Parasitology. 45:147-154.

Harper, J. T., E. Waanders, and P. J. Keeling. 2005. On the monophyly of chromalveolates using a six-protein phylogeny of eukaryotes. International Journal of Systematic and Evolutionary Microbiology. 55: 487-496.

Keeling P. J. 2004. The diversity and evolutionary history of plastids and their hosts. American Journal of Botany. 91(10): 1481-1493.

Levine, N. D. 1985. Phylum Apicomplexa. In: Lee, J. J., S.H. Hunter, and E. C. Bovee, eds. An Illustrated Guide to the Protozoa. Allen Press. Lawrence, Kansas. pp. 322-374. 

Margulis, L. and K. Schwartz. 1998. Five kingdoms, an illustrated guide to the phyla of life on earth. 3rd Edition. W. H. Freeman and Company.  New York.

Patterson, D. J. 1999. The diversity of eukaryotes. American Naturalist. 154 (Suppl.): S96–S124.

Taylor, F.J.R. 1976. Flagellate Phylogeny: A Study in Conflicts. Journal of Protozoology. 23: 28-40.

Taylor, F.J.R. 1999. Ultrastructure as a control for protistan molecular phylogeny. The American Naturalist. 154(supplement): S125-S136.

 

By Jack R. Holt.  Last revised: 03/03/2013