Альвеолаттар: Протисттердің жоғары тобының эволюциясы мен сипаттамасы

Superphylum of protists

The alveolates (meaning "pitted like a honeycomb") are a group of protists, considered a major clade and superphylum within Eukarya. They are currently grouped with the stramenopiles and Rhizaria among the protists with tubulocristate mitochondria into the SAR supergroup.

The development of plastids among the alveolates is intriguing. Cavalier Smith proposed the alveolates developed from a chloroplast containing ancestor, which also gave rise to the Chromista (the chromalveolate hypothesis). Other researchers have speculated that the alveolates originally lacked plastids and possibly the dinoflagellates and Apicomplexa acquired them separately. However, it now appears that the alveolates, the dinoflagellates, the Chromerida and the heterokont algae acquired their plastids from a red alga with evidence of a common origin of this organelle in all these four clades.

A Bayesian estimate places the evolution of the alveolate group at ~. The Alveolata consist of Myzozoa, Ciliates, and Colponemids. In other words, the term Myzozoa, meaning "to siphon the contents from prey", may be applied informally to the common ancestor of the subset of alveolates that are neither ciliates nor colponemids. Predation upon algae is an important driver in alveolate evolution, as it can provide sources for endosymbiosis of novel plastids. The term Myzozoa is therefore a handy concept for tracking the history of the alveolate phylum. The ancestors of the alveolate group may have been photosynthetic. The ancestral alveolate probably possessed a plastid. Chromerids, apicomplexans, and peridinin dinoflagellates have retained this organelle. Going one step even further back, the chromerids, the peridinin dinoflagellates and the heterokont algae have been argued to possess a monophyletic plastid lineage in common, i. e. acquired their plastids from a red alga, While the common ancestor of alveolates may also have possessed some of these characteristics, it has been argued that Myzocytosis was not one of these characteristics, as ciliates ingest prey by a different mechanism. have been unable to rule out that the shared stramenopile alveolate plastid could have been recycled multiple times in the alveolate phylum, the source being stramenopile alveolate donors, through the mechanism of ingestion and endosymbiosis. Ciliates are a model alveolate, having been genetically studied in great depth over the longest period of any alveolate lineage. They are unusual among eukaryotes in that reproduction involves a micronucleus and a macronucleus. Their reproduction is easily studied in the lab, and made them a model eukaryote historically. Being entirely predatory and lacking any remnant plastid, their development as a phylum illustrates how predation and autotrophy