thatbiogeek
Registered Member
Keeling, Patrick J. (2004) Diversity and Evolutionary History of Plastids and Their Hosts American Journal of Botany. 91:1481-1493
LINKS: PDF or HTML format
ABSTRACT:
By synthesizing data from individual gene phylogenies, large concatenated gene trees, and other kinds of molecular, morphological, and biochemical markers, we begin to see the broad outlines of a global phylogenetic tree of eukaryotes. This tree is apparently composed of five large assemblages, or "supergroups." Plants and algae, or more generally eukaryotes with plastids (the photosynthetic organelle of plants and algae and their nonphotosynthetic derivatives) are scattered among four of the five supergroups. This is because plastids have had a complex evolutionary history involving several endosymbiotic events that have led to their transmission from one group to another. Here, the history of the plastid and of its various hosts is reviewed with particular attention to the number and nature of the endosymbiotic events that led to the current distribution of plastids. There is accumulating evidence to support a single primary origin of plastids from a cyanobacterium (with one intriguing possible exception in the little-studied amoeba Paulinella), followed by the diversification of glaucophytes, red and green algae, with plants evolving from green algae. Following this, some of these algae were themselves involved in secondary endosymbiotic events. The best current evidence indicates that two independent secondary endosymbioses involving green algae gave rise to euglenids and chlorarachniophytes, whereas a single endosymbiosis with a red algae gave rise to the chromalveolates, a diverse group including cryptomonads, haptophytes, heterokonts, and alveolates. Dinoflagellates (alveolates) have since taken up other algae in serial secondary and tertiary endosymbioses, raising a number of controversies over the origin of their plastids, and by extension, the recently discovered cryptic plastid of the closely related apicomplexan parasites.
This article is number 7 on AMJBOT's most read articles, so you can see it's been looked at quite a bit. Since it's publication in 2004, this article has been cited in 56 subsequent papers as reported by ISI Web of Knoledge.
The article seems a good candidate for discussion here. It has an interesting and possibly overarching hypothesis, which if correct alters the way we think about plastid evolution and would explain why it has been so difficult to understand basal Eukaryote evolution using chloroplast genes. It is four years old, so maybe some of you have read it already.
I've skimmed the article and it seems interesting. I'm going to read it and post my thoughts on my blog. Does anyone here think they'd like to discuss it? I'll read it more thoroughly tonight and post what I think in the morning.
I think I'll also look through the more recent articles which have cited Keeling (2004) and see how his hypothesis has held up and what others have done with it.
Jessica
ETA: The journal looks long, but there are about two pages of citations and quite a few large diagrams so it really isn't that bad. The illustration of endosymbiosis in the history of plastid evolution is really interesting.
LINKS: PDF or HTML format
ABSTRACT:
By synthesizing data from individual gene phylogenies, large concatenated gene trees, and other kinds of molecular, morphological, and biochemical markers, we begin to see the broad outlines of a global phylogenetic tree of eukaryotes. This tree is apparently composed of five large assemblages, or "supergroups." Plants and algae, or more generally eukaryotes with plastids (the photosynthetic organelle of plants and algae and their nonphotosynthetic derivatives) are scattered among four of the five supergroups. This is because plastids have had a complex evolutionary history involving several endosymbiotic events that have led to their transmission from one group to another. Here, the history of the plastid and of its various hosts is reviewed with particular attention to the number and nature of the endosymbiotic events that led to the current distribution of plastids. There is accumulating evidence to support a single primary origin of plastids from a cyanobacterium (with one intriguing possible exception in the little-studied amoeba Paulinella), followed by the diversification of glaucophytes, red and green algae, with plants evolving from green algae. Following this, some of these algae were themselves involved in secondary endosymbiotic events. The best current evidence indicates that two independent secondary endosymbioses involving green algae gave rise to euglenids and chlorarachniophytes, whereas a single endosymbiosis with a red algae gave rise to the chromalveolates, a diverse group including cryptomonads, haptophytes, heterokonts, and alveolates. Dinoflagellates (alveolates) have since taken up other algae in serial secondary and tertiary endosymbioses, raising a number of controversies over the origin of their plastids, and by extension, the recently discovered cryptic plastid of the closely related apicomplexan parasites.
This article is number 7 on AMJBOT's most read articles, so you can see it's been looked at quite a bit. Since it's publication in 2004, this article has been cited in 56 subsequent papers as reported by ISI Web of Knoledge.
The article seems a good candidate for discussion here. It has an interesting and possibly overarching hypothesis, which if correct alters the way we think about plastid evolution and would explain why it has been so difficult to understand basal Eukaryote evolution using chloroplast genes. It is four years old, so maybe some of you have read it already.
I've skimmed the article and it seems interesting. I'm going to read it and post my thoughts on my blog. Does anyone here think they'd like to discuss it? I'll read it more thoroughly tonight and post what I think in the morning.
I think I'll also look through the more recent articles which have cited Keeling (2004) and see how his hypothesis has held up and what others have done with it.
Jessica
ETA: The journal looks long, but there are about two pages of citations and quite a few large diagrams so it really isn't that bad. The illustration of endosymbiosis in the history of plastid evolution is really interesting.
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