Abstract
Phylogenetic interrelationships among all 18 families of Poales were assessed by cladistic analysis of chloroplast DNA rbcL and atpB sequences from 65 species. There are two well-supported main clades; the graminoid clade with Poaceae (grasses), Anarthriaceae, Centrolepidaceae, Ecdeiocoleaceae, Flagellariaceae, Joinvilleaceae, and Restionaceae; and the cyperoid clade with Cyperaceae, Juncaceae, and Thurniaceae. A sister group relationship between Poaceae and Ecdeiocoleaceae is identified with strong support. The sister group of this pair is Joinvilleaceae. These relationships help in elucidating the evolution of grasses and the grass spikelet. Dating of the tree was done by nonparametric rate smoothing of rbcL molecular evolution. Most Poales families date back to the Cretaceous >65 million years ago (mya). Dispersal-vicariance analysis indicates that the Poales originated in South America, the cyperoid clade in West Gondwana (South America or Africa), and the graminoid clade in East Gondwana (Australia). The Trans-Antarctic connection between South America and Australia, and its breakup about 35 mya, probably influenced the evolution of the Poales and the graminoid clade in particular, leading to vicariance between the continents, but the separation of Africa from the other Gondwanan areas, completed about 105 mya, is too old for such a relation.
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Claims 9
Claim · model-written summary
Poales comprised two well-supported main clades, graminoid and cyperoid.
- Outcome
- two well-supported main cladese0
Verbatim
e0“There are two well-supported main clades; the graminoid clade with Poaceae (grasses), Anarthriaceae, Centrolepidaceae, Ecdeiocoleaceae, Flagellariaceae, Joinvilleaceae, and Restionaceae; and the cyperoid clade with Cyperaceae, Juncaceae, and Thurniaceae”
t0“POALES”
Claim · model-written summary
Poaceae and Ecdeiocoleaceae were strongly supported sister groups.
- Outcome
- sister group relationship between Poaceae and Ecdeiocoleaceaee0
Verbatim
e0“A sister group relationship between Poaceae and Ecdeiocoleaceae is identified with strong support”
Claim · model-written summary
Joinvilleaceae was the sister group of the Poaceae and Ecdeiocoleaceae pair.
- Taxon
- JoinvilleaceaeJoinvilleaceaee0
- Outcome
- sister group of this paire0
Verbatim
e0“The sister group of this pair is Joinvilleaceae”
e1“between Poaceae and Ecdeiocoleaceae”
Claim · model-written summary
Most Poales families were dated to the Cretaceous, more than 65 million years ago.
Verbatim
e0“Most Poales families date back to the Cretaceous >65 million years ago (mya)”
Claim · model-written summary
Dispersal-vicariance analysis placed the Poales origin in South America.
Verbatim
e0“Dispersal-vicariance analysis indicates that the Poales originated in South America”
Claim · model-written summary
The cyperoid clade was inferred to originate in West Gondwana.
Verbatim
e0“the cyperoid clade in West Gondwana (South America or Africa)”
Claim · model-written summary
The graminoid clade was inferred to originate in East Gondwana.
Verbatim
e0“the graminoid clade in East Gondwana (Australia)”
Claim · model-written summary
The Trans-Antarctic connection and breakup probably influenced Poales evolution through vicariance.
Verbatim
e0“The Trans-Antarctic connection between South America and Australia, and its breakup about 35 mya, probably influenced the evolution of the Poales and the graminoid clade in particular, leading to vicariance between the continents”
Claim · model-written summary
African separation was judged too old to explain this vicariance.
Verbatim
e0“the separation of Africa from the other Gondwanan areas, completed about 105 mya, is too old for such a relation”
e1“evolution of the Poales”