Alloteropsis
| Alloteropsis | |
|---|---|
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| Alloteropsis cimicina | |
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Monocots |
| (unranked): | Commelinids |
| Order: | Poales |
| Family: | Poaceae |
| Genus: |
Alloteropsis Presl |
| Type species | |
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Alloteropsis distachya (syn. of A. semialata) Presl |
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| Synonyms | |
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Alloteropsis (from the Greek allotrios ("strange") and opsis ("appearance")) is a genus of Old World plants in the grass family.
The group is widely distributed in tropical and subtropical parts of Africa, Asia and Australia, as well as on certain islands in the Indian and Pacific Oceans. The genus is unusual among plants in that it includes species with both C3 and C4 photosynthetic pathways, and ongoing research is investigating these taxa as a case study in how carbon concentrating mechanisms for photosynthesis evolve in land plants.
Most of the species of Alloteropsis use variants of the C4 photosynthetic pathway, but A. semialata ssp. eckloniana uses the C3 photosynthetic pathway. Phylogenetic reconstructions of the evolutionary relationships between these species have led to two hypotheses about how photosynthetic pathways have evolved within the group. First, C4 photosynthesis evolved in three lineages within this group, leading to independently derived realisations of this pathway (the hypothesis of multiple C4 origins). Secondly, that there was a single origin of C4 photosynthesis within the genus, and the C3 taxon, A. s. ecklonia, was subsequently derived from a C4ancestor (the reversion hypothesis). Since C4 photosynthesis is a complex trait, its evolution followed by a reversion to the ancestral type of C3 photosynthesis would represent an exception to Dollo's law.
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