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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - The recent and rapid spread of Themeda triandra
AU - Dunning, Luke T.
AU - Liabot, Anne-Lise
AU - Olofsson, Jill K.
AU - Smith, Emma K.
AU - Vorontsova, Maria S.
AU - Besnard, Guillaume
AU - Simpson, Kimberley J.
AU - Lundgren, Marjorie R.
AU - Addicott, Eda
AU - Gallagher, Rachael V.
AU - Chu, Yingying
AU - Pennington, R. Toby
AU - Christin, Pascal-Antoine
AU - Lehmann, Caroline E. R.
PY - 2017
Y1 - 2017
N2 - Tropical savannas cover over 20% of land surface. They sustain a high diversity of mammalian herbivores and promote frequent fires, both of which are dependent on the underlying grass composition. These habitats are typically dominated by relatively few taxa, and the evolutionary origins of the dominant grass species are largely unknown. Here, we trace the origins of the genus Themeda, which contains a number of widespread grass species dominating tropical savannas. Complete chloroplast genomes were assembled for seven samples and supplemented with chloroplast and nuclear ITS markers for 71 samples representing 18 of the 27 Themeda species. Phylogenetic analysis supports a South Asian origin for both the genus and the widespread dominant T. triandra. This species emerged similar to 1.5 Ma from a group that had lived in the savannas of Asia for several million years. It migrated to Australia similar to 1.3 Ma and to mainland Africa similar to 0.5 Ma, where it rapidly spread in pre-existing savannas and displaced other species. Themeda quadrivalvis, the second most widespread Themeda species, is nested within T. triandra based on whole chloroplast genomes, and may represent a recent evolution of an annual growth form that is otherwise almost indistinguishable from T. triandra. The recent spread and modernday dominance of T. triandra highlight the dynamism of tropical grassy biomes over millennial time-scales that has not been appreciated, with dramatic shifts in species dominance in recent evolutionary times. The ensuing species replacements likely had profound effects on fire and herbivore regimes across tropical savannas.
AB - Tropical savannas cover over 20% of land surface. They sustain a high diversity of mammalian herbivores and promote frequent fires, both of which are dependent on the underlying grass composition. These habitats are typically dominated by relatively few taxa, and the evolutionary origins of the dominant grass species are largely unknown. Here, we trace the origins of the genus Themeda, which contains a number of widespread grass species dominating tropical savannas. Complete chloroplast genomes were assembled for seven samples and supplemented with chloroplast and nuclear ITS markers for 71 samples representing 18 of the 27 Themeda species. Phylogenetic analysis supports a South Asian origin for both the genus and the widespread dominant T. triandra. This species emerged similar to 1.5 Ma from a group that had lived in the savannas of Asia for several million years. It migrated to Australia similar to 1.3 Ma and to mainland Africa similar to 0.5 Ma, where it rapidly spread in pre-existing savannas and displaced other species. Themeda quadrivalvis, the second most widespread Themeda species, is nested within T. triandra based on whole chloroplast genomes, and may represent a recent evolution of an annual growth form that is otherwise almost indistinguishable from T. triandra. The recent spread and modernday dominance of T. triandra highlight the dynamism of tropical grassy biomes over millennial time-scales that has not been appreciated, with dramatic shifts in species dominance in recent evolutionary times. The ensuing species replacements likely had profound effects on fire and herbivore regimes across tropical savannas.
KW - Biogeography
KW - C-4 grassland
KW - savanna
KW - evolution
KW - molecular dating
KW - Themeda triandra
KW - PLANT DIVERSITY
KW - C-4 GRASSLANDS
KW - FIRE
KW - VEGETATION
KW - POACEAE
KW - DIVERSIFICATION
KW - EVOLUTIONARY
KW - PHYLOGENY
KW - GRAMINEAE
KW - EXPANSION
U2 - 10.1080/23818107.2017.1391120
DO - 10.1080/23818107.2017.1391120
M3 - Journal article
VL - 164
SP - 327
EP - 337
JO - Botany letters
JF - Botany letters
SN - 2381-8107
IS - 4
ER -