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Abstract Detail

Tropical Biology

Vorontsova, Maria S. [1], Nanjarisoa, Olinirina P. [2], Hackel, Jan [3], Besnard, Guillaume [3], Linder, Peter [4].

The Grasses and Grasslands of Madagascar: a multidisciplinary Investigation.

The dominant narrative regarding human arrival in Madagascar has long stated that people arrived 2,500 years ago to a largely forested island, with anthropogenic destruction responsible for the 65% of Madagascar’s land area now covered in grasslands and savannas. Scarcity of lake bed deposits have made paleoenvironmental reconstruction difficult. One piece of the puzzle regarding Madagascar’s grasslands remains missing: the grasses themselves have never been fully documented or considered in an ecological perspective. Herbarium specimens of Malagasy grasses (family Poaceae) were studied, taxonomic revisions produced, and new species described during the six years of this project. Regular field work has targeted locations of poorly known endemic grasses and species knowledge has been built up throughout the island. Phylogenetic trees were reconstructed and dating was carried out in order to document all instances of Poaceae diversifications into Madagascar. Plot data recording species composition, phylogenetic diversity, and disturbance levels has been gathered at 80 sites. 217 of Madagascar’s 541 grass species are endemic, a level of endemicity in line with the grass floras of other subtropical islands. We have identified 97 endemic lineages of grasses, which have colonised Madagascar primarily from Africa, with a mean age of 3.5 million years. Half of the grass dispersals into Madagascar were C4 lineages pre-adapted to open habitats. The earliest endemic lineage Lecomtella madagascariensis arrived ca 22 million years ago. Madagascar’s High Plateau is home to a unique and endemic grass flora. A checklist if the Itremo Protected Area has revealed 99 species of Poaceae, with 20 restricted to the High Plateau. Phylogenetic diversity within grassy ecosystems of Madagascar decreases in areas with strong physical disturbance, indicating ecosystems dynamics typical of natural assemblages. We demonstrate that Madagascar is home to an ancient and diverse grass flora, with local species assemblages functioning similarly to natural ecosystems. This suggests that pre-human Madagascar was home to at least some tropical grassy biomes. Work continues to determine where these were located, and how can they be distinguished from anthropogenic landscapes resulting from forest destruction.

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Related Links:
Grasses and savannas of Madagascar project outline
Kew news article
Kew Madagascar Conservation Centre

1 - Royal Botanic Gardens, Kew, Comparative Plant & Fungal Biology, Richmond, Surrey, TW9 3AE, UK
2 - Kew Madagascar Conservation Centre, Lot II J 131 B, Ambodivoanjo, Ivandry, Antananarivo , 101, Madagascar
3 - CNRS/ENSFEA/IRD/Université Toulouse III, Laboratoire Evolution & Diversité Biologique (EDB, UMR 5174), 118 route de Narbonne, Toulouse, 31062, France

Phylogenetic Diversity
Indian Ocean
new species
land use.

Presentation Type: Oral Paper
Session: 21, Tropical Biology
Location: Fort Worth Ballroom 1/Omni Hotel
Date: Tuesday, June 27th, 2017
Time: 8:45 AM
Number: 21002
Abstract ID:461
Candidate for Awards:None

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