title: Madagascar's grasses and grasslands: anthropogenic or natural?
abstract: Grasses, by their high productivity even under very low pCO2, their ability to survive repeated burning and to tolerate long dry seasons, have transformed the terrestrial biomes in the Neogene and Quaternary. The expansion of grasslands at the cost of biodiverse forest biomes in Madagascar is often postulated as a consequence of the Holocene settlement of the island by humans. However, we show that the Malagasy grass flora has many indications of being ancient with a long local evolutionary history, much predating the Holocene arrival of humans. First, the level of endemism in the Madagascar grass flora is well above the global average for large islands. Second, a survey of many of the more diverse areas indicates that there is a very high spatial and ecological turnover in the grass flora, indicating a high degree of niche specialization. We also find some evidence that there are both recently disturbed and natural stable grasslands: phylogenetic community assembly indicates that recently severely disturbed grasslands are phylogenetically clustered, whereas more undisturbed grasslands tend to be phylogenetically more evenly distributed. From this evidence, it is likely that grass communities existed in Madagascar long before human arrival and so were determined by climate, natural grazing and other natural factors. Humans introduced zebu cattle farming and increased fire frequency, and may have triggered an expansion of the grasslands. Grasses probably played the same role in the modification of the Malagasy environments as elsewhere in the tropics.
authors.affiliation: Comparative Plant and Fungal Biology, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK m.vorontsova@kew.org.
authors.forename: Maria S
authors.identifier: http://orcid.org/0000-0003-0899-1120
authors.initials: MS
authors.lastname: Vorontsova
authors.affiliation: CNRS-UPS-ENFA, UMR5174, EDB (Laboratoire Evolution et Diversité Biologique), Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Besnard
authors.affiliation: Comparative Plant and Fungal Biology, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK.
authors.forename: Félix
authors.initials: F
authors.lastname: Forest
authors.affiliation: Comparative Plant and Fungal Biology, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK.
authors.forename: Panagiota
authors.initials: P
authors.lastname: Malakasi
authors.affiliation: Bioinformatics and Spatial Analysis, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK School of Geography, University of Nottingham, Nottingham NG7 2RD, UK.
authors.forename: Justin
authors.initials: J
authors.lastname: Moat
authors.affiliation: Comparative Plant and Fungal Biology, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK.
authors.forename: W Derek
authors.initials: WD
authors.lastname: Clayton
authors.affiliation: Comparative Plant and Fungal Biology, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK.
authors.forename: Paweł
authors.initials: P
authors.lastname: Ficinski
authors.affiliation: School of Health Sciences, University of East Anglia, Norwich, Norfolk NR4 7TJ, UK.
authors.forename: George M
authors.initials: GM
authors.lastname: Savva
authors.affiliation: Kew Madagascar Conservation Centre, II J 131 B, Ambodivoanjo, Ivandry, Antananarivo 101, Madagascar.
authors.forename: Olinirina P
authors.initials: OP
authors.lastname: Nanjarisoa
authors.affiliation: Département Botanique, Parc de Tsimbazaza, B.P. 4096, Antananarivo 101, Madagascar.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Razanatsoa
authors.affiliation: Kew Madagascar Conservation Centre, II J 131 B, Ambodivoanjo, Ivandry, Antananarivo 101, Madagascar Ecole Supérieure des Sciences Agronomiques, Université d'Antananarivo, Antananarivo 101, Madagascar.
authors.forename: Fetra O
authors.initials: FO
authors.lastname: Randriatsara
authors.affiliation: National Museums of Kenya, Museum Hill Road, PO Box 45166, Nairobi 00100, Kenya.
authors.forename: John M
authors.initials: JM
authors.lastname: Kimeu
authors.affiliation: National Museums of Kenya, Museum Hill Road, PO Box 45166, Nairobi 00100, Kenya.
authors.forename: W R Quentin
authors.initials: WR
authors.lastname: Luke
authors.affiliation: Forestry Training Institute, Olmotonyi, PO Box 943, Arusha, Tanzania.
authors.forename: Canisius
authors.initials: C
authors.lastname: Kayombo
authors.affiliation: Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, Zurich 8008, Switzerland.
authors.forename: H Peter
authors.initials: HP
authors.lastname: Linder
mesh_terms: D000383:Agriculture; D000818:Animals; D044822:Biodiversity; D005075:Biological Evolution; D002417:Cattle; D065948:Grassland; D006801:Humans; D008270:Madagascar; D006109:Poaceae / Q000235:genetics* / Q000502:physiology*
keywords: Poaceae; endemism; neogene; phylogenetic community assembly; species turnover