Cheryl & ethnovet: Evolutionary history and leaf succulence as explanations for medicinal use in aloes and the global popularity of Aloe vera.

Monday, 16 November 2015

Evolutionary history and leaf succulence as explanations for medicinal use in aloes and the global popularity of Aloe vera.

2015 Feb 26;15:29. doi: 10.1186/s12862-015-0291-7.

Grace OM^1,², Buerki S³, Symonds MR⁴, Forest F⁵, van Wyk AE⁶, Smith GF^7,^8,⁹, Klopper RR^10,¹¹, Bjorå CS¹², Neale S¹³, Demissew S¹⁴, Simmonds MS¹⁵, Rønsted N¹⁶.

Author information

¹Jodrell Laboratory, Royal Botanic Gardens, Kew, Surrey, London, TW9 3DS, UK. o.grace@kew.org.
²Natural History Museum of Denmark, University of Copenhagen, Sølvgade 83 Entrance S, DK1307, Copenhagen K, Denmark. o.grace@kew.org.
³Department of Life Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, UK. s.buerki@nhm.ac.uk.
⁴Centre for Integrative Ecology, School of Life & Environmental Sciences, Deakin University, 221 Burwood Highway, Burwood, Victoria, 3125, Australia. matthew.symonds@deakin.edu.au.
⁵Jodrell Laboratory, Royal Botanic Gardens, Kew, Surrey, London, TW9 3DS, UK. f.forest@kew.org.
⁶Department of Plant Science, H.G.W.J. Schweickerdt Herbarium, University of Pretoria, Pretoria, 0002, South Africa. braam.vanwyk@up.ac.za.
⁷Biosystematics Research & Biodiversity Collections Division, South African National Biodiversity Institute, Private Bag X101, Pretoria, 0001, South Africa. G.Smith@sanbi.org.za.
⁸Department of Botany, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth, 6031, South Africa. G.Smith@sanbi.org.za.
⁹Departamento de Ciências da Vida, Centre for Functional Ecology, Universidade de Coimbra, 3001-455, Coimbra, Portugal. G.Smith@sanbi.org.za.
¹⁰Department of Plant Science, H.G.W.J. Schweickerdt Herbarium, University of Pretoria, Pretoria, 0002, South Africa. R.Klopper@sanbi.org.za.
¹¹Biosystematics Research & Biodiversity Collections Division, South African National Biodiversity Institute, Private Bag X101, Pretoria, 0001, South Africa. R.Klopper@sanbi.org.za.
¹²Natural History Museum, University of Oslo, PO Box 1172, Blindern, NO-0318, Oslo, Norway. charlotte.bjora@nhm.uio.no.
¹³Centre for Middle Eastern Plants, Royal Botanic Garden Edinburgh, 20A Inverleith Row, Edinburgh, EH3 5LR, UK. s.neale@cmep.org.uk.
¹⁴Department of Plant Biology and Biodiversity Management, National Herbarium, College of Natural Sciences, Addis Ababa University, PO Box 3434, Addis Ababa, Ethiopia. sebseb.demissew@gmail.com.
¹⁵Jodrell Laboratory, Royal Botanic Gardens, Kew, Surrey, London, TW9 3DS, UK. m.simmonds@kew.org.
¹⁶Natural History Museum of Denmark, University of Copenhagen, Sølvgade 83 Entrance S, DK1307, Copenhagen K, Denmark. nronsted@snm.ku.dk.

Abstract

BACKGROUND:

Aloe vera supports a substantial global trade yet its wild origins, and explanations for its popularity over 500 related Aloe species in one of the world's largest succulent groups, have remained uncertain. We developed an explicit phylogenetic framework to explore links between the rich traditions of medicinal use and leaf succulence in aloes.

RESULTS:

The phylogenetic hypothesis clarifies the origins of Aloe vera to the Arabian Peninsula at the northernmost limits of the range for aloes. The genus Aloe originated in southern Africa ~16 million years ago and underwent two major radiations driven by different speciation processes, giving rise to the extraordinary diversity known today. Large, succulent leaves typical of medicinal aloes arose during the most recent diversification ~10 million years ago and are strongly correlated to the phylogeny and to the likelihood of a species being used for medicine. A significant, albeit weak, phylogenetic signal is evident in the medicinal uses of aloes, suggesting that the properties for which they are valued do not occur randomly across the branches of the phylogenetic tree.

CONCLUSIONS:

Phylogenetic investigation of plant use and leaf succulence among aloes has yielded new explanations for the extraordinary market dominance of Aloe vera. The industry preference for Aloe vera appears to be due to its proximity to important historic trade routes, and early introduction to trade and cultivation. Well-developed succulent leaf mesophyll tissue, an adaptive feature that likely contributed to the ecological success of the genus Aloe, is the main predictor for medicinal use among Aloe species, whereas evolutionary loss of succulence tends to be associated with losses of medicinal use. Phylogenetic analyses of plant use offer potential to understand patterns in the value of global plant diversity.