Preface

Discoveries of new species have always represented a demanding challenge for mankind, derived from the human wish to improve the quality of his own life. Each new specie has always been considered as a potential new food or medicine, as well as a possible source of fuel or clothes. But today, exploring new animal and plant species mainly derives from men's effort to try to understand the life on Earth in order to tackle some of the problems caused by his own species.

The current world's biodiversity consists of an innumerable amount of dynamic species in constant pursuit of the best solutions to react and survive the natural and anthropic environmental changes, suggesting us innovative strategies to overcome human limits and live better.

*"Blind metaphysical necessity, which is certainly the same always and every where, could produce no variety of things. All that diversity of natural things which we find suited to different times and places could arise from nothing but the ideas and will of a Being necessarily existing."* 

(from *Philosophiae naturalis principia matematica*, Isaac Newton, 1687)

Divided into 15 chapters written by internationally renowned contributors, this book offers a few case studies about the diversity of many life forms. It includes systematic overviews, biogeographic and phylogenic backgrounds, species composition and spatial distribution in more or less restricted areas of the world, offering to the reader an overall view of the present condition in which our planet is.

> **Oscar Grillo** Stazione Sperimentale di Granicoltura per la Sicilia, Caltagirone Biodiversity Conservation Centre, University of Cagliari Italy

> > **Gianfranco Venora**

Stazione Sperimentale di Granicoltura per la Sicilia, Caltagirone, Italy

**1** 

*France*

**Biodiversity and Evolution in the** *Vanilla* **Genus** 

Gigant Rodolphe1,2, Bory Séverine1,2, Grisoni Michel2 and Besse Pascale1

Since the publication of the first vanilla book by Bouriquet (1954c) and the more recent review on vanilla biodiversity (Bory et al., 2008b), there has been a world regain of interest for this genus, as witnessed by the recently published vanilla books (Cameron, 2011a; Havkin-Frenkel & Belanger, 2011; Odoux & Grisoni, 2010). A large amount of new data regarding the genus biodiversity and its evolution has also been obtained. These will be

*Vanilla* Plum. ex Miller is an ancient genus in the Orchidaceae family, Vanilloideae sub-

*Vanilla* species are distributed throughout the tropics between the 27th north and south parallels, but are absent in Australia. The genus is most diverse in tropical America (52 species), and can also be found in Africa (14 species) and the Indian ocean islands (10 species), South-East Asia and New Guinea (31 species) and Pacific islands (3 species) (Portères, 1954). From floral morphological observations, Portères (1954) suggested a primary diversification centre of the *Vanilla* genus in Indo-Malaysia, followed by dispersion on one hand from Asia to Pacific and then America, and on the other hand from Madagascar to Africa. This hypothesis was rejected following the first phylogenetic studies of the genus (Cameron, 1999, 2000) which suggested a different scenario with an American origin of the genus (160 to 120 Mya) and a transcontinental migration of the *Vanilla* genus before the break-up of Gondwana (Cameron, 2000, 2003, 2005; Cameron et al., 1999). The genetic differentiation between New World and Old World species observed would therefore be a consequence of the further separation of the continents. Our recent molecular phylogeny using chloroplastic *psa*B, *psb*B, *ps*bC, and *rbc*L regions (Bouetard et al., 2010) supported the hypothesis of an American origin of the genus (figure 1). However, the recent discovery of a fossilized orchid pollinaria (20 Mya) (Ramirez et al., 2007) allowed the dating of Vanilloidae sub family at 72 Mya, well after the separation of Gondwana which questions

the hypothesis of a vicariate evolution of the *Vanilla* genus (Bouetard et al., 2010).

Transoceanic dispersion appears more credible and would have been implied at least three times in the evolution of the *Vanilla* genus (figure 1). This was demonstrated by dating a *Vanilla* molecular phylogeny, testing these two extreme evolutionary scenarios (vicariate

reviewed in the present paper and new data will also be presented.

family, Vanilleae tribe and Vanillinae sub-tribe (Cameron, 2004, 2005).

**2. Biogeography, taxonomy and phylogeny**

**2.1 Distribution and phylogeography**

**1. Introduction**

<sup>1</sup>*University of La Reunion, UMR PVBMT*

*2CIRAD, UMR PVBMT,* 
