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Conserving Diversity of Wild Palnt Genetic Resources: A Case Study of Wild Coffea Taxa in the Mascarenes Island.

M.E. Dulloo
Mauritian Wildlife Foundation
Port-Louis Mauritius


Home | Contents | Abstract | Introduction | Table 1 | Case Study | Ecogeographic Survey


Abstract

The Mascarene Islands located in the south west Indian Ocean contains several endemic Coffea taxa, namely C. mauritiana, C. macrocarpa and C. myrtifolia, belonging to the Mascarocoffea section, which are known to be caffeine free. This attribute makes the Coffea germplasm of this region a very important genetic resource worth conserving. This paper reviews recent studies undertaken on the diversity of the wild Coffea taxa in the Mascarene Islands, principally on Mauritius, as a basis for developing conservation strategies for the germplasm in the region. An ecogeographic survey was undertaken to determine the distribution of the different Coffea taxa and to assess their conservation status in the wild. The amount of variability in the wild population of Coffea was also studied using both molecular techniques (RAPD) and morphological characterisation. The result of these studies showed the distinctiveness of a new entity within the C. macrocarpa species and identified key populations with high diversity. The paper also describes different complementary approaches to the conservation of Coffea germplasm and in particular the role of Botanic Garden in plant genetic resource conservation.

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Introduction

The Mascarene archipelago lies to the east of Madagascar in the south west of the Indian Ocean, between latitudes 19 60’ - 21 07’ S and longitudes 55 30’ - 63 50’ E. It comprises the islands of Mauritius, Rodrigues (which is politically part of Mauritius) and La Réunion (a French overseas département). Mauritius and La Réunion are 150 km apart and Rodrigues is 574 km east of Mauritius. Table 1 gives a comparative analysis of the geographical and physical characteristic of each of the Mascarene islands. By virtue of their insular nature the Mascarene Islands possess a rich diversity of endemic plant species, each with different set of species. This is because these islands are of different ages (Table 1) and the floral composition reflects the different evolutionary stages of the islands which makes the Mascarene Islands an interesting place to study plant evolution. The Flora and vegetation of the Mascarene islands has been described in detail by Strahm (1994) and Dulloo (1998).

Table 1: Geographical and physical characteristics of Mascarene Islands.


Island Altitude (m) Latitude Longitude Age (x 106 yrs) Land Area (Km2) Max.
Mauritius 20º 20’ 57º 30’ >8 1865 828
La Réunion 21º 07’ 55º 30’ 3 2500 3069
Rodrigues 19º 60’ 63º 50’ 1.54 110 393

Ever since the discovery of the Mascarene Islands in the early sixteenth century by the Europeans, there have been a systematic destruction of the natural forests of these islands, which in turn has led to the extinction of the great majority of the indigenous flora and fauna. Although the natural history of the Mascarene has been studied for a long time by visiting naturalists, conservation activities only started in the mid twentieth century with the pioneering studies of Vaughan and Wiehe (1937). This work has been the basis for the delimitation of many of the early Nature Reserves in Mauritius, declared between 1951 and 1974. In La Rèunion however, there has been no legal delimitation of protected areas except for a small reserve at Mare Longue. Early hands on conservation activities focussed on the endangered avifauna of Mauritius with the help of international organisations like Smithsonian Institute and International Council for Bird Preservation (ICBP, now BirdLife International) and later the Jersey Wildlife Preservation Trust (JWPT).

It was only in 1982, that a plant project was developed, through IUCN/WWF plants programme, to rescue critically endangered plants through ex situ conservation and to document the status of endangered plants in the wild (IUCN & WWF, 1984). A Red Data book on Rodrigues has been published as a result of this work (Strahm, 1989). The IUCN/WWF project also investigated some measures to protect the native forests from degradation involving the manual elimination of exotic plants from small areas of forests.

Over the past 10 years, without losing the focus on species conservation, the work has been increasingly integrated with habitat protection and restoration (Dulloo et al., 1996). This trend in conservation application has arisen following the recognition that no single conservation technique, be it ex situ or in situ, adequately conserves the full range of genetic diversity of wild species. Developing strategies for conserving wild plant genetic resources require detail diversity studies of the targeted species. Recently a study was undertaken at the University of Birmingham to determine the diversity in the wild populations of Coffea in the Mascarene Islands (Dulloo, 1998). The study was sponsored by the International Plant Genetic Resources Institute (IPGRI), Mauritian Wildlife Foundation (MWF) and the British Council (Mauritius Branch). The main aims of this research project were :


Using this project as a case study, this paper discusses principles of diversity studies and describes the complimentary conservation strategies for wild plant genetic resources, which are necessary for an effective conservation of the genetic diversity of the target species.

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Case Study

Diversity of Coffea in the Mascarene Islands In the Mascarene Islands, three putative Coffea species, namely: C. mauritiana Lam., C. macrocarpa A. Rich. and C. myrtifolia (A. Rich.) Leroy have been described (Leroy, 1989), but it is recognised that the wild populations exhibit extensive variability which has not been fully described (Leroy, 1971). Various morphological types have been collected in the two islands and have been given new names to be subsequently abandoned (Leroy, 1971; Leroy, 1989). The Coffea taxa from the Mascarene Islands belongs to the section Mascarocoffea, characterised by the absence of caffeine, a fact first reported by Bertrand (1902). The oldest known collection of a Mascarocoffea species, C. mauritiana Lam. was made on Ile Bourbon (now La Réunion) in 1716 by the apothecary Gaudron de Saint-Malo (Chevalier, 1938) and subsequently a wide diversity of species have been collected in this region (Portères, 1962; Leroy 1962; 1972). Presently, it is believed that there are about 56 species within the Malagasy-Mascarene region, making it an important centre of diversity for Coffea (Charrrier, 1978).

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Ecogeographic survey

An ecogeographic survey is an essential first step in the development of a comprehensive strategy for the conservation and use of plant genetic resources (Guarino et al., 1997) and models for carrying out an ecogeographic survey or study is described in detail by Maxted et al. (1995) and further developed in Maxted and Guarino (1997). In this case study, ecogeographic data were collated from herbarium specimens from four major herbaria holding collections of Mascarene Coffea, namely: Royal Botanic Gardens, Kew, Laboratoire de Phanérogamie, Museum National d’Histoire Naturelle, Paris, Mauritius Sugar Industry Research Institute and Université de la Réunion. This survey was supplemented by detailed field surveys of wild Coffea species in the Mascarene Islands. The geographical and ecological distribution of the different Coffea species in the Mascarene Islands, principally in Mauritius, were determined and an assessment of the IUCN conservation status of native Coffea species made.

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