Notes and records Preliminary observations indicate that giant tortoise ingestion improves seed germination for an endemic ebony species in Mauritius

Native forest in Mauritius has been reduced to patchy degraded fragments and the extinction risk of constituent rare endemic plants is compounded by poor seed germination (Page & D’Argent, 1997; Safford, 1997; Nyhagen et al., 2005). Endemic fruiting plants evolved alongside a number of ecologically important large frugivores that are now extinct, such as the dodo (Raphus cucullatus L.) and two species of giant tortoises (Geochelone inepta Günther and Geochelone triserrata Günther). Seed adaptations required to survive frugivore ingestion intact, such as a thickened seed coat, may in turn prevent germination if the seed is not ingested (Temple, 1977) and result in varying levels of dependency upon ingestion for germination. It is suggested that contemporary poor germination results from partial dependence on ingestion by these extinct frugivores. The giant tortoise has been shown to be an effective disperser of viable seeds on Aldabra in the Indian Ocean (Hnatiuk, 1978) and seed germination of a tomato variety in the Galapagos is dependent on giant tortoise ingestion (Rick & Bowman, 1961). No study to date, however, has investigated whether giant tortoise ingestion influences the germination success of seeds of endemic Mauritian plant species. Preliminary experimental results are presented here on the effects of tortoise ingestion on seed germination, using the endemic Mauritian ebony Diospyros egrettarum Richardson and – as an analogue for the extinct Mauritian tortoises – the Aldabra giant tortoise Geochelone gigantea Schweigger. Materials and methods