Format: ORAL

Jasper J.A. Obico1, R. Sedricke C. Lapuz2, Julie F. Barcelona3, Pieter B. Pelser3

1 Department of Biology, College of Arts and Sciences, University of the Philippines Manila, Padre Faura St., Ermita 1000, Manila, Philippines. 2 School of Biological Sciences, The University of Hong Kong, Pok Fu Lam Road, Hong Kong SAR, China. 3 School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand.

Rafflesiaare rare holoparasitic plants. In the Philippines, all but one species are found only on single islands. This study aimed to better understand the factors contributing to this distribution pattern. Specifically, we sought to determine whether narrow environmental tolerances of host and/or parasite species might explain their island endemicity.We used Maxent species distribution modeling to identify areas with suitable habitat forR. lagascae,R. lobata, andR. speciosaand theirTetrastigmahost species. These analyses were carried out for current climate conditions and two future climate change scenarios.Although species distribution models indicated suitable environmental conditions for theTetrastigmahost species in many parts of the Philippines, considerably fewer areas are inferred to have suitable conditions for the threeRafflesiaspecies. Some of these areas are found on islands from which they have not been reported. All three species will face significant threats as a result of climate change.Our results suggest that limited inter-island dispersal abilities and/or specific environmental requirements are likely responsible for the current pattern of island endemicity of the threeRafflesiaspecies, rather than environmental requirements of theirTetrastigmahost species.