International Journal of Ecology and Environmental Sciences 33(1): 1-21, 2007 © INTERNATIONAL SCIENTIFIC PUBLICATIONS, NEW DELHI Floristic Analysis and Biogeography of Tubiflorae in Some Arid Regions 2 NAHED EL-HUSSEINI1, MONIER M. ABD EL-GHANI1* AND SALAH I. EL-NAGGAR 1 The Herbarium, Faculty of Science, Cairo University, Giza 12613, Egypt *author for correspondence; Email: [email protected] 2 Botany Department, Faculty of Science, Assiut University, Egypt ABSTRACT The species distribution and biogeography of the Egyptian Tubiflorae were examined in detail. We found 284 species of vascular plants belonging to 96 genera and 12 families, making the Egyptian Tubiflorae richer in species than that of other arid region floras: Libya and Saudi Arabia. The most species rich families were Scrophulariaceae, Boraginaceae, Labitae, Convolvulaceae and Solanaceae, constituting more than 85% of the total species in the order. The generic spectrum dominated by a suite of species-rich genera (Convolvulus, Heliotropium, Veronica, Solanum, Salvia, Cuscuta, Echium, Ipomoea and Orobanche). Therophytes were the most dominant life forms among the families, followed by chamaephytes and hemicryptophytes. Boraginaceae and Scrophulariaceae had the highest share of annuals. Remarkable distribution patterns of the life forms in the seven studied biogeographic zones were noticed. Trees were dominant in the Mediterranean zone, while shrubs, perennial herbs and therophytes were dominant in the Sinai. Altogether 8 endemic species and 14 near-endemics were included in the Tubiflorae of Egypt; mostly from southern Sinai. We found that Labiatae and Scrophulariaceae were the families with higher concentration of endemics. Notably, Teucrium was among the genera of the Mediterranean Africa with highest endemism. Gamma diversity varied from 171 in the Sinai Peninsula to 43 and 39 in the Oases of the western Desert and along the Red Sea, respectively. Interestingly, highest significant values of similarity and species turnover (beta diversity) were observed between the Oases and the Nile lands. It is worthy noting the combined effect of both temperature and precipitation on gamma diversity of Tubiflorae in the 7 biogeographic zones. Our results indicated that almost one- half of the species showed a certain degree of consistency, i.e., with narrow geographic expansion. On the basis of UPGMA clustering and PCoA analysis, 4 floristic groups were recognized, each include one or more biogeographic zone. The occurrence of the species of Tubiflorae in the adjacent regional arid floras and their phytochorological affinities, were discussed. Key Words: Geographical Distribution, Diversity, Desert Ecosystems, Flora, Endemism, Phytogeography INTRODUCTION and Lentibulariaceae) and 284 species comprising 13.7% of the total flora. It is a group of great import- Tubiflorae is by far the largest order of the Egyptian ance, not only for its species diversity, but also for the vascular flora. Generally, Engler and Diels (1936) capacity of their species to colonize a great variety of recognised the order Tubiflorae to be composed of 8 environments, wide range of life forms, habitats and suborders and 23 families of the flowering plants. On distribution patterns (Täckholm 1974, Boulos 2000 the other hand, Hutchinson (1959) organized the and 2002). Interestingly, one third of its total number families in 5 orders: Verbenales, Solanales, Personales, of species was considered endangered and vulnerable (El Boraginales and Lamiales. In Egypt, it is represented by Hadidi 1979). However, Boulos (1989) enumerated 14 5 suborders (Convolvulineae, Boragineae, Verbenineae, desert plant species belonging to Boraginaceae, Solanineae, and Acanthineae), 96 genera, 12 families Convolvulaceae, Labiatae, Orobanchaceae and Sola- (Convolvulaceae, Boraginaceae, Verbenaceae, Avicen- naceae of promising economic potentialities. It also niaceae, Labiatae, Solanaceae, Scrophulariaceae, Oro- includes shrubs that present clear adaptation syndromes banchaceae, Globulariaceae, Acanthaceae, Pedaliaceae, to the arid and semi-arid environs (e.g. pubescence and 2 El Husseini et al.: Diversity and Distribution of Tubiflorae Int. J. Ecol. Environ. Sci. spinescence), which have given them a great diversi- Tubiflorae have been taxonomically revised (Boulos fication not only in Egypt, but also in the entire Middle 2000 & 2002), our basic knowledge on the diversity East and Mediterranean North Africa. Furthermore, the and biogeography of this order is still fragmentary and order constitutes a model system for the study of arid far from complete. This paper attempts to analyse and biogeographical patterns, and could generate useful interpret the diversity in relation to relative family and information for the conservation of certain vegetation genus sizes, spatial distribution patterns and phyto- enclaves inside the country and the whole region as geography of the members of Tubiflorae particularly in well. In fact, the Convention on Inter-national Trade in Egypt, compared to another North African arid country Endangered Species of wild Fauna and Flora (CITES (Libya), and Saudi Arabia as well. It also stresses the 1990) includes most of the families of Tubiflorae in its need to combine taxonomic, floristic, life form Appendix 2 and a considerable number of its species are differentiations and biogeographical parameters to listed in Appendix 1. understand the relationship between plant habit and Biological diversity, or biodiversity, refers to the the speciation propensity of the Tubiflorae. variety of distinct ecosystems or habitats, the number and variety of species within them, and the range of genetic diversity within the populations of these species. MATERIALS AND METHODS Two attributes of biodiversity have attracted particular attention from the international conservation commu- The provisional account presented here was based on nity: gamma diversity (the total number of species in an the authors' own data from field work carried out during area), and endemism (the number of species in that area several years (1999-2005) in all seasons from different that occur nowhere else). Because these two attributes parts of Egypt; especially those from the Oases of the reflect the complexity, uniqueness and intactness of western Desert, Sinai and Gebel Elba. In addition, an natural ecosystems, they are believed to indicate overall inventory of all available herbarium collections from patterns of biodiversity in a useful manner. Phylo- Egypt was compiled, and taxonomic determinations genetic diversity is in part a function of the size of a were revised. The plant materials assembled by M.M. flora, and partly of the pattern of distribution of the Abd El-Ghani and S. El-Naggar during their field work species into higher taxa (Fenner et al. 1997). Recently in western Saudi Arabia for the former and Gebel the pattern of species distribution among higher taxa Akhdar in Libya for the latter were also used. Specimens has been shown to be an effective indicator of phylo- were examined from the herbarium of Cairo University genetic diversity (Williams and Humphries 1994). (CAI), the herbarium of the Agriculture Museum The biogeography of the flora of Egypt is still (CAIM) and the herbarium of Assiut University (AST). poorly documented, and with few notable exceptions Taxonomic revisions for some families and genera of (El Hadidi et al. 1996, Abd El-Ghani and El-Sawaf Egyptian Tubiflorae were also consulted (El-Husseini 2004), there has been little attempt to analyze the 1986, El-Husseini and Zareh 1989, Hepper 1998, El biogeographical implications of most species distri- Hadidi et al. 1999). Nomenclature and species dis- bution patterns. Khedr et al. (2002) reported that the tribution was based mainly on Täckholm (1974) and flora of Egypt contains many families and genera Boulos (2000, 2002) for Egypt, Collenette (1985) and relative to the number of species (120 families, 742 Chaudhary and Al-Jowaid (1999) for Saudi Arabia, and genera, 2088 species) and a relatively large number of Jafri and El-Gadi (1977-1985) for Libya. The system of oligotypic families, each represented by only one or a phyogeographical territories of Egypt that proposed by few species. They suggested that a flora, in which the El Hadidi (2000) was adopted in this study. Each species are distributed among numerous genera or territory will be here referred to as "biogeographic zone". families, or other higher-order ranks, should contain Thus seven major biogeographic zones were included in greater phylogenetic diversity and genomic information this study: the Mediterranean (M), the Nile region (N), than one in which the same number of species is the Eastern Desert (De), Sinai Peninsula (S), the Red concentrated into fewer higher-order taxa. The high Sea coastal land (R), Gebel Elba (GE) and the Oases of fraction (97%) of native species in the Egyptian flora the Western Desert (O). The biogeographical analysis may reflect fewer opportunities to acquire more species was done down to species level. A species list that per genus or per family, due to fewer successful biotic formed the base of the analysis was prepared using the invasions as well as lower speciation rates. authors' plant collections and field notes, all relevant Despite the fact that some families of Egyptian references and floras of Egypt and adjacent countries. 33: 1-21 El Husseini et al.: Diversity and Distribution of Tubiflorae 3 Two levels of biogeographic analysis were considered: influencing