Introduction DIVERSITY AND ECOLOGY OF DIPLAZIUM

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CHAPTER 2 DIVERSITY AND ECOLOGY OF DIPLAZIUM

2.1. Introduction

The number of organisms in a particular area is determined by speciation and extinction, and by immigration and local loss. The relative importance of these processes depends upon the scale of investigation. Ecological processes are crucial to many theories of speciation Godfray Lawton 2001. Delimitation of species is, of course, performed by choice of a certain combination of critical characters on comparative-morphological basis. Each Linnaean species is essentially a self-perpetuating population in the genetic sense, i.e. a mixture of individual which are to a larger or smaller degree genetically different. The genetically defined characters do not manifest themselves in exactly the same way in different individuals, as their manifestation in influenced during the stages of their ontogenetical development by the environmental condition Steenis 1957. Many environmental factors can affect various ferns, including the present of other plants, the activities of animals amongst which man now plays a predominant role in many areas, and a whole range of physical and climatic factors Edie 1978. For the sake of simplicity, most authors on fern taxonomy usually explained the main factors which act on ferns growing under or less natural conditions. These factors include the substratum where the fern grows, type of soil, rock, ect., surrounding vegetation, exposure to light and climatic conditions, microclimate which surrounds the fern itself temperatures, humidity, etc., and availability of water. In order to grasp a better understanding in species delimitation on Diplazium and also to recognize the correlation between ecology and species richness, ecological studies of this genus from Western Malesia are conducted by doing field studies, specimens examination, and literatures study. The aims of this study are: 1 to study the ecology of Diplazium species and 2 to recognize the diversity of Diplazium species in the different habitat gradient. 14

2.2. Materials and Methods