| DISTRIBUTION AND DIVERSITY OF DRAGONFLIES IN SELECTED AREAS IN MINDANAO Mark Anthony J. Torres and Cesar G. Demayo |
| ABSTRACT This study was conducted to determine distribution and species diversity of dragonflies from selected areas in Northern Mindanao. Individual dragonflies were identified based on existing pictorial keys and published taxonomic identification keys. Cluster analysis, species richness and other diversity indices were used to determine variability within, between and among populations of the same species and between species. Results showed that of the 594 samples collected, 16 known and 13 unknown species were identified. Variants within species were also observed based from qualitative differences in the wing characters. Systematic relationships of species including the variant forms were assessed based on cluster analysis of qualitative characters. Populations were also observed to differ based on species richness and other known diversity indices. Implications of the study in the conservation and protection of dragonflies are discussed. INTRODUCTION Our everyday life tells us of one equivalent phenomenon in all types of organisms that ever lived in this planet - variability. Since the time of Wallace and Darwin, these variations have been a central theme in the continuous growth of the biological sciences. The variations that we see are evidences of three important processes in nature that include gene mutation, changes in the chromosome number and in its structure and genetic recombination (Espino, 1987). These variations are also the raw materials from which natural selection acts upon by guiding the direction of evolutionary change. Considering the myriad of variations that occur in nature, biological form - its diversity, varieties and it's meaning - must be studied from different approaches. This however has earlier prompted the marriages of the different fields of sciences such as statistics, systematics and conservation biology. Systematics with the use of different statistical tools provided necessary information for ecological studies and conservation management. The advent of computers also proved useful in understanding the variations that occur in nature. Phenetics for example is largely a product of computers in the late 1960's.. Phenetics involves the need to score and code characters aided with computer applications to describe characters in numerical terms. Such computer applications can be used in the investigation of the evolutionary processes that cause the differentiation of populations of species and in the identification of divergent populations for Conservation Management purposes. The members of the insect suborder Anisoptera - known to us as dragonflies, exemplify this fundamental and basic characteristic of life. In the Philippines alone, numerous dragonflies belonging to four families have been identified and documented (Needham and Gyger, 1939). This number of dragonflies however does not represent the totality of dragonfly fauna in the islands. The bulk of the type specimens in the monograph prepared by Needham and Gyger came largely from only few localities, chiefly from Los Ba�os, Manila and Zamboanga. This is one big reason to suppose that there are more of these dragonflies in the country waiting to be discovered and documented. And while the need to record and document not only the Anisopteran fauna but also the other species of insects in the Philippines has already been stressed by a number of biologists, studies on this subject matter has remained in the hands of only a few systematists and ecologists. Reasons for the lack of such studies include the fact that these do not fall within the main priorities of the government. The Philippines being a third world country cannot afford to invest much in such studies. Moreover, such studies are not of prime priorities of academic institutions. The lack of scientists interested in such studies is due to the lack of funding and support. Most of the Entomologists in the country are more interested with pest species than with such species of insects such as the dragonfly that apparently is perceived to have no economic importance. Academic and scientific institutions can however help motivate researchers to do systematic studies on these insects. Universities in the Philippines especially in Mindanao and most specifically in the City of Iligan where a number of waterfalls can still be seen can start by giving support and recognition to researchers studying these insects. Only very few studies were conducted on this group of insects in the Philippines thus, it is urgent to conduct studies especially on community structure and systematic relationships of dragonflies in selected areas in Mindanao. This study was aimed to create a reference collection for study and appreciation, to document regional diversity and variability of species of anisopterous odonata, to document faunal representation in environments undergoing or threatened with alteration by human or natural forces and to provide material for taxonomic and ecological studies. |