Systematics, Biogeography and Evolutionary Radiations of the Cyphophthalmi (Arachnida, Opiliones)

点击翻译按钮获取中文摘要

Cyphophthalmi constitutes a suborder of the arachnid order Opiliones (daddy-long-legs). Of ancient origin and widespread distribution, they live in the leaf litter of undisturbed temperate to tropical humid forests. Cyphophthalmids have been found in all continents, except Antarctica, and in most islands of continental origin, such as New Zealand, New Caledonia, Sumatra, and Madagascar. Many of the places they inhabit qualify as biodiversity hotspots, areas collectively comprising only 1.4% of the land surface area of the Earth and recommended for preferential conservation policies for having high diversity. Due to their localized distribution and scant dispersal ability, cyphophthalmids have been chosen as a model to study evolutionary radiations in islands of continental origin, biogeography, and potential issues of conservation biology. To do so, the taxonomy and evolutionary relationships among its species need to be worked out. We will use scanning electron microscopy to study the morphology of the cyphophthalmids and will generate lists of characters to be analyzed with standard phylogenetic algorithms. Other specimens will be used for genetic studies in order to generate DNA sequence data also to be analyzed phylogenetically. Both sets of information (morphology and DNA) will be used to propose the evolutionary relationships of the members of the group and to establish a classification. The evolutionary trees will also aid studies of biogeographic patterns and earth history. Evolutionary analyses will be aided with the use of software written to work in parallel on a large multiprocessor computer cluster. Extensive field work in New Zealand, South Africa, Madagascar, tropical West Africa and southeast Asia is required to obtain material suitable for laboratory work and to document undescribed diversity. Systematics, biogeography, and the study of evolutionary radiations have contributed to a better understanding of the patterns observed in nature. Optimizing the knowledge of diversity across geographic areas, cladogenesis, and speciation may benefit from the use of model systems. The potential use of Cyphophthalmi as a new model in evolutionary biology has driven a dual study of the higher systematics of the group and the exploration of one of their most spectacular adaptive radiations, the one undergone in New Zealand. The research will develop a new model system to integrate phylogenetic and biogeographic patterns with evolutionary studies of explosive radiations, and will form the basis for future studies on biodiversity estimates and conservation biology. Global knowledge of the Cyphophthalmi, with a database containing geographical information and illustrations for all the estimated 180 species of the group, will be made available. During the process, one undergraduate and one graduate student will be fully trained in arachnid evolutionary biology. The value of the research project thus has both scientific and social interests.