The spiders of the world are a diverse and ecologically important group of organisms, living in nearly all terrestrial habitats and constituting significant predators in these communities. Taxonomically they are disposed into 105 families, and one of the largest and most comprehensive collections of spider specimens is housed at the American Museum of Natural History. Researchers there are employing modern molecular methods to conduct DNA sequencing of targeted genes, to gain data useful in the phylogenetic analysis of evolutionary relationships among these families and with potential arthropod relatives. Target loci include the 18S ribosomal genes, the histone H4 genes, and the nuclear ubiquitin genes. Morphological characters also are being studied and are to be integrated with the molecular results in a combined analysis. A reliable phylogeny of the spiders will facilitate future studies of their geographical distributions, modes of speciation, and ecological specializations.
