This project will chronicle the evolution and diversification of the orb-weaving spiders to resolve a long-standing problem in animal evolution, that is, the origin and genealogical relationships of the main groups of orb-weavers. Ubiquitous, diverse, and exclusively predatory, spiders are one the most diverse and fascinating animal groups and the dominant arthropod predators in most terrestrial ecosystems. Orb-weavers are remarkable not only because of the high number of species described so far, but also because of the extraordinary architectural diversity of their foraging webs, ranging from highly geometric snare designs, often regarded as a pinnacle of animal engineering, to sheet and irregular cob webs. Understanding web evolution and diversification requires an empirically robust hypothesis about the underlying genealogical patterns?the spider tree of life. Traditional anatomical and genetic methods have not yet produced a compelling answer to this problem, and thus our understanding of the evolution of this group is far from satisfactory. The researchers of this project will use new methods to gather genetic data to answer this long-standing question. The results of this research will be of interest to many biologists working on any comparative aspects of orb-weavers because it will provide the genomic resources and the fundamental comparative basis for studies on a broad diversity of topics (silk biology, sexual selection, venom evolution, etc.). This project will serve as a training platform for postdoctoral, graduate and undergraduate researchers. In addition, the project will produce a public exhibit at the Harvard Museum of Natural History that will explore the evolution and biology of orb-weaving spiders.
A team of three investigators, experts in arachnid systematics and with a long and productive history of research collaboration, will generate novel data through the sequencing of 120 transcriptomes and target capture approaches using modern DNA sequencing techniques for phylogenetic inference for a taxonomic sample of orbicularians that would include representatives of all 21 known families of orb-weavers and a diverse array of outgroups. These genomic data will be used to infer the family-level phylogenetic relationships of orb-weaving spiders using a diversity of analytical techniques. The PIs will also analyze a morphological matrix of 85 selected orbicularians largely based on extensive data already at hand. This project will use the results of the phylogenetic analyses to carry out comparative analyses of orb-weaver diversification and of web architecture evolution.
