**Preface to "Phylogenomic, Biogeographic, and Evolutionary Research Trends in Arachnology"**

You are about to read a book dedicated to arachnids and arachnology, focusing on arachnid systematics, biogeography, and evolution. Arachnids represent a hyperdiverse, yet understudied, group of invertebrate animals. The diversity of spiders, scorpions, and harvestmen may be relatively well documented, while additional orders remain enigmatic. Arachnids range from sub-millimeter to dinner plate sizes and exhibit an astonishing array of morphologies and sexual biologies, making them excellent models in the study of the interplay of natural and sexual selection. Only a handful of arachnid genomes have so far been annotated, but genomic data are beginning to be utilized in phylogenetic analyses at species and higher taxonomic levels. In fact, systematics focusing on arachnids has been at the forefront of this discipline, with recent contributions uncovering the utility of transcriptomic and genomic data in deciphering the tree of life. Into this wealth of phylogenomic data, arachnologists routinely weave phenotypic and ecological variables for truly integrative evolutionary studies. Arachnids show diverse, and oftentimes clade-predictable, patterns in dispersal biology. As a consequence, some clades have become textbook examples of vicariant biogeography, while others, e.g., those traveling aerially by silken sails, maintain lively patterns of gene flow over continents. Together, arachnids can help us understand the Earth's biogeographic history as well as the evolution of complex biodiversity hotspots. Considering arachnid age and deep phylogenetic splits, their evolutionary landscape is uniquely diverse and calls for new original and synthetic research.

> **Matjaz Kuntner ˇ** *Editor*
