10-Minute Presentation
Systematics, Evolution, and Biodiversity
Joseph Arguelles
American Museum of Natural History
Brooklyn, New York
Cheryl Hayashi
American Museum of Natural History
New York, New York
Aerial foraging webs have long enamored the public and scientists alike, becoming nearly synonymous with Order Araneae itself and being largely credited with the evolutionary success of the Araneomorphae (true spiders). Despite this, the RTA (retrolateral tibial apophysis) clade, which accounts for nearly 50% of all spider species, has secondarily abandoned the web-spinning behavior. These spiders actively hunt, relying instead on keen eyesight and cryptic coloration for stalking and ambushing unsuspecting prey. This talk will focus on the evolution of the silk and visual systems in six species of RTA spiders, including Lycosidae (wolf spiders), Oxyopidae (lynx spiders) and Salticidae (jumping spiders). Preliminary, genomic and transcriptomic analyses showed that stalking spiders possess more opsin genes than ambush predators and web-spinning spiders, with additional differences observed in Rhodopsin composition when comparing diurnal hunters (Salticidae) and nocturnal hunters (Lycosidae), implying differential investment in the visual system related to predation strategy. Phylogenetic analysis of spider silk genes (including over 100 new RTA silk genes) recovered RTA ampullate spidroins separate from major ampullate silk genes of the web-spinning spiders (Araneoidea). Despite this, amino acid composition and clustering analyses of full-length silk genes suggest putatively similar mechanical behavior of these proteins. Additionally, salticid silk genes were found to almost entirely lack the poly-Alanine motif associated with fiber strength and present across all other spider lineages investigated thusfar, implying key mechanical differences perhaps associated with their novel jumping behavior.