Abstract
Spiders, a keystone predatory group for terrestrial ecosystem balance, have underexplored gut microbiotas. We collected 1090 spiders from 34 families in southwestern China, performing 16S rRNA sequencing to investigate their gut microbiota. Wandering and ambushing spiders exhibited higher α-diversity, while web-building spiders showed the lowest α-diversity with the highest endosymbiont infection rates. Gut microbiota diversity was significantly higher in Guizhou-region spiders than in Sichuan-region spiders. All spiders showed high amount of endosymbiont ASVs, which varied with foraging strategies and regions. Additionally, closer geographic distances between spiders were associated with more similar gut microbiota diversity levels. Environmental factor analysis preliminary revealed a positive correlation between precipitation and gut microbiota diversity, though its generalizability is limited by geographic sampling. Random processes were the primary drivers of spiders' gut microbial community assembly. Our findings highlight that spider gut microbiota assembly is predominantly driven by stochastic processes but regulated by foraging strategies and geographic factors, providing a framework for understanding predator-microbe interactions in spiders.