Repeated habitat shifts and varying dispersal rates between habitats shape ecomorphological assembly of wandering <i>Ctenidae</i> spiders across continents

Abstract

Despite numerous lineages exhibiting ecologically and phenotypically similar species across continents, the interplay between evolutionary convergence and biogeographical dispersal in shaping continental community assembly remains largely unknown. Tropical wandering spiders (Ctenidae) are a diverse group of terrestrial predators with a pantropical distribution, exhibiting a variety of specialised morphotypes across different habitats. We used phylogenetic comparative methods to investigate the role of ecomorphological convergence through continental in situ diversification and biogeographic dispersal in assembling tropical wandering spiders (Ctenidae). We address three evolutionary questions: (1) Did independent habitat shifts result in the repeated origin of similar morphologies? (2) Is similarity in morphology across continental assemblages caused by evolutionary convergence or by biogeographic dispersal? (3) Are there differences in dispersal rates between different ecomorphs (ground and arboreal) and if so how does this affect community assembly? Ancestral habitat reconstruction suggests that ctenids were likely originally arboreal and later colonized terrestrial habitats at least six times independently. We detected morphological shifts on the phylogeny in carapace height, spine length of the first legs, and leg span that were associated with habitat transitions. Our biogeographic analyses suggest that ground-dwelling ctenids show significantly higher dispersal rates compared to arboreal ctenids. Our findings imply that ctenid ecomorphological diversity in certain continental areas originated from in situ diversification within specific biogeographical regions, driven by multiple habitat shifts closely linked to morphological changes. Furthermore, our study reveals that ctenid assembly across various regions has also been influenced by long-distance dispersal events of evolutionarily conserved ground-adapted forms.