Taxon‐dependent multisite species turnover in fragmented habitats: comparing zeta diversity across birds, butterflies, and cursorial hunting spiders

Abstract

Habitat fragmentation alters species diversity and reshapes community composition. However, conventional pairwise approaches to compositional variation (i.e. beta diversity metrics) do not explicitly characterize how species sharing or turnover change with the number of habitat patches. In addition, cross‐taxon differences associated with variation in dispersal abilities and habitat requirements remain underexplored. Here, we examined zeta diversity, which quantifies species sharing and compositional turnover with an increasing number of patches (i.e. zeta order), for three taxa (i.e. birds, butterflies, and cursorial hunting spiders) in a fragmented urban landscape, based on survey data comprising 83 bird, 126 butterfly, and 79 spider species recorded across 30 remnant woodlot patches between 2017 and 2026. Birds showed a greater proportion of species occupying many patches than butterflies and spiders. Shared species declined with zeta order across all taxa, with steeper declines in butterflies and spiders at lower orders. As the order increased, shared species became increasingly likely to be retained across additional patches, particularly for birds. The explanatory variance of environmental factors in species turnover increased with order, particularly for birds, in which turnover was primarily driven by interpatch distance and two habitat composition factors (i.e. the proportions of woodlands and wetlands) across orders. Interpatch distance also appeared to be an important predictor for spiders, but not for butterflies. For both invertebrate groups, however, various other landscape and habitat characteristics influenced turnover, depending on zeta order. The findings suggest that patterns of species turnover in fragmented habitats are taxon‐ and order‐dependent, likely reflecting changes in the relative contribution of rare versus widespread species due to differences in their dispersal abilities and habitat requirements. Our study highlights the need for taxon‐ and order‐specific conservation strategies, such as maintaining habitat heterogeneity and improving landscape connectivity, to promote metacommunity persistence in fragmented habitats.