Skip to main content
Dryad

Of islands on islands: Natural habitat fragmentation drives microallopatric differentiation in the context of distinct biological assemblages

Steigerwald, Emma1; Paetsch, Judith2; Drück, Dana2; Fritsch, Jana2; Klaka, Marie2; Kennedy, Susan2; Gillespie, Rosemary3; Krehenwinkel, Henrik2

Published Jun 23, 2025 on Dryad. https://doi.org/10.5061/dryad.mgqnk996x

Data files

Jun 23, 2025 version files 3.92 MB

Click names to download individual files

Abstract

An important evolutionary hypothesis posits that much of the biodiversity we see today was generated by the interplay of colonization, extinction, adaptation, and speciation during episodes of natural habitat fragmentation. To interrogate the generality of this hypothesis, we leverage the natural experiment provided by arthropod communities in kīpuka—patches of Hawaiian wet forest isolated by lava flows. With DNA metabarcoding, we provide the first simultaneous exploration of ecological and evolutionary characteristics in the kīpuka system. At both species- and haplotype-equivalent scales, we find that diversity scales with kīpuka area, and that kīpuka accelerate the distance decay of similarity relative to continuous forest. Open lava, kīpuka edges, and the centers of the smallest kīpuka host lower inter- and intra-specific richness, are more biologically homogeneous, and have higher proportions of non-native OTUs than kīpuka centers for the order we could test (Araneae). Our work shows how natural habitat fragmentation stimulates, in tandem, ecological shifts in community composition and genetic differentiation. The strong signatures of both ecological and evolutionary processes highlight the importance of studying both processes simultaneously if we are to understand how biological communities respond to change.