What Defines the Groupwise Compositional Turnover of Eurasian Phylloscopus Warblers? Insights From Zeta (ζ) Diversity and MS-GDM

Aim

This study examines how environmental variables determine the co-occurrence of Phylloscopus warblers. It was carried out using an integrated zeta (ζ) diversity estimation method and multisite generalised dissimilarity modelling (MS-GDM).

Location

Phylloscopus species spanning Eurasia.

Study Period

Observations made during the breeding season for each species from 2014 to 2023.

Major Taxa Studied

We specifically focussed on complexes/superspecies groups within the genus Phylloscopus to address this question. The groups defined on recent phylogeny are the P. castaniceps complex, P. cantator group, P. borealis group, P. burkii complex, P. affinis group, P. proregulus group, P. inornatus complex, P. davisoni group, P. fuscatus group, P. collybita group, P. trochiloides complex and P. tenellipes group.

Methods

We used ζ diversity estimations to quantify the extent of compositional turnover and diversity across multiple sites. We further used MS-GDM to gain insights into how various environmental variables impact species composition.

Results

The composition of the groups we analysed is shaped by environmental conditions. The normalised difference snow index considerably impacts turnover within the P. castaniceps complex, with species such as P. castaniceps showing adjacency to snowy areas. Elevation and gravity anomalies play an essential role in the turnover of species in the P. cantator and P. borealis groups. The prevalence of positive gravity anomalies (variations in gravitational strength) in hilly areas determines the compositional differences within the P. burkii complex. The turnover of the P. proregulus group is influenced by both artificial night lights and gravitational anomalies. The turnover in the P. trochiloides complex and the P. davisoni, P. collybita and P. tenellipes groups is influenced by soil moisture, elevation, gravity anomalies and aridity index, emphasising the varied ecological niches of these species.

Conclusions

This study improves our understanding of the compositional shift of Phylloscopus leaf warblers over space and reveals the mechanisms underlying shifts in their composition across regions and the impact of changes in climatic patterns. As a result, this study is an important resource for ecologists and conservationists.