The ecological factors driving specialisation in species interaction networks along environmental gradients at large spatial scales are poorly understood. Although such drivers can have synergistic impacts, previous work has mainly assessed effects of network type and the abiotic environment separately. We conducted a meta-analysis of existing network data to assess the interactive effects and relative importance of these drivers of specialisation in ant-plant networks at global scales. We collated 74 ant plant networks from 1979–2023, categorised into four network types: plants that provide ants nesting sites (myrmecophytes); plants that provide only food sources (myrmecophiles); plants for which ants disperse seeds (myrmecochories); plants on which ants forage only (foraging). We explored how network specialisation varies between interaction types with elevation, latitude, and anthropogenic disturbance. We used a standard measure of network specialisation (H2’), tested whether standardising this against network null models influenced results (H2’ z-score), and measured phylogenetic network specialisation (dsi*). We found that H2’ was strongly affected by habitat disturbance, elevation and interaction type in a manner congruent with previous work, However, these effects disappeared once H2’ was standardised (H2’ z-score). The disappearance of these effects indicates that previous results may relate to variation in network structure rather than specialisation. This is supported by the existence of correlations between network species richness/weighted connectance and H2’. Phylogenetic network specialisation (dsi*) was greater for myrmecophytes than for other three network types. This probably relates to closer co-evolution between partners in myrmecophytic network. Phylogenetic network specialisation did not vary significantly with elevation, latitude or anthropogenic disturbance. Our results demonstrate that ant-plant network types, in this case relating to strength of mutualistic interaction, is the main driver of network specialisation, and that previously reported impacts of latitude, elevation and anthropogenic habitat disturbance are likely to have been mediated mediated via correlations with network size.

Agricultural expansion has markedly reduced forests and reconfigured landscapes. These changes incur a well-known detrimental impact on the biodiversity of local forest patches, but the effects on species persistence at entire landscapes comprised of multiple patches are debated. We investigated how regional diversity is affected by habitat loss, fragmentation, and cattle grazing, and how species respond to deforestation both locally and regionally. We also investigated how the heterogeneity in species distribution (beta-diversity) buffers landscapes against local diversity losses. The vast majority of the 251 ant species found in our study were negatively affected by both habitat loss and cattle at local forest patches, drastically reducing diversity at these patches compared to pristine forests. Despite local declines in diversity, however, heavily fragmented landscapes could still retain most species due to the high heterogeneity in species distribution. We found that beta-diversity is the main component of regional diversity. Results from several studies suggest that this component is maximized when remnant primary habitats in a landscape are spread across vast areas. Although preserving local diversity may be important for the adequate functioning of the ecosystem locally, our results indicate that the maintenance of many small forest patches in a landscape can buffer regional biodiversity against local species losses. Our results suggest that even small forest remnants in otherwise deforested landscapes can prevent most regional-scale species extirpations, and therefore also merit conservation efforts.

Agricultural expansion has markedly reduced forests and reconfigured landscapes. These changes incur a well-known detrimental impact on the biodiversity of local forest patches, but the effects on species persistence at broader geographic scales are widely debated. We investigated how regional diversity is affected by habitat loss, fragmentation, and cattle grazing, and how species respond to deforestation both locally and regionally. We also investigated how the heterogeneity in species distribution (beta-diversity) alters species responses across scales. The vast majority of the 251 ant species found in our study were negatively affected by both habitat loss and cattle at local forest patches, drastically reducing diversity at these patches compared to pristine forests. Despite local declines in diversity, however, heavily fragmented landscapes could still retain most species due to the high heterogeneity in species distribution. Beta-diversity is the main component of regional diversity, and this component is maximized when remnant primary habitats in a landscape are spread across vast areas. Although preserving local diversity may be important for the adequate functioning of the ecosystem, our results indicate that the maintenance of many small forest patches in a landscape can buffer regional biodiversity against local species extinctions. Our results suggest that even small forest remnants in otherwise deforested landscapes can prevent most regional-scale species extirpations, and therefore also merit conservation efforts.

Current climate change is disrupting biotic interactions and eroding biodiversity worldwide. However, species sensitive to drought, high temperatures and climate variability might persist in microclimatic refuges, such as leaf shelters built by arthropods. We conducted a distributed experiment across an 11,790 km latitudinal gradient to explore how the importance of leaf shelters for terrestrial arthropods changes with latitude, elevation and underlying climate. Our analyses revealed leaf shelters to be key facilitative elements for the diversity of arthropods. Predator diversity and overall biomass within shelters increased with local drought and temperature variability, regardless of latitude and elevation. In contrast, shelter usage by herbivores increased with abundance of predators on those same plants and in wetter climates. Projected increase in climatic variability and drought in certain geographic regions is therefore likely to enhance the importance of biotic refuges, especially for predators, in mitigating the impact of climate change on species persistence.