Pettersson, L. B. | Search bioRxiv

bioRxiv2025

The interplay of climate change, urbanization, and species traits shapes European butterfly population trends

Species populations naturally fluctuate, yet long-term trend analysis can reveal patterns of success, decline, or stability under global change pressures. While responses to climate change are well-documented, its synergy with another major global driver, urbanization, remains understudied. Here, we analyzed long-term monitoring data from over 8,400 populations of 145 butterfly species across Europe, representing a high diversity of species traits, to assess population trends in response to climate change and urbanization. We examined how population responses vary between urban and rural contexts, providing insights into the influence of site-specific conditions. Climate warming was associated with population declines, which were more pronounced in urban areas. The effect of precipitation varied between environments: increases in precipitation generally benefited populations in rural areas but had detrimental effects in urban ones. Aridity consistently drove population declines across environments, with slightly stronger effects in urban areas. Species with colder climatic niches declined the most in response to warming, increased aridity, and reduced precipitation, while trophic specialists were particularly vulnerable to aridity and precipitation changes in urban environments. Although increasing urbanization did not explain overall population trends, its effects became evident when considering species traits, with certain traits being more vulnerable to urbanization. Specifically, species with narrow climatic niches declined the most in response to urbanization in rural areas, while those and larger body sizes decline the most in urban environments. Our findings highlight the complex interplay between environmental change, landscape context, and species traits in shaping biodiversity outcomes. Importantly, our results suggest that urbanization generally amplifies the impact of climate change on insect population trends.

ecology↗

bioRxiv2021

Airborne environmental DNA metabarcoding for the monitoring of terrestrial insects - a proof of concept

Biodiversity is in decline due to human land use, exploitation, and climate change. To be able to counteract this alarming trend it is paramount to closely monitor biodiversity at global scales. Because this is practically impossible with traditional methods, the last decade has seen a strong push for solutions. In aquatic ecosystems the monitoring of species from environmental DNA (eDNA) has emerged as one of the most powerful tools at our disposal but in terrestrial ecosystems the power of eDNA for monitoring has so far been hampered by the local scale of the samples. In this study we report the first attempt to detect insects from airborne eDNA. We compare our results to two traditional insect monitoring projects (1) using light trapping for moth monitoring and (2) transect counts for the monitoring of butterflies and wild bees. While we failed to detect many of the same species monitored with the traditional methods, airborne eDNA metabarcoding revealed DNA from from six classes of Arthropods, and twelve order of Insects - including representatives from all of the four largest orders: Diptera (flies), Lepidoptera (butterflies and moths), Coleoptera (beetles) and Hymenoptera (bees, wasps and ants). We also recovered DNA from nine species of vertebrates, including frogs, birds and mammals as well as from 12 other phyla. We suggest that airborne eDNA has the potential to become a powerful tool for terrestrial biodiversity monitoring, with many impactful applications including the monitoring of pests, invasive or endangered species or disease vectors.

ecology↗