Seed Production and 22 Years of Climatic Changes in an Everwet Neotropical ForestVleminckx, Jason; Hogan, J. Aaron; Metz, Margaret R.; Comita, Liza S.; Queenborough, Simon A.; Wright, S. Joseph; Valencia, Renato; Zambrano, Milton; Garwood, Nancy C.
doi: 10.1111/ele.70019pmid: 40172570
Examining the cues and drivers influencing seed production is crucial to better understand forest resilience to climate change. We explored the effects of five climatic variables on seed production over 22 years in an everwet Amazonian forest, by separating direct effects of these variables from indirect effects mediated through flower production. We observed a decline in seed production over the study period, which was primarily explained by direct effects of rising nighttime temperatures and declining average vapour pressure deficits. Higher daytime temperatures were positively related to seed output, mainly through a flower‐mediated effect, while rainfall effects on seed production were more nuanced, showing either positive or negative relationships depending on the seasonal timing of rains. If these trends continue, they are likely to lead to significant changes in forest dynamics, potentially impacting both forest structure and species composition.
Colourful Urban Birds: Bird Species Successful in Urban Environments Have More Elaborate Colours and Less BrownIbáñez‐Álamo, Juan Diego; Delhey, Kaspar; Izquierdo, Lucía; Valcu, Mihai; Kempenaers, Bart
doi: 10.1111/ele.70106pmid: 40183148
Rapidly expanding urbanisation presents significant challenges to wildlife. Consequently, many studies have investigated the impact of urbanisation on diverse organisms. However, despite the ecological relevance of animal colouration, its association with urbanisation remains poorly understood. Using a global database, we computed an index of urban success for 1287 bird species and quantified its association with estimates of plumage colour. Our analyses showed that birds that do well in urban environments are more likely to be blue, dark grey and black, and less likely to be brown or yellow. After considering phylogenetic relatedness, only the effects of yellow and brown remained significant. Species with high urban success also exhibit more elaborate colours, but not higher sexual dichromatism. We provide eco‐evolutionary explanations for these results. Assemblage‐level analyses did not support the urban colour homogenisation hypothesis: Urban bird communities were more colour‐diverse after accounting for species richness. Our findings suggest that plumage colours are part of an urban‐associated syndrome.
The Release of Non‐Native Gamebirds Is Associated With Amplified Zoonotic Disease RiskMichels, Emile; Hansford, Kayleigh; Perkins, Sarah E.; McDonald, Robbie A.; Medlock, Jolyon M.; Tschirren, Barbara
doi: 10.1111/ele.70115pmid: 40256856
Spillback—where non‐native species increase native pathogen prevalence—is potentially an important mechanism by which non‐natives contribute to zoonotic disease emergence. However, spillback has not yet been directly demonstrated because it is difficult to disentangle from confounding factors which correlate with non‐native species abundance and native pathogen prevalence. Here, we capitalise on replicated, quasi‐experimental releases of non‐native pheasants (Phasianus colchicus) to compare vector abundance and native pathogen prevalence between sites with similar local conditions but different non‐native densities. Prevalence of Borrelia spp. (the causative agent of Lyme disease) in questing ticks was almost 2.5x higher in woods where pheasants are released compared to control woods, with a particularly strong effect on Borrelia garinii, a bird specialist genospecies. Furthermore, adult (but not nymphal) ticks tended to be more abundant at pheasant‐release woods. This work provides evidence that non‐native species can impact zoonotic pathogen prevalence via spillback in ecologically relevant contexts.
Environmental Gradients Linked to Human Impacts, Not Species Richness, Drive Regional Variation in Community Stability in Coral Reef FishesTsai, Cheng‐Han; Connolly, Sean R.
doi: 10.1111/ele.70001pmid: 40176304
The stabilising effect of biodiversity on aggregate community properties is well‐established experimentally, but its importance in naturally assembled communities at larger scales requires considering its covariation with other biotic and abiotic factors. Here, we examine the diversity–stability relationship in a 27‐year coral reef fish time series at 39 reefs spanning 10° latitude on Australia's Great Barrier Reef. We find that an apparent relationship between species richness and synchrony of population fluctuations is driven by these two variables' covariation with proximity to coastal influences. Additionally, coral cover volatility destabilises fish assemblages by increasing average population variability but not synchrony, an effect mediated by changes in the intensity of density regulation in the fish community. Our findings indicate that these two environmental factors, both of which are strongly influenced by anthropogenic activity, impact community stability more than diversity does, but by distinct pathways reflecting different underlying community‐dynamic processes.
Voltinism Shifts in Response to Climate Warming Generally Benefit Populations of Multivoltine ButterfliesWepprich, Tyson; Henry, Erica; Haddad, Nick M.
doi: 10.1111/ele.70018pmid: 40172582
Climate change is implicated as one contributor to insect declines. Insects may respond to warming by advancing phenology and increasing the number of generations each year (voltinism). However, if earlier phenology changes cue‐response relationships, then late‐season generations might lack time to complete diapause development before winter and result in doomed ‘lost generations’. Using 27 years of monitoring of 30 multivoltine butterfly species, we find the opposite, as larger late‐season generations (voltinism shifts) are associated with more positive overwinter population growth rates. The potential threat of lost generations is limited to late‐season species at cooler sites in years with early frosts. Overall, long‐term population trends are positively correlated with larger late‐season generations, suggesting that they are an adaptive response to climate warming. Still, overwinter population growth rates and long‐term population trends have declined over time as the benefits of voltinism shifts have been insufficient to reverse population declines.
Networks in Aquatic Communities Collapse Upon Neonicotinoid‐Induced StressBarmentlo, S. Henrik; Schrama, Maarten; Cieraad, Ellen; Snoo, Geert R.; Musters, C. J. M.; Bodegom, Peter M.; Vijver, Martina G.
doi: 10.1111/ele.70121pmid: 40260489
Freshwater ecosystems worldwide are under pressure from neonicotinoid insecticides. While it is recognised that communities of species are responsible for ecosystem functioning, it remains unknown if neonicotinoid‐induced community transformations negatively affect ecosystem functioning. Therefore, we employed an experimental approach with 36 naturally established freshwater ecosystems exposed to increasing field‐realistic concentrations of the neonicotinoid thiacloprid. Upon exposure, we found severe degradation of ecosystem functioning in the form of loss of organic matter consumption and dramatic shifts in primary productivity. This functional decline coincides with strongly eroded species co‐occurrence networks to the point that these are indistinguishable from randomised assemblages of species. Together, these findings show how current environmental concentrations of a neonicotinoid can strongly disrupt freshwater ecosystem functioning via degradation of the invertebrate food web. Since this dramatic ecosystem degradation occurs below nearly all identified ecotoxicological risks, we call here for the reconsideration of the use of these insecticides.