Vulnerability of bat-plant pollination interactions due to environmental change

High Resource Overlap and a Consistently Generalised Pattern of Interactions in a Bat-Flower Network in a Seasonally Dry Landscape

Pollination is an ecosystem process that is crucial to maintain biodiversity and ecosystem function. Bats are important pollinators in the tropics and are an integral part of complex plant-pollinator interaction networks. However, network analysis-based approaches are still scarce at the plant species and bat community levels. We used metabarcoding to identify plant taxa present in pollen from fur and faecal samples collected across 1 year from three nectar-feeding bat roosts in central Mexico. We calculated the frequency of occurrence of plant taxa and assembled a zoocentric network of bat-plant interactions. We constructed a year-long network, encompassing the entire period of sampling, two seasonal networks comprising the wet and dry seasons, and six individual networks from sampling at two-month intervals across the year. Four species of nectar-feeding bats interacted with 36 plant species from 16 families. We found highly generalised interaction patterns across networks corresponding with opportunistic feeding behaviour by bats, with little seasonal variation in network structure. There was high resource overlap between bat species, and bats visited a diverse range of plant species even during periods with a high abundance of particular resources in the landscape. The diverse diet of nectar-feeding bats emphasises the importance of floristically rich natural habitats in the landscape to provide reliable foraging resources year-round in a seasonally variable system. While a generalised network structure is thought to increase robustness, further research is necessary to understand how fluctuations in pollinator abundance and diversity in the face of land use and climate change may impact bat-flower networks and the consequences to plant communities.

Bat pollinators: a decade of monitoring reveals declining visitation rates for some species in Thailand

Bats are important pollinators, but they are difficult to study since they are volant and nocturnal. Thus, long-term studies of nectarivorous bats are scarce, despite their potential to help assess trends in bat populations and their pollination services. We used capture rates of nectarivorous bats at chiropterophilous flowers in order to examine temporal trends in bat visitation in an area that is undergoing extensive land use change. We mist-netted at five bat-pollinated plant taxa (Durio zibethinus, Musa acuminata, Oroxylum indicum, Parkia speciosa, and Sonneratia spp.) in southern Thailand over six years between 2011 and 2021. We found that the most common bat species, Eonycteris spelaea, was the main visitor at all five plant taxa and had consistent visitation rates across all study years. In contrast, two other important pollinators, Macroglossus minimus and M. sobrinus, showed 80% declines in the number of individuals netted at mangrove apple (Sonneratia spp.) and banana (Musa acuminata) flowers, respectively. These findings suggest that E. spelaea (a large, cave-roosting species with a broad diet) is more tolerant of anthropogenic change than are Macroglossus bats (small, foliage-roosting species with specialized diets), which may in turn affect the reproductive success of plants pollinated by these species. Our study demonstrates how decade-long monitoring can reveal species-specific temporal patterns in pollinator visitation, emphasizing the need for tailored conservation plans. While the conservation status of most nectarivorous bats in the area is Least Concern, our results indicate that population studies in Southeast Asia are urgently needed for updated bat species conservation assessments.

Global warming impairs the olfactory floral signaling in strawberry

BACKGROUND

Global warming is expected to impact the chemical communication between flowering plants and their pollinators. Surprisingly, it is unknown whether and how temperature-induced changes in scent emission affect pollinator behavior. Strawberry (Fragaria x ananassa) is a plant primarily pollinated by bees and hoverflies, with the former group being particularly attracted to the floral scent they emit.

RESULTS

Using chemical analytical, electrophysiological, and behavioral approaches we tested whether temperature-induced shifts in floral scent of strawberry affect chemical communication with its main bee pollinators (Apis mellifera, Bombus terrestris, Osmia bicornis). While strawberry flowers in the optimum scenario released 10.4 ng/flower/hour, mainly p-anisaldehyde (81%) and seven other scent compounds, in the warmer scenario, the flowers did not emit any detectable scent. In the behavioral experiments, the pollinators were attracted by the scents of the optimum scenario.

CONCLUSIONS

We predict that the absence of detectable scent emissions from strawberry plants grown under heat stress will reduce the attractiveness of the flowers to the bee pollinators. Our study raises important ecological and agricultural questions, as decreased attractiveness of flowers to pollinators might potentially lead to insufficient bee pollination, with potential negative consequences for ecosystem functioning and crop yields, particularly in regions reliant on bees as primary pollinators. Given that our study centered on bee pollinators, it is needed to conduct further research to evaluate the impact on hoverflies.

Changing with the times: Seasonal environmental gradients unveil dynamic bat assemblages and vulnerability

Uncovering the temporal and spatial dynamics of biological communities in response to biotic and abiotic drivers is essential to predict the effects of environmental change on biodiversity. Similarly, estimating species vulnerability in the face of such dynamics is crucial for implementing effective conservation actions. We explored how bat diversity changes over the year across an altitudinal gradient and identified the environmental drivers that shape bat communities. By analysing species' marginality within the biophysical niche space, we evaluated bats' vulnerability to foreseeable environmental changes. Our results suggest that altitude, the proportion of forest cover and shrub cover are the main drivers shaping bat communities year-round. Additionally, while some bat species are restricted to a single ecological assemblage (or ecological preferences group), others show greater plasticity throughout the year. Importantly, we found that although bats associated with highland habitats and forests could be particularly vulnerable to environmental changes (in particular Myotis mystacinus), this vulnerability correlates poorly with their national conservation status. We suggest that species' ecological plasticity is critical for the resilience of biological communities exposed to environmental changes and should be considered when planning tailored conservation strategies.

A species-level trait dataset of bats in Europe and beyond

Knowledge of species' functional traits is essential for understanding biodiversity patterns, predicting the impacts of global environmental changes, and assessing the efficiency of conservation measures. Bats are major components of mammalian diversity and occupy a variety of ecological niches and geographic distributions. However, an extensive compilation of their functional traits and ecological attributes is still missing. Here we present EuroBaTrait 1.0, the most comprehensive and up-to-date trait dataset covering 47 European bat species. The dataset includes data on 118 traits including genetic composition, physiology, morphology, acoustic signature, climatic associations, foraging habitat, roost type, diet, spatial behaviour, life history, pathogens, phenology, and distribution. We compiled the bat trait data obtained from three main sources: (i) a systematic literature and dataset search, (ii) unpublished data from European bat experts, and (iii) observations from large-scale monitoring programs. EuroBaTrait is designed to provide an important data source for comparative and trait-based analyses at the species or community level. The dataset also exposes knowledge gaps in species, geographic and trait coverage, highlighting priorities for future data collection.

Evaluating the persistence and utility of five wild Vitis species in the context of climate change

Crop wild relatives (CWRs) have the capacity to contribute novel traits to agriculture. Given climate change, these contributions may be especially vital for the persistence of perennial crops, because perennials are often clonally propagated and consequently do not evolve rapidly. By studying the landscape genomics of samples from five Vitis CWRs (V. arizonica, V. mustangensis, V. riparia, V. berlandieri and V. girdiana) in the context of projected climate change, we addressed two goals. The first was to assess the relative potential of different CWR accessions to persist in the face of climate change. By integrating species distribution models with adaptive genetic variation, additional genetic features such as genomic load and a phenotype (resistance to Pierce's Disease), we predicted that accessions from one species (V. mustangensis) are particularly well-suited to persist in future climates. The second goal was to identify which CWR accessions may contribute to bioclimatic adaptation for grapevine (V. vinifera) cultivation. To do so, we evaluated whether CWR accessions have the allelic capacity to persist if moved to locations where grapevines are cultivated in the United States. We identified six candidates from V. mustangensis and hypothesized that they may prove useful for contributing alleles that can mitigate climate impacts on viticulture. By identifying candidate germplasm, this study takes a conceptual step toward assessing the genomic and bioclimatic characteristics of CWRs.

The importance of pollination and dispersal syndromes for the conservation of Cerrado Rupestre fragments on ironstone outcrops immersed in an agricultural landscape

Studies on pollination and seed dispersal are essential for the conservation of plant diversity. In this study, we aimed to evaluate the pollination and dispersal syndromes of five fragments of the Cerrado Rupestre immersed in an agricultural landscape to answer the following questions: (i) What is the frequency of pollination and dispersal syndromes among species and individuals?; (ii) Which are the predominant pollination and seed dispersal syndromes in this environment?. A total of 66 species, belonging to 44 genera and 29 botanical families, were evaluated. Melittophily was the most common type of pollination syndrome, observed in 54.55% of the species, followed by phalenophily (9.09%), cantharophily, ornithophily, quiropterophilly and sphingophily (all 3.03%), and psychophilly (1.51%). Generalist pollination represented 22.73% of the records. Of the 1246 individuals identified, 59.23% were melitophilous, 25.20% generalists, 5.86% phalenophilous, 3.37% quiropterophilous, 2.49% cantharophilous, 2.25% ornithophilous, 1.44% sphingophilous and 0.16% psychophilous. Regarding dispersion syndromes, zoochory was the most common type of dispersion, observed in 68.18% of the species, followed by anemochory (28.79%) and autochory (3.03%). On the other hand, the frequency among individuals differed from the values found for frequency among species. Of the 1246 individuals identified, 55.38% were anemochoric, 43.10% zoochoric, and 1.52% autochoric. Our results demonstrate the predominance of biotic syndromes in the community, especially melittophily and zoochory, contributing to a better understanding of the functionality and availability of resources in the community, as well as indispensable information for the conservation, management, and restoration of natural environments.