Biology subjects

Smith, H. G.

Publications and source records attributed to Smith, H. G..

5 recordsLinked to original sources

bioRxiv2024

Warm or bright - temperature and light microhabitat use in insect pollinators

O_LIEnvironmental heterogeneity in forest understories creates microhabitat niches that differ both spatially and temporally in light intensity and temperature. Do animal communities segregate in relation to these niche dimensions and can this be explained by functional traits? Answering these questions is particularly important for insect pollinators as they play a critical role in maintaining flowering plant biodiversity. C_LIO_LIBumblebees are essential pollinators of high altitude/latitude ecosystems and are particularly sensitive to climate change. In early spring, they forage on bilberry, a keystone species in heterogeneous habitats - hemi- boreal forests. We capitalized on these conditions to study species-specific selection of foraging niches in relation to abiotic conditions. C_LIO_LIWe combined full-day monitoring of bumblebee communities foraging in bilberry-dominated forests with joint species distribution modelling, which showed that temperature conditioned species occurrence, while light intensity explained species abundance. The inclusion of functional traits did not improve the overall explanatory and predictive power of the models. C_LIO_LIOur results suggest that temperature acts as a first filter of the local species pool and that species, once present, partition along a light intensity gradient. This study confirms and extends upon previous findings that microhabitat partitioning may act a mechanism underpinning bumblebee coexistence. It highlights the importance of focusing on micro-scales when studying how species interact with their environment, as this could, for example help improve our ability to predict consequences of global changes. C_LI

ecology↗

bioRxiv2024

Forest habitat and forest dominated landscapes are associated with bumblebee species with visual traits related to light sensitivity

While functional traits like body size have been extensively linked to species distributions, the influence of sensory traits on species responses to environmental changes remains underexplored. Particularly, the relationship between light sensitivity and niche segregation across different distributional extents - local habitat conditions and across entire landscapes - remains unclear. In this study, we examined bumblebee communities monitored across Norway on grassland and forest habitats within landscapes varying in forest cover within 1 km radii. We investigated whether the eye parameter - a visual trait measuring the trade-off between light sensitivity (high values) and visual resolution (low values) - was associated with local habitat types and the forest cover at the landscape scale. Additionally, we combined bumblebee-plant interactions with a plant trait, to determine if bumblebee light sensitivity correlated with the shade tolerance of the plants they foraged on. Our findings showed that bumblebee species with high eye parameters were more common and abundant in forest habitats and areas with greater forest cover, while species with low eye parameters showed the opposite trend. This pattern was also reflected at the community level, as indicated by the community-weighted mean of the eye parameter which increased with forest cover and was higher in forest habitats. Furthermore, bumblebees with higher eye parameters tended to forage on plants with greater shade tolerance. These results suggest that visual adaptations for light sensitivity contribute to shaping bumblebee species distributions across different scales. Overall, our study underscores the importance of pollinator vision in understanding species niches, in relation to habitat use and foraging behaviour. By relating pollinator visual abilities to plant niches for the first time, this study provides an important basis for future modelling of plant-pollinator interactions and targeted conservation measures for both plants and pollinators in forested landscapes.

ecology↗

bioRxiv2023

Molecular basis for short-chain thioester hydrolysis by acyl hydrolase domains in trans-acyltransferase polyketide synthases

Polyketide synthases (PKSs) are multi-domain enzymatic assembly lines that biosynthesise a wide selection of bioactive natural products from simple building blocks. In contrast to their cis-acyltransferase (AT) counterparts, trans-AT PKSs rely on stand-alone AT domains to load extender units onto acyl carrier protein (ACP) domains embedded in the core PKS machinery. Trans-AT PKS gene clusters also encode acyl hydrolase (AH) domains, which are predicted to share the overall fold of AT domains, but hydrolyse aberrant acyl chains from ACP domains, thus ensuring efficient polyketide biosynthesis. How such domains specifically target short acyl chains, in particular acetyl groups, tethered as thioesters to the substrate-shuttling ACP domains, with hydrolytic rather than acyl transfer activity, has remained unclear. To answer these questions, we solved the first structure of an AH domain and performed structure-guided activity assays on active site variants. Our results offer key insights into chain length control and selection against coenzyme A-tethered substrates, and clarify how the interaction interface between AH and ACP domains contributes to recognition of cognate and non-cognate ACP domains. Combining our experimental findings with molecular dynamics simulations allowed for the production of a data-driven model of an AH:ACP domain complex. Our results advance the currently incomplete understanding of polyketide biosynthesis by trans-AT PKSs, and provide foundations for future bioengineering efforts.

biochemistry↗

bioRxiv2020

Reducing ecological complexity using the archetype approach - an application to natural pest control

Natural control of crop pests has the potential to complement or replace intensive agricultural practices, but its mainstream application requires reliable predictions in diverse socioecological settings. In lack of a widely accepted model of natural pest control, we review existing modelling approaches and critically examine their potential to provide understanding and predictions across agricultural landscapes. Models that explicitly represent the underlying mechanisms are better positioned to represent the diversity and context sensitivity of natural pest control than correlative models. Such mechanistic models have used diverse techniques to represent crop-pest-enemy combinations at various spatiotemporal scales. However, certain regions of the world and socioeconomic aspects of natural pest control are underrepresented, while modelling approaches are restricted by a fundamental trade-off between generality and realism. We propose that modelling natural pest control across agroecosystems requires a framework of context-specific generalizations, based on empirical evidence and theoretical expectations. Reviewed models of natural pest control indicate potential attributes of such a general predictive framework.

ecology↗

bioRxiv2019

A global synthesis reveals biodiversity-mediated benefits for crop production

Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield-related ecosystem services can be maintained by few abundant species or rely on high richness remains unclear. Using a global database from 89 crop systems, we partition the relative importance of abundance and species richness for pollination, biological pest control and final yields in the context of on-going land-use change. Pollinator and enemy richness directly supported ecosystem services independent of abundance. Up to 50% of the negative effects of landscape simplification on ecosystem services was due to richness losses of service-providing organisms, with negative consequences for crop yields. Maintaining the biodiversity of ecosystem service providers is therefore vital to sustain the flow of key agroecosystem benefits to society.

ecology↗