Biology subjects

Colgan, T. J.

Publications and source records attributed to Colgan, T. J..

6 recordsLinked to original sources

bioRxiv2025

Envenomation leads to venom protein reduction and recovery delay in bumblebee workers

The evolution and deployment of venom systems in animals has been central to their ecological success, though not without costs. For social bees, venom plays a key role in nest defence yet for species, such as honeybees, the act of stinging generally leads to death. However, for other social bee species, such as bumblebees, where stinging is not apparently fatal, it raises the question of what, if any, are the costs associated with venom usage (envenomation). Here, we investigated proteomic changes in the venom sac, the primary reservoir for venom storage, of Bombus terrestris workers over a short time-course post-envenomation. Our analysis reveals three key findings: 1) envenomation leads to changes in the venom sac proteome with affected proteins generally reduced in the bumblebee venom sac, suggestive of a molecular cost; 2) quantified reductions of traditional venom-associated proteins post-envenomation indicate changes in venom composition post-usage; and 3) recovery of reduced venom-associated proteins post-envenomation was delayed further indicating a potential cost at the molecular level associated with usage. Overall, our findings provide new insights into the consequences of venom usage in bumblebees.

zoology↗

bioRxiv2025

A chromosome-level genome assembly and resequencing data reveal low DNA methylation and reduced diversity in the solitary bee pollinator Osmia cornuta

Bees provide essential pollination services that contribute to ecosystem stability, as well as the sustainability of economic crop yields. Due to concerns over global and local declines, improving our understanding of these ecologically and commercially important species is crucial for determining their capacity to respond and adapt to environmental challenges. The European orchard bee (Osmia cornuta) is a solitary bee of increasing agricultural importance due to its role in the pollination of fruit crops, yet lacks genomic resources. Using cost-effective Nanopore-only long-read sequencing, we report the first genome assembly for O. cornuta, spanning 647.56Mb across 727 contigs (N50=3.94Mb) at a high level of completeness (99.88% BUSCO complete). In line with the expected number of chromosomes in this species, 16 major scaffolds were assembled to chromosome-level. Also, we provisionally investigated the epigenomic architecture of O. cornuta, finding low numbers of CG dinucleotides that were either 5-methylated or 5-hydroxymethylated, providing additional evidence for the limited role methylation plays in gene regulation in Hymenopterans. To generate improved gene annotations, we combined transcriptomic- and orthology-based approaches, leading to the prediction of 12,144 genes and 25,964 proteins, showing exceptionally high BUSCO completeness (99.64%). Lastly, through whole-genome resequencing of a representative dataset, we provisionally find patterns of reduced nucleotide diversity and lower recombination rates within O. cornuta compared to other bee species. Collectively, our study provides a novel insight into the genome architecture of a key pollinator, providing an important resource to facilitate further genomic studies. Significance statementSolitary bees are crucial pollinators for crops and wild plants, but scientists have lacked the genetic blueprints needed to understand how these species might adapt to environmental threats like climate change and habitat loss. Using modern and cost-effective technologies, we generated the complete genome of the European orchard bee, an economically important fruit pollinator. This comprehensive genetic resource provides the foundation for future research on solitary bee biology and conservation, necessary to understand their adaptive potential in the face of environmental challenges. In line with this, we analysed this species genetic variation across populations in Germany using a small, representative dataset and found surprisingly low genetic diversity and limited evidence of gene recombination during reproduction, which are factors that could restrict its capacity to evolve in response to environmental challenges.

genomics↗

bioRxiv2024

Simulated climate warming scenarios lead to earlier emergence and increased weight loss but have no effect on overwintering survival in solitary bees

Insect pollination is critical for both wildflower stability and agricultural yields, with solitary bees being a group of pollinators of fundamental importance. However, documented declines in populations, exacerbated by environmental pressures, including climate change, pose significant threats to the provision of ecosystem services. Exposure to elevated temperatures during periods of dormancy, such as overwintering, is predicted to lead to phenological shifts, changes in condition, and impacts on survival. However, we currently lack studies that inform how such aspects are affected in future climate change scenarios. Using simulated temperature regimes informed by predictions of the Intergovernmental Panel on Climate Change, we exposed overwintering mason bees (Osmia species) to three field-relevant temperature profiles based on either present-day overwintering temperatures or future temperatures predicted under two major climate warming scenarios (SSP2-4.5 and SSP5-8.5) and measured how temperature exposure affected emergence timing, weight loss and survival. We found that exposure to temperatures under intermediate and worst-case climate warming scenarios led to earlier emergence by approximately three and six weeks, respectively, with increasing divergences in timing of emergence between the sexes of Osmia bicornis, which may lead to intraspecific phenological mismatches. While we found no effect of temperature on overwintering survival rates, we observed increased weight loss prior to emergence but found that in contrast to other studies, it only mildly mediated shifts in emergence timing brought about by temperature exposure, suggesting that weight loss is unlikely to play a major role as a trigger of emergence timing in mason bees. Our study contributes to the growing literature highlighting the impact that temperatures under climate change models will have on the timing of key life events for essential pollinators, which may have consequences at the population and community levels.

ecology↗

bioRxiv2024

Queen number shapes worker longevity, fecundity and gene expression in the invasive, highly polygynous ant Tapinoma magnum

In social animals, reproductive activity and ageing patterns are influenced by group composition. A well-documented phenomenon in monogynous (one-queen) insect societies is that queen presence affects worker fecundity and longevity. Little is known about whether and how workers respond to queen number variation in polygynous (multi-queen) species and how their queens age. We created queenless, one-queen, and two-queen colonies of the invasive, polygynous ant Tapinoma magnum to examine worker survival, fecundity, oxidative stress resistance, and fat body gene expression. Additionally, we compared fecundity and brain and fat body transcriptomes of young and old queens. Queenless workers experienced the highest mortality, contrasting with monogynous species where queen removal typically extends lifespan. Workers in single-queen colonies lived longer and were more fertile than in two-queen colonies. Queen number did not directly affect oxidative stress resistance or fat body transcription, though the latter depended on an interaction with worker task. Furthermore, younger nurses demonstrated higher fecundity, oxidative stress resistance and upregulated antioxidant genes compared to older foragers. Absent or minor shifts in fecundity and transcription with queen age, respectively, indicated physiological stability with age. Our research highlights distinct caste- and tissue-specific ageing patterns in this supercolonial species, deviating from typical monogynous ants.

evolutionary biology↗

bioRxiv2021

Genomic architecture and sexually dimorphic expression underlying immunity in the red mason bee, Osmia bicornis

Insect pollinators provide crucial ecosystem services yet face increasing environmental pressures. The challenges posed by novel and reemerging pathogens on bee health means we need to improve our understanding of the immune system, an important barrier to infections and disease. Despite its importance, for certain ecologically important species, such as solitary bees, our understanding of the genomic basis and molecular mechanisms underlying immune potential, and how intrinsic and extrinsic factors may influence immune gene expression is lacking. Here, to improve our understanding of the genomic architecture underlying immunity of a key solitary bee pollinator, we characterised putative immune genes of the red mason bee, Osmia bicornis. In addition, we used publicly available RNA-seq datasets to determine how sexes differ in immune gene expression and splicing but also how pesticide exposure may affect immune gene expression in females. Through comparative genomics, we reveal an evolutionary conserved set of more than 500 putative immune-related genes. We found genome-wide patterns of sex-biased gene expression, including immune genes involved in antiviral-defence. Interestingly, the expression of certain immune genes were also affected by exposure to common neonicotinoids, particularly genes related to haemocyte proliferation. Collectively, our study provides important insights into the gene repertoire, regulation and expression differences in the sexes of O. bicornis, as well as providing additional support for how neonicotinoids can affect immune gene expression, which may affect the capacity of solitary bees to respond to pathogenic threats.

evolutionary biology↗

bioRxiv2021

Genomic signatures of recent adaptation in a wild bumblebee

Behavioral experiments and analyses of observation records have shown that environmental changes threaten insect pollinators, creating risks for agriculture and ecosystem stability. Despite their importance, we know little about how wild insects or other animals can adapt in response to environmental pressures. To understand the genomic bases of adaptation in an ecologically important pollinator, we analyzed genomes of Bombus terrestris bumblebees collected across Great Britain. We reveal extensive genetic diversity within this population, and strong signatures of recent adaptation throughout the genome. More specifically, we find that selection recently affected key processes underpinning environmental interactions, including neurobiology, wing development, and response to xenobiotics. We also discover unusual features of the genome, including a 53-gene region that lacks genetic diversity in many bee species, and a horizontal gene transfer from a Wolbachia bacteria. The genetic diversity and gene flow we observe for this species could support its resilience to ongoing and future challenges. Overall, we provide important insight on the genetic health of an ecologically and economically important pollinator and reveal mechanisms by which it has recently adapted. The approach we used could help to understand how species differ in their adaptive potential, and to develop conservation strategies for those most at risk.

evolutionary biology↗