Biology subjects

Bleidorn, C.

Publications and source records attributed to Bleidorn, C..

7 recordsLinked to original sources

bioRxiv2026

Rapid spread of nutritional Wolbachia symbionts across and within solitary bee species

Maternally inherited, intracellular Bacteria of the genus Wolbachia are extremely widespread among arthropods. Their evolutionary success is owed to frequent host shifts and rapid subsequent spread within host populations, often facilitated by Wolbachia-induced reproductive manipulations. Theory suggests that carrying Wolbachia must also be beneficial for a successful spread, however the nature of such benefits remains unclear. Here, we demonstrate that Wolbachias success in many solitary bee species is strongly associated with the presence of a gene cassette enabling Wolbachia to synthesize Biotin (vitamin B7). This ability is absent from almost all other Wolbachia strains but common among bee associated strains. We show that Wolbachia occurs in up to 70% of all bee species and that strains carrying this rare genomic element have independently spread into numerous bee hosts recently. We further demonstrate that the presence of the biotin operon is associated with specialised diets in several bee species, suggesting a previously overlooked nutritional role of Wolbachia in this group of important pollinators. Overall, our results suggest that nutritional benefits provided by symbionts may represent a more widespread and important mechanism by which reproductive manipulators spread into new host species than previously appreciated.

evolutionary biology↗

bioRxiv2022

Probing the evolutionary dynamics of whole-body regeneration within planarian flatworms

Why some animals can regenerate while many others cannot remains a fascinating question. Even amongst planarian flatworms, well-known for their ability to regenerate complete animals from small body fragments, species exist that have restricted regeneration abilities or are entirely regeneration incompetent. Towards the goal of probing the evolutionary dynamics of regeneration, we have assembled a diverse live collection of planarian species from around the world. The combined quantification of species-specific head regeneration abilities and comprehensive transcriptome-based phylogeny reconstructions reveals multiple independent transitions between robust whole-body regeneration and restricted regeneration in the freshwater species. Our demonstration that the RNAi-mediated inhibition of canonical Wnt signalling can nevertheless bypass all experimentally tractable head regeneration defects in the current collection indicates that the pathway may represent a hot spot in the evolution of planarian regeneration defects. Combined with our finding that Wnt signalling has multiple roles in the reproductive system of the model species S. mediterranea, this raises the possibility of a trade-off between egg-laying and asexual reproduction by fission/regeneration as a driver of regenerative trait evolution. Although initial quantitative comparisons of Wnt signalling levels, reproductive investment, and regenerative abilities across the collection confirm some of the models predictions, they also highlight the diversification of molecular mechanisms amongst the divergent planarian lineages. Overall, our study establishes a framework for the mechanistic evolution of regenerative abilities and planarians as model taxon for comparative regeneration research.

evolutionary biology↗

bioRxiv2022

Patchwork: alignment-based retrieval and concatenation of phylogenetic markers from genomic data

MotivationIncreased output from the latest short-read sequencers makes low-coverage whole-genome sequencing (LC-WGS) an increasingly affordable approach to large-scale phylogenetics. Despite offering several advantages over prevailing sequencing strategies, few tools exist to work with this data type within a phylogenomic context. Due to the fragmented nature of LC-WGS genomes, their use have mostly been restricted to easy-to-assemble, high-copy-number regions such as organelle genomes and or ribosomal genes. ResultsWe here present a new method for mining phylogenetic markers directly from an assembled genome. Homologous regions are obtained via an alignment search, followed by a "hit-stitching" phase, in which adjacent or overlapping regions are concatenated together. Finally, a novel sliding window technique is used to trim non-coding regions from the alignments. We demonstrate the utility of Patchwork by recovering near-universal single-copy orthologs (USCOs) in the annelid Dimorphilus gyrociliatus. AvailabilityPatchwork is available from Github under the GNU General Public license version 3. Contactfelix.thalen@uni-goettingen.de Supplementary informationSupplementary data are available at github.com/Animal-Evolution-and-Biodiversity/benchmarking-patchwork.

bioinformatics↗

bioRxiv2018

Breaking the ladder: Evolution of the ventral nerve cord in Annelida

A median, segmented, annelid nerve cord has repeatedly been compared to the arthropod and vertebrate nerve cords and became the most used textbook representation of the annelid nervous system. Recent phylogenomic analyses, however, challenge the hypothesis that a subepidermal rope-ladder-like ventral nerve cord (VNC) composed of a paired serial chain of ganglia and somata-free connectives represents neither a plesiomorphic nor a typical condition in annelids.\n\nUsing a comparative approach by combining phylogenomic analyses with morphological methods (immunohistochemistry and CLSM, histology and TEM), we compiled a comprehensive dataset to reconstruct the evolution of the annelid VNC. Our phylogenomic analyses generally support previous topologies. However, the so far hard-to-place Apistobranchidae and Psammodrilidae are now incorporated among the basally branching annelids with high support. Based on this topology we reconstruct an intraepidermal VNC as ancestral state in Annelida. Thus, a subepidermal ladder-like nerve cord clearly represents a derived condition.\n\nBased on the presented data, a ladder-like appearance of the ventral nerve cord evolved repeatedly, and independently of the transition from an intraepidermal to a subepidermal cord during annelid evolution. Our investigations thereby question a common origin of the bilaterian median ganglionated VNC and propose an alternative set of neuroanatomical characteristics of the last common ancestor of Annelida or perhaps even Spiralia.

evolutionary biology↗

bioRxiv2018

Infections patterns and fitness effects of Rickettsia and Sodalis symbionts in the green lacewing Chrysoperla carnea

Endosymbionts are wide-spread among insects and can play an essential role in host ecology. The common green lacewing (Chrysoperla carnea s. str.) is a neuropteran insect species which is widely used as a biological pest control. We screened for endosymbionts in natural and laboratory populations of the green lacewing using diagnostic PCR amplicons. We found the endosymbiont Rickettsia to be very common in all screened populations, whereas a so far uncharacterized Sodalis strain was solely found in laboratory populations. The new Sodalis strain was characterized using a whole genome shotgun approach. Its draft genome revealed an approximate genome size of 4.3 Mbp and the presence of 5213 coding sequences. Phylogenomic analyses indicated that this bacterium is the sister taxon of S. praecaptivus. In an experimental approach, we found a negative impact of Sodalis on the reproduction success of the green lacewing. Co-infections with Rickettsia and Sodalis caused an even higher decrease of reproductive success than single Sodalis infections. In contrast, no significant fitness differences were found in Rickettsia infected green lacewings compared to uninfected lacewings. The Rickettsia/Sodalis/Ch. carnea system presents a promising model to study evolutionary endosymbiont-host interactions in Neuroptera and endosymbiont-endosymbiont interactions in general. The economic and ecological importance of green lacewings in biological pest control warrants a more profound understanding of its biology, which might be strongly influenced by symbionts.

evolutionary biology↗

bioRxiv2018

Prot-SpaM: Fast alignment-free phylogeny reconstruction based on whole-proteome sequences

Word-based or alignment-free sequence comparison has become an active area of research in bioinformatics. While previous word-frequency approaches calculated rough measures of sequence similarity or dissimilarity, some new alignment-free methods are able to accurately estimate phylogenetic distances between genomic sequences. One of these approaches is Filtered Spaced Word Matches. Herein, we extend this approach to estimate evolutionary distances between complete or incomplete proteomes; our implementation of this approach is called Prot-SpaM. We compare the performance of Prot-SpaM to other alignment-free methods on simulated sequences and on various groups of eukaryotic and prokaryotic taxa. Prot-SpaM can be used to calculate high-quality phylogenetic trees from whole-proteome sequences in a matter of seconds or minutes and often outperforms other alignment-free approaches. The source code of our software is available through Github:\n\nhttps://github.com/jschellh/ProtSpaM

bioinformatics↗

bioRxiv2017

Is It Time To Retire Wolbachia Multilocus Sequence Typing (MLST)?

Wolbachia (Alphaproteobacteria, Rickettsiales) is the most common, and arguably one of the most important inherited symbionts. Molecular differentiation of Wolbachia strains is routinely performed with a set of five multilocus sequence typing (MLST) markers. However, since its inception in 2006, the performance of MLST in Wolbachia strain typing has not been assessed objectively. Here, we evaluate the properties of Wolbachia MLST markers and compare it to 252 other single copy loci present in the genome of most Wolbachia strains. Specifically, we investigated how well MLST performs at strain differentiation, at reflecting genetic diversity of strains, and as phylogenetic marker. We find that MLST loci are outperformed by other loci at all tasks they are currently employed for, and thus that they do not reflect the properties of a Wolbachia strain very well. We argue that whole genome typing approaches should be used for Wolbachia typing in the future. Alternatively, if few-loci-approaches are necessary, we provide a characterization of 252 single copy loci for a number a criteria, which may assist in designing specific typing systems or phylogenetic studies.

evolutionary biology↗