Biology subjects

Steiner, F. M.

Publications and source records attributed to Steiner, F. M..

11 recordsLinked to original sources

bioRxiv2026

Viral infection patterns in ants are affected by colony structure and phylogenetic lineage

Across ant species, there are differences in how their societies are structured. Single-queened (monogynous) societies only have one reproducing queen in the colony, and new queens disperse and start colonies independently. In multiple-queened (polygynous) societies, the colony instead can contain several reproductive queens, and newborn queens often remain and reproduce within their natal colony. As a result, polygynous societies are comparatively larger, more genetically diverse, and can span large areas through several interconnected nests, whereas monogynous societies are typically smaller in scale. In this study, we investigated how these different social structures, as well as their phylogenetic lineage, affect the diversity (number of virus species per ant sample) and abundance (number of viral sequences per sample) of viruses in ants. We produced pooled RNA sequence libraries from 15 ant species, representing both monogynous and polygynous social structures, and the two largest ant subfamilies: Formicinae and Myrmicinae, with each library containing the RNA of up to 400 individual worker ants from a single population. We identified 168 virus species in total, of which 152 species were new to science. Out of these 168 viruses, 59 were active viruses based on the host immune response. We observed that polygynous ant species harbor a higher diversity of viruses and also tend to have higher virus abundance compared to monogynous species. Also, the ant subfamily Myrmicinae had a higher virus diversity than Formicinae. These findings highlight how social structure and evolutionary history shape viral diversity in ants.

genomics↗

bioRxiv2026

Below-ground ants follow pheromones more quickly under dark conditions, but pheromones do not affect decision accuracy nor aggression

Communication allows organisms to quickly convey information vital for survival or fitness. Chemical communication and speed-accuracy trade-offs are ubiquitous in animal decision making. Most studies have used species which forage mainly above-ground species, tested in an epigean setting, but it remains unclear whether below-ground species behave similarly. Here, we use the below-ground ant Tetramorium alpestre to assess the efficacy of above- vs. below-ground mazes, the accuracy of decisions when using natural vs. artificial pheromones, the presence of a speed-accuracy trade-off, and the pheromones effect on aggression. Ants decided more quickly under below-ground than above-ground conditions, indicating they may be distracted by above-ground stimuli. Ants followed both natural and artificial trails but in direct competition preferred artificial trails, likely due to a higher pheromone concentration. Surprisingly, no speed-accuracy trade off was observed during path decision-making. Lastly, population origin but not pheromones affected if and how aggression occurred in presence of trail and home-range marking pheromones. We argue that the design of behavioural tests should match the lifestyle of the focal organism. We further speculate that speed-accuracy trade-offs likely are highly species- and context-specific and other factors besides chemicals seem important to trigger aggression, at least in this species.

animal behavior and cognition↗

bioRxiv2026

Population structure and genetic diversity of smooth newts (Lissotriton vulgaris) in North Tyrol, Austria: influences of allochthonous individuals and conservation implications

Amphibians are threatened worldwide by various environmental and anthropogenic factors, making non-invasive conservation studies particularly valuable. Newts are one example of a thus challenged amphibian group. In Austria, local population declines of newts have been observed, with the smooth newt (Lissotriton vulgaris) being strongly affected. In this study, skin swabs were used as a non-invasive method to gather DNA, combined with established microsatellite markers. We sampled 139 L. vulgaris individuals at ten sites in North Tyrol, Austria, and, for comparison, 22 L. vulgaris meridionalis individuals in Brixen, Italy. We genotyped all individuals and analysed their population structure. We demonstrate the presence of three distinct L. vulgaris population clusters and find differences in population structure between supposedly introduced allochthonous L. vulgaris individuals and autochthonous populations, as evidenced by differences in Bayesian clustering and elevated values of the fixation index FST. A captive population in a zoological garden, with origins in the Kramsacher Loar in the Tyrolean Unterland (eastern part of Tyrol), performed poorly in terms of conservation genetics, with low genetic diversity (number of alleles) and clear genetic differentiation from populations in the wild (high pairwise FST values with wild individuals, clear separation in cluster analysis). Habitat restoration programs are a crucial aspect of amphibian conservation, as they restore ecosystems that are critical to the animals survival. While breeding programs can play an additional role in the future, they must carefully consider genetic diversity to ensure resilient and viable populations, especially in the face of climate change and chytrid fungus infection. This study emphasizes the significance of considering the geographic origin and genetic diversity of newts in conservation efforts. It also serves as a foundation for future population genetic studies of newts in Austria.

molecular biology↗

bioRxiv2023

The radiation of Austral teals and the evolution of flightlessness

The origin and evolution in the Southern Hemisphere of the Austral teals, consisting of the grey-teal and brown-teal species complexes, remains poorly understood due to limited molecular data. With the group containing multiple independent examples of flight loss, understanding the evolutionary history of the group is of significant interest for functional genomic studies into the evolution of flightlessness. Here we present the first whole mitogenome-based phylogeny of the Austral teals. We show that the group diverged from a common ancestor with mallards in the late Miocene and soon after radiated into the brown-teal and grey-teal lineages, as well as the widely distributed pintails and green-winged ducks. The brown-teal species complex, which includes the volant brown and Chatham Island teals as well as the flightless, sub-Antarctic Auckland and Campbell Island teals, radiated within the past 0.9 - 2.2 million years. The divergence of the extinct Chatham Island teal, and the stepping-stone colonisation of the Auckland and Campbell Islands occurred from mainland New Zealand. Morphological changes towards flightlessness are also present in the volant brown teal on mainland New Zealand, suggesting that this group was on the pathway to flightlessess, which accelerated in some insular island lineages.

evolutionary biology↗

bioRxiv2022

Decrypting the microbiota on the black soldier fly's (Hermetia illucens L., Diptera: Stratiomyidae) egg surface and their origin during development

The increasing global population leads to a soaring demand for protein for food and feed, and also challenges in organic waste management are growing. All this leads to environmental stress, causing biodiversity loss and an increase in greenhouse gas emissions. Alternative and sustainable animal protein sources are needed to reduce the negative environmental impact of food production. In the last years, the black soldier fly (BSF) has been proposed to substitute animal protein, since BSF may consume and reduce a variety of waste organic matter. Successful industrial rearing of BSF depends on a flourishing reproduction of adults, which is influenced not only by environmental but also by physiological factors. The BSF female oviposits single eggs into clutches close to decomposing organic matter and conspecific eggs. Studies have shown that microbes play a significant role in the oviposition of BSF eggs. In this study, we focus on the surface microbiota of the egg and its origin. We investigated if the microbiota is inoculated before, during, or actively after oviposition. For this purpose, we analysed the microbiota in the larval haemolymph and the gut of larvae raised on sterilized and non-sterilized feed, the pupal cell pulp, the wash of the egg-laying apparatus and the eggs directly collected after oviposition, the ovarian eggs and the empty female abdomen, the eggs with contact to adult BSF, and sterilized eggs. The bacterial communities were identified through 16S rRNA gene sequencing to assess the stage in BSF development during which the microbial colonization of the egg surface occurs. We demonstrated that bacteria differ among life stages resulting in a shift during BSF development from dominance of Enterobacteriaceae during the larval stage to dominance of Burkholderiaceae spp. in all analysed eggs. A predominant microbiota is present before oviposition and persists through all life stages, however, the overall populations structure successively shifts during development. A better understanding of egg surface microbiota and oviposition attractants could significantly increase egg production and facilitate the mass harvesting of BSF larvae. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=125 SRC="FIGDIR/small/520758v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@1faf08borg.highwire.dtl.DTLVardef@1c66b02org.highwire.dtl.DTLVardef@19b5658org.highwire.dtl.DTLVardef@141b369_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstract.C_FLOATNO Illustration of the sampling procedure to assess egg surface microbiome of black soldier fly and its origin: Larval fed with unsterile (GU) and sterile (GS) feed and the larval haemolymph of GS (LH), the pupal cell pulp (CP), and from the female adults after mating, a wash of the egg-laying apparatus (WS) and the afterwards placed eggs of the egg-laying apparatus (EA), eggs collected from the ovary (EO) and the empty female abdomen (FA), eggs collected from a fly cage after forced exposure to adults (EC) and sterilized (ES). C_FIG

microbiology↗

bioRxiv2021

Evolutionary history of an Alpine archaeognath(Machilis pallida) - insights from different variant types

Reconstruction of species histories is a central aspect of evolutionary biology. Patterns of genetic variation within and among populations can be leveraged to elucidate evolutionary processes and demographic histories. However, interpreting genetic signatures and unraveling the contributing processes can be challenging, in particular for non-model organisms with complex reproductive modes and genome organization. One way forward is the combined consideration of patterns revealed by different molecular markers (nuclear vs. mitochondrial) and types of variants (common vs. rare) that differ in their age, mode and rate of evolution. Here, we applied this approach to Machilis pallida (Archaeognatha), an Alpine jumping bristletail considered parthenogenetic and triploid. We generated de-novo transcriptome and mitochondrial assemblies to obtain high-density data to investigate patterns of mitochondrial and common and rare nuclear variation in 17 M. pallida individuals sampled across the Alps from all known populations. We find that the different variant types capture distinct aspects of the evolutionary history and discuss the observed patterns in the context of parthenogenesis, polyploidy and survival during glaciation. This study highlights the potential of different variant types to unravel complex evolutionary scenarios and the suitability of M. pallida and the genus Machilis as a study system for the evolution of sexual strategies and polyploidization during environmental change. We also emphasize the need for further research which will be stimulated and facilitated by these newly generated resources and insights.

evolutionary biology↗

bioRxiv2021

No influence of antibiotic on locomotion in Drosophila nigrosparsa after recovery, but influence on microbiome, possibly mediating wing-morphology change

Antibiotics, such as tetracycline, has been frequently used to cure endosymbiont Wolbachia in arthropods. After the symbionts had been removed, the hosts must be waited for some generations to recover from side effects of the antibiotics. Knowledge of potential long-term effects of the antibiotic is important. Here, we treated Drosophila nigrosparsa with and without antibiotic tetracycline for three generations and two generations recovering time to investigate effects of the tetracycline on the flies concerning locomotion of larvae and adults, wing morphology, and gut microbiome of adults. In addition, gut-microbiome restoration was tested as a solution to reducing potential side effects of tetracycline on the flies microbiome more quickly. We found significant differences in larval and adult locomotion within groups but no significant differences among the control, antibiotic-treated, and gut-restoration groups. We found a slight differentiation of wing morphology into the three groups and significant differences in bacterial abundance among groups. The influence of tetracycline on the gut microbiome may have contributed to wing-morphology differences among groups, which would be an indirect effect of the antibiotic. Together with the absence of an effect on locomotion, this suggests that checking for both direct and indirect effects of tetracycline after a particular recovery time before using tetracycline curing is important. The microbiome of the gut-restoration group was not like that of the control group. Therefore, gut restoration cannot be used to remove effects of tetracycline in D. nigrosparsa, at least in the setup used here.

microbiology↗

bioRxiv2021

Hybridization dynamics and extensive introgression in the Daphnia longispina species complex: new insights from a high-quality Daphnia galeata reference genome

Hybridization and introgression are recognized as an important source of variation that influence adaptive processes; both phenomena are frequent in the genus Daphnia, a keystone zooplankton taxon in freshwater ecosystems that comprises several species complexes. To investigate genome-wide consequences of introgression between species, we provide here the first high-quality genome assembly for a member of the Daphnia longispina species complex, Daphnia galeata. We further re-sequenced 49 whole genomes of three species of the complex and their interspecific hybrids both from genotypes sampled in the water column and from single resting eggs extracted from sediment cores. Populations from habitats with diverse ecological conditions offered an opportunity to study the dynamics of hybridization linked to ecological changes and revealed a high prevalence of hybrids. Using phylogenetic and population genomic approaches, we provide first insights into the intra- and interspecific genome-wide variability in this species complex and identify regions of high divergence. Finally, we assess the length of ancestry tracts in hybrids to characterize introgression patterns across the genome. Our analyses uncover a complex history of hybridization and introgression reflecting multiple generations of hybridization and backcrossing in the Daphnia longispina species complex. Overall, this study and the new resources presented here pave the way for a better understanding of ancient and contemporary gene flow in the species complex and facilitate future studies on resting egg banks accumulating in lake sediment.

evolutionary biology↗

bioRxiv2020

Differential gene expression in Drosophila melanogaster and D. nigrosparsa infected with the same Wolbachia strain

Wolbachia, maternally inherited endosymbionts, infect nearly half of all arthropod species. Wolbachia manipulate their hosts to maximize their transmission, but they can also provide benefits such as nutrients and resistance to viruses for their hosts. The Wolbachia strain wMel was recently found to increase locomotor activities and possibly trigger cytoplasmic incompatibility in the fly Drosophila nigrosparsa. Here, we compared differential gene expression in Drosophila melanogaster (original host) and D. nigrosparsa (novel host), both uninfected and infected with wMel, using RNA sequencing to see if the two Drosophila species respond to the infection in the same or different ways. A total of 2164 orthologous genes were used. We found species-specific gene expression patterns. Significant changes shared by the fly species were confined to the expression of genes involved in heme binding and oxidation-reduction; the two host species differently changed the expression of genes when infected. Some of the genes were down-regulated in the infected D. nigrosparsa, which might indicate small positive effects of Wolbachia. We discuss our findings also in the light of how Wolbachia survive within both the native and the novel host.

microbiology↗

bioRxiv2020

Wolbachia affect behavior and possibly reproductive compatibility but not thermoresistance, fecundity, and morphology in a novel transinfected host, Drosophila nigrosparsa

Wolbachia, intracellular endosymbionts, are estimated to infect about half of all arthropod species. These bacteria manipulate their hosts in various ways for their maximum benefits. The rising global temperature may accelerate species migration and, thus, horizontal transfer of Wolbachia may occur across species previously not in contact. We transinfected and then cured the alpine fly Drosophila nigrosparsa with Wolbachia strain wMel to study its effects on this species. We found low Wolbachia titer, possibly cytoplasmic incompatibility, and an increase in locomotion of both infected larvae and adults compared with cured ones. However, no change in fecundity, no impact on heat and cold tolerance, and no change in wing morphology were observed. Although Wolbachia increased locomotor activities in this species, we conclude that D. nigrosparsa may not benefit from the infection. Still, D. nigrosparsa can serve as a host for Wolbachia because vertical transmission is possible but may not be as high as in the native host of wMel, Drosophila melanogaster.

ecology↗

bioRxiv2019

Classic and introgressed selective sweeps shape mimicry loci across a butterfly adaptive radiation

Natural selection leaves distinct signatures in the genome that can reveal the targets and history of adaptive evolution. By analysing high-coverage genome sequence data from four major colour pattern loci sampled from nearly 600 individuals in 53 populations, we show pervasive selection on wing patterns across the Heliconius adaptive radiation. The strongest signatures correspond to loci with the greatest phenotypic effects, consistent with visual selection by predators, and are found in colour patterns with geographically restricted distributions. These recent sweeps are similar between co-mimics and indicate colour pattern turn-over events despite strong stabilizing selection. Using simulations we compare sweep signatures expected under classic hard sweeps with those resulting from adaptive introgression, an important aspect of mimicry evolution in Heliconius. Simulated recipient populations show a distinct volcano pattern with peaks of increased genetic diversity around the selected target, consistent with patterns found in some populations. Our genomic data provide unprecedented insights into the recent history of selection across the Heliconius adaptive radiation.

evolutionary biology↗