Biology subjects

Koblmueller, S.

Publications and source records attributed to Koblmueller, S..

5 recordsLinked to original sources

bioRxiv2026

Parallel connectivity and genomic divergence but heterogeneous demographic history in sympatric Mediterranean clingfishes

Understanding the extent to which marine connectivity can be predicted from shared oceanographic and biogeographic conditions remains a central challenge in marine ecology and evolution. Comparative analyses of sympatric species provide a powerful framework for testing whether common environmental contexts generate repeatable patterns of population structure and connectivity and if this also unfolds on a genomic level. Here, we investigated this question in the endemic Mediterranean clingfish genus Gouania, a group of cryptobenthic gravel-beach specialists with limited adult mobility and a short pelagic larval phase. We combined whole-genome resequencing of two sympatric eastern Mediterranean species (G. orientalis and G. hofrichteri) around Crete and Kythira with Lagrangian particle drift simulations, mitochondrial phylogeography across all five Gouania species and demographic reconstructions using MSMC2. Passive drift simulations predicted strong isolation of Kythira and restricted exchange between northern and southern Crete. These predictions closely matched genome-wide population structure in both species, revealing highly concordant patterns of connectivity despite independent evolutionary histories. Shared population contrasts were furthermore associated with a significant excess of parallel genomic divergence, with both genomic windows and candidate genes overlapping more frequently than expected by chance. Nevertheless, most differentiated genomic regions remained species-specific and functional enrichment analyses identified no dominant shared pathways, suggesting a largely polygenic basis of divergence. In contrast to the strong concordance observed for contemporary connectivity and genomic divergence, mitochondrial phylogeographic patterns and species-level demographic histories were considerably more heterogeneous across the genus. Together, our results demonstrate that the predictability of marine population structure is scale-dependent: shared seascapes can generate repeatable patterns of connectivity and partially parallel genomic divergence, whereas deeper phylogeographic and demographic histories remain strongly influenced by species-specific historical processes.

evolutionary biology↗

bioRxiv2025

The genomics of convergent adaptation to intertidal gravel beaches in Mediterranean clingfishes

IntroductionUnderstanding the genetic basis of widespread phenotypic convergence, particularly for complex morphological traits, remains a major challenge in evolutionary biology. The Mediterranean gravel beach clingfishes of the genus Gouania provide an excellent system to study this phenomenon. Within this genus, two distinct morphotypes, "slender" and "stout", have repeatedly evolved, adapting to different microhabitats. These morphotypes differ in multiple complex traits, including body elongation, head compression, vertebral number, eye size, and the structure of the adhesive disc. Materials and MethodsIn a first step, to scrutinize phylogenetic convergence, we combined 3D morphometrics of the pelvic girdle and skull, with molecular species delimitation based on >660 DNA barcodes, and a phylogenomic framework based on more than 3,400 single-copy orthologs. Secondly, by employing whole-genome resequencing and a novel "convergence score" statistic, we examined genomic convergence across multiple levels: nucleotides, sequences, genes, and functional pathways. Results and DiscussionWhile we found no evidence of large-scale genomic or protein-level convergence, we identified promising candidate regions at the level of single variants, genes, and biological pathways. Notably, a longer shared (but interrupted) haplotype around the morphogene adam12 was associated with convergent traits. The lack of simple genomic patterns may reflect the radiations age and the complex genetic basis of the underlying morphological traits (e.g., eye-size, neurocranium shape). Altogether, our findings highlight the importance of assessing genomic convergence at multiple molecular levels to uncover diagnostic signals across varying evolutionary processes and timescales. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=149 SRC="FIGDIR/small/675783v1_ufig1.gif" ALT="Figure 1"> View larger version (61K): org.highwire.dtl.DTLVardef@58265eorg.highwire.dtl.DTLVardef@13f1deaorg.highwire.dtl.DTLVardef@c51d79org.highwire.dtl.DTLVardef@112217d_HPS_FORMAT_FIGEXP M_FIG C_FIG

evolutionary biology↗

bioRxiv2022

Ectoparasitism in Polystomatidae (Neodermata, Monogenea): phylogenetic position and mitogenome of Sphyranura euryceae, a parasite of the Oklahoma salamander

BackgroundPolystomatidae represents a monogenean group whose representatives infect mainly (semi)-aquatic tetrapods. Sphyranuridae with its single genus (Sphyranura) exhibits ectoparasitism on salamander hosts and was traditionally considered a sister-group to Polystomatidae based on the presence of a well-developed opisthaptor yet was distinguished due to the presence of a single pair of haptoral suckers, as opposed to the three pairs present in polystomatids. However, more recent molecular work supported its inclusion within Polystomatidae, at an early diverging, yet unresolved, position in the clade of polystomatids that otherwise exhibit endoparasitism of batrachians. Resolving the position of Sphyranura in relation to Polystomatidae is a prerequisite for understanding the factors driving evolution and the shifts between ecto- and endoparasitism in Polystomatidae. MethodsVarious staining methods were used to morphologically characterise collected specimens of Sphyranura. The mitochondrial genome was assembled from WGS data. Based on a combination of nuclear (18S, 28S rRNA) and mitochondrial markers (cox1, 12S) we inferred the phylogeny of Polystomatidae using Bayesian inference and maximum likelihood methods. ResultsBased on morphological examination and comparison with type material, specimens of Sphyranura infecting Oklahoma salamander (Eurycea tynerensis) at Greathouse Spring, Arkansas (USA), were identified as S. euryceae, a new distributional record for the species. Along with an amended diagnosis of Sphyranura we provide the first molecular data for S. euryceae. Mitochondrial level comparison reveals instances of tRNA gene rearrangements in polystomatids. Our phylogeny identifies two clades within polystomatids infecting tetrapods, one infecting exclusively batrachians, the other mainly known from chelonians. Although not fully supported, Sphyranura appears as the earliest branching lineage within the former. ConclusionsWith Sphyranura nested within Polystomatidae, we consider Sphyranuridae invalid. Sphyranuras apparent early branching position indicates ectoparasitism is an ancestral trait with endoparasitism having evolved later in the Polbatrach clade. However, the reduced number of haptoral suckers in representatives of Sphyranura is a derived characteristic potentially resulting from paedomorphic evolution. Whilst there is an indication towards phylogenetic congruence of polystomatids and their batrachian hosts, the same was not true for polystomatid parasites of chelonians with evidence of multiple host switches. Furthermore, geographic distribution of hosts was not found to drive polystomatid phylogeny.

evolutionary biology↗

bioRxiv2021

Somewhere I Belong: Phylogenetic Comparative Methods and Machine Learning to Investigate the Evolution of a Species-Rich Lineage of Parasites

AO_SCPLOWBSTRACTC_SCPLOWA substantial portion of biodiversity evolved through adaptive radiation. However, the effects of explosive speciation on species interactions remain poorly understood. Metazoan parasites infecting radiating host lineages could improve our knowledge because of their intimate host relationships. Yet limited molecular, phenotypic, and ecological data discourage multivariate analyses of evolutionary patterns and encourage the use of discrete characters. Here, we assemble new molecular, morphological, and host range data widely inferred from a species-rich lineage of parasites (Cichlidogyrus, Platyhelminthes: Monogenea) infecting cichlid fishes to address data scarcity. We infer a multi-marker (28S/18S rDNA, ITS1, COI mtDNA) phylogeny of 58/137 species and characterise major lineages through synapomorphies inferred from mapping morphological characters. We predict the phylogenetic position of species without DNA data through shared character states, a combined molecular-morphological phylogenetic analysis, and a classification analysis with support vector machines. Based on these predictions and a cluster analysis, we assess the systematic informativeness of continuous characters, search for continuous equivalents for discrete characters, and suggest new characters for morphological traits not analysed to date. We also model the attachment/reproductive organ and host range evolution using the data of 136/137 described species and multivariate phylogenetic comparative methods (PCMs). We show that discrete characters can mask phylogenetic signals but can be key for characterising species groups. Regarding the attachment organ morphology, a divergent evolutionary regime for at least one lineage was detected and a limited morphological variation indicates host and environmental parameters affecting its evolution. However, moderate success in predicting phylogenetic positions, and a low systematic informativeness and high multicollinearity of morphological characters call for a revaluation of characters included in species characterisations.

evolutionary biology↗

bioRxiv2020

Potassium Carbonate (K2CO3) - A cheap, non-toxic and high-density floating solution for microplastic isolation from beach sediments

Beaches are good indicators for microplastic distribution and local microplastic pollution. Multiple methods have been developed for extracting microplastics from sediment, mainly through density separation. However, the chemicals applied are often expensive and harmful for the user or to the environment. We briefly review the problems associated with the use of these chemicals and present a new floatation solution, potassium carbonate (K2CO3) that has many advantages over available media. It is non-toxic and cheap, and with a density of 1.54 g/cm3 the K2CO3 solution yielded a mean recovery rate of around 92% for PVC, one of the densest polymers, that cannot be easily extracted with alternative floatation agents. We propose that the use of K2CO3 is particularly promising for long term and large-scale monitoring studies, not least because it allows an increasing involvement of citizen scientists, hopefully leading to an increased public awareness of the plastic problem in the seas.

ecology↗