Evaluating a species phylogeny using ddRAD SNPs: Cyto-nuclear discordance and introgression in the salmonid genus Thymallus (Salmonidae).

Hybridization and introgression are very common among freshwater fishes due to the dynamic nature of hydrological landscapes. Cyclic patterns of allopatry and secondary contact provide numerous opportunities for interspecific gene flow, which can lead to discordant paths of evolution for mitochondrial and nuclear genomes. Here, we used double digest restriction-site associated DNA sequencing (ddRADseq) to obtain a genome-wide single nucleotide polymorphism (SNP) dataset comprehensive for allThymallus (Salmonidae)species to infer phylogenetic relationships and evaluate potential recent and historical gene flow among species. The newly obtained nuclear phylogeny was largely concordant with a previously published mitogenome-based topology but revealed a few cyto-nuclear discordances. These incongruencies primarily involved the placement of internal nodes rather than the resolution of species, except for one European species where anthropogenic stock transfers are thought to be responsible for the observed pattern. The analysis of four contact zones where multiple species are found revealed a few cases of mitochondrial capture and limited signals of nuclear introgression. Interestingly, the mechanisms restricting interspecific gene flow might be distinct; while in zones of secondary contact, small-scale physical habitat separation appeared as a limiting factor, biologically based reinforcement mechanisms are presumed to be operative in areas where species presumably evolved in sympatry. Signals of historical introgression were largely congruent with the routes of species dispersal previously inferred from mitogenome data. Overall, the ddRADseq dataset provided a robust phylogenetic reconstruction of the genus Thymallus including new insights into historical hybridization and introgression, opening up new questions concerning their evolutionary history.

Optimizing waterborne eDNA capture from waterholes in savanna systems under remote field conditions.

Environmental DNA (eDNA) is used for biodiversity assessments in a variety of ecosystems across the globe, whereby different eDNA concentration, preservation and extraction methods can outperform others depending on the sampling conditions and environment. Tropical and subtropical ecosystems in Africa are among the less studied systems concerning eDNA-based monitoring. Waterholes in arid parts of southern Africa represent important agglomeration points for terrestrial mammals, and the eDNA shed into such waterbodies provides a powerful source of information for monitoring mammalian biodiversity in the surrounding area. However, the applied methods for eDNA sampling, preservation and filtering in different freshwater systems vary greatly, and rigorous protocol testing in African freshwater systems is still lacking. This study represents the first attempt to examine variations in eDNA concentration, preservation and extraction methods under remote field conditions using waterborne eDNA in a savanna system. Collected samples were heavily affected by microalgal and bacterial growth, impeding eDNA capture and PCR success. We demonstrate clear effects of the methodological choices, which also depend on the state of eDNA. A preliminary metabarcoding run showed little taxonomic overlap in mammal species detection between two metabarcoding primers tested. We recommend water filtering (using filters with pore sizes >1 µm) over centrifugation for eDNA concentration, Longmire's solution for ambient temperature sample preservation and Qiagen's DNeasy PowerSoil Pro Kit for DNA extraction of these inhibitor-prone samples. Furthermore, at least two independent metabarcoding markers should be utilized in order to maximize species detections in metabarcoding studies.

Applying molecular genetic data at different scales to support conservation assessment of European Habitats Directive listed species: A case study of Eurasian otter in Austria.

Evaluating intraspecific genetic structure and diversity is fundamental to assessing a species' conservation status, but direct incorporation of such information into legal frameworks such as the EU's Habitats Directive is surprisingly rare. How genetic structure aligns with EU member state boundaries or biogeographic regions may be very important in designing management plans or achieving legislative goals. The Eurasian fish otter experienced a sharp population decline during the 20th century but is currently re-expanding in several countries. The species is listed under Annex II and IV of the European Habitats Directive, and member states are obliged to assess the species separately across different biogeographic regions. We genotyped 2492 otter spraints across four provinces in Austria, collected between 2017 and 2021. A total of 384 different genotypes were identified, supporting densities along river habitats from 0.1 to 0.47 otters per river km (mean: 0.306), with a resampling-based simulation supporting limited density overestimation at survey lengths of 20 km or more. Three distinct genetic clusters were revealed, two of them presumably reflecting two relict populations whereas the source of the third cluster is unknown. The geographic extent of the three clusters does not coincide with provincial or biogeographic boundaries, both relevant for assessment and management within existing national or European legislative frameworks. We advocate more consideration of genetic structure in the assessment and conservation management planning of species listed in the European Habitats Directive.

Isolation and characterization of the CYP2D6 gene in Felidae with comparison to other mammals.

The highly polymorphic CYP2D6 protein metabolizes about 25% of commonly used drugs and underlies a broad spectrum of drug responses among individuals. In contrast to extensive knowledge on the human CYP2D6 gene, little is known about the gene in non-human mammals. CYP2D6 mRNA from 23 cats (Felidae) spanning seven species were compared to available CYPD6 sequences in ten additional mammals and multiple allelic variants in humans. A relatively high mean dN/dS ratio (0.565) was observed, especially within Felidae. Pairwise dN/dS ratios were non-monotonically distributed with respect to evolutionary distance suggesting either positive selection or retention of slightly deleterious mutations. Positive selection on specific codons, most notably in regions involved in substrate recognition and membrane anchoring is supported and the possible influence of diet on specific amino acid changes in substrate binding sites is discussed.

Genomics and the challenging translation into conservation practice.

The global loss of biodiversity continues at an alarming rate. Genomic approaches have been suggested as a promising tool for conservation practice as scaling up to genome-wide data can improve traditional conservation genetic inferences and provide qualitatively novel insights. However, the generation of genomic data and subsequent analyses and interpretations remain challenging and largely confined to academic research in ecology and evolution. This generates a gap between basic research and applicable solutions for conservation managers faced with multifaceted problems. Before the real-world conservation potential of genomic research can be realized, we suggest that current infrastructures need to be modified, methods must mature, analytical pipelines need to be developed, and successful case studies must be disseminated to practitioners.