Gabriel F. Ulrich


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Ulrich

First Name

Gabriel F.

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0000-0002-2092-1152

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2021 - 202520
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Publications 1 - 10 of 20
  • Herbarium digitisation sheds light on historical distribution and drivers of population extinction of a peat bog specialist
    Item type: Journal Article
    Ulrich, Gabriel F.; Guggisberg, Alessia; Pellissier, Loïc; et al. (2025)
    Plants, People, Planet
    Societal Impact StatementBiodiversity loss threatens ecosystem services and human well-being. Understanding the extent and causes of changes in biodiversity over time can help protect species and their habitats. Herbaria house carefully documented and curated specimens collected by generations of botanists. We show how historical herbarium specimens can be made usable for the conservation of species through digitisation and georeferencing. Revisiting localities where a species occurred in the past can reveal population extinctions, identify the causes of biodiversity change and contribute to the development of effective conservation measures.Summary Habitat loss and degradation threaten biodiversity globally. The habitat of the peat bog specialist Eriophorum vaginatum has declined dramatically over the past two centuries, and contemporary habitat degradation and climate change may threaten remaining populations. We aimed to estimate population extinction frequencies, identify drivers of extinctions, and assess the extinction risk of remaining E. vaginatum populations in Switzerland. We searched, digitised and georeferenced historical E. vaginatum specimens from nine Swiss herbaria, and revisited 197 localities where the species was collected between 1803 and 1949, to assess population extinctions. To identify environmental predictors of local extinctions, we used species distribution modelling (SDM). With the resulting model, we predicted extinction probabilities for contemporary E. vaginatum populations. Our revisitation study revealed that extinctions were most common on the Swiss Plateau, a densely populated and intensively farmed region, where 68% of populations became extinct. Extinctions were less common in the other biogeographic areas of Switzerland. The strongest predictors of extinction were soil nutrient content, pH and nearby plantations, whereas the presence of large wetland and wetland-like areas and nearby shrubland were the strongest predictors of persistence. We predicted a high risk of extinction for 3.2% of the remaining populations. This study highlights the value of historical herbarium records in assessing long-term environmental impacts on species. We emphasise the ongoing threats to E. vaginatum from agriculture and climate change and underscore the importance of conserving and restoring large habitats with protective buffer zones.
  • Sampling historical DNA to assess the impact of habitat loss on genetic diversity in a peatland-specialist
    Item type: Other Conference Item
    Ulrich, Gabriel F.; Rayo, Enrique; Guggisberg, Alessia; et al. (2022)
    European Conservation Genetics Meeting (ConsGen22) Abstract Book
    Genetic diversity is the basis for adaptation to changing environmental conditions such as climate change. Human-induced habitat loss and landscape fragmentation are important drivers of population size reduction which can lead to genetic diversity loss. As a peat bog specialist, the cottongrass Eriophorum vaginatum has undergone major habitat loss in Switzerland during the past two centuries as a consequence of wetland drainage and peat extraction. Habitat loss has mainly occurred in the central plateau, a densely populated and relatively warm biogeographic region of Switzerland. In the pilot study for a monitoring of genetic diversity in Switzerland, E. vaginatum is monitored retrospectively using samples from natural history collections to understand the potential loss or change of genetic diversity during the last century. We developed a sampling scheme to select available E. vaginatum vouchers and corresponding contemporary samples for whole-genome re-sequencing (WGS) to assess whether past habitat loss has mediated the extinction or isolation of genotypes that are potentially adaptive under future climate change. From >700 vouchers available in seven different Swiss herbaria, we selected 226 specimens from across Switzerland considering age, spatial distribution, and habitat change. We tested and optimized DNA extraction protocols and performed WGS to identify methodological challenges and possible limitations of the data. With this project, we aim to measure genetic diversity change in E. vaginatum and to better understand consequences of habitat loss on the potential of species to adapt to climate change.
  • Sampling historical DNA to assess the impact of habitat loss on genetic diversity in a peatland-specialist
    Item type: Other Conference Item
    Ulrich, Gabriel F.; Rayo, Enrique; Guggisberg, Alessia; et al. (2022)
    PSC Symposium 2022: From Place to Space - Tracing the Spatial Dimension of Plant Sciences
  • Using historical specimens from collections to assess genetic diversity change
    Item type: Other Conference Item
    Ulrich, Gabriel F.; Rayo, Enrique; Guggisberg, Alessia; et al. (2023)
  • Harnessing herbaria to assess geographic extent and genetic consequences of habitat loss
    Item type: Other Conference Item
    Ulrich, Gabriel F.; Rayo, Enrique; Guggisberg, Alessia; et al. (2022)
    400 Years Botanical Collections - Implications for Present-Day Research. International Symposium in Honour of Caspar Bauhin (1560–1624)
    Genetic diversity is one of three levels of biodiversity and the raw material for evolution to act on. Population size reduction via loss of habitat and connectivity can lead to loss of neutral and adaptive genetic diversity. The Hare’s tail cottongrass (Eriophorum vaginatum) is strongly associated with peat bogs and has undergone major habitat loss in Switzerland, especially in the Central Plateau, over the last two centuries as a consequence of wetland drainage and peat extraction. Assessing herbarium-based georeferencing data and observation records indicates a reduced occurrence of E. vaginatum, especially under relatively warm and dry climates. This raises the question of whether habitat loss has caused a reduction in genetic diversity in general and of variants adaptive under warm conditions in particular. We selected 226 herbarium specimens, collected between 1804 and 1949, from seven Swiss herbaria for whole genome re-sequencing. Where possible, we additionally collected contemporary samples from the same or a nearby location. By comparing the genetic diversity of historical and contemporary samples, we will examine whether an overall loss of genetic diversity has occurred in E. vaginatum across Switzerland. We will assess historical genotype-climate associations in order to test whether genetic variants associated with warm climatic conditions occur at reduced frequency in the contemporary gene pool. With this project, which is part of a pilot study for monitoring genetic diversity in Switzerland, we hope to contribute to a better understanding of the genomic consequences of habitat loss by making use of specimens and metadata stored in herbaria.
  • Monitoring genetic diversity: A genomics-based pilot study for Switzerland
    Item type: Other Conference Item
    Fischer, Martin C.; Reutimann, Oliver; Ulrich, Gabriel F.; et al. (2024)
    Proceedings World Biodiversity Forum 2024
    Genetic diversity is the raw material of evolution and is essential for species to adapt to changing environments. To date, systematic monitoring of genetic diversity on a national scale has rarely been undertaken. We have initiated a pilot study on genetic diversity monitoring in Switzerland, with the aim of assessing genetic diversity indicators for five animal and plant species, thereby gaining the practical experience necessary for setting up a genomics-based monitoring programme. The five selected species occur in habitats of national importance or in anthropogenically modified landscapes. We de novo assembled their reference genomes, sampled >1,200 individuals across all biogeographic regions in Switzerland, and re-sequenced their full genomes. For two species, we used a museomic approach to go back up to 200 years into the past. Together, these data enable detailed conservation-relevant analyses, not only of genetic diversity, but also of runs of homozygosity (ROH) and estimates of effective population size (Ne), and provide unprecedented insights into temporal changes in genetic diversity in natural populations. With the experience gained, it is now possible to monitor genetic diversity at a national scale. An ongoing challenge is to develop scientifically sound but intuitive indicators, which can be effectively communicated to relevant authorities and stakeholders for implementation in conservation management.
  • Wie steht es um die genetische Vielfalt der Kreuzkröte in der Schweiz
    Item type: Other Conference Item
    Fischer, Martin C.; Reutimann, Oliver; Ulrich, Gabriel F.; et al. (2024)
    30. Herpeto-Kolloquium / 30e colloque herpétologique
  • GenDiv - Monitoring der genetischen Vielfalt in der Schweiz
    Item type: Presentation
    Fischer, Martin C.; Reutimann, Oliver; Ulrich, Gabriel F.; et al. (2023)
  • Quantitative trait locus analysis of parasitoid counteradaptation to symbiont-conferred resistance
    Item type: Journal Article
    Ulrich, Gabriel F.; Zemp, Niklaus; Vorburger, Christoph; et al. (2021)
    Heredity
    Insect hosts and parasitoids are engaged in an intense struggle of antagonistic coevolution. Infection with heritable bacterial endosymbionts can substantially increase the resistance of aphids to parasitoid wasps, which exerts selection on parasitoids to overcome this symbiont-conferred protection (counteradaptation). Experimental evolution in the laboratory has produced counteradapted populations of the parasitoid wasp Lysiphlebus fabarum. These populations can parasitize black bean aphids (Aphis fabae) protected by the bacterial endosymbiont Hamiltonella defensa, which confers high resistance against L. fabarum. We used two experimentally evolved parasitoid populations to study the genetic architecture of the counteradaptation to symbiont-conferred resistance by QTL analysis. With simple crossing experiments, we showed that the counteradaptation is a recessive trait depending on the maternal genotype. Based on these results, we designed a customized crossing scheme to genotype a mapping population phenotyped for the ability to parasitize Hamiltonella-protected aphids. Using 1835 SNP markers obtained by ddRAD sequencing, we constructed a high-density linkage map consisting of six linkage groups (LGs) with an overall length of 828.3 cM and an average marker spacing of 0.45 cM. We identified a single QTL associated with the counteradaptation to Hamiltonella in L. fabarum on linkage group 2. Out of 120 genes located in this QTL, several genes encoding putative venoms may represent candidates for counteradaptation, as parasitoid wasps inject venoms into their hosts during oviposition.
  • Genomic erosion in a habitat specialist over time and space
    Item type: Doctoral Thesis
    Ulrich, Gabriel F. (2025)
Publications 1 - 10 of 20