1. The genetic consequences of population marginality : a case study in maritime pineAdélaïde Theraroz, Carlos Guadaño-Peyrot, Juliette Archambeau, Sara Pinosio, Francesca Bagnoli, Andrea Piotti, Camilla Avanzi, Giovanni G. Vendramin, Ricardo Alía, Delphine Grivet, Marjana Westergren, Santiago C. González-Martínez, 2024, original scientific article Abstract: Aim: Marginal tree populations, either those located at the edges of the species' rangeor in suboptimal environments, are often a valuable genetic resource for biologicalconservation. However, there is a lack of knowledge about the genetic consequencesof population marginality, estimated across entire species' ranges. Our study ad-dresses this gap by providing information about several genetic indicators and theirvariability in marginal and core populations identified using quantitative marginalityindices.Location: Southwestern Europe and North Africa.Methods: Using 10,185 SNPs across 82 populations of maritime pine (Pinus pinasterAit.), a widespread conifer characterised by a fragmented range, we modelled therelationship of seven genetic indicators potentially related to population evolution-ary resilience, namely genetic diversity (based on both all SNPs and outlier SNPs),inbreeding, genetic differentiation, recessive genetic load and genomic offset, withpopulation geographical, demo-historical and ecological marginality (as estimated bynine quantitative indices). Models were constructed for both regional (introducinggene pool as a random factor) and range-wide spatial scales.Results: We showed a trend towards decreasing overall genetic diversity and increas-ing differentiation with geographic marginality, supporting the centre-periphery hy-pothesis (CPH). However, we found no correlation between population inbreedingand marginality, while geographically marginal populations had a lower recessive ge-netic load (only models without the gene pool effect). Ecologically marginal popula-tions had a higher genomic offset, suggesting higher maladaptation to future climate,albeit some of these populations also had high genetic diversity for climate outliers.Main Conclusions: Overall genetic diversity (but not outlier-based estimates) and dif-ferentiation patterns support the CPH. Ecologically marginal populations and those atthe southern edge could be more vulnerable to climate change due to higher climate maladaptation, as predicted by genomic offsets, and/or lower potentially adaptive ge-netic diversity. This risk is exacerbated by typically small effective population sizesand increasing human impact in marginal populations.
Keywords: population genetics, conservation genetics, marginal populations, Pinus pinaster, genetic indicators
Published in DiRROS: 29.08.2024; Views: 131; Downloads: 429
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2. Evaluation of the rbcL marker for metabarcoding of marine diatoms and inference of population structure of selected generaTimotej Turk Dermastia, Ivano Vascotto, Janja Francé, David Stanković, Patricija Mozetič, 2023, original scientific article Abstract: Diatoms are one of the most important phytoplankton groups in the world’s oceans. There are responsible for up to 40% of the photosynthetic activity in the Ocean, and they play an important role in the silicon and carbon cycles by decoupling carbon from atmospheric interactions through sinking and export. These processes are strongly influenced by the taxonomic composition of diatom assemblages. Traditionally, these have been assessed using microscopy, which in some cases is not reliable or reproducible. Next-generation sequencing enabled us to study diversity in a high-throughput manner and uncover new distribution patterns and diversity. However, phylogenetic markers used for this purpose, such as various 18S rDNA regions, are often insufficient because they cannot distinguish between some taxa. In this work, we demonstrate the performance of the chloroplast-encoded rbcL marker for metabarcoding marine diatoms compared to microscopy and 18S-V9 metabarcoding using a series of monthly samples from the Gulf of Trieste (GoT), northern Adriatic Sea. We demonstrate that rbcL is able to detect more taxa compared to 18S-V9 metabarcoding or microscopy, while the overall structure of the diatom assemblage was comparable to the other two methods with some variations, that were taxon dependent. In total, 6 new genera and 22 new diatom species for the study region were identified. We were able to spot misidentification of genera obtained with microscopy such as Pseudo-nitzschia galaxiae, which was mistaken for Cylindrotheca closterium, as well as genera that were completely overlooked, such as Minidiscus and several genera from the Cymatosiraceae family. Furthermore, on the example of two well-studied genera in the region, namely Chaetoceros and particularly Pseudo-nitzschia, we show how the rbcL method can be used to infer even deeper phylogenetic and ecologically significant differences at the species population level. Despite a very thorough community analysis obtained by rbcL the incompleteness of reference databases was still evident, and we shed light on possible improvements. Our work has further implications for studies dealing with taxa distribution and population structure, as well as carbon and silica flux models and networks.
Keywords: rbcL, metabarcoding, monitoring, diatoms, population genetics, Pseudo-nitzschia, Adriatic
Published in DiRROS: 12.07.2024; Views: 228; Downloads: 142
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3. Monitoring of species’ genetic diversity in Europe varies greatly and overlooks potential climate change impactsPeter Pearman, Olivier Broennimann, Tsipe Aavik, Tamer Albayrak, Paulo Célio Alves, Filipos Aravanopoulos, Laura Bertola, Aleksandra Biedrzycka, Elena Bužan, Vlatka Čubrić Čurik, Katja Kavčič Sonnenschein, Marjana Westergren, 2024, original scientific article Abstract: Genetic monitoring of populations currently attracts interest in the context of the Convention on Biological Diversity but needs long-term planning and investments. However, genetic diversity has been largely neglected in biodiversity monitoring, and when addressed, it is treated separately, detached from other conservation issues, such as habitat alteration due to climate change. We report an accounting of efforts to monitor population genetic diversity in Europe (genetic monitoring effort, GME), the evaluation of which can help guide future capacity building and collaboration towards areas most in need of expanded monitoring. Overlaying GME with areas where the ranges of selected species of conservation interest approach current and future climate niche limits helps identify whether GME coincides with anticipated climate change effects on biodiversity. Our analysis suggests that country area, financial resources and conservation policy influence GME, high values of which only partially match species’ joint patterns of limits to suitable climatic conditions. Populations at trailing climatic niche margins probably hold genetic diversity that is important for adaptation to changing climate. Our results illuminate the need in Europe for expanded investment in genetic monitoring across climate gradients occupied by focal species, a need arguably greatest in southeastern European countries. This need could be met in part by expanding the European Union’s Birds and Habitats Directives to fully address the conservation and monitoring of genetic diversity.
Keywords: genetics, monitoring, population genetic diversity, Europe
Published in DiRROS: 22.01.2024; Views: 527; Downloads: 364
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