Browsing by Subject "SPATIAL GENETIC-STRUCTURE"

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  • Valtonen, Mia; Palo, Jukka U.; Aspi, Jouni; Ruokonen, Minna; Kunnasranta, Mervi; Nyman, Tommi (2014)
  • Fountain, Toby; Duvaux, Ludovic; Horsburgh, Gavin; Reinhardt, Klaus; Butlin, Roger K. (2014)
  • Fountain, Toby; Husby, Arild; Nonaka, Etsuko; DiLeo, Michelle; Korhonen, Janne H.; Rastas, Pasi; Schulz, Torsti Michael; Saastamoinen, Marjo Anna Kaarina; Hanski, Ilkka Aulis (2018)
    Dispersal is important for determining both species ecological processes, such as population viability, and its evolutionary processes, like gene flow and local adaptation. Yet obtaining accurate estimates in the wild through direct observation can be challenging or even impossible, particularly over large spatial and temporal scales. Genotyping many individuals from wild populations can provide detailed inferences about dispersal. We therefore utilized genomewide marker data to estimate dispersal in the classic metapopulation of the Glanville fritillary butterfly (Melitaea cinxia L.), in the Aland Islands in SW Finland. This is an ideal system to test the effectiveness of this approach due to the wealth of information already available covering dispersal across small spatial and temporal scales, but lack of information at larger spatial and temporal scales. We sampled three larvae per larval family group from 3732 groups over a six-year period and genotyped for 272 SNPs across the genome. We used this empirical data set to reconstruct cases where full-sibs were detected in different local populations to infer female effective dispersal distance, that is, dispersal events directly contributing to gene flow. On average this was one kilometre, closely matching previous dispersal estimates made using direct observation. To evaluate our power to detect full-sib families, we performed forward simulations using an individual-based model constructed and parameterized for the Glanville fritillary metapopulation. Using these simulations, 100% of predicted full-sibs were correct and over 98% of all true full-sib pairs were detected. We therefore demonstrate that even in a highly dynamic system with a relatively small number of markers, we can accurately reconstruct full-sib families and for the first time make inferences on female effective dispersal. This highlights the utility of this approach in systems where it has previously been impossible to obtain accurate estimates of dispersal over both ecological and evolutionary scales.
  • Gargiulo, Roberta; Pironon, Samuel; Zheleznaya, Ekaterina; Sanchez, Michele D.; Balazs, Zoltan R.; Podar, Dorina; Wilkinson, Timothy; Jäkäläniemi, Anne; Kull, Tiiu; Väre, Henry; Fay, Michael F. (2019)
    Aim We investigated the phylogeographical history of a clonal-sexual orchid, to test the hypothesis that current patterns of genetic diversity and differentiation retain the traces of climatic fluctuations and of the species reproductive system. Location Europe, Siberia and Russian Far East. Taxon Cypripedium calceolus L. (Orchidaceae). Methods Samples (>900, from 56 locations) were genotyped at 11 nuclear microsatellite loci and plastid sequences were obtained for a subset of them. Analysis of genetic structure and approximate Bayesian computations were performed. Species distribution modelling was used to explore the effects of past climatic fluctuations on the species range. Results Analysis of genetic diversity reveals high heterozygosity and allele diversity, with no geographical trend. Three genetic clusters are identified with extant gene pools derived from ancestral demes in glacial refugia. Siberian populations exhibit different plastid haplotypes, supporting an early divergence for the Asian gene pool. Demographic results based on genetic data are compatible with an admixture event explaining differentiation in Estonia and Romania and they are consistent with past climatic dynamics inferred through species distribution modelling. Current population differentiation does not follow isolation by distance model and is compatible with a model of isolation by colonization. Main conclusions The genetic differentiation observed today in C. calceolus preserves the signature of climatic fluctuations in the historical distribution range of the species. Our findings support the central role of clonal reproduction in the reducing loss of diversity through genetic drift. The dynamics of the clonal-sexual reproduction are responsible for the persistence of ancestral variation and stability during glacial periods and post-glacial expansion.
  • Vanderpoorten, Alain; Patino, Jairo; Desamore, Aurelie; Laenen, Benjamin; Gorski, Piotr; Papp, Beata; Hola, Eva; Korpelainen, Helena; Hardy, Olivier (2019)
    1. Bryophytes are typically seen as extremely efficient dispersers. Experimental evidence suggests that efficient short-distance dispersal coupled with random long-distance dispersal (LDD) leads to an inverse isolation effect. Under the latter, a higher genetic diversity of colonizing propagules is expected with increasing isolation, counteracting differentiation beyond the range of short-distance dispersal. 2. This expectation is tested from a review of evidence on spatial genetic structure and analyses of isolation-by-distance (IBD) at different scales. 3. A decay of the IBD signal, characterized by non-significant slopes between kinship coefficients and geographic distance was observed beyond 100 m. A second slope shift was observed at distances larger than 1 km, with a proportion of significant slopes in more than one third of the datasets. 4. The decay of the IBD signal beyond 100 m, which reflects efficient LDD, is consistent with the inverse isolation hypothesis. Persistence of a significant IBD signal at medium ranges in one third of the analysed cases suggests, however, that the inverse isolation effect is not a rule in bryophyte spore dispersal. Furthermore, the higher proportion of significant IBD patterns observed at scales over 100 km likely marks the limits of regional dispersal, beyond which an increasingly smaller proportion of spores travel. 5. Synthesis. We discuss the differences between experimental and genetic estimates of spore dispersal and conclude that geographic distance remains a significant proxy of spore colonization rates, with major consequences for our understanding of actual migration capacities in bryophytes, and hence, our capacity to model range shifts in a changing world.