Věroslava Hadincová

Higher genetic diversity in recolonized areas than in refugia of Alnus glutinosa triggered by continent‐wide lineage admixture

Genetic admixture is supposed to be an important trigger of species expansions because it can create the potential for selection of genotypes suitable for new climatic conditions. Up until now, however, no continent‐wide population genetic study has performed a detailed reconstruction of admixture events during natural species expansions. To fill this gap, we analysed the postglacial history of Alnus glutinosa, a keystone species of European swamp habitats, across its entire distribution range using two molecular markers, cpDNA and nuclear microsatellites. CpDNA revealed multiple southern refugia located in the Iberian, Apennine, Balkan and Anatolian Peninsulas, Corsica and North Africa. Analysis of microsatellites variation revealed three main directions of postglacial expansion: (i) from the northern part of the Iberian Peninsula to Western and Central Europe and subsequently to the British Isles, (ii) from the Apennine Peninsula to the Alps and (iii) from the eastern part of the Balkan Peninsula to the Carpathians followed by expansion towards the Northern European plains. This challenges the classical paradigm that most European populations originated from refugial areas in the Carpathians. It has been shown that colonizing lineages have met several times and formed secondary contact zones with unexpectedly high population genetic diversity in Central Europe and Scandinavia. On the contrary, limited genetic admixture in southern refugial areas of A. glutinosa renders rear‐edge populations in the Mediterranean region more vulnerable to extinction due to climate change.

Migration Patterns of Subgenus Alnus in Europe since the Last Glacial Maximum: A Systematic Review

Background/Aims Recently, new palaeoecological records supported by molecular analyses and palaeodistributional modelling have provided more comprehensive insights into plant behaviour during the last Quaternary cycle. We reviewed the migration history of species of subgenus Alnus during the last 50,000 years in Europe with a focus on (1) a general revision of Alnus history since the Last Glacial Maximum (LGM), (2) evidence of northern refugia of Alnus populations during the LGM and (3) the specific history of Alnus in particular European regions. Methodology We determined changes in Alnus distribution on the basis of 811 and 68 radiocarbon-dated pollen and macrofossil sites, respectively. We compiled data from the European Pollen Database, the Czech Quaternary Palynological Database, the Eurasian Macrofossil Database and additional literature. Pollen percentage thresholds indicating expansions or retreats were used to describe patterns of past Alnus occurrence. Principal Findings An expansion of Alnus during the Late Glacial and early Holocene periods supports the presence of alders during the LGM in southern peninsulas and northerly areas in western Europe, the foothills of the Alps, the Carpathians and northeastern Europe. After glaciers withdrew, the ice-free area of Europe was likely colonized from several regional refugia; the deglaciated area of Scandinavia was likely colonized from a single refugium in northeastern Europe. In the more northerly parts of Europe, we found a scale-dependent pattern of Alnus expansion characterised by a synchronous increase of Alnus within individual regions, though with regional differences in the times of the expansion. In southern peninsulas, the Alps and the Carpathians, by contrast, it seems that Alnus expanded differently at individual sites rather than synchronously in whole regions. Conclusions Our synthesis supports the idea that northern LGM populations were important sources of postglacial Alnus expansion. The delayed Alnus expansion apparent in some regions was likely a result of environmental limitations.

Flow cytometry, microsatellites and niche models reveal the origins and geographical structure of Alnus glutinosa populations in Europe

BACKGROUND AND AIMS Polyploidy in plants has been studied extensively. In many groups, two or more cytotypes represent separate biological entities with distinct distributions, histories and ecology. This study examines the distribution and origins of cytotypes of Alnus glutinosa in Europe, North Africa and western Asia. METHODS A combined approach was used involving flow cytometry and microsatellite analysis of 12 loci in 2200 plants from 209 populations combined with species distribution modelling using MIROC and CCSM climatic models, in order to analyse (1) ploidy and genetic variation, (2) the origin of tetraploid A. glutinosa, considering A. incana as a putative parent, and (3) past distributions of the species. KEY RESULTS The occurrence of tetraploid populations of A. glutinosa in Europe is determined for the first time. The distribution of tetraploids is far from random, forming two geographically well-delimited clusters located in the Iberian Peninsula and the Dinaric Alps. Based on microsatellite analysis, both tetraploid clusters are probably of autopolyploid origin, with no indication that A. incana was involved in their evolutionary history. A projection of the MIROC distribution model into the Last Glacial Maximum (LGM) showed that (1) populations occurring in the Iberian Peninsula and North Africa were probably interconnected during the LGM and (2) populations occurring in the Dinaric Alps did not exist throughout the last glacial periods, having retreated southwards into lowland areas of the Balkan Peninsula. CONCLUSIONS Newly discovered tetraploid populations are situated in the putative main glacial refugia, and neither of them was likely to have been involved in the colonization of central and northern Europe after glacial withdrawal. This could mean that neither the Iberian Peninsula nor the western part of the Balkan Peninsula served as effective refugial areas for northward post-glacial expansion of A. glutinosa.

Genetic differentiation and plasticity interact along temperature and precipitation gradients to determine plant performance under climate change

Summary Understanding species’ abilities to cope with changing climate is a key prerequisite for predicting the future fates of species and ecosystems. Despite considerable research on species responses to changing climate, we still lack understanding of the role of specific climatic factors, and their interactions, for species responses. We also lack understanding of the relative importance of plasticity vs. adaptation in determining the observed responses. As a model, we use a dominant clonal grass, Festuca rubra, originating from a natural climatic grid of 12 localities in western Norway that allows factorial combinations of temperature (mean growing season temperatures ranging from 6.5°C to 10.5°C) and precipitation (annual precipitation ranging from 600 mm to 2700 mm). We grew clones from all populations in four growth chambers representing the four climatic extremes in the climate grid (warm/cold × wet/dry). Genetic differentiation and direction and magnitude of plastic responses vary systematically among populations throughout the climatic grid. Growth-related plant traits are highly plastic and their degree of plasticity depends on their origin. In contrast, the traits reflecting species’ foraging strategy are not plastic but vary with the climate of origin. Levels of plasticity of growth-related traits and genetically differentiated foraging traits thus might constrain local populations’ ability to cope with novel climates. Synthesis: Shifts in temperature and precipitation, at the scale and direction expected for the region in the next century, are likely to dramatically affect plant performance. This study illustrates how the interplay between genetic differentiation and plasticity in response to both temperature and precipitation will affect the specific responses of species to climate change. Such complex responses will affect how climate-change impacts scale up to the community and ecosystem levels. Future studies thus need to specifically consider regionally relevant climate-change projections, and also explore the role of genetic differentiation and plasticity and how this varies within local floras. Our study also demonstrates that even widespread species with seemingly broad climatic niches may strongly differ in their population performance and plasticity. Climate-change studies should therefore not be limited to rare and restricted species. This article is protected by copyright. All rights reserved.

European invasion of North American Pinus strobus at large and fine scales: high genetic diversity and fine-scale genetic clustering over time in the adventive range.

Background North American Pinus strobus is a highly invasive tree species in Central Europe. Using ten polymorphic microsatellite loci we compared various aspects of the large-scale genetic diversity of individuals from 30 sites in the native distribution range with those from 30 sites in the European adventive distribution range. To investigate the ascertained pattern of genetic diversity of this intercontinental comparison further, we surveyed fine-scale genetic diversity patterns and changes over time within four highly invasive populations in the adventive range. Results Our data show that at the large scale the genetic diversity found within the relatively small adventive range in Central Europe, surprisingly, equals the diversity found within the sampled area in the native range, which is about thirty times larger. Bayesian assignment grouped individuals into two genetic clusters separating North American native populations from the European, non-native populations, without any strong genetic structure shown over either range. In the case of the fine scale, our comparison of genetic diversity parameters among the localities and age classes yielded no evidence of genetic diversity increase over time. We found that SGS differed across age classes within the populations under study. Old trees in general completely lacked any SGS, which increased over time and reached its maximum in the sapling stage. Conclusions Based on (1) the absence of difference in genetic diversity between the native and adventive ranges, together with the lack of structure in the native range, and (2) the lack of any evidence of any temporal increase in genetic diversity at four highly invasive populations in the adventive range, we conclude that population amalgamation probably first happened in the native range, prior to introduction. In such case, there would have been no need for multiple introductions from previously isolated populations, but only several introductions from genetically diverse populations.

Cross-amplification and multiplexing of SSR markers for Alnus glutinosa and A. incana

We investigated 39 previously developed Betula, Alnus, and Corylus simple sequence repeat (SSR) markers for their utility in the cross-generic amplification of two European alder species, i.e., Alnus glutinosa and A. incana. Of these markers, ten loci had successful amplification within Alnus species. Finally, we designed two multiplexes composed of eight and nine loci for A. glutinosa and A. incana, respectively. Multiplexes were tested on 100 samples from five different populations of each species across Europe. The majority of loci had a relatively high genetic diversity, were in Hardy–Weinberg equilibrium, and showed low error rates and low occurrence of null alleles. By comparing sequences of source species and both Alnus species, we concluded that repeat motifs of five of these ten loci differed from those described for the source species. These differences represent mainly the modifications of the original motifs and affected compound or interrupted repeats as well as pure ones. The repeat motifs of three loci of the two alder species also differed. These mutations could lead to erroneous estimates of allele homology, because alleles with identical lengths will not have the same number of repeat units. Hence, before using microsatellite markers in studies comparing two or more species, they should be carefully examined and sequenced to ensure that allele homology is really stable and not affected by various inserts that change the sequence.

Transgenerational plasticity as an important mechanism affecting response of clonal species to changing climate

Abstract In spite of the increasing number of studies on the importance of transgenerational plasticity for species response to novel environments, its effects on species ability to respond to climate change are still largely unexplored. We study the importance of transgenerational plasticity for response of a clonal species Festuca rubra. Individuals from four natural populations representing two levels of temperature and two levels of precipitation were cultivated in four growth chambers that simulate the temperature and precipitation of origin of the populations (maternal phase). Each population was represented in each growth chamber. After 6 months, single young ramets of these plants were reshuffled among the growth chambers and let to grow for additional 2 months (offspring phase). The results show that transgenerational effects (i.e., maternal phase conditions) significantly modify species response to novel climates, and the direction and intensity of the response depend on the climate of origin of the plants. For traits related to recourse acquisition, the conditions of maternal phase, either alone or in interaction mainly with climate of origin, had stronger effect than the conditions of cultivation. Overall, the maternal climate interacted more intensively with the climate of origin than with the offspring climate. The direction of the effect of the maternal climate was of different directions and intensities depending on plant origin and trait studied. The data demonstrated strong significant effects of conditions during maternal phase on species response to novel climates. These transgenerational affects were, however, not adaptive. Still, transgenerational plasticity may be an important driver of species response to novel conditions across clonal generations. These effects thus need to be carefully considered in future studies exploring species response to novel climates. This will also have strong effects on species performance under increasingly variable climates expected to occur with the climate change.

Adaptive differentiation of Festuca rubra along a climate gradient revealed by molecular markers and quantitative traits

Species response to climate change is influenced by predictable (selective) and unpredictable (random) evolutionary processes. To understand how climate change will affect present-day species, it is necessary to assess their adaptive potential and distinguish it from the effects of random processes. This will allow predicting how different genotypes will respond to forecasted environmental change. Space for time substitution experiments are an elegant way to test the response of present day populations to climate variation in real time. Here we assess neutral and putatively adaptive variation in 11 populations of Festuca rubra situated along crossed gradients of temperature and moisture using molecular markers and phenotypic measurements, respectively. By comparing population differentiation in putatively neutral molecular markers and phenotypic traits (QST-FST comparisons), we show the existence of adaptive differentiation in phenotypic traits and their plasticity across the climatic gradient. The observed patterns of differentiation are due to the high genotypic and phenotypic differentiation of the populations from the coldest (and wettest) environment. Finally, we observe statistically significant covariation between markers and phenotypic traits, which is likely caused by isolation by adaptation. These results contribute to a better understanding of the current adaptation and evolutionary potential to face climate change of a widespread species. They can also be extrapolated to understand how the studied populations will adjust to upcoming climate change without going through the lengthy process of phenotyping.