Summary
• Here, palaeobotanical and genetic data for common beech (Fagus sylvatica) in Europe are used to evaluate the genetic consequences of long-term survival in refuge areas and postglacial spread.
• Four large datasets are presented, including over 400 fossil-pollen sites, 80 plant-macrofossil sites, and 450 and 600 modern beech populations for chloroplast and nuclear markers, respectively.
• The largely complementary palaeobotanical and genetic data indicate that: (i) beech survived the last glacial period in multiple refuge areas; (ii) the central European refugia were separated from the Mediterranean refugia; (iii) the Mediterranean refuges did not contribute to the colonization of central and northern Europe; (iv) some populations expanded considerably during the postglacial period, while others experienced only a limited expansion; (v) the mountain chains were not geographical barriers for beech but rather facilitated its diffusion; and (vi) the modern genetic diversity was shaped over multiple glacial–interglacial cycles.
• This scenario differs from many recent treatments of tree phylogeography in Europe that largely focus on the last ice age and the postglacial period to interpret genetic structure and argue that the southern peninsulas (Iberian, Italian and Balkan) were the main source areas for trees in central and northern Europe.

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-8137.2006.01740.x

A new scenario for the Quaternary history of European beech populations: palaeobotanical evidence and genetic consequences

Most plants combine sexual and clonal reproduction, and the balance between the two may vary widely between and within species. There are many anecdotal reports of plants that appear to have abandoned sex for clonal reproduction, yet few studies have quantified the degree of sexual variation in clonal plants and fewer still have determined the underlying ecological and/or genetic factors. Recent empirical work has shown that some clonal plants exhibit very wide variation in sexual reproduction that translates into striking variation in genotypic diversity and differentiation of natural populations. Reduced sexual reproduction may be particularly common at the geographical margins of species’ ranges. Although seed production and sexual recruitment may often be limited by biotic and abiotic aspects of the environment in marginal populations, genetic factors, including changes in ploidy and sterility mutations, may also play a significant role in causing reduced sexual fertility. Moreover, environmental suppression of sexual recruitment may facilitate the evolution of genetic sterility because natural selection no longer strongly maintains the many traits involved in sex. In addition to the accumulation of ‘neutral’ sterility mutations in highly clonal populations, the evolution of genetic infertility may be facilitated if sterility is associated with enhanced vegetative growth, clonal propagation or survival through either resource reallocation or pleiotropy. However, there are almost no experimental data with which to distinguish among these possibilities. Ultimately, wide variation in genotypic diversity and gene flow associated with the loss of sex may constrain local adaptation and the evolution of the geographical range limit in clonal plants.

The loss of sex in clonal plants

Somatic embryogenesis is a phylogenetically ancient trait that allows sessile plants to grow in a modular fashion and to respond plastically to different environmental cues. It facilitates damage repair and permits clonal growth, the capacity to produce potentially independent but genetically identical offspring. Clonal growth is observed to originate from both the shoot or the root part of the plant body and it has been assigned various ecological functions such as reproduction, exploitation and persistence. These functions are rooted in two basic morphological characteristics of clonal growth: the longevity and the length of the connection between clonal parts. Clonality, although an ancient trait, shows a polyphyletic distribution among plant taxa with a strong representation especially among monocots. Phylogenetically controlled comparisons show that clonality is more common among species that occur in cold or nutrient-poor habitats and under poor light conditions. The frequent occurrence of clonals among aquatic species is confounded by the fact that many aquatics are monocots. This however does not necessarily preclude a functional ecological explanation. It is further shown that longevity and length of connection covary negatively, yielding two distinct clonal growth strategies (fragmenting versus compact, persistent clones) with a preference for the more common habitat trait combinations: nutrient-rich, shaded and/or wet versus nutrient-poor, open and/or dry, respectively.

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Comparative ecology of clonal plants

We present here the results of pollen analysis of two sequences of about 8.06 m and 11.90 m length, originating from two adjacent peat bogs in the southern part of Transylvania province, Romania (155 and 122 pollen spectra). The vegetation record, which is supported by 17 14 C dates, begins in the Late Glacial interstadial when forest recolonisation began with the development of Pinus, without a pioneer Betula phase. Picea began to expand from regional refuges. After a well-defined Younger Dryas, the Holocene opens with the expansion of Betula, Ulmus and Picea, followed, at about 10 400 cal. yr BP, by Fraxinus, Quercus and Tilia. The Corylus optimum is correlated with the Atlantic chronozone (after 8600 cal. yr BP). The local establishment of Carpinus occurred at about 6500 cal. yr BP, with a maximum at about 5700 cal. yr BP. Fagus pollen is regularly recorded after 8200 cal. yr BP. This taxon became dominant at about 3700 cal. yr BP. The first indications of human activities appear at around 7200 cal. yr BP. Copyright 2005 John Wiley & Sons, Ltd.

Late Glacial and Holocene vegetation history in the southern part of Transylvania (Romania): pollen analysis of two sequences from Avrig

Boreal peat bogs contain distinctive insects in addition to widely distributed generalists, including species restricted to bogs (tyrphobionts) and species characteristic of bogs but not confined to them (tyrphophiles). Bogs raised above the water table form characteristic habitat islands in southern boreal and temperate forest zones. Many bogs have persisted for hundreds and even thousands of years, preserving relict ecosystems related to subarctic biomes. The historical development and nature of individual bogs are reflected by differences among their insects, which are of great biogeographical and ecological interest. The environmental sensitivity of bogs also makes insects valuable as bioindicators. Moreover, few readily accessible bogs remain in a natural state. Given the scientific interest of bog insects and the fact that each relict bog habitat island is unique, further studies of the diversity of bog faunas are merited, and the conservation of these habitats should be strongly supported by entomologists.

Insect biodiversity of boreal peat bogs

Diversified development of mountain mires, Bohemian Forest, Central Europe, in the last 13,000 years

The current approaches to the study of clonal plants are reviewed. Most studies concentrate at the level of the ramet and clonal fragment exploring the “microscopic” view of clonal plants, dealing with the translocation of resources, clonal integration, plasticity of growth etc. The information gained, by this approach can be used in the understanding of higher levels of organization within the clonal system either with the help of spatially explicit modelling techniques, or by using means and distributions of size within a population instead of studying individual ramets separately. Plant scientists use the term clone with two meanings, viz. (a) a set of physiologically connected, but potentially independent ramets, and (b) a set of genetically identical, but potentially physically separated individuals. The overlap of these terms differs between individual plant species, depending on the extent of physical separation of the ramets and the degree of physiological integration between the ramets; the lower the frequency of ramet separation, the closer are the physiological and genetic concepts of the clone. Three critical areas seem to be neglected in clonal plant research: (a) the interrelationship between hierarchical levels in clonal plants, (b) the particular spatial structure of their environment, and (c) the importance of clonal plants in different ecological communities.

Plant clonality: Biology and diversity

Three clonal rhizomatous grarninoids ( Carex gracilis, C. vesicaria and Calamagrostis canescens), co-dominants of Central European marshlands, were examined for their response to waterlogging. A three-year growth study was carried with treatments where the water level was (a) below, (b) at, and (c) above the soil surface to assess the changes in allocation of plant biomass and modular structure. In waterlogged plants total biomass production was lower. The relatively greater shoot systems of waterlogged plants were characterized by the production of a greater number ot tiller modules (of the order of 20%). Roots were the most supressed organs both in sedges and C. canescens. Higher leaf area ratios and specific leaf areas in stressed plants indicate the relative enlargement of photosynthetic structures where stems form a significant component of the shoot (LWR 0.5 as in sedges) then above-ground biomass and rhizomes in stressed plants increased and leaf area index became higher. Variation of the mean module biomass in particular species was also associated with the LWR characteristics: modules of Carex gracilis and C. vesicaria were stable in biomass in all the treatments and reached 0.97 + 0.04 g and 0.44 -I- 0.03 g, respectively; in Calamagrostis the biomass of tillers varied. The number of modules increased in all species under waterlogging regardless of the architectural and re.allocation differences between species. The increase in clonai modules is regarded as a general adaptive response to the stress of waterlogging.

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Allocation plasticity and modular structure in clonal graminoids in response to waterlogging

The success of alien species for migration beyond their primary area of distribution, ie plant invasions, is affected by multiple factors which should be readily distinguished into two distinctive categories: physical/abiotic and biotic factors While the prevailingly deterministic physical events can be broadly stated for the whole Earth, the highly stochastic biotic events are less predictable for a large region, mainly due to evolutionary changes in the genome of individual organisms/species and in the constellation of genomes within particular communities/ecosystems In mountain areas, a better understanding of plant invasions requires both a detailed knowledge of the physical environment, and comprehensive data with regard to the participant flora, vegetation and landscape ecology Similar prerequisites are also needed for the analysis of relationships between plant invasions and climate change In Central Europe, favourable conditions exist for these studies in the eastern Hercynian mountains, where meteorological, geological and botanical data have been gathered for several centuries These central European middle-mountains are exposed to two inseparable components of global change: climate change (temperature, sunshine duration) and regional change (pollution, precipitation) More than one-century-long measurements on Sniezska Peak confirm a continual climate warming (annual means some 06 C higher) and increasingly erratic precipitations The final quarter of the 20th century has seen a continual increase of SO2, NOx and harmful pollutants which has caused an imbalance in plant and animal populations/communities, of which the most obvious manifestation is the catastrophic decline of coniferous forests Alien plant populations are spreading in an explosive way on the summits of the middle-mountains, their successive penetration into native plant associations threatening the biogeographical status of national parks

Plant Invasions in Central European Middle-Mountains: A Result of Global Change ?

During the last two decades, J.B. Harborn6 has contributed to the scientific literature with several books from the field of chemical ecology or ecological biochemistry. In these books he participated as author or as editor. The books concern mainly the biochemical aspects of plant animal coevolution, or ecological chemistry and biochemistry of plant substances. Professor Harbome evaluates the subject in regular reviews in Natural Product Reports. The chemoecological aspect can also be found in his original scientific papers, on the phytochemistry of flavonoids. For all this activity he was recently awarded the silver medal of the International Society of Chemical Ecology. His Introduction to Ecological Biochemistry is a monograph with a selection of very interesting, widely investigated and important subjects in the field of chemical ecology, presented by an experienced scientist and author. The relatively small extent of the book, of about 300 pages, naturally limits the choice of subjects. Many interesting and fruitful results did not get into the book. This, however, is often the case with books which serve as an introduction to a large interdisciplinary field, such as chemical ecology or ecological biochemistry. The fourth edition of this book is sufficient proof of its success, and thus also of the choice of subjects which, however, have several times been complemented since the first edition of 1977. In this fourth edition there are ten chapters devoted largely to chemoecological relations. They are: 1. The plant and its biochemical adaptation to the environment. 2. Biochemistry of plant pollination. 3. Plant toxins and their effects on animals. 4. Hormonal interactions between plants and animals. 5. Insect feeding preferences. 6. Feeding preferences of vertebrates, including man. 7. The co-evolutionary arms race: Plant defence and animal response. 8. Animal pheromones and defence substances. 9. Biochemical interactions between higher plants. 10. Higher plant lower plant interactions: Phytoalexins and phytotoxins. Each chapter is elaborated and compiled independently and as a whole. Each has its own introduction in which the author acquaints the reader with the history and various aspects of the topic. Then he goes into general and specific matters documented with many examples taken from original papers. Each chapter then closes with the author's conclusion or summary and a very valuable bibliography in two parts. One part, a list of books and review articles, is important mainly for beginners in the field, but a specialist may also appreciate it. The other part gives a list of references to the original papers discussed in individual chapters. This way of compiling the bibliography is particularly suitable for a book of Introduction type, and every reader is thus safely led to farther information in the field. This division of the book and the bibliography is useful both for students and professionals in the individual subjects, as well as for the readers intersted in the field as a whole. The subject index and the index of plant and animal species will be helpful for all readers. The character, extent and value of the information provided in this book is useful for chemists, chemical ecologists and specialists in agriculture. It can also serve as a good handbook for those who work in basic research and at universities, but also for specialists with practical aspirations.

Lenka Soukupová

Papers

Diversified development of mountain mires, Bohemian Forest, Central Europe, in the last 13,000 years

Plant clonality: Biology and diversity

Allocation plasticity and modular structure in clonal graminoids in response to waterlogging

Plant Invasions in Central European Middle-Mountains: A Result of Global Change ?

Bookreviews: New books in ecology