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Zürich, Switzerland

Schurr F.M.,University of Potsdam | Schurr F.M.,Goethe University Frankfurt | Schurr F.M.,Montpellier University | Pagel J.,University of Potsdam | And 15 more authors.
Journal of Biogeography

Range dynamics causes mismatches between a species' geographical distribution and the set of suitable environments in which population growth is positive (the Hutchinsonian niche). This is because source-sink population dynamics cause species to occupy unsuitable environments, and because environmental change creates non-equilibrium situations in which species may be absent from suitable environments (due to migration limitation) or present in unsuitable environments that were previously suitable (due to time-delayed extinction). Because correlative species distribution models do not account for these processes, they are likely to produce biased niche estimates and biased forecasts of future range dynamics. Recently developed dynamic range models (DRMs) overcome this problem: they statistically estimate both range dynamics and the underlying environmental response of demographic rates from species distribution data. This process-based statistical approach qualitatively advances biogeographical analyses. Yet, the application of DRMs to a broad range of species and study systems requires substantial research efforts in statistical modelling, empirical data collection and ecological theory. Here we review current and potential contributions of these fields to a demographic understanding of niches and range dynamics. Our review serves to formulate a demographic research agenda that entails: (1) advances in incorporating process-based models of demographic responses and range dynamics into a statistical framework, (2) systematic collection of data on temporal changes in distribution and abundance and on the response of demographic rates to environmental variation, and (3) improved theoretical understanding of the scaling of demographic rates and the dynamics of spatially coupled populations. This demographic research agenda is challenging but necessary for improved comprehension and quantification of niches and range dynamics. It also forms the basis for understanding how niches and range dynamics are shaped by evolutionary dynamics and biotic interactions. Ultimately, the demographic research agenda should lead to deeper integration of biogeography with empirical and theoretical ecology. © 2012 Blackwell Publishing Ltd. Source

Desurmont G.A.,University of Neuchatel | Laplanche D.,University of Neuchatel | Schiestl F.P.,Institute of Systematic Botany | Turlings T.C.J.,University of Neuchatel
BMC Ecology

Background: The role of plant ontogeny on investment in direct defense against herbivores is well accepted, but the transition from the vegetative to the reproductive stage can also affect indirect resistance traits (i.e. attraction of the natural enemies of plant attackers). Here, we conducted behavioral bioassays in olfactometers to determine whether the developmental stage (vegetative, pre-flowering, and flowering) of Brassica rapa plants affects attraction of Cotesia glomerata, a parasitoid of the herbivore Pieris brassicae, and examined the blends of volatile compounds emitted by plants at each developmental stage. Results: Pieris-infested plants were always more attractive to parasitoids than control plants and plants infested by a non-host herbivore, independently of plant developmental stage. On the other hand, the relative attractiveness of Pieris-infested plants was ontogeny dependent: Pieris-infested plants were more attractive at the pre-flowering stage than at the vegetative stage, and more attractive at the vegetative stage than at the flowering stage. Chemical analyses revealed that the induction of leaf volatiles after herbivory is strongly reduced in flowering plants. The addition of synthetic floral volatiles to infested vegetative plants decreased their attractiveness to parasitoids, suggesting a trade-off between signaling to pollinators and parasitoids. Conclusion: Our results show that putative indirect resistance traits are affected by plant development, and are reduced during B. rapa reproductive stage. The effects of ontogenetic shifts in resource allocation on the behavior of members of the third trophic level may have important implications for the evolution of plant defense strategies against herbivores. © Desurmont et al. Source

Tkach N.,Martin Luther University of Halle Wittenberg | Ree R.H.,Field Museum of Natural History | Kuss P.,Institute of Systematic Botany | Roser M.,Martin Luther University of Halle Wittenberg | Hoffmann M.H.,Martin Luther University of Halle Wittenberg
Molecular Phylogenetics and Evolution

The origin of the arctic flora covering the northernmost treeless areas is still poorly understood. Arctic plants may have evolved in situ or immigrated from the adjacent ecosystems. Frequently arctic species have disjunctive distributions between the Arctic and high mountain systems of the temperate zone. This pattern may result from long distance dispersal or from glacial plant migrations and extinctions of intermediate populations. The hemiparasitic genus Pedicularis is represented in the Arctic by c. 28 taxa and ranks among the six most species-rich vascular plant genera of this region. In this study, we test the hypothesis that these lineages evolved from predecessors occurring in northern temperate mountain ranges, many of which are current centers of diversity for the genus. We generated a nuclear ribosomal and chloroplast DNA phylogeny including almost all of the arctic taxa and nearly half of the genus as a whole. The arctic taxa of Pedicularis evolved 12-14 times independently and are mostly nested in lineages that otherwise occur in the high mountains of Eurasia and North America. It appears that only three arctic lineages arose from the present-day center of diversity of the genus, in the Hengduan Mountains and Himalayas. Two lineages are probably of lowland origin. Arctic taxa of Pedicularis show considerable niche conservatism with respect to soil moisture and grow predominantly in moist to wet soils. The studied characteristics of ecology, morphology, and chromosome numbers of arctic Pedicularis show a heterogeneous pattern of evolution. The directions of morphological changes among the arctic lineages show opposing trends. Arctic taxa are chiefly diploid, the few tetraploid chromosome numbers of the genus were recorded only for arctic taxa. Five arctic Pedicularis are annuals or biennials, life forms otherwise rare in the Arctic. Other genera of the Orobanchaceae consist also of an elevated number of short-lived species, thus hemiparasitism may favor this life form in the Arctic. © 2014 Elsevier Inc. Source

Linder H.P.,University of Zurich | de Klerk H.M.,Stellenbosch University | Born J.,Institute of Systematic Botany | Born J.,Swiss Federal Institute of forest | And 4 more authors.
Journal of Biogeography

Aim To test whether it is possible to establish a common biogeographical regionalization for plants and vertebrates in sub-Saharan Africa (the Afrotropical Region), using objective multivariate methods. Location Sub-Saharan Africa (Afrotropical Region). Methods We used 1° grid cell resolution databases for birds, mammals, amphibians and snakes (4142 vertebrate species) and c.13% of the plants (5881 species) from the Afrotropical Region. These databases were analysed using cluster analysis techniques to define biogeographical regions. A β(sim) dissimilarity matrix was subjected to a hierarchical classification using the unweighted pair-group method with arithmetic averages (UPGMA). The five group-specific biogeographical regionalizations were compared against a regionalization developed from a combined database, and a regionalization that is maximally congruent with the five group-specific datasets was determined using a consensus classification. The regionalizations were interpreted against measures of spatial turnover in richness and composition for the five datasets as well as the combined dataset. Results We demonstrate the existence of seven well-defined and consistent biogeographical regions in sub-Saharan Africa. These regionalizations are statistically defined and robust between groups, with minor taxon-specific biogeographical variation. The proposed biogeographical regions are: Congolian, Zambezian, Southern African, Sudanian, Somalian, Ethiopian and Saharan. East Africa, the West African coast, and the transitions between the Congolian, Sudanian and Zambezian regions are unassigned. The Cape area in South Africa, Afromontane areas and the coastal region of East Africa do not emerge as distinct regions but are characterized by high neighbourhood heterogeneity, rapid turnover of species and high levels of narrow endemism. Main conclusions Species distribution data and modern cluster analysis techniques can be used to define biogeographical regions in Africa that reflect the patterns found in both vertebrates and plants. The consensus of the regionalizations between different taxonomic groups is high. These regions are broadly similar to those proposed using expert opinion approaches. Some previously proposed transitional zones are not recognized in this classification. © 2012 Blackwell Publishing Ltd. Source

Vegetation of four coastal ecosystems of eastern continental Greece and of Sterea Ellas, including dune, marshland, wet meadow, reed bed and aquatic habitats, was studied in several years. The flora of the investigated regions consists of 217 taxa belonging to 42 families and 135 genera, most of which are reported for the first time. The majority of taxa are Therophytes (101 taxa, 46%); Hemicryptophytes and Geophytes are also well represented in the life form spectrum. From a chorological point of view the Mediterranean element (123 taxa, 57%) outweight the rest while the most diverse group of widespread taxa occupies the second place (83 taxa, 38%). The macrophytic vegetation was analysed following the Braun-Blanquet method. Twenty one plant communities were found belonging to twelve alliances, ten orders and eight phytosociological classes. The vegetation units distinguished are described, documented in form of phytosociological tables, and compared with similar communities from other Mediterranean countries. According to directive 92/43/EU, nine habitat types were delimited through the assessment of the dominant vegetation types. Source

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