For all researches, please visit our "Peer-reviewed publications" page.
Dellinger A, Essl F, Hojsgaard D, Kirchheimer B, Klatt S, Dawson W et al. (2015)
The New phytologist.
Biological invasions can be associated with shifts of the species' climatic niches but the incidence of such shifts is under debate. The reproductive system might be a key factor controlling such shifts because it influences a species' evolutionary flexibility. However, the link between reproductive systems and niche dynamics in plant invasions has been little studied so far. We compiled global occurrence data sets of 13 congeneric sexual and apomictic species pairs, and used principal components analysis (PCA) and kernel smoothers to compare changes in climatic niche optima, breadths and unfilling/expansion between native and alien ranges. Niche change metrics were compared between sexual and apomictic species. All 26 species showed changes in niche optima and/or breadth and 14 species significantly expanded their climatic niches. However, we found no effect of the reproductive system on niche dynamics. Instead, species with narrower native niches showed higher rates of niche expansion in the alien ranges. Our results suggest that niche shifts are frequent in plant invasions but evolutionary potential may not be of major importance for such shifts. Niche dynamics rather appear to be driven by changes of the realized niche without adaptive change of the fundamental climatic niche.
Keywords: adaptation, asexual reproduction, niche shifts, plant invasion, reproductive system, species distribution modelling
Neubauer T, Harzhauser M, Mandic O, Georgopoulou E, Kroh A (2015)
Palaeogeography, Palaeoclimatology, Palaeoecology.
We investigate the distributions of representatives of the family Melanopsidae (Gastropoda: Caenogastropoda: Cerithioidea) from the late Cretaceous to present-day. The present contribution discusses and partly revises former schemes of melanopsid dispersal during the Cenozoic, all of which were based on outdated stratigraphic and tectonic concepts as well as an incompletely considered fossil record. Conflating a comprehensive and stratigraphically well-constrained fossil record, modern paleogeographical reconstructions and contemporary climate data, our goal is to present a thorough model of melanopsid distribution and its changes over the Cenozoic as well as its paleogeographical and climatic constraints. The family Melanopsidae evolved about 90Ma ago in the late Turonian from brackish cerithioidean ancestors. Cretaceous and Paleogene species occur in marginal marine to brackish environments along the shores of the Tethys and Paratethys seas. The extant clades of Melanopsis likely derive from the evolution of freshwater Melanopsis on the Balkan Peninsula back in the late early Miocene. Up to the Pliocene, freshwater species spread toward southwestern and southeastern Europe and successively replaced brackish-water representatives, paralleling a general decline of latter systems during the late Cenozoic. The southwards expansion of Melanopsis and its simultaneous retreat from northern latitudes resulted in the disjunct distribution pattern observed today. The genus Holandriana first appeared in northern Italy in the late early Miocene. The genera Microcolpia and Esperiana both first occurred in the late Miocene and likely derive from brackish-water Melanopsis species native to peri-Paratethyan lakes. The present-day biogeographic isolation of the three latter genera and Melanopsis roots in the climatic deterioration and the disappearance of major lake systems in southeastern Europe. While thermophilous Melanopsis retreated to the warm, dry climates of the Mediterranean and Middle East, Holandriana, Microcolpia and Esperiana adapted to the seasonal, cold-temperate climate of southeastern and eastern Europe and some species became restricted to thermal springs.
Keywords: Biodiversity, Biogeography, Brackish-water, Climate, Freshwater, Gastropoda
Pellissier L, Eidesen P, Ehrich D, Descombes P, Schönswetter P, Tribsch A et al. (2015)
Journal of Biogeography.
Aim High intra-specific genetic diversity is necessary for species adaptation to novel environments under climate change, but species tracking suitable conditions are losing alleles through successive founder events during range shift. Here, we investigated the relationship between range shift since the Last Glacial Maximum (LGM) and extant population genetic diversity across multiple plant species to understand variability in species responses. Location: The circumpolar Arctic and northern temperate alpine ranges. Methods: We estimated the climatic niches of 30 cold-adapted plant species using range maps coupled with species distribution models and hindcasted species suitable areas to reconstructions of the mid-Holocene and LGM climates. We computed the species-specific migration distances from the species glacial refugia to their current distribution and correlated distances to extant genetic diversity in 1295 populations. Differential responses among species were related to life-history traits. Results: We found a negative association between inferred migration distances from refugia and genetic diversities in 25 species, but only 11 had statistically significant negative slopes. The relationships between inferred distance and population genetic diversity were steeper for insect-pollinated species than wind-pollinated species, but the difference among pollination system was marginally independent from phylogenetic autocorrelation. Main conclusion: The relationships between inferred migration distances and genetic diversities in 11 species, independent from current isolation, indicate that past range shifts were associated with a genetic bottleneck effect with an average of 21% loss of genetic diversity per 1000 km−1. In contrast, the absence of relationship in many species also indicates that the response is species specific and may be modulated by plant pollination strategies or result from more complex historical contingencies than those modelled here.
Keywords: Arctic plants, Last Glacial Maximum, climate change, climatic niche, migration, species distribution models
Pichler U, Hauser M, Wolf M, Bernardi M, Gadermaier G, Weiss R et al. (2015)
PloS one 10(5) e0120038.
BACKGROUND: Pollen released by allergenic members of the botanically unrelated families of Asteraceae and Cupressaceae represent potent elicitors of respiratory allergies in regions where these plants are present. As main allergen sources the Asteraceae species ragweed and mugwort, as well as the Cupressaceae species, cypress, mountain cedar, and Japanese cedar have been identified. The major allergens of all species belong to the pectate lyase enzyme family. Thus, we thought to investigate cross-reactivity pattern as well as sensitization capacities of pectate lyase pollen allergens in cohorts from distinct geographic regions. METHODS: The clinically relevant pectate lyase pollen allergens Amb a 1, Art v 6, Cup a 1, Jun a 1, and Cry j 1 were purified from aqueous pollen extracts, and patients' sensitization pattern of cohorts from Austria, Canada, Italy, and Japan were determined by IgE ELISA and cross-inhibition experiments. Moreover, we performed microarray experiments and established a mouse model of sensitization. RESULTS: In ELISA and ELISA inhibition experiments specific sensitization pattern were discovered for each geographic region, which reflected the natural allergen exposure of the patients. We found significant cross-reactivity within Asteraceae and Cupressaceae pectate lyase pollen allergens, which was however limited between the orders. Animal experiments showed that immunization with Asteraceae allergens mainly induced antibodies reactive within the order, the same was observed for the Cupressaceae allergens. Cross-reactivity between orders was minimal. Moreover, Amb a 1, Art v 6, and Cry j 1 showed in general higher immunogenicity. CONCLUSION: We could cluster pectate lyase allergens in four categories, Amb a 1, Art v 6, Cup a 1/Jun a 1, and Cry j 1, respectively, at which each category has the potential to sensitize predisposed individuals. The sensitization pattern of different cohorts correlated with pollen exposure, which should be considered for future allergy diagnosis and therapy.
Keywords: Arctic plants, Last Glacial Maximum, climate change, climatic niche, migration, species distribution models
Rouget M, Robertson M, Wilson J, Hui C, Essl F, Renteria J et al. (2015)
Diversity and Distributions.
Aim We develop a framework for quantifying invasions based on lagged trends in invasions (‘invasion debt’) with the aim of identifying appropriate metrics to quantify delayed responses at different invasion stages – from introduction to when environmental impacts occur. Location World-wide; detailed case study in South Africa. Methods We define four components of invasion debt: the number of species not yet introduced but likely to be introduced in the future given current levels of introduction/propagule pressure; the establishment of introduced species; the potential increase in area invaded by established species (including invasive species); and the potential increase in impacts. We demonstrate the approach in terms of number of species for 21 known invasive Australian Acacia species globally and estimate three components of invasion debt for 58 Acacia species already introduced to South Africa by quantifying key invasion factors (environmental suitability, species invasion status, residence time, propagule pressure, spread rate and impacts). Results Current global patterns of invasive species richness reflect historical trends of introduction – most acacia species that will become invasive in southern Africa have already invaded, but there is a substantial establishment debt in South and North America. In South Africa, the likely consequence of invasion debt over the next 20 years was estimated at: four additional species becoming invasive with an average increase of 1075 km2 invaded area per invasive species. We estimate that this would require over US$ 500 million to clear. Main conclusions Our results indicate that invasion debt is a valuable metric for reporting on the threats attributable to biological invasions, that invasion debt must be factored into strategic plans for managing global change, and, as with other studies, they highlight the value of proactive management. Given the uncertainty associated with biological invasions, further work is required to quantify the different components of invasion debt.
Keywords: Acacia, biological invasions, climatic suitability, global change, invasive species, lag phase, risk assessment, tree invasions
Rubel F, Brugger K, Pfeffer M, Chitimia-Dobler L, Didyk Y, Leverenz S et al. (2015)
Ticks and Tick-borne Diseases.
The goal of this paper is to present up-to-date maps depicting the geographical distribution of Dermacentor species in Europe based on georeferenced sampling sites. Therefore, a dataset was compiled, resulting in 1,286 D. marginatus (Sulzer, 1776) and 1,209 D. reticulatus (Fabricius, 1794) locations. Special emphasis is given to the region of the European Alps depicting a presumable climate barrier of the mountains and to overlaps in the distribution of both species as well as on the situation in eastern European countries. For the latter newly described Dermacentor findings comprise 59 locations in Romania and 62 locations in Ukraine. The geographical distributions of both species in Europe range from Portugal to Ukraine (and continue to the east of Kazakhstan). Although it is well known that D. marginatus is adapted to a warmer and drier climate at more southern latitudes and D. reticulatus to a moderately moist climate at more northern latitudes, the distribution limits of both species were not well known. Here, the northern and southern distribution limits for both species in Europe, as determined from the georeferenced database, were specified for D. marginatus by the belt of 33 - 51∘ N latitude and for D. reticulatus by the belt of 41 - 57∘ N latitude. Thus, overlapping species distributions were found between 41∘ N and 51∘ N.
Keywords: Dermacentor-associated pathogens, Distribution map, Georeferenced locations, Ixodid ticks, Tick-borne diseases
Wasof S, Lenoir J, Aarrestad P, Alsos I, Armbruster W, Austrheim G et al. (2015)
Global Ecology and Biogeography.
Aim Previous research on how climatic niches vary across species ranges has focused on a limited number of species, mostly invasive, and has not, to date, been very conclusive. Here we assess the degree of niche conservatism between distant populations of native alpine plant species that have been separated for thousands of years. Location European Alps and Fennoscandia. Methods Of the studied pool of 888 terrestrial vascular plant species occurring in both the Alps and Fennoscandia, we used two complementary approaches to test and quantify climatic-niche shifts for 31 species having strictly disjunct populations and 358 species having either a contiguous or a patchy distribution with distant populations. First, we used species distribution modelling to test for a region effect on each species' climatic niche. Second, we quantified niche overlap and shifts in niche width (i.e. ecological amplitude) and position (i.e. ecological optimum) within a bi-dimensional climatic space. Results Only one species (3%) of the 31 species with strictly disjunct populations and 58 species (16%) of the 358 species with distant populations showed a region effect on their climatic niche. Niche overlap was higher for species with strictly disjunct populations than for species with distant populations and highest for arctic–alpine species. Climatic niches were, on average, wider and located towards warmer and wetter conditions in the Alps. Main conclusion Climatic niches seem to be generally conserved between populations that are separated between the Alps and Fennoscandia and have probably been so for 10,000–15,000 years. Therefore, the basic assumption of species distribution models that a species' climatic niche is constant in space and time – at least on time scales 104 years or less – seems to be largely valid for arctic–alpine plants.
Keywords: Alpine plants, arctic plants, climatic niche, disjunct distribution, distant populations, niche conservatism, niche optimum, niche overlap, niche width, species distribution modelling
Chen C, Qi Z, Xu X, Comes H, Koch M, Jin X et al. (2014)
Understanding the formation of Mediterranean-African-Asian disjunctions: evidence for Miocene climate-driven vicariance and recent long-distance dispersal in the Tertiary relict Smilax aspera (Smilacaceae)
The New Phytologist 204(1) 243-55.
Tethyan plant disjunctions, including Mediterranean-African-Asian disjunctions, are thought to be vicariant, but their temporal origin and underlying causes remain largely unknown. To address this issue, we reconstructed the evolutionary history of Smilax aspera, a hypothesized component of the European Tertiary laurel forest flora. Thirty-eight populations and herbarium specimens representing 57 locations across the species range were sequenced at seven plastid regions and the nuclear ribosomal internal transcribed spacer region. Time-calibrated phylogenetic and phylogeographic inferences were used to trace ancestral areas and biogeographical events. The deep intraspecific split between Mediterranean and African-Asian lineages is attributable to range fragmentation of a southern Tethyan ancestor, as colder and more arid climates developed shortly after the mid-Miocene. In the Mediterranean, climate-induced vicariance has shaped regional population structure since the Late Miocene/Early Pliocene. At around the same time, East African and South Asian lineages split by vicariance, with one shared haplotype reflecting long-distance dispersal. Our results support the idea that geographic range formation and divergence of Tertiary relict species are more or less gradual (mostly vicariant) processes over long time spans, rather than point events in history. They also highlight the importance of the Mediterranean Basin as a centre of intraspecific divergence for Tertiary relict plants.
Keywords: african, analyses, ancestral area reconstruction, chloroplast dna, disjunctions, eurasian, molecular dating, phylogenetic, phylogeographical inference
Sánchez S, Gómez E, Martín M, De Miguel A, Urban A, Barriuso J (2014)
Experiments on the life cycle and factors affecting reproduction of Sphaerosporella brunnea provide evidence for rapid asexual propagation by conidiospores and for homothallism in an ectomycorrhizal competitor of cultivated truffle species
Fungal Ecology 8 59-65.
Sphaerosporella brunnea is a pioneer and opportunist ectomycorrhizal species, and the most common fungal competitor in nurseries producing plants mycorrhized with Tuber species. Our objective was to learn more about its life cycle as the first step to manage its presence in greenhouses. Conidiation and formation of resting spore-like structures were found to be triggered by aeration and to be highest on CMA medium. In pot experiments S. brunnea was able to form ectomycorrhizas and ascocarps rapidly, in 2 and 3 months respectively, if substratum moisture was high. Both mycelia and conidiospores were effective sources of inoculum for mycorrhization. This species seems to be homothallic as apothecia have been obtained after inoculations with single monospore isolates. Propagation by mitospores and homothallism are poorly documented in ECM fungi, therefore these results may be of fundamental interest beyond the question of greenhouse management.
Keywords: Conidiation, Controlled mycorrhization, Dichobotrys, Mycorrhized plants, Nurseries, Truffle cultivation
Vilaça S, Biosa D, Zachos F, Iacolina L, Kirschning J, Alves P et al. (2014)
Mitochondrial phylogeography of the European wild boar: the effect of climate on genetic diversity and spatial lineage sorting across Europe
Journal of Biogeography 41(5) 987-998.
Aim: Climate changes in the past had a deep impact on the evolutionary history of many species and left genetic signatures that are often still detectable today. We investigated the geographical pattern of mitochondrial DNA divesity in the European wild boar (Sus scrofa). Our final aims were to clarify the influence of present and past climatic conditions, infer the geographical posi- tion of glacial refugia, and suggest post-glacial spatial dynamics. Location: Europe. Methods: D-loop sequences were obtained for 763 individuals from Portugal to western Russia. Phylogenetic, multivariate and interpolation methods were used to describe the genetic and geographical patterns. Climatic suitability during the Last Glacial Maximum (LGM) was predicted using MaxEnt. The effect of present and past suitability on the observed patterns of diversity was evaluated by multiple linear regression. Results: We confirmed the existence of a ubiquitous mitochondrial clade in Europe (E1), an endemic clade in Italy (E2) and a few East Asian haplotypes (A), presumably introgressed from domestic pigs. No Near Eastern haplotypes were detected. Genetic divergence was not simply related to geographical distance. A clear south–north decreasing gradient of diversity was observed, with maximum levels in putative glacial refugia. Latitudinal variation in climatic conditions during the LGM was shown to be a good predictor of current genetic diversity. Moreover, an unexpected similarity between Iberia and east- ern Europe was observed, while central European populations showed a higher affinity to the Italian gene pool. Main conclusions: The current distribution of mitochondrial genetic diversity was highly influenced by past climatic events, especially those related to the LGM, and is consistent with a major contribution of the Italian peninsula and the Balkans to the post-glacial recolonization of northern areas. More recent processes, such as restocking and extensive hunting, probably acted at rather local scales, without great impact on the global pattern of mitochondrial diversity.
Keywords: Climate change, Last Glacial Maximum, Sus scrofa, genetic differentiation, glacial refugia, mtDNA, phylogeography