First Miocene fossils of Vivianiaceae shed new light on phylogeny,divergence times,and historical biogeography of Geraniales

The origin of Geraniales (approximately 900 species in three families: Geraniaceae, Melianthaceae, and Vivianiaceae) is traced back to the Cretaceous of Gondwana, yet their geotemporal history is largely unknown because of a limited fossil record and incomplete phylogenies. In the present study, we provide the first fossil record of Vivianiaceae and a highly resolved molecular phylogeny for all extant Geraniales genera. Our results support the hypothesis that five (instead of three) families should be recognized in the order Geraniales: Francoaceae A. Juss. (Francoa, Greyia, Tetilla), Geraniaceae Juss. (Erodium, Geranium, Monsonia, Pelargonium), Hypseocharitaceae Wedd. (monogeneric), Melianthaceae Horan. (Bersama, Melianthus), and Vivianiaceae Klotzsch (Balbisia, Rhynchotheca, Viviania). The four major lineages (i.e. Geraniaceae, Francoaceae + Melianthaceae, Hypseocharitaceae, Vivianiaceae) all originated within a narrow time frame during the Eocene (36.9–49.9 Mya) based on the five fossil calibration points. The divergence of most of the extant genera occurred much later, from the Miocene onwards. The South American–South African disjunction in Francoaceae apparently goes back to long distance dispersal with an estimated divergence time of the lineages in the Middle Miocene [11.2 (5.9–17.7) Mya]. Diversification in Melianthus appears to be much more recent than previously assumed [starting approximately 3.4 (1.9–5.2) Mya rather than approximately 8–20 Mya]. However, divergence of the Andean Hypseocharis lineage [36.9 (31.9–42.8) Mya] significantly predates the main Andean uplift: Current distributions likely go back to northward migrations and subsequent extinctions in Patagonia. Similarly, Rhynchotheca, Balbisia, and Viviania have a current southern distribution limit > 10°N of the fossil finds, indicating a massive northward displacement. The present evidence suggests that niche conservatism likely played a major role in the historical biogeography of Geraniales. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??.     

An assemblage of early Oligocene lizards (Squamata) from the locality of Boutersem (Belgium), with comments on the Eocene–Oligocene transition

A diverse, new lizard assemblage from the early Oligocene of Belgium is described. The Boutersem railway local fauna is the most species‐rich lizard assemblage yet reported from the European early Oligocene. Four lizard taxa are present: Lacertidae, Anguidae, Scincoidea and Platynota. One new species is described, Folisaurus boutersemensis sp. nov . This fauna provides new insight into the profound turnover that took place during the Eocene/Oligocene boundary in Europe. The new fauna confirms a marked decrease in diversity across the Eocene/Oligocene boundary. Two groups encountered in the European late Eocene became extinct (Iguanidae*, Glyptosaurinae). Estimates of species‐level extinctions range up to 80%. These estimates include members of virtually all the families present in the late Eocene. The relative importance of climate change and biotic interactions in controlling this pattern is discussed, and negative interactions between lizards and new carnivorous mammals are favoured. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155 , 148–170.     

Population genetics of Manihot esculenta ssp. flabellifolia gives insight into past distribution of xeric vegetation in a postulated forest refugium area in northern Amazonia

The Guianas have often been proposed as a forest refugium; however, this view has received little testing. Studies of population genetics of forest taxa suggest that the central part of French Guiana remained forested, while the southern part (currently forested) may have harboured more open vegetation. Insights into the population structure of species restricted to non-forested habitats can help test this hypothesis. Using six microsatellite loci, we investigated the population genetics of French Guianan accessions of Manihot esculenta ssp. flabellifolia , a taxon restricted to coastal savannas and to rocky outcrops in the densely forested inland. Coastal populations were highly differentiated from one another, and our data suggest a recent colonization of these savannas by M. esculenta ssp. flabellifolia in a west-to-east process. Coastal populations were strongly differentiated from inselberg populations, consistent with an ancient separation of these two groups, with no or low subsequent gene flow. This supports the hypothesis that the central part of the region may have remained forested since the Last Glacial Maximum, impeding the establishment of Manihot . Contrary to coastal populations, inselberg Manihot populations were strikingly homogeneous at a broad spatial scale. This suggests they were connected until recently, either by a large continuous savanna area or by smaller, temporary disturbed areas shifting in space.     

Latitudinal patterns of magnitude and interannual variability in net ecosystem exchange regulated by biological and environmental variables

Over the last two and half decades, strong evidence showed that the terrestrial ecosystems are acting as a net sink for atmospheric carbon. However the spatial and temporal patterns of variation in the sink are not well known. In this study, we examined latitudinal patterns of interannual variability (IAV) in net ecosystem exchange (NEE) of CO₂ based on 163 site-years of eddy covariance data, from 39 northern-hemisphere research sites located at latitudes ranging from ∼29°N to ∼64°N. We computed the standard deviation of annual NEE integrals at individual sites to represent absolute interannual variability (AIAV), and the corresponding coefficient of variation as a measure of relative interannual variability (RIAV). Our results showed decreased trends of annual NEE with increasing latitude for both deciduous broadleaf forests and evergreen needleleaf forests. Gross primary production (GPP) explained a significant proportion of the spatial variation of NEE across evergreen needleleaf forests, whereas, across deciduous broadleaf forests, it is ecosystem respiration (Re). In addition, AIAV in GPP and Re increased significantly with latitude in deciduous broadleaf forests, but AIAV in GPP decreased significantly with latitude in evergreen needleleaf forests. Furthermore, RIAV in NEE, GPP, and Re appeared to increase significantly with latitude in deciduous broadleaf forests, but not in evergreen needleleaf forests. Correlation analyses showed air temperature was the primary environmental factor that determined RIAV of NEE in deciduous broadleaf forest across the North American sites, and none of the chosen climatic factors could explain RIAV of NEE in evergreen needleleaf forests. Mean annual NEE significantly increased with latitude in grasslands. Precipitation was dominant environmental factor for the spatial variation of magnitude and IAV in GPP and Re in grasslands.     

Nicotiana plumbaginifolia plants silenced for the ATP-binding cassette transporter gene NpPDR1 show increased susceptibility to a group of fungal and oomycete pathogens

The behaviour of Nicotiana plumbaginifolia plants silenced for the ATP-binding cassette transporter gene NpPDR1 was investigated in response to fungal and oomycete infections. The importance of NpPDR1 in plant defence was demonstrated for two organs in which NpPDR1 is constitutively expressed: the roots and the petal epidermis. The roots of the plantlets of two lines silenced for NpPDR1 expression were clearly more sensitive than those of controls to the fungal pathogens Botrytis cinerea , Fusarium oxysporum sp., F. oxysporum f. sp. nicotianae , F. oxysporum f. sp. melonis and Rhizoctonia solani , as well as to the oomycete pathogen Phytophthora nicotianae race 0. The Ph gene-linked resistance of N. plumbaginifolia to P. nicotianae race 0 was totally ineffective in NpPDR1 -silenced lines. In addition, the petals of the NpPDR1 -silenced lines were spotted 15%–20% more rapidly by B. cinerea than were the controls. The rapid induction (after 2–4 days) of NpPDR1 expression in N. plumbaginifolia and N. tabacum mature leaves in response to pathogen presence was demonstrated for the first time with fungi and one oomycete: R. solani , F. oxysporum and P. nicotianae . With B. cinerea , such rapid expression was not observed in healthy mature leaves. NpPDR1 expression was not observed during latent infections of B. cinerea in N. plumbaginifolia and N. tabacum , but was induced when conditions facilitated B. cinerea development in leaves, such as leaf ageing or an initial root infection. This work demonstrates the increased sensitivity of NpPDR1 -silenced N. plumbaginifolia plants to all of the fungal and oomycete pathogens investigated.     

Rapid changes in fish community structure and habitat distribution following the precipitation of lake phosphorus with aluminium

1. Fish community structure and habitat distribution of the abundant species roach, perch and ruffe were studied in Lake Nordborg (Denmark) before (August 2006) and after (August 2007) aluminium treatment to reduce internal phosphorus loading. 2. Rapid changes in fish community structure, abundance and habitat distribution occurred following a decline in in‐lake phosphorus concentrations from 280 to 37 μg P L^?1 and an increase in Secchi depth transparency from 1.1 to 1.9 m (August). The proportion of perch in overnight gill net catches increased, whilst roach decreased, and the average weight of all key species increased. 3. The habitat distribution of perch and roach changed from a high proportion in the upper pelagic and littoral zones in 2006, towards enhanced proportions in the deeper pelagic and profundal zone in 2007. The abundance of large‐bodied zooplankton increased and the abundance of benthic invertebrates decreased in the same period, suggesting that the habitat shift was not induced by food limitation. 4. Ruffe shifted from the littoral and upper profundal zones towards the deep profundal zone, likely reflecting an increased predation risk in the littoral zone and better oxygen conditions in the deep profundal. 5. Our results indicate that enhanced risk of predation in the upper pelagic and the littoral zones and perhaps improved oxygen concentrations in the deeper profundal zone at decreasing turbidity are responsible for the observed habitat shift. The results indicate that fish respond rapidly to changes in nutrient state, both in terms of community structure and habitat use.     

Molecular and morphometric variation in two sibling species of the genus Praomys (Rodentia: Muridae): implications for biogeography

The rodent genus Praomys is widely distributed in the African tropics. The species are cryptic, rendering the species taxonomy unclear. There are differences of opinion concerning the specific status of Praomys misonnei and Praomys tullbergi, and their geographical distribution. We sequenced the cytochrome b and/or the 16S gene of 221 specimens from 12 countries in order to evaluate the genetic variability within these two species, and to precisely determine their geographical distribution. Morphological and morphometrical analyses on the sequenced specimens were also performed to find criteria useful for the identification of museum specimens. Our results confirm that P. misonnei and P. tullbergi are two valid species that can be separated by molecular data. However, no single discrete morphological character or simple metric measurement can be used to discriminate them. The percentage of misclassified individuals in multivariate discriminant analysis is relatively high (10%). The two species have allopatric distributions: P. tullbergi occurs in West Africa, from eastern Guinea to western Ghana, and P. misonnei is widely distributed from eastern Ghana to western Kenya. Within P. misonnei we identified three or four major geographical clades: a West Central African clade, an East African clade, a Nigerian clade, and a possible West African clade. Within P. misonnei, high geographical morphometrical variability was also identified. The role of both rivers and Pleistocene forest refugia in promoting speciation within the genus Praomys is discussed. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160 , 397–419.     

Biogeography meets conservation: the genetic structure of the endangered lycaenid butterfly Lycaena helle (Denis & Schiffermüller, 1775)

Cold‐adapted species are thought to have had their largest distribution ranges in central Europe during the glacial periods. Postglacial warming caused severe range shifts of such taxa into higher latitudes and altitudes. We selected the boreomontane butterfly Lycaena helle (Denis & Schiffermüller, 1775) as an example to demonstrate the genetic effects of range changes, and to document the recent status of highly fragmented remnant populations. We analysed five polymorphic microsatellite loci in 1059 individuals sampled at 50 different localities scattered over the European distribution area of the species. Genetic differentiation was strong among the mountain ranges of western Europe, but we did not detect similarly distinct genetic groups following a geographical pattern in the more eastern areas. The Fennoscandian populations form a separate genetic group, and provide evidence for a colonization from southern Finland via northern Scandinavia to south‐central Sweden. Species distribution modelling suggests a large extension of the spatial distribution during the last glacial maximum, but highlights strong retractions to a few mountain areas under current conditions. These findings, combined with our genetic data, suggest a more or less continuous distribution of L. helle throughout central Europe at the end of the last ice age. As a consequence of postglacial warming, the species retreated northwards to Fennoscandia and escaped increasing temperatures through altitudinal shifts. Therefore, the species is today restricted to population remnants located at the mountain tops of western Europe, genetically isolated from each other, and evolved into genetically unique entities. Rising temperatures and advancing habitat destruction threaten this wealth of biodiversity. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 155–168.     

Do photosynthetic limitations of evergreen Quercus ilex leaves change with long‐term increased drought severity?

Seasonal drought can severely impact leaf photosynthetic capacity. This is particularly important for Mediterranean forests, where precipitation is expected to decrease as a consequence of climate change. Impacts of increased drought on the photosynthetic capacity of the evergreen Quercus ilex were studied for two years in a mature forest submitted to long‐term throughfall exclusion. Gas exchange and chlorophyll fluorescence were measured on two successive leaf cohorts in a control and a dry plot. Exclusion significantly reduced leaf water potential in the dry treatment. In both treatments, light‐saturated net assimilation rate (A_max), stomatal conductance (g_s), maximum carboxylation rate (V_cmax), maximum rate of electron transport (J_max), mesophyll conductance to CO₂ (g_m) and nitrogen investment in photosynthesis decreased markedly with soil water limitation during summer. The relationships between leaf photosynthetic parameters and leaf water potential remained identical in the two treatments. Leaf and canopy acclimation to progressive, long‐term drought occurred through changes in leaf area index, leaf mass per area and leaf chemical composition, but not through modifications of physiological parameters.