Trophic level asynchrony in rates of phenological change for marine,freshwater and terrestrial environments

Recent changes in the seasonal timing (phenology) of familiar biological events have been one of the most conspicuous signs of climate change. However, the lack of a standardized approach to analysing change has hampered assessment of consistency in such changes among different taxa and trophic levels and across freshwater, terrestrial and marine environments. We present a standardized assessment of 25 532 rates of phenological change for 726 UK terrestrial, freshwater and marine taxa. The majority of spring and summer events have advanced, and more rapidly than previously documented. Such consistency is indicative of shared large scale drivers. Furthermore, average rates of change have accelerated in a way that is consistent with observed warming trends. Less coherent patterns in some groups of organisms point to the agency of more local scale processes and multiple drivers. For the first time we show a broad scale signal of differential phenological change among trophic levels; across environments advances in timing were slowest for secondary consumers, thus heightening the potential risk of temporal mismatch in key trophic interactions. If current patterns and rates of phenological change are indicative of future trends, future climate warming may exacerbate trophic mismatching, further disrupting the functioning, persistence and resilience of many ecosystems and having a major impact on ecosystem services.     

Combination Chemotherapy using L-Asparaginase,Daunorubicin, and Cytosine Arabinoside in Adults with Acute Myelogenous Leukaemia

Cytosine arabinoside and daunorubicin used in an intensive intermittent regimen have been shown to be an effective combination for the induction of complete remissions in 14 out of 23 adult patients with acute myelogenous leukaemia. This gives an overall complete remission rate of 60%. A further patient had a good partial remission. The addition of L-asparaginase to the regimen has not increased the incidence of remission and there were more side effects in the L-asparaginasetreated group. Of the 10 patients treated with L-asparaginase in addition to cytosine arabinoside and daunorubicin, five achieved a complete remission. Of the 13 patients treated with cytosine arabinoside and daunorubicin without L-asparaginase, nine achieved a complete remission and one a good partial remission.     

Estimating the recombination frequency for the MN and the Ss loci

Linkage analysis of 146 informative families for MN and Ss resulted in an estimate of the recombination frequency greater than previously reported. Our total is 7 recombinant children out of 467 individuals, including 1 confirmed recombinant (retested and HLA-compatible) and 6 not verified. The 95% confidence interval of our estimate of recombination is 0.0033-0.0167. Our results are compared with two earlier studies.     

The biogeography of Miniopterus bats (Chiroptera: Miniopteridae) from the Comoro Archipelago inferred from mitochondrial DNA

The endemic fauna of the Comoro Archipelago is composed of a mixture of taxa originating from Africa and Madagascar. Bats are the only native land dwelling mammals on this archipelago, but the biogeographical origins for the vast majority of species within this group are ambiguous. We report here genetic analyses based on two mitochondrial DNA markers to infer the origin of Comorian bats belonging to a reputed species complex of Miniopterus that is further distributed across Africa and Madagascar. Phylogenetic reconstructions show that east African M. minor are not closely related to the insular Miniopterus of Madagascar and the Comoros (Grande Comore and Anjouan). The latter cluster into two distinct, monophyletic clades (Clade 1 and Clade 2). Representatives of these clades occur sympatrically both on the Comoros and on Madagascar, and are distinguished by a large genetic distance (K2P: 9.9% for cytochrome b). No haplotypes are shared between any islands, suggesting the absence of contemporary gene flow. Populations of the widespread Clade 1 are furthermore characterized by a significant inter‐island structure (Φ_CT = 0.249), and by high haplotype and nucleotide diversities (h = 0.90–0.98, π = 0.04–0.06). Demographic analyses of Clade 1 suggest secondary contact between two distinct phylogroups (Subclade 1 A and 1B) that reached Grande Comore and Anjouan, and a large, stable population with a long evolutionary history on Madagascar. These results and the current distribution of related lineages suggest that the Comoros were colonized independently at least two or three times by ancestors from Madagascar.     

Natural colonization or introduction? Phylogeographical relationships and morphological differentiation of house geckos (Hemidactylus) from Madagascar

Several house gecko species of the genus Hemidactylus are almost cosmopolitan lizards, with distributions that have probably been shaped by natural transoceanic dispersal as well as by more recent human introductions. Here we revise the Hemidactylus populations of Madagascar and compare them genetically with populations from other sites in the Indian Ocean region. Morphological data strongly confirm the occurrence of three Hemidactylus species on Madagascar: Hemidactylus frenatus , distributed along the western coast of Madagascar; H. platycephalus , restricted to the north-west and the widespread H. mercatorius that occurs throughout the island, including coastal areas at sea level as well as big cities (Antananarivo, Fianarantsoa) at altitudes of 1200–1300 m above sea level. Analyses of partial sequences of the 16S rRNA gene in 46 Hemidactylus specimens from Madagascar, East Africa, South Asia, and the Comoro and Mascarene archipelagos demonstrated the presence of a fourth species, H. brooki, on the Mascarenes (Réunion, Rodrigues, and Mauritius) and Comoros (Moheli). The Malagasy populations of H. platycephalus were genetically uniform and differentiated from the African and Comoroan specimens studied. H. frenatus had a relatively low genetic differentiation over the whole region with no recognizable phylogeographical structure, indicating more recent colonizations or introductions. In contrast, H. mercatorius showed a strong phylogeographical structure of haplotypes, with two distinctly different lineages in Madagascar. Moreover, all Malagasy specimens differed strongly from the single African specimen included. This indicates that populations of H. mercatorius in Madagascar have a long history that predates human settlement.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 83 , 115–130.     

Northern tamarisk beetle (Diorhabda carinulata) and tamarisk (Tamarix spp.) interactions in the Colorado River basin

Northern tamarisk beetles (Diorhabda carinulata) were released in the Upper Colorado River Basin in the United States in 2004–2007 to defoliate introduced tamarisk shrubs (Tamarix spp.) in the region's riparian zones. The primary purpose was to control the invasive shrub and reduce evapotranspiration (ET) by tamarisk in an attempt to increase stream flows. We evaluated beetle–tamarisk interactions with MODIS and Landsat imagery on 13 river systems, with vegetation indices used as indicators of the extent of defoliation and ET. Beetles are widespread and exhibit a pattern of colonize–defoliate–emigrate, so that riparian zones contain a mosaic of completely defoliated, partially defoliated, and refoliated tamarisk stands. Based on satellite data and ET algorithms, mean ET before beetle release (2000–2006) was 416 mm/year compared to postrelease (2007–2015) ET of 355 mm/year (p < 0.05) for a net reduction of 61 mm/year. This is lower than initial literature projections that ET would be reduced by 300–460 mm/year. Reasons for the lower‐than‐expected ET reductions are because baseline ET rates are lower than initially projected, and percentage ET reduction is low because tamarisk stands tend to regrow new leaves after defoliation and other plants help maintain canopy cover. Overall reductions in tamarisk green foliage during the study are 21%. However, ET in the Upper Basin has shown a steady decline since 2007 and equilibrium has not yet been reached. Defoliation is now proceeding from the Upper Basin into the Lower Basin at a rate of 40 km/year, much faster than initially projected.     

Nice weather for bettongs: using weather events,not climate means,in species distribution models

Current applications of species distribution models (SDM) are typically static, in that they are based on correlations between where a species has been observed (ignoring the date of the observation) and environmental features, such as long‐term climate means, that are assumed to be constant for each site. Because of this SDMs do not account for temporal variation in the distribution of suitable habitat across the range of a species. Here, we demonstrate the temporal variability in the potential geographic distributions of an endangered marsupial, the northern bettong Bettongia tropica as a case study. Models of the species distribution using temporally matched observations of the species with weather data (including extreme weather events) at the time of species observations, were better able to define habitat suitability, identify range edges and uncover competitive interactions than models based on static long‐term climate means. Droughts and variable temperature are implicated in low densities and local extinctions of northern bettong populations close to range edges. Further, we show how variable weather can influence the results of competition with the common rufous bettong Aepyprymnus rufescens. Because traditional SDMs do not account for temporal variability of suitable habitat, static SDMs may underestimate the impacts of climate change particularly as the incidence of extreme weather events is likely to rise.     

Evidence that BDNF regulates heart rate by a mechanism involving increased brainstem parasympathetic neuron excitability

Autonomic control of heart rate is mediated by cardioinhibitory parasympathetic cholinergic neurons located in the brainstem and stimulatory sympathetic noradrenergic neurons. During embryonic development the survival and cholinergic phenotype of brainstem autonomic neurons is promoted by brain‐derived neurotrophic factor (BDNF). We now provide evidence that BDNF regulates heart rate by a mechanism involving increased brainstem cardioinhibitory parasympathetic activity. Mice with a BDNF haploinsufficiency exhibit elevated resting heart rate, and infusion of BDNF intracerebroventricularly reduces heart rate in both wild‐type and BDNF+/? mice. The atropine‐induced elevation of heart rate is diminished in BDNF+/? mice and is restored by BDNF infusion, whereas the atenolol‐induced decrease in heart rate is unaffected by BDNF levels, suggesting that BDNF signaling enhances parasympathetic tone which is diminished with BDNF haploinsufficiency. Whole‐cell recordings from pre‐motor cholinergic cardioinhibitory vagal neurons in the nucleus ambiguus indicate that BDNF haploinsufficiency reduces cardioinhibitory vagal neuron activity by increased inhibitory GABAergic and diminished excitatory glutamatergic neurotransmission to these neurons. Our findings reveal a previously unknown role for BDNF in the control of heart rate by a mechanism involving increased activation of brainstem cholinergic parasympathetic neurons

     

Variation in Outcrossing Rates in Eichhornia paniculata: Temporal Changes in Populations of Contrasting Style Morph Structure

Abstract Surveys of mating-system parameters in populations of the annual, self-compatible, tristylous, emergent aquatic, Eichhornia paniculata (Pontederiaceae) from N.E. Brazil and Jamaica have indicated that the species exhibits a wide range of outcrossing rates. To investigate whether temporal variation in outcrossing rate was also a feature of populations, open-pollinated families were sampled from five populations of contrasting style morph structure from N.E. Brazil over three consecutive years (1987–1989). Multilocus estimates of outcrossing rate ( t ) were obtained from assays of isozyme polymorphisms using starch gel electrophoresis. There was significant variation both among populations and between years in the frequency of outcrossing. Outcrossing in three tristylous populations was high ( t > 0.80), with relatively small fluctuations occurring over the three-year sampling period. In contrast, in a dimorphic and monomorphic population considerable self-fertilization occurred and the frequency of outcrossing declined significantly from 1987 to 1989 in both populations. In the dimorphic population, increased selfing was associated with a marked reduction in population size and an increase in the frequency of selfing variants of the mid-styled morph. The significance of temporal variation in outcrossing frequency in plant populations is discussed in relation to its effect on population genetic structure and recent models of mating-system evolution.     

Signaling or Not-Signaling: Variation in Vulnerability and Defense Tactics of Armored Ground Crickets (Acanthoplus Speiseri: Orthoptera, Tettigoniidae, Hetrodinae)

Male Orthoptera singing from exposed perches are at risk from acoustically- and visually-hunting predators. The defensive reactions of armored ground crickets (Acanthoplus speiseri) include falling silent, dropping from their perch, alarm stridulation and autohaemorrhaging. Male and female ground crickets show different reactivity (i.e. the number or intensity of defense tactics used) to predation, depending on level of exposure: calling males were more reactive when approached during daylight, compared with in the dark. During daylight, calling males were more reactive than silent, cryptic, males and females. The level of response presumably reflected the riskiness of the individual’s behavior and situation at that time. Plasticity of response to predation allows individuals to balance risky behavior (i.e. acoustic signaling from exposed perches) by being more reactive to potential threats.