Male‐killer dynamics in Danaus chrysippus (L.) (Lepidoptera: Nymphalidae) in East Africa

Within certain regions in East Africa, the butterfly Danaus chrysippus (L.) shows female‐biased population sex ratio, because of the production by some females of all‐female broods, as a result of infection by maternally inherited, male‐killing bacterium of the genus Spiroplasma. In this study, we describe a 3‐year field survey for the population dynamics of the male‐killing Spiroplasma in D. chrysippus in four independent localities, namely Uganda, Ghana, Sudan and Madagascar. The prevalence of the bacterium was found to show extensive variations at multiple scales among different sites, in various countries, seasons and years. A novel, selection‐based hypothesis was suggested to explain the high variability of male‐killer prevalence over space and time, based on the existence of an adaptive link between larval food‐plant density and the magnitude of resource reallocation fitness advantage for the male‐killer.     

Bio‐energetics underpins the spatial response of North Sea plaice (Pleuronectes platessa L.) and sole (Solea solea L.) to climate change

Climate change is currently one of the main driving forces behind changes in species distributions, and understanding the mechanisms that underpin macroecological patterns is necessary for a more predictive science. Warming sea water temperatures are expected to drive changes in ectothermic marine species ranges due to their thermal tolerance levels. Here, we develop a mechanistic tool to predict size‐ and season‐specific distributions based on the physiology of the species and the temperature and food conditions in the sea. The effects of climate conditions on physiological‐based habitat utilization was then examined for different size‐classes of two commercially important fish species in the North Sea, plaice, Pleuronectes platessa, and sole, Solea solea. The two species provide an attractive comparison as they differ in their physiology (e.g. preferred temperature range). Combining dynamic energy budget (DEB) models with the temperature and food conditions estimated by an ecosystem model (ERSEM), allowed spatial differences in potential growth (as a proxy for habitat quality) to be estimated for 2 years with contrasting temperature and food conditions. The resulting habitat quality maps were in broad agreement with observed ontogenetic and seasonal changes in distribution as well as with the recent changes in distribution which could be attributed to an increase in coastal temperatures. Our physiological‐based model provides a powerful tool to explore the effect of climate change on the spatio‐temporal fish dynamics, predict effects of local or broad‐scale environmental changes and provide a physiological basis for observed changes in species distributions.     

Comparative phylogeographies of six species of hinged terrapins (Pelusios spp.) reveal discordant patterns and unexpected differentiation in the P. castaneus/P. chapini complex and P. rhodesianus

Using up to 2117 bp of mitochondrial DNA and up to 2012 bp of nuclear DNA, we analysed phylogeographic differentiation of six widely distributed species of African hinged terrapins (Pelusios spp.) representing different habitat types. Two taxa each live in savannahs or in forests and mesic savannahs, respectively, and the remaining two species occur in intermediate habitats. The species living in forests and mesic savannahs do not enter dry savannahs, whereas the savannah species may occur in dry and wet savannahs and even in semi‐arid steppe regions. We found no obvious correlation between habitat type and phylogeographic pattern: one savannah species (P. rhodesianus) shows phylogeographic structure, i.e. pronounced genetic differences among geographically distinct populations, and the other (P. nanus) not. One species inhabiting forests and mesic savannahs (P. carinatus) has phylogeographic structure, the other (P. gabonensis) not. The same pattern is true for the two ecologically intermediate species, with phylogeographic structure present in P. castaneus and absent in P. chapini. Nuclear evidence suggests that the latter two taxa with abutting and partially overlapping ranges are distinct, while mtDNA is only weakly differentiated. Pelusios castaneus shows pronounced phylogeographic structure, which could reflect Pleistocene range interruptions correlated with the fluctuating forest cover in West and Central Africa. Our results do not support the recognition of an extinct subspecies of P. castaneus for the Seychelles. Pelusios carinatus contains two well supported clades, which are separated by the Congo River. This species is closely related to P. rhodesianus, a taxon consisting of two deeply divergent mitochondrial clades. One of these clades is paraphyletic with respect to P. carinatus, but the two clades of P. rhodesianus are not differentiated in the studied nuclear markers and, again, paraphyletic with respect to P. carinatus. Using mtDNA sequences from the type material of P. rhodesianus, we were able to allocate this name to one of the two clades. However, owing to the confusing relationships of P. rhodesianus and P. carinatus, we refrain from taxonomic decisions.     

Spatial ecology of bluetongue lizards (Tiliqua spp.) in the Australian wet–dry tropics

New technologies for quantifying animal locations enable us to document habitat‐selection patterns of cryptic taxa in extraordinary detail. Northern bluetongues (Tiliqua scincoides intermedia) and centralian bluetongues (Tiliqua multifasciata) are large heavy‐bodied scincid lizards that are broadly sympatric in the wet–dry tropics of north‐western Australia. We used data from GPS‐based radiotelemetry (n = 49 lizards, tracked for 2–121 days, total n = 61 640 locations) to examine the size, internal structure and overlap of lizard home ranges. Despite substantial habitat differences at our two study sites (semi‐arid and relatively pristine habitat at Keep River National Park, Northern Territory, vs. highly disturbed and fragmented flood plain habitat in an agricultural area near Kununurra, Western Australia), home ranges were similar between the two areas, and between the two species. Our radio‐tracked lizards continued to disperse into previously unused areas throughout the duration of the study, so that the total areas used by lizards continued to increase. Based on the minimum convex polygon method, total home ranges averaged 4 ha (range 2–12 ha), but only about two‐thirds of each home range was used intensively. Each home range had multiple core areas, and overlap of core as well as peripheral areas (especially with same‐sex conspecifics) was high at the disturbed (Western Australia) site where lizard densities were high. The concentration of lizard activity within small core areas, often used by multiple individuals, suggests that these heavily used sites are critical to lizard conservation. However, the lizards' infrequent long‐distance displacements also make them vulnerable to changes in the wider landscape mosaic. Because GPS‐based radiotelemetry can quantify habitat use at finer spatial and temporal scales than earlier technologies, it can provide a robust base for management of at‐risk fauna.     

A multi‐parent advanced generation inter‐cross (MAGIC) population for genetic analysis and improvement of cowpea (Vigna unguiculata L. Walp.)

Multi‐parent advanced generation inter‐cross (MAGIC) populations are an emerging type of resource for dissecting the genetic structure of traits and improving breeding populations. We developed a MAGIC population for cowpea (Vigna unguiculata L. Walp.) from eight founder parents. These founders were genetically diverse and carried many abiotic and biotic stress resistance, seed quality and agronomic traits relevant to cowpea improvement in the United States and sub‐Saharan Africa, where cowpea is vitally important in the human diet and local economies. The eight parents were inter‐crossed using structured matings to ensure that the population would have balanced representation from each parent, followed by single‐seed descent, resulting in 305 F₈ recombinant inbred lines each carrying a mosaic of genome blocks contributed by all founders. This was confirmed by single nucleotide polymorphism genotyping with the Illumina Cowpea Consortium Array. These lines were on average 99.74% homozygous but also diverse in agronomic traits across environments. Quantitative trait loci (QTLs) were identified for several parental traits. Loci with major effects on photoperiod sensitivity and seed size were also verified by biparental genetic mapping. The recombination events were concentrated in telomeric regions. Due to its broad genetic base, this cowpea MAGIC population promises breakthroughs in genetic gain, QTL and gene discovery, enhancement of breeding populations and, for some lines, direct releases as new varieties.     

Lignans from the Twigs of Euonymus alatus (Thunb.) Siebold and Their Biological Evaluation

A new sesquilignan, euonymolin A ( 1 ), and six known lignans, (?)‐de‐O‐methylmagnolin ( 2 ), (+)‐de‐O‐methylepimagnolin A ( 3 ), (+)‐syringaresinol ( 4 ), (+)‐pinoresinol ( 5 ), (+)‐medioresinol ( 6 ), and (+)‐lariciresinol 4′‐O‐β‐d ‐glucopyranoside ( 7 ), were isolated from the twigs of Euonymus alatus (Thunb .) Siebold (Celastraceae). The structures of the isolated compounds were elucidated based on spectroscopic analyses, including extensive 1D‐ and 2D‐NMR techniques, HR‐MS analysis and circular dichroism (CD) data, and the literature data. All of the isolated compounds were evaluated for antiproliferative activity against A549, SK‐OV‐3, SK‐MEL‐2, and HCT‐15 cell lines and inhibition of nitric oxide (NO) production in a lipopolysaccharide (LPS)‐activated BV2 cell line. All compounds showed cytotoxicity against the SK‐MEL‐2 cell line with IC₅₀ values of 23.24 – 48.14 μm and inhibited NO production in LPS‐activated BV‐2 cells with IC₅₀ values of 6.75 – 23.53 μm .     

Effect of UV‐C Radiation on Resistance of Romaine Lettuce (Lactuca sativa L.) Against Botrytis cinerea and Sclerotinia minor

The aim of this research was to examine the effect of UV‐C on resistance of lettuce to Botrytis cinerea and Sclerotinia minor. Analysis of the lesion surfaces showed that plants exposed to UV‐C were less susceptible to the two pathogens, especially on the fourth day after inoculation. Chlorophyll, carotenoid contents and malondialdehyde and hydrogen peroxide were assayed after 1 day and 4 days. Lettuces treated with UV‐C and inoculated showed an increase in chlorophyll and carotenoid content, especially 24 h after inoculation, and low values of the two indicators of oxidative stress as compared with lettuces which were inoculated but did not receive UV‐C treatment.     

Development and evaluation of novel salt‐tolerant Eucalyptus trees by molecular breeding using an RNA‐Binding‐Protein gene derived from common ice plant (Mesembryanthemum crystallinum L.)

The breeding of plantation forestry trees for the possible afforestation of marginal land would be one approach to addressing global warming issues. Here, we developed novel transgenic Eucalyptus trees (Eucalyptus camaldulensis Dehnh.) harbouring an RNA‐Binding‐Protein (McRBP) gene derived from a halophyte plant, common ice plant (Mesembryanthemum crystallinum L.). We conducted screened‐house trials of the transgenic Eucalyptus using two different stringency salinity stress conditions to evaluate the plants’ acute and chronic salt stress tolerances. Treatment with 400 mM NaCl, as the high‐stringency salinity stress, resulted in soil electrical conductivity (EC) levels >20 mS/cm within 4 weeks. With the 400 mM NaCl treatment, >70% of the transgenic plants were intact, whereas >40% of the non‐transgenic plants were withered. Treatment with 70 mM NaCl, as the moderate‐stringency salinity stress, resulted in soil EC levels of approx. 9 mS/cm after 2 months, and these salinity levels were maintained for the next 4 months. All plants regardless of transgenic or non‐transgenic status survived the 70 mM NaCl treatment, but after 6‐month treatment the transgenic plants showed significantly higher growth and quantum yield of photosynthesis levels compared to the non‐transgenic plants. In addition, the salt accumulation in the leaves of the transgenic plants was 30% lower than that of non‐transgenic plants after 15‐week moderate salt stress treatment. There results suggest that McRBP expression in the transgenic Eucalyptus enhances their salt tolerance both acutely and chronically.     

The impact of Broussonetia papyrifera (L.) vent. on community characteristics in the forest and forest–savannah transition ecosystems of Ghana

Following its introduction in the late 1960s, Broussonetia papyrifera L. Vent. Moraceae (paper mulberry) has emerged as a major exotic invasive species in Ghana's forest ecosystems. This study was carried out to assess the effects of B. papyrifera invasion on community composition in forest and forest–savannah transition ecosystems. Comparative and removal experiments were conducted in paired B. papyrifera invaded versus uninvaded plots. In the comparative assessment, species composition was found to be similar in both invaded and uninvaded plots. However, relative per cent cover of resident species and guilds including Chromolaena odorata, indigenous broadleaves and indigenous grasses were significantly lower in invaded plots. Seven months after B. papyrifera was experimentally removed from invaded stands, cover by indigenous broadleaves increased by 35%, as against only 5% in control plots at the forest site. However, at the transition site, the increase in per cent cover of indigenous broadleaves (18%) was not significantly different from control (2.5%) plots. We conclude that B. papyrifera has the capacity to reduce the abundance of indigenous broadleaf species, although its removal is more likely to favour regeneration in a forest than a forest–savannah transition ecosystem.     

Chemical Composition of Ballota macedonica Vandas and Ballota nigra L. ssp. foetida (Vis.) Hayek Essential Oils – The Chemotaxonomic Approach

The essential oils isolated from fresh aerial parts of Ballota macedonica (two populations) and Ballota nigra ssp. foetida were analyzed by GC and GC/MS. Eighty five components were identified in total; 60 components in B. macedonica oil (population from the Former Yugoslav Republic of Macedonia), 34 components in B. macedonica oil (population from the Republic of Serbia), and 33 components in the oil of B. nigra ssp. foetida accounting for 93.9%, 98.4%, and 95.8% of the total oils, respectively. The most abundant components in B. macedonica oils were carotol (13.7 – 52.1%), germacrene D (8.6 – 24.6%), and (E)‐caryophyllene (6.5 – 16.5%), while B. nigra ssp. foetida oil was dominated by (E)‐phytol (56.9%), germacrene D (10.0%), and (E)‐caryophyllene (4.7%). Multivariate statistical analyses (agglomerative hierarchical cluster analysis and principal component analysis) were used to compare and discuss relationships among Ballota species examined so far based on their volatile profiles. The chemical compositions of B. macedonica essential oils are reported for the first time.     

Identification and validation of reference genes for RT‐qPCR analysis in banana (Musa spp.) under Fusarium wilt resistance induction conditions

Banana (Musa spp.) is severely damaged by Fusarium wilt caused by Fusarium oxysporum f. sp. cubense (Foc). Biocontrol by inducing systemic resistance has been considered as one of the most important strategies to improve plant health. Very few studies have investigated appropriate reference gene selection for RT‐qPCR (quantitative real‐time polymerase chain reaction) analysis suitable for conditions of systemic activated resistance. In this study, we assessed over a time‐course the expression of seven candidate reference genes (EF1, TUB, ACT1, ACT2, L2, RPS2 and RAN) for Cavendish cultivar Brazilian (Musa spp. AAA) and dwarf banana cultivar Guangfen No. 1 (Musa spp. ABB) that were inoculated by Bacillus subtilis strain TR21 and Foc. We choose these plants because they are commonly planted in Southern China. Expression stability of the candidate genes was evaluated using various software packages (GeNorm, NormFinder and BestKeeper). L2 and TUB genes displayed maximum stability in Guangfen No. 1. In Brazilian, ACT1 and TUB were the most stable genes. To further validate the suitability of the reference genes identified in this study, the expression of pathogenesis‐related 1 (PR1) gene under TR21 and Foc strains Foc004/Foc009 treatments was also studied. Identified reference genes in this work that are most suitable for normalizing gene expression data in banana under Fusarium wilt resistance induction conditions will contribute to the understanding of disease resistance mechanisms induced by biocontrol strains in banana.     

A landscape genetics approach reveals ecological‐based differentiation in populations of holm oak (Quercus ilex L.) at the northern limit of its range

The holm oak plays a relevant role in the functioning of Mediterranean forests. In the area north of Garda Lake, Italian Prealps, holm oak populations are at the northernmost edge of their distribution. Being peripheral, these populations are of particular interest for ecological, evolutionary and conservation studies. Through an explicit individual‐based landscape genetics approach, we addressed the following questions: (1) are levels of genetic variation reduced in these marginal populations compared with central populations?; (2) despite the narrow geographical scale, do individual‐based analyses have some power to detect genetic differentiation?; (3) do environmental and/or climatic factors exert a role in shaping patterns of genetic variation and differentiation? Through a Bayesian method, we identified three clusters whose genetic variability can be considered to be of the same order as that recorded in central Quercus ilex populations. Although being geographically very close (< 20 km), the differentiation was statistically significant (P < 0.05) with global F _st and Φ _Pt values of 0.019 and 0.038, respectively. Geography and phylogeography could not be invoked to explain this differentiation. A redundancy discriminant analysis revealed that relevant eco‐pedological and climatic features, such as soil depth, aspect, elevation and humidity, were correlated with the observed pattern of differentiation. Toblino was ecologically separated from the other clusters, as it lies on deep soil with subhumid conditions. The differentiation of the Brione–Ranzo–Val Busa cluster appeared to be related to superficial soils and drier conditions, whereas the Nanzone–Padaro cluster was differentiated mainly according to its mid‐elevation. Coupling spatial and genetic information on a local scale proved to be effective to investigate the evolutionary and demographic history of peripheral populations. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??.