How to tell a shrub from a tree: A life‐history perspective from a South African savanna

The ecological differences between ‘shrubs’ and ‘trees’ are surprisingly poorly understood and clear ecological definitions of these two constructs do not exist. It is not clear whether a shrub is simply a small tree or whether shrubs represent a distinct life‐history strategy. This question is of special interest in African savannas, where shrubs and trees often co‐dominate, but are often treated uniformly as ‘woody plants’ even though the tree to shrub ratio is an important determinant of ecosystem functioning. In this study we use data from a long‐term fire experiment, together with a trait‐based approach to test (i) if woody species usually classified as shrubs or trees in African savanna differ in key traits related to disturbance and resource use; and (ii) if these differences justify the interpretation of the two growth forms as distinct life‐history strategies. We measured for 22 of the most common woody plant species of a South African savanna 27 plant traits related to plant architecture, life‐history, leaf characteristics, photosynthesis and resprouting capacity. Furthermore we evaluated their performance during a long‐term fire experiment. We found that woody plants authors call (i) shrubs; (ii) shrubs sometimes small trees; and (3) trees responded differently to long‐term fire treatments. We additionally found significant differences in architecture, diameter‐height‐allometry, foliage density, resprouting vigour after fire, minimum fruiting height and foliar δ¹³C between these three woody plant types. We interpret these findings as evidence for at least two different life‐history‐strategies: an avoidance/adaptation strategy for shrubs (early reproduction + adaptation to minor disturbance) and an escape strategy for trees (promoted investment in height growth + delayed reproduction).     

Behavioural responses of the seven‐spot ladybird Coccinella septempunctata to plant headspace chemicals collected from four crop Brassicas and Arabidopsis thaliana,infested with Myzus persicae

1 Insects using olfactory stimuli to forage for prey/hosts are proposed to encounter a ‘reliability–detectability problem’, where the usability of a stimulus depends on its reliability as an indicator of herbivore presence and its detectability. 2 We investigated this theory using the responses of female seven‐spot ladybirds Coccinella septempunctata (Coleoptera: Coccinellidae) to plant headspace chemicals collected from the peach‐potato aphid Myzus persicae and four commercially available Brassica cultivars; Brassica rapa L. cultivar ‘turnip purple top’, Brassica juncea L. cultivar ‘red giant mustard’, Brassica napus L. cultivar ‘Apex’, Brassica napus L. cultivar ‘Courage’ and Arabidopsis thaliana. For each cultivar/species, responses to plants that were undamaged, previously infested by M. persicae and infested with M. persicae, were investigated using dual‐choice Petri dish bioassays and circular arenas. 3 There was no evidence that ladybirds responded to headspace chemicals from aphids alone. Ladybirds significantly preferred headspace chemicals from B. napus cv. Apex that were undamaged compared with those from plants infested with aphids. For the other four species/cultivars, there was a consistent trend of the predators being recorded more often in the half of the Petri dish containing plant headspace chemicals from previously damaged and infested plants compared with those from undamaged ones. Furthermore, the mean distance ladybirds walked to reach aphid‐infested A. thaliana was significantly shorter than to reach undamaged plants. These results suggest that aphid‐induced plant chemicals could act as an arrestment or possibly an attractant stimulus to C. septempunctata. However, it is also possible that C. septempunctata could have been responding to aphid products, such as honeydew, transferred to the previously damaged and infested plants. 4 The results provide evidence to support the ‘reliability–detectability’ theory and suggest that the effectiveness of C. septempunctata as a natural enemy of aphids may be strongly affected by which species and cultivar of Brassica are being grown.     

Spatial and temporal diversity in hyperparasitoid communities of Cotesia glomerata on garlic mustard,Alliaria petiolata

1. Interactions between two trophic levels can be very intimate, often making species dependent on each other, something that increases with specialisation. Some specialised multivoltine herbivores may depend on multiple plant species for their survival over the course of a growing season, especially if their food plants are short‐lived and grow at different times. Later generations may exploit different plant species from those exploited by previous generations. 2. Multivoltine parasitoids as well as their natural enemies must also find their hosts on different food plants in different habitats across the season. Secondary hyperparasitoid communities have been studied on cocoons of the primary parasitoid, Cotesia glomerata (Hymenoptera: Braconidae), on black mustard (Brassica nigra) – a major food plant of its host, the large cabbage white (Pieris brassicae) – which grows in mid‐summer. 3. Here, hyperparasitoid communities on C. glomerata pupal clusters were studied on an early‐season host, garlic mustard, Alliaria petiolata, over ‘time’ (one season, April–July) in six closely located ‘populations’ (c. 2 km apart), and within two different ‘areas’ at greater separation (c. 100 km apart). At the plant level, spatial effects of pupal ‘location’ (canopy or bottom) on the plant were tested. 4. Although large‐scale separation (area) did not influence hyperparasitism, sampling time and small‐scale separation (population) affected hyperparasitism levels and composition of hyperparasitoid communities. Location on the plant strongly increased proportions of winged species in the canopy and proportions of wingless species in bottom‐located pupae. 5. These results show that hyperparasitism varies considerably at the local level, but that differences in hyperparasitoid communities do not increase with spatial distance.     

(Chemotaxonomic) Implications of Postharvest/Storage‐Induced Changes in Plant Volatile Profiles – the Case of Artemisia absinthium L. Essential Oil

The plant volatile profile and the essential‐oil chemical composition change during the storage of plant material. The objective of this study was to develop a mathematical model able to predict, explain, and quantify these changes. Mathematical equations, derived under the assumption that the essential oil contained within plant material could be treated as an ideal solution (Raoult's law), were applied for tracking of postharvest changes in the volatile profile of Artemisia absinthium L. (the essential oils were analyzed by GC‐FID and GC/MS). Starting from a specific chemical composition of an essential‐oil sample obtained from plant material after a short drying period (typically 5–10 d), and by using the equations derived from this model, one could easily predict evaporation‐induced changes in the volatile profile of the plant material. Based on the composition of the essential‐oil sample obtained after a given storage time t, it is possible to identify those components that were involved in chemical reactions, both as reactants and possible products. The established model even allowed the recognition of pairs of transformation, i.e., ‘daughter’ products and their ‘parent’ compounds. The obtained results highlight that the essential‐oil composition is highly dependent on the storage period of any plant material and urges caution in different types of phytochemical studies, especially chemotaxonomic ones, or practical application.     

Vegetation and soil patterning in semi-arid mulga lands of Eastern Australia

Vegetation and soil patterns across a 200 ha semi-arid site 40 km north-west of Louth, NSW, are described using plant cover data from line transects and soils data from points, sampled systematically (50 m intervals) across the site. A patterned sequence of alternating groves and intergroves with three vegetation types was identified: an Eragrostis eriopoda savanna occurring on runoff slopes (<0.5%) from low ridges, with a Monachather paradoxa savanna occurring at the toe of these runoff slopes (intergroves), followed by an Acacia anuera woodland occurring on runon areas (groves, either as discrete islands or more continuous along drainage lines). Data on landform, micro-topography, and hydrological features indicate that the grove-intergrove pattern is maintained by differential erosion–deposition processes similar to the dynamic erosion–transfer–sink geomorphic systems described for Central Australia. This vegetation grove–intergrove patterning in Eastern Australia is similar to, but differs in detail from, such patterns reported for arid and semi-arid Western and Central Australia. Groves or ‘bands’ of A. anuera in the Centre and the West tend to occur on the downslope side of ‘risers’ or on ‘convex slope-breaks’ where in the East such groves occur in distinct 'steps’ or ‘flats’ in the landscape; there is a drop into the grove and a sharp ‘erosion-scarp’ below the grove. A prominent ‘grass band’, identified by cluster analysis as the M. paradoxa community type, occurs immediately upslope of A. anuera groves in the East. The A. anuera groves in the East are also fertile’ patches as soils data demonstrate that groves have much higher levels of organic and exchangeable nutrients (and plant cover) than soils in the intergroves. This paper demonstrates that patterning in mulga lands is more extensive geographically, and has a wider climatic range, than previously reported.     

Elimination of Apple Mosaic Virus and Raspberry Bushy Dwarf Virus from Infected Red Raspberry (Rubus idaeus L.) by Tissue Culture

Experiments with ApMV infected ‘Malling Landmark’ and RBDV infected ‘Schamp;önemannamp;’ and ‘Trentamp;’ plants were carried out to evaluate a) the dependence of virus eradication on explant size and mass propagation. b) the reliability of results of ELISA tests on in vitro plantlets. With ApMV a correlation between virus elimination and explant size was observed, whereas with RBDV even plantlets from the smallest established explants were still infected. With ApMV, in vitro multiplication for three subsequent subcultures did not lead to further virus elimination, with RBDV this was observed in two cases. ELISA test results for both viruses, ApMV and RBDV, were identical when small in vitro plantlets, long-term stored plants, or potted plants from the same origin were tested, indicating that virus tests are possible with very young plant material and can be used to select virus-free plants in vitro. Tissue culture permits long-term storage of plant viruses. It is also suitable tor plant virus propagation and could be a useful aid in plant virus purification. For commercial multiplication only virus-indexed plant material should be used for establishment and further propagation in vitro.     

Taxonomic complexity,population genetics,and plant conservation in Scotland

Summary

Groups of plants that are undergoing active diversification often do not fall into neat and tidy taxonomies. In such groups it can sometimes be very difficult to establish what does, and what does not, constitute a species. This presents problems for species-based conservation programmes that are based around prioritised species-lists (e.g. the UK Biodiversity Action Plans; BAPs), particularly as the inclusion or exclusion of taxa on these lists largely determines the allocation of conservation resources. This is an important issue as almost half of the BAP priority higher plant species for which Scotland has prime responsibility are taxonomically controversial.

Recent research using population genetic approaches to tackle some taxonomically complex plant groups has enhanced our understanding of their biology. Such approaches provide objective and independent assessments of whether a given entity is distinct or not. This information can then be used to contribute towards the decision making process of which taxa to prioritise for conservation, and address specific questions regarding BAP listed species. In the long term, however, a broader issue needs tackling. Actively evolving groups often contain a series of localised lineages, as well as complex populations that exhibit atypical levels of morphological diversity. These types of diversity do not fit well into a ‘standard’ species-based conservation system. In most cases protection will best be supplied by designated site protection or wider countryside habitat schemes. Where additional protection is need, a conservation policy is required that accepts the diversity in these actively evolving groups for what it is, rather than trying to squeeze it into conservation legislation derived for taxa whose delimitation is routine.     

Scale-dependent equilibrium in highly heterogeneous islands: plant geography of the northern Great Barrier Reef sand cays and shingle islets

In contrast to classical island biogeographical predictions, plant species richness is not monotonically related to island area or isolation for the northern Great Barrier Reef islands, and this cannot be accounted for as a ‘small island effect’. Many islands are composed of different terrain units bearing different floristic assemblages suggesting a modified‘terrain-floristic element’model for island biogeography. This requires definition of a time-scale for equilibrium considerations and emphasizes that equilibrium or first order perturbation (‘relaxation’) models may be inappropriate for some archipelagos.     

Seasonal selection and resource dynamics in a seasonally polyphenic butterfly

Seasonal polyphenisms are widespread in nature, yet the selective pressures responsible for their evolution remain poorly understood. Previous work has largely focussed either on the developmental regulation of seasonal polyphenisms or putative ‘top‐down’ selective pressures such as predation that may have acted to drive phenotypic divergence. Much less is known about the influence of seasonal variation in resource availability or seasonal selection on optimal resource allocation. We studied seasonal variation in resource availability, uptake and allocation in Araschnia levana L., a butterfly species that exhibits a striking seasonal colour polyphenism consisting of predominantly orange ‘spring form’ adults and black‐and‐white ‘summer form’ adults. ‘Spring form’ individuals develop as larvae in the late summer, enter a pupal diapause in the fall and emerge in the spring, whereas ‘summer form’ individuals develop directly during the summer months. We find evidence for seasonal declines in host plant quality, and we identify similar reductions in resource uptake in late summer, ‘spring form’ larvae. Further, we report shifts in the body composition of diapausing ‘spring form’ pupae consistent with a physiological cost to overwintering. However, these differences do not translate into detectable differences in adult body composition. Instead, we find minor seasonal differences in adult body composition consistent with augmented flight capacity in ‘summer form’ adults. In comparison, we find much stronger signatures of sex‐specific selection on patterns of resource uptake and allocation. Our results indicate that resource dynamics in A. levana are shaped by seasonal fluctuations in host plant nutrition, climatic conditions and intraspecific interactions.     

Beyond reified categories: multidimensional identifications among ‘black’ and ‘Indian’ groups in Columbia and Mexico

Analyses of multicultural state-dictated social categories are often governed by those same categories, even while they deconstruct them. Nonetheless, these categories are often used in public spheres such as national imaginary or ethno-political activism. Taking a different point of departure, that of representations rather than the categories themselves, the aim of our paper is to understand the modes of classification that are relevant among four populations in Colombia and Mexico who would, a priori, be categorized as ‘black’ or ‘Indian’. The daily reality of these groups indicates other possible internal, sometimes even intersecting, kinds of categorizations, which, far from naturalizing the ‘Indian’ and ‘black’ categories, in fact reveal place-based social identifications. These identifications seem closer to the everyday lives and practices of the people in question, and underscore the local conceptions of their presence and agency in a given spot.     

Population studies of native grass-endophyte symbioses provide clues for the roles of host jumps and hybridization in driving their evolution

Fungal endophytes in the genera Epichloë and Neotyphodium, collectively termed the epichloae, have fascinated biologists for decades. These intriguing fungi, also referred to as ‘class 1 or clavicipitaceous endophytes’, spend the large majority, or even their entire life cycle, within the tissues of their cool‐season grass hosts without eliciting any symptoms of infection. While all epichloae reside within the intercellular spaces of aboveground vegetative grass tissues, the species at the symbiotic extreme are known as Neotyphodium, and the intimacy of their interaction extends to the reproductive (flowering) stage. At this point, fungal filaments (hyphae) nondestructively invade the developing ovaries of their host and are incorporated into perfectly viable, healthy seeds. Thus, these endophytes live solely within the tissues of their host plants and are transmitted maternally from generation to generation. A second life history characteristic of interest is that while all Epichloë and some Neotyphodium species are haploid, a great many of the strictly seed‐transmitted Neotyphodium spp. are interspecific hybrids. This phenomenon may be critical for the success of these symbioses over longer spans of evolutionary time and will be discussed in greater detail below. A third characteristic, and one of the primary reasons these grass endophytes have received so much attention over the last three decades, is the strong mutualistic nature these relationships often exhibit. In exchange for photosynthetically derived carbon, the endophytes protect their cool‐season grass hosts from grazing herbivores and a variety of abiotic stresses. It has been hypothesized that these three biological phenomena are related ( Schardl & Craven 2003 ), perhaps with the former two driving the third, and it is here that the recent article in Molecular Ecology entitled ‘Genetic diversity in epichloid endophytes of Hordelymus europaeus suggests repeated host jumps and interspecific hybridizations’, by Oberhofer & Leuchtmann (2012) , provides critical clues to linking these traits together. While the large majority of studies have focused on documenting the ever‐increasing list of mutualistic qualities attributed to these fungi, very few have taken an exhaustive population‐level approach to document plant and endophyte genotypes within a naturally occurring system ( Faeth et al. 2010 ; Jani et al. 2010 ; Tintjer & Rudgers 2006 ). Such information is crucial to more fully elucidate the factors shaping grass‐endophyte symbioses and those often driving these relationships to mutualistic extremes.     

Differential repair of excision gaps generated by transposable elements of the ‘Ac family’

Studies on transposable elements of the Ac family have led to different models for excision gap repair in either plants or Drosophila. Excision products generated by the plant transposable elements Ac and Tam3 imply a more or less straightforward ligation of broken ends; excision products of the Drosophila P element indicate the involvement of ‘double-strand break’ (DSB) repair. Recent findings that excision products of Ac and Tam3 can also contain traces of the element ends indicate, however, that DSB repair might be an alternative repair mechanism in plants. A functional DSB repair mechanism in plants can also be deduced from the observed rapid increases of Ac copy number during plant development and from the involvement of Ac in the generation of internal Ac deletions. On the other hand, alternative repair mechanisms may also be functional in Drosophila, because some of the ‘footprints’ generated upon P excision can be explained by a mechanism that has been postulated for excision gap repair in plants. It is concluded that plants and Drosophila can use similar repair mechanisms, but that the predominance of a certain repair mechanism is determined by the host.     

The origins of nations

Although the nation, as a named community of history and culture, possessing a common territory, economy, mass education system and common legal rights, is a relatively modern phenomenon, its origins can be traced back to pre‐modern ethnic communities. Such named ethnies with their myths of common descent, common memories, culture and solidarity, and associations with a homeland, are found in both the ancient and the medieval periods in many areas of the world. Two kinds of ethnie are important for the origins and routes of the formation of nations. Territorial, ‘civic’ nations tend to develop from aristocratic ‘lateral’ ethnies through a process of ‘bureaucratic incorporation’ of outlying regions and lower classes into the ethnic culture of the upper classes, as occurred in France, England and Spain. The more numerous ‘ethnic’ nations, on the other hand, have emerged from demotic ‘vertical’ ethnies through processes of cultural mobilization that turn an often religiously defined and passive community into an active, politicized nation. Here the intellectuals and professionals replace the state as agents of popular mobilization, creating new ‘maps’ and ‘moralities’ through the uses of landscape and golden ages of a rediscovered and reconstructed communal past, as in Ireland, Finland and Switzerland. It is from these often ancient ties and sentiments that modern nations draw much of their power and durability today.     

Assessing group differences in biodiversity by simultaneously testing a user‐defined selection of diversity indices

Comparing diversities between groups is a task biologists are frequently faced with, for example in ecological field trials or when dealing with metagenomics data. However, researchers often waver about which measure of diversity to choose as there is a multitude of approaches available. As Jost (2008, Molecular Ecology, 17 , 4015) has pointed out, widely used measures such as the Shannon or Simpson index have undesirable properties which make them hard to compare and interpret. Many of the problems associated with the use of these ‘raw’ indices can be corrected by transforming them into ‘true’ diversity measures. We introduce a technique that allows the comparison of two or more groups of observations and simultaneously tests a user‐defined selection of a number of ‘true’ diversity measures. This procedure yields multiplicity‐adjusted P‐values according to the method of Westfall and Young (1993, Resampling‐Based Multiple Testing: Examples and Methods for p‐Value Adjustment, 49, 941), which ensures that the rate of false positives (type I error) does not rise when the number of groups and/or diversity indices is extended. Software is available in the R package ‘simboot’.     

Origins and implications of apid bees (Hymentopera: Apidae) in French Polynesia

Island plant–pollinator networks are typically simpler than their continental counterparts and this can make them less resilient to disturbance from exotic species. French Polynesia has a very low diversity of bees, but their status as either native or introduced species has been largely speculative. We combine previous studies with new DNA sequence data to show that 11 bee species have now been recorded for French Polynesia. Haplotype variation at the ‘barcode’ region of the mitochondrial gene cytochrome c oxidase subunit I (COI) for four of these species, Ceratina dentipes Freise, Xylocopa sonorina Smith, Braunsapis puangensis (Cockerell) and Amegilla pulchra (Smith), indicates that they all represent very recent introductions. Apis mellifera Linnaeus was a purposefully introduced species, and four megachilid species probably arrived due to human‐aided dispersal through maritime activities in the Pacific. The two remaining bee species, an unidentified partial specimen of a halictid bee and the colletid bee Hylaeus (P.) tuamotuensis Michener, are collectively known from only four specimens collected in the 1930s and their provenance is uncertain. French Polynesia therefore comprises a region where recently introduced bee species greatly overwhelm any possible native bee fauna. These introductions are likely to have major ecosystem impacts, including disruptions of existing plant–pollinator networks and facilitating the spread of weedy plant species, as well as positive impacts for agriculture. Future biosecurity initiatives need to consider these potential impacts and the likely routes of dispersal to effectively control any further unintended introductions.     

Conservation in a cup of water: estimating biodiversity and population abundance from environmental DNA

Three mantras often guide species and ecosystem management: (i) for preventing invasions by harmful species, ‘early detection and rapid response’; (ii) for conserving imperilled native species, ‘protection of biodiversity hotspots’; and (iii) for assessing biosecurity risk, ‘an ounce of prevention equals a pound of cure.’ However, these and other management goals are elusive when traditional sampling tools (e.g. netting, traps, electrofishing, visual surveys) have poor detection limits, are too slow or are not feasible. One visionary solution is to use an organism’s DNA in the environment (eDNA), rather than the organism itself, as the target of detection. In this issue of Molecular Ecology, Thomsen et al. (2012) provide new evidence demonstrating the feasibility of this approach, showing that eDNA is an accurate indicator of the presence of an impressively diverse set of six aquatic or amphibious taxa including invertebrates, amphibians, a fish and a mammal in a wide range of freshwater habitats. They are also the first to demonstrate that the abundance of eDNA, as measured by qPCR, correlates positively with population abundance estimated with traditional tools. Finally, Thomsen et al. (2012) demonstrate that next‐generation sequencing of eDNA can quantify species richness. Overall, Thomsen et al. (2012) provide a revolutionary roadmap for using eDNA for detection of species, estimates of relative abundance and quantification of biodiversity.     

2 Protein Folding and its Implications for the Production of Recombinant Proteins

Abstract

Humans have utilised plant derived natural products as medicines for millenia. Moreover, many contemporary pharmaceuticals are also natural products or derivatives thereof. However, the full potential of these compounds remains to be exploited because often they are: complex and difficult to synthesise; found in low quantities; produced by undomesticated and sometimes rare plants; and, their synthesis is routinely influenced by weather conditions. Potentially, the in vitro culture of cells from the corresponding plant species could circumvent some of these problems but the growth of plant cells on an industrial scale is also problematic. The recent isolation and culture of cambial meristematic cells (CMCs), stem cells which ordinarily generate the plant vasculature, may now provide a key platform technology to help realise the full potential of plant natural products.     

The Untold Sacrifice: The Monotony and Incompleteness of Self-Sacrifice in Northeast Brazil

There is no such thing as an accidental sacrifice. Sacrifice is always pre-meditated, and if not entirely goal-oriented, at the very least inherently meaningful as a process in itself. This paper is about how we might begin to understand sacrifices that do not conform to these rules. It concerns the question: does sacrifice exist outside of its (often) dramatic, self-conscious elaboration? Within the Brazilian Catholic tradition everyday life – ideally characterised by monotonous, undramatic, acts of self-giving – is ‘true sacrifice’. For ordinary Catholics, the challenge is not how to self-sacrifice, but how to make one's mundane life of self-sacrifice visible whilst keeping one's gift of suffering ‘free’. In this paper I describe, ethnographically, the work entailed as one of ‘revelation’ and use the problems thrown up to reflect upon both the limits and advantages of Western philosophical versus anthropological understandings of Christian sacrificial practices to date.     

No effect of larval experience on adult host preferences in Polygonia c‐album (Lepidoptera: Nymphalidae): on the persistence of Hopkins’ host selection principle

Abstract 1. The possible effect of juvenile imprinting or ‘chemical legacy’ on the subsequent oviposition – often called the ‘Hopkins’ host selection principle’– has been a controversial but recurrent theme in the literature on host‐plant preference. While it appears possible in principle, experimental support for the hypothesis is equivocal. The present study points out that it is also important to consider its theoretical implications, and asks under what circumstances, if any, it should be favoured by natural selection. 2. Following this reasoning, it is predicted that host preference in the polyphagous butterfly Polygonia c‐album L. (Lepidoptera, Nymphalidae) should not be influenced by larval environment. This was tested by rearing larvae on three natural host plants: the high‐ranked Urtica dioica and the medium‐ranked Salix cinerea and Ribes uva‐crispa, and exposing the naive females to oviposition choices involving the same set of plants. 3. It was found that larval host plant had no effect on oviposition decisions of the adult female. Hence, the Hopkins’ host selection principle does not seem to be applicable in this species. 4. Based on recent insights on how accuracy of environmental versus genetic information should affect the control of developmental switches, the conditions that could favour the use of juvenile cues in oviposition decisions are discussed. Although the Hopkins’ host selection hypothesis cannot be completely ruled out, we argue that the circumstances required for it to be adaptive are so specific that it should not be invoked as a general hypothesis for host selection in plant‐feeding insects.