Escape from natural enemies during climate-driven range expansion: a case study

Abstract.  1. A major, and largely unexplored, uncertainty in projecting the impact of climate change on biodiversity is the consequence of altered interspecific interactions, for example between parasitoids and their hosts. The present study investigated parasitism in the Brown Argus butterfly, Aricia agestis ; a species that has expanded northward in Britain during the last 30  years in association with climate warming.
2.  Aricia agestis larvae suffered lower mortality from parasitoids in newly colonised areas compared with long-established populations. This result was consistent over four consecutive generations (2 years) when comparing one population of each type, and also when several populations within the historical and recently colonised range of the species were compared within a single year. Thus, A. agestis appears to be partially escaping from parasitism as it expands northwards.
3. Reduced parasitism occurred despite the fact that several of the parasitoid species associated with A. agestis were already present in the newly colonised areas, supported predominantly by an alternative host species, the Common Blue butterfly, Polyommatus icarus .
4. As the species expand their distributions into areas of increased climatic suitability, invasion fronts may escape from natural enemies, enhancing rates of range expansion. The results suggest that the decoupling of interspecific interactions may allow some species to exploit a wider range of environments and to do so more rapidly than previously thought possible.     

Seasonal acclimation of leaf respiration in Eucalyptus saligna trees: impacts of elevated atmospheric CO2 and summer drought

Understanding the impacts of atmospheric [CO₂] and drought on leaf respiration (R) and its response to changes in temperature is critical to improve predictions of plant carbon‐exchange with the atmosphere, especially at higher temperatures. We quantified the effects of [CO₂]‐enrichment (+240 ppm) on seasonal shifts in the diel temperature response of R during a moderate summer drought in Eucalyptus saligna growing in whole‐tree chambers in SE Australia. Seasonal temperature acclimation of R was marked, as illustrated by: (1) a downward shift in daily temperature response curves of R in summer (relative to spring); (2)≈60% lower R measured at 20^oC (R₂₀) in summer compared with spring; and (3) homeostasis over 12 months of R measured at prevailing nighttime temperatures. R₂₀, measured during the day, was on average 30–40% higher under elevated [CO₂] compared with ambient [CO₂] across both watered and droughted trees. Drought reduced R₂₀ by≈30% in both [CO₂] treatments resulting in additive treatment effects. Although [CO₂] had no effect on seasonal acclimation, summer drought exacerbated the seasonal downward shift in temperature response curves of R. Overall, these results highlight the importance of seasonal acclimation of leaf R in trees grown under ambient‐ and elevated [CO₂] as well as under moderate drought. Hence, respiration rates may be overestimated if seasonal changes in temperature and drought are not considered when predicting future rates of forest net CO₂ exchange.     

A molecular phylogeny of the Trichogrammatidae (Hymenoptera: Chalcidoidea), with an evaluation of the utility of their male genitalia for higher level classification

Abstract A molecular phylogeny of the Trichogrammatidae (Hymenoptera: Chalcidoidea) is presented. This group of minute egg parasitoids is known from a broad range of host insects. The phylogeny produced, the first of any kind for the family, utilizes 121 taxa in fifty‐two of the eighty‐four recognized genera. Results were inferred from the ribosomal RNA regions 18S, 28S‐D2 and 28S‐D3, all aligned according to secondary structure models. Parsimony analysis was performed on both a complete and reduced dataset, in which ambiguous regions as defined by secondary structure were eliminated. The reduced dataset produced a much less resolved phylogenetic hypothesis. Only the complete dataset was utilized for Bayesian and maximum likelihood analyses. A robust‐choice Bayesian hypothesis stemmed from the concatenation of five distinct character set parameters. The results are compared with the current classification based primarily on male genitalia. Although our conclusions are partially congruent with the accepted hypothesis of trichogrammatid relationships, none of the currently adopted assemblages was recovered as monophyletic. Nevertheless, the structure of the male genitalia does correspond with relative taxon position in the molecular hypotheses. In general, the greatest genitalic simplification and fusion characterizes taxa treated as the most derived in the molecular hypotheses. Several groups are consistently recovered, but relationships between these groups and other genera vary with the analytical method. A new classification of the Trichogrammatidae is proposed. It includes one tribe, Trichogrammatini, within the subfamily Trichogrammatinae, and three tribes, Paracentrobiini, Chaetostrichini and Oligositini, within the Oligositinae. All tribes are more narrowly defined than previously and many genera are treated as incertae sedis within each subfamily. The results are interpreted in the light of morphological evidence, and the placement of genera not represented in molecular analysis is inferred by morphology alone. Host associations throughout the family are varied, although the molecular results suggest that Trichogrammatidae primitively parasitized Coleoptera, with more recent radiations onto other insect orders, such as Lepidoptera and Hemiptera.     

Rethinking psychosis: the disadvantages of a dichotomous classification now outweigh the advantages

Emil Kraepelin would clearly recognize his 19th century dichotomy within current operational classifications of psychosis. However, he might be surprised at its survival, given the extent to which it has been undermined by the weight of currently available empirical evidence. The failure of this evidence to influence diagnostic practice reflects not only the comfortable simplicity of the dichotomous approach, but also the fact that this approach has for many years continued to receive support from some areas of research, particularly genetic epidemiology. This, however, is changing and findings from genetic epidemiology are being reappraised. More importantly, the potential of molecular genetics to indicate biological systems involved in psychopathology has been recognized, and with it the potential to develop diagnostic classifications that have greater biological validity. Crucially, this will facilitate diagnostic schemes with much greater clinical utility, allowing clinicians to select treatments based on underlying pathogenesis. Recent molecular genetic findings have demonstrated very clearly the inadequacies of the dichotomous view, and highlighted the importance of better classifying cases with both psychotic and affective symptoms. In this article we discuss these issues and suggest ways forward, both immediately and for DSM-V and ICD-11. If psychiatry is to translate the opportunities offered by new research methodologies, we must move to a classificatory approach that is worthy of the 21st century.     

A method for rapid extraction of Providencia chromosomal DNA and restriction enzyme digestion in agarose pellets

A simple and fast (2–3 d) method is described for the extraction and restriction endonuclease digestion of bacterial chromosomal DNA in low melting point agarose pellets. The technique minimized the random mechanical shearing of DNA caused by conventional preparative methods and improved the resolution of electrophoretic band patterns, particularly for the smaller (< 10 kb) fragments. The method was tested on 14 strains of Providencia stuartii and Prov. rustigianii .     

THE RESPIRATION OF TOBACCO LEAVES IN THE 20-HOUR PERIOD FOLLOWING INOCULATION WITH TOBACCO MOSAIC VIRUS

The effect of infection with tobacco mosaic virus on the respiration rates of detached tobacco leaves in the period immediately after inoculation differed in plants grown at different times of the year. During winter, infection increased respiration rates, and in summer decreased them. In winter-grown plants, increasing the light intensity during the period before inoculation decreased respiration rates after infection. Extending the day length for winter-grown plants did not alter the effect of infection on respiration. Respiration rates began to change in less than 1 hr. after inoculation and are unlikely to be associated with the formation of new virus.