Prebreeding moult, plumage and evidence for a presupplemental moult in the Great Knot Calidris tenuirostris

We studied the prebreeding moult and resulting plumage in a long-distance migrant sandpiper (Scolopacidae), the Great Knot Calidris tenuirostris , on the non-breeding grounds (northwest Australia), on arrival at the staging grounds after the first migratory flight (eastern China) and on or near the Russian breeding grounds (Russian data from museum specimens). We show that breeding plumage scores and breast blackness were affected not only by the increase in moulted feathers but also in the wearing down of overlaying pale tips of fresh feathers. Birds migrating from Australia and arriving in China had completed or suspended moult, but more moult must occur in Asia as Russian specimens had moulted more of their mantle and scapular feathers. Russian birds had significantly more red feathering on their upperparts than had birds in Australia or those arriving in China. The increase in reddish feathers cannot by accounted for simply by continuation of the prealternate moult. Instead, a third, presupplemental moult must occur, in which red-marked feathers replace some scapular and especially mantle feathers that were acquired in a prealternate moult only 1–3 months earlier. Great Knot sexes show little size and plumage dimorphism, whereas two other sandpipers that have supplemental plumages (Ruff Philomachus pugnax and Bar-tailed Godwit Limosa lapponica ) are thought to be highly sexually selected. Bidirectional sexual selection may therefore be involved in the evolution of a supplemental plumage in Great Knots.     

Global warming and excess nitrogen may induce butterfly decline by microclimatic cooling

Global warming may explain the current poleward shift of species distributions. However, paradoxically, climatic warming can lead to microclimatic cooling in spring by advancing plant growth, an effect worsened by excess nitrogen. We suggest that spring-developing but thermophilous organisms, such as butterflies hibernating as egg or larva, are particularly sensitive to the cooling of microclimates. Using published data on butterfly trends in distribution, we report a comparatively greater decline in egg–larva hibernators in European countries with oceanic climates and high nitrogen deposition, which supports this explanation. Furthermore, trends in abundance from a nationwide butterfly monitoring scheme reveal a 63% decrease over 13 years (1992–2004) for egg–larva hibernators in the Netherlands, contrasting with a nonsignificant trend in adult–pupa hibernators. This evidence supports the hypothesis that these environmental changes pose new threats to spring-developing, thermophilous species. We underline the threat of climate change to biodiversity, as previously suggested on the basis of mobility, habitat fragmentation and evolutionary adaptation, but we here emphasize a different ecological axis of change in habitat quality.     

Media and Nation Building: How the Iban Became Malaysian

Media and Nation Building: How the Iban Became Malaysian . John Postill. New York: Berghahn, 2006. 231 pp.     

Do pollen feeding,pupal‐mating and larval gregariousness have a single origin in Heliconius butterflies? Inferences from multilocus DNA sequence data

Phylogenetic information is useful in understanding the evolutionary history of adaptive traits. Here, we present a well-resolved phylogenetic hypothesis for Heliconius butterflies and related genera. We use this tree to investigate the evolution of three traits, pollen feeding, pupal-mating behaviour and larval gregariousness. Phylogenetic relationships among 60 Heliconiina species (86% of the subtribe) were inferred from partial DNA sequences of the mitochondrial genes cytochrome oxidase I , cytochrome oxidase II and 16S rRNA, and fragments of the nuclear genes elongation factor-1α , apterous , decapentaplegic and wingless (3834 bp in total). The results corroborate previous hypotheses based on sequence data in showing that Heliconius is paraphyletic, with Laparus doris and Neruda falling within the genus, demonstrating a single origin for pollen feeding but with a loss of the trait in Neruda . However, different genes are not congruent in their placement of Neruda ; therefore, monophyly of the pollen feeding species cannot be ruled out. There is also a highly supported monophyletic 'pupal-mating clade' suggesting that pupal mating behaviour evolved only once in the Heliconiina. Additionally, we observed at least three independent origins for larval gregariousness from a solitary ancestor, showing that gregarious larval behaviour arose after warning coloration.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 221–239.     

The Control of Inter-pollination between Sweet and Flint Corn

The breeding system of sweet corn, a sugary seeded race of Zeamays L., was studied by randomly planting equal numbers of sweetand flint plants and determining the amount of cross-pollinationmeasured by the contamination on sweet ears. It was found thatinter-crossing with flint varied significantly from plant toplant; the out-crossing generally was lower than anticipated.The effects of date of silking and tasselling, and protandryof sweet plants on their out-crossing was demonstrated by usingmultiple regression analysis. Even so, as prediction was stillnot satisfactory other factors must have been involved. Thesevariables were all highly correlated. A relation between contaminationand temporal isolation was established; this was similar tothat for spatial isolation. It was postulated that there mayhave been genetical control of inter-pollination, as later earson the same sweet-corn plants were not less contaminated thanearlier ones and because out-crossing was generally low throughoutthe experiment.     

Interactions between plant growth and soil nutrient cycling under elevated CO2: a meta-analysis

free air carbon dioxide enrichment (FACE) and open top chamber (OTC) studies are valuable tools for evaluating the impact of elevated atmospheric CO₂ on nutrient cycling in terrestrial ecosystems. Using meta‐analytic techniques, we summarized the results of 117 studies on plant biomass production, soil organic matter dynamics and biological N₂ fixation in FACE and OTC experiments. The objective of the analysis was to determine whether elevated CO₂ alters nutrient cycling between plants and soil and if so, what the implications are for soil carbon (C) sequestration. Elevated CO₂ stimulated gross N immobilization by 22%, whereas gross and net N mineralization rates remained unaffected. In addition, the soil C : N ratio and microbial N contents increased under elevated CO₂ by 3.8% and 5.8%, respectively. Microbial C contents and soil respiration increased by 7.1% and 17.7%, respectively. Despite the stimulation of microbial activity, soil C input still caused soil C contents to increase by 1.2% yr^?1. Namely, elevated CO₂ stimulated overall above‐ and belowground plant biomass by 21.5% and 28.3%, respectively, thereby outweighing the increase in CO₂ respiration. In addition, when comparing experiments under both low and high N availability, soil C contents (+2.2% yr^?1) and above‐ and belowground plant growth (+20.1% and+33.7%) only increased under elevated CO₂ in experiments receiving the high N treatments. Under low N availability, above‐ and belowground plant growth increased by only 8.8% and 14.6%, and soil C contents did not increase. Nitrogen fixation was stimulated by elevated CO₂ only when additional nutrients were supplied. These results suggest that the main driver of soil C sequestration is soil C input through plant growth, which is strongly controlled by nutrient availability. In unfertilized ecosystems, microbial N immobilization enhances acclimation of plant growth to elevated CO₂ in the long‐term. Therefore, increased soil C input and soil C sequestration under elevated CO₂ can only be sustained in the long‐term when additional nutrients are supplied.     

Oviposition Behaviour and Reproductive Performance of Trichogramma australicum Girault (Hymenoptera: Trichogrammatidae) Reared in Artificial Diet

Biotypes of Trichogramma australicum were reared on artificial diet "A", Helicoverpa armigera (Hübner) (natural host) eggs and Sitotroga cerealella (Olivier) (factitious host) eggs. We evaluated the quality of these biotypes by comparing their oviposition behaviour and reproductive performance on H. armigera eggs. Female T. australicum reared in vitro accepted H. armigera eggs for oviposition and displayed similar behavioural components of oviposition to females reared on natural hosts. However, handling time during oviposition in H. armigera eggs by females from in vitro rearing was significantly longer than handling time of females reared on the natural host because the females needed a significantly longer time for host feeding. In vitro reared females produced significantly more progeny and parasitised more H. armigera eggs than the females reared on S. cerealella. Improvements to the artificial diet for T. australicum may reduce handling time of the in vitro reared females and increase the female population. These improvements may include changes in nutrient content and size of the artificial eggs.     

Response of native parasitoids to a range-expanding host

Abstract 1. As species shift their geographic distributions, new feeding interactions with natural enemies such as parasitoids, and resources such as host plants, may be established, and existing interactions may be severed. 2. The leaf mining moth Phyllonorycter leucographella (Zeller, 1850) (Lep.: Gracillariidae) first colonised the southern United Kingdom in the mid 1980s associated with its ancestral host plant Pyracantha coccinea M. Roem. (Rosaceae), which is widely cultivated in the U.K. The moth has since spread northwards to central Scotland and has been recorded feeding on a novel host plant, Crataegus monogyna L. 3. The combined effects of latitude and time since colonisation on parasitoid community responses to the arrival of this novel host were investigated across its U.K. range. The response of parasitoids to colonisation of C. monogyna was also investigated. 4. Both the observed richness of parasitoid species associated with P. leucographella, and the proportion of P. leucographella parasitised declined with latitude and towards the current range margin. A combination of a latitudinal gradient in parasitoid and alternative host species richness is likely to lead to the trends in species richness and parasitism observed. 5. Experimental host patches exposed to parasitism beyond the current range margin of P. leucographella experienced low levels of parasitism consistent with range‐margin populations, indicating an instantaneous response by native parasitoids to availability of the novel host. Parasitism levels and numbers of associated species in the U.K. were similar to those observed in the species’ native range in Turkey. 6. The host plant switch to C. monogyna was not associated with an altered parasitoid assemblage, but rates of parasitism were significantly higher on the novel host plant. 7. Alterations in the incidence and frequency of victim‐enemy interactions as species shift their geographic ranges may be key in determining rates of range expansion and the impact invading species have on ecological communities.     

Site tenacity and survival rates of Wrens Troglodytes troglodytes and Treecreepers Certhia familiaris in a Nottinghamshire wood

Mark-recapture data from 20 years of standardized mist-netting were used to investigate site tenacity and adult survival rates of Wrens Troglodytes troglodytes and Treecreepers Certhia familiaris in an English woodland. Within breeding seasons, a high proportion of Wren (but not Treecreeper) recaptures occurred in the same part of the wood as the original capture. Between breeding seasons, a high proportion of recaptures of adult males (but not of adult females) occurred in the same part of the wood as the original capture. Both species experienced exceptionally high mortality during the severe winters of 1978–1979 and 1985–1986, and, in the case of Wren, all or almost all birds which had previously bred in the wood probably died. Outside of these two cold winters, apparent (minimum) adult survival rates of Wrens and Treecreepers showed very different temporal patterns of variation. Wren survival rates were negatively correlated with the number of snow days in winter, whilst Treecreeper survival was negatively correlated with the amount of winter rainfall. After allowing for the influence of winter weather, apparent survival rates of adult Wrens were density dependent, indicating that either mortality or permanent emigration out of the wood was density dependent. There was some evidence from British and Irish ringing recoveries that movements of adult Wrens may be density dependent. The apparent survival rate of adult Wrens was probably an important factor determining the size of the local breeding population.