Seasonal changes in the reproductive and life-history traits of Chrysomela populi L. (Coleoptera: Chrysomelidae)

Seasonal changes in the reproductive and life‐history traits of Chrysomela populi L. were investigated in Shobara (34°52′N, 133°01′E), Japan, in 2004 and 2005. Larvae were hatched and reared under natural photoperiod and temperature in 8 different periods between late April and early September in 2004. The incidence of adult diapause increased with progression of the season in 2004. The critical timing of diapause induction, as defined by 50% of females entering diapause, was estimated to occur between late July and early August. No effects of season on the survival rate from hatching to adult emergence, percentage ovipositing females and percentage females that deposited viable eggs were clearly detected. Adult weight at emergence fluctuated seasonally, which was probably caused by air temperature. No effect of season on the oviposition period was observed among females that averted diapause. Females that entered diapause in 2004 started oviposition from the first day of May in 2005. Reproductive output was significantly greater in diapause females than in non‐diapause females. This increase in the reproductive output of diapause females was caused by elongation of the oviposition period and consequently by enlargement of the number of egg clutches deposited. These results suggest that the seasonal timing of diapause induction in females of C. populi would be affected by various risks and benefits to reproduction and survival.     

Heterozygosity is linked to the costs of immunity in nestling great tits (Parus major)

There is growing evidence that heterozygosity–fitness correlations (HFCs) are more pronounced under harsh conditions. Empirical evidence suggests a mediating effect of parasite infestation on the occurrence of HFCs. Parasites have the potential to mediate HFCs not only by generally causing high stress levels but also by inducing resource allocation tradeoffs between the necessary investments in immunity and other costly functions. To investigate the relative importance of these two mechanisms, we manipulated growth conditions of great tit nestlings by brood size manipulation, which modifies nestling competition, and simultaneously infested broods with ectoparasites. We investigated under which treatment conditions HFCs arise and, second, whether heterozygosity is linked to tradeoff decisions between immunity and growth. We classified microsatellites as neutral or presumed functional and analyzed these effects separately. Neutral heterozygosity was positively related to the immune response to a novel antigen in parasite‐free nests, but not in infested nests. For nestlings with lower heterozygosity levels, the investments in immunity under parasite pressure came at the expenses of reduced feather growth, survival, and female body condition. Functional heterozygosity was negatively related to nestling immune response regardless of the growth conditions. These contrasting effects of functional and neutral markers might indicate different underlying mechanisms causing the HFCs. Our results confirm the importance of considering marker functionality in HFC studies and indicate that parasites mediate HFCs by influencing the costs of immune defense rather than by a general increase in environmental harshness levels.     

Possible pathogens of social wasps (Hymenoptera: Vespidae) and their potential as biological control agents

Abstract

Boutin et al. (2006) claimed that American and Eurasian red squirrels use an unknown environmental cue to anticipate the availability of the abundant food of an autumn seed mast, and produce more young than usual in the previous spring and summer. But these small mammals need increased supplies of protein to produce and support young, therefore they must have had access to some other protein‐rich food that was available before the mast was ripe. There are other small mammalian seed‐eaters that increase their reproductive output ahead of the maturation of a seed mast. It seems likely that, in each case, females are able to produce extra young in advance because they eat the amino acid‐rich inflorescences and unripe seeds of the mast and/or larval insects that also increase their numbers in the spring of a mast year by eating the same enriched plant food.     

Metabolic approaches to understanding climate change impacts on seasonal host‐macroparasite dynamics

Climate change is expected to alter the dynamics of infectious diseases around the globe. Predictive models remain elusive due to the complexity of host–parasite systems and insufficient data describing how environmental conditions affect various system components. Here, we link host–macroparasite models with the Metabolic Theory of Ecology, providing a mechanistic framework that allows integrating multiple nonlinear environmental effects to estimate parasite fitness under novel conditions. The models allow determining the fundamental thermal niche of a parasite, and thus, whether climate change leads to range contraction or may permit a range expansion. Applying the models to seasonal environments, and using an arctic nematode with an endotherm host for illustration, we show that climate warming can split a continuous spring‐to‐fall transmission season into two separate transmission seasons with altered timings. Although the models are strategic and most suitable to evaluate broad‐scale patterns of climate change impacts, close correspondence between model predictions and empirical data indicates model applicability also at the species level. As the application of Metabolic Theory considerably aids the a priori estimation of model parameters, even in data‐sparse systems, we suggest that the presented approach could provide a framework for understanding and predicting climatic impacts for many host–parasite systems worldwide.     

The impact of aging on innate and adaptive immunity in the human female genital tract

Mucosal tissues in the human female reproductive tract (FRT) are primary sites for both gynecological cancers and infections by a spectrum of sexually transmitted pathogens, including human immunodeficiency virus (HIV), that compromise women''s health. While the regulation of innate and adaptive immune protection in the FRT by hormonal cyclic changes across the menstrual cycle and pregnancy are being intensely studied, little to nothing is known about the alterations in mucosal immune protection that occur throughout the FRT as women age following menopause. The immune system in the FRT has two key functions: defense against pathogens and reproduction. After menopause, natural reproductive function ends, and therefore, two overlapping processes contribute to alterations in immune protection in aging women: menopause and immunosenescence. The goal of this review is to summarize the multiple immune changes that occur in the FRT with aging, including the impact on the function of epithelial cells, immune cells, and stromal fibroblasts. These studies indicate that major aspects of innate and adaptive immunity in the FRT are compromised in a site‐specific manner in the FRT as women age. Further, at some FRT sites, immunological compensation occurs. Overall, alterations in mucosal immune protection contribute to the increased risk of sexually transmitted infections (STI), urogenital infections, and gynecological cancers. Further studies are essential to provide a foundation for the development of novel therapeutic interventions to restore immune protection and reverse conditions that threaten women''s lives as they age.     

BRE over-expression promotes growth of hepatocellular carcinoma

BRE, also known as TNFRSF1A modulator and BRCC45, is an evolutionarily highly conserved protein. It is a death receptor-associated protein in cytoplasm and a component of BRCA1/2-containing DNA repair complex in nucleus. BRE was found to have anti-apoptotic activity. Over-expression of BRE by transfection promoted survival of cell lines against apoptotic induction; whereas depletion of the protein by siRNA resulted in the opposite. In vivo anti-apoptotic activity of BRE was demonstrated by significant attenuation of Fas-induced acute fulminant hepatitis in transgenic mice expressing the human protein specifically in the liver. BRE was also implicated in tumor promotion by the accelerated tumor growth of Lewis Lung carcinoma transfected with human BRE; and by high expression of BRE specifically in the tumoral regions of human hepatocellular carcinoma (HCC). The present study was to test directly if transgenic expression of BRE in livers could promote HCC development in neonatal diethylnitrosamine model. By 8 months after tumor induction, the maximal sizes of tumor nodules of transgenic mice were significantly larger than those of the non-transgenic controls, although the numbers of tumor nodules between the two groups did not significantly differ. Importantly, as in human HCC, the mouse endogenous BRE level was up-regulated in mouse HCC nodules. These results show that BRE over-expression can indeed promote growth, though not initiation, of liver tumors. Furthermore, the common occurrence of BRE over-expression in human and mouse HCC suggests that up-regulation of BRE is functionally important in liver tumor development.     

Some reflections on evolutionary theories,With a classification of fitness

Using a classical life history model (the Smith & Fretwell model of the evolution of offspring size), it is demonstrated that even in the presence of overwhelming empirical support, the testability of predictions derived from evolutionary models can give no guarantee that the underlying fitness concept is sound. Non-awareness of this problem may cause considerable justified but avoidable criticism. To help understanding the variable use of fitness in evolutionary models and recognizing potentially problematic areas which need careful consideration, a hierarchical classification of definitions of fitness used in evolutionary models is presented. As a conclusion, it is advocated to use the term fitness more conscientiously than currently often practised and to think more about ways to develop fitness-free evolutionary theories compatible with Darwin's ideas.     

Verhalten von Kranichfamilien (Grus grus) in Brutrevieren Nordostdeutschlands: Investition der Altv?gel in ihre Nachkommen

Zusammenfassung Junge Graukraniche haben einen weniger guten Jagderfolg bzw. eine geringere Rate bei der Nahrungsaufnahme als Altvögel. Dieses Defizit sollte durch die elterliche Investition bei der Jungenaufzucht kompensiert werden. Untersuchungen zum Zeitbudget und zum Aufwand aus dem Brutgebiet fehlen bisher. Mit Hilfe markierter Jungkraniche (Farbringe, Sender) wurde das Verhalten der Eltern und ihrer Nachkommen erfasst, um die Investitionen in Beziehung zum Reproduktionserfolg zu analysieren. Die Eltern sicherten mit 39,6% fast viermal so häufig wie Altvögel ohne Junge (Übersommerer). Bei Paaren mit zwei Nachkommen waren diese Aufwendungen höher als bei Paaren mit nur einem Jungvogel. Das Weibchen profitierte vom verstärkten Sichern des Männchens (Männchen: durchschnittlich 43,9%, Weibchen 35,3%) und konnte so vermutlich schneller seine Investition in die Gelegeproduktion ausgleichen. Die Revierverteidigung bzw. Feindabwehr übernahmen meist die Männchen. Die Beteiligung des Männchens förderte den Aufzuchterfolg, der auf zwei Junge begrenzt ist. Die Jungen profitierten von den Leistungen ihrer Eltern. Sie konnten mit geringem Sicherungsaufwand (11,9%) Nahrung suchen (67,7%, Eltern 42,8%) und so ihre geringere Aufnahmerate kompensieren. 77,9% der Jungkraniche überlebten vom Zeitpunkt des Markierens im Juni bis zum Abzug ins Überwinterungsgebiet im Oktober/November (84% der Einzeljungen und 75% bei Familien mit zwei Nachkommen).Junge Kraniche müssen einen wesentlichen Teil des Tages Nahrung aufnehmen, um den Energiebedarf für ein schnelles Wachstum sicherzustellen. Bei einer negativen Energiebilanz aufgrund zu vieler Störreize können die Erfolge bei der Jungenaufzucht sinken. Im Rahmen der Landschaftsplanung ist vor allem in Räumen mit einer hohen Siedlungsdichte des Kranichs auf eine stärkere Bebauung (z. B. mit Windkraftanlagen) oder Zerschneidung durch weitere Verkehrswege und Energieleitungen zu verzichten.

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Behaviour of Crane (Grus grus) families in their breeding territories in Northeast Germany: parental care and investment

Summary Juveniles and immature birds normally have less foraging ability and a lower food intake rate than adults. This — it has been presumed — is compensated for by parental care and investment during juvenile development. Studies of time budgets and parental investment of Common Cranes were carried out in the years 1995 to 1999 in Northeast Germany. Having first marked young Cranes (colour rings, radio transmitters), we analysed the behaviour of parents and offspring to correlate this with reproductive success. Parents with young (39.6%) were four times more vigilant than non-breeders. The investment of pairs with two young was significantly (p<0.001) higher than in pairs with only one young. Females profited from the high vigilance rate of their males (males mean 43.9%, females 35.3%) and were thus able probably to compensate for their investment in the clutch faster because of higher food intake. Defence of the territory against other cranes and defence against predators were tasks mostly undertaken by males. If the males participated in the rearing of the young, the pair were able to rear two juveniles to fleding.The young profited from parental care. They were able to feed most of the time (67.7%) with lower vigilance costs (11.9%; 27.7% less than parents), and thus possibly compensated for their lower feeding success. Rearing of two young, however, must be the upper limit of possible investment of adults. So far there has been no evidence of families with three grown-up young in a stopover region or on the wintering grounds. The survival of juveniles from the date of ringing in June up to the migration to the wintering sites in mid-November amounts to 77.9%, with 84% for families with one young and 75% for those with two young. Accordingly the reproductive success was higher for pairs with two young (1.32 juv./pair) than with one young (0.84 juv/pair).The long-term survival of the population in a man-made landscape is only possible with an appropriate reproductive success. The offspring of crane families have to feed throughout the major part of the day in order to gain their energy for the high metabolic rate during growth. With a negative energy balance because of too much disturbance, the reproductive success will decrease. Future landscape planning should avoid new traffic structures, buildings (e.g. wind turbines) or power lines at least in areas of high crane density.