bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimentally increased aggressiveness reduces population kin structure and subsequent recruitment in red grouse Lagopus lagopus scoticus
Authors: MOUGEOT FRANÇOIS , PIERTNEY STUART B. , LECKIE FIONA , EVANS SHARON , MOSS ROBERT , REDPATH STEVE M. , HUDSON PETER J. 
Published: September 2010

Summary

According to the ‘territorial behaviour’ hypothesis, red grouse population cycles are caused by delayed density‐dependent changes in male aggressiveness influencing recruitment. These lagged changes in aggressiveness might be caused by changes in the kin structuring of male populations and differential aggressive behaviour between kin and non‐kin (‘kinship’ hypothesis).
A population‐level manipulation of male aggressiveness in autumn affected the kin structure of male populations, their subsequent aggressiveness, and recruitment of both sexes. On two moors, we implanted the old territorial cocks in autumn with testosterone on an experimental area (T‐areas) and with sham implants on a control area (C‐areas).
Increased aggressiveness in autumn t reduced recruitment in autumns t and t+ 1, and breeding density of both sexes in springs t+ 1 and t+ 2, confirming previous studies elsewhere. A new observation was that cocks on T‐areas had bigger combs (an ornament whose size is testosterone‐dependent) than those on C‐areas for at least 1·5 years after treatment, evidence that they remained more aggressive.
Increased aggressiveness reduced not only subsequent density but also kin structuring among territorial cocks. This is consistent with the ‘kinship’ hypothesis that changes in the kin structure of male populations mediate year‐to‐year changes in male aggressiveness.
Increased aggressiveness did not increase intensity of infection by the dominant intestinal nematode Trichostrongylus tenuis, which might have affected recruitment through reduced breeding success. Moreover, breeding success after treatment was no lower on the T‐ than on the C‐areas.
The results show for the first time that increased aggressiveness affects both kin structure and subsequent recruitment, supporting a key assumption of the kinship hypothesis for red grouse population cycles.
The roles of extinction and colonization in generating species–energy relationships
Authors: EVANS KARL L. , GREENWOOD JEREMY J. D. , GASTON KEVIN J. 
Published: September 2010

SummaryPositive correlations between energy and species richness are frequently observed, but the causal mechanisms of such species–energy relationships have rarely been identified conclusively.The more individuals hypothesis (MIH) describes one possible cause of positive species–energy relationships. It suggests that greater resource availability in high‐energy areas increases population sizes, reducing local extinction rates and promoting species richness. It predicts that extinction rates will be lower in high‐energy areas and that, because a given change in population size has a greater influence on extinction risk when initial populations are small, such relationships will be more pronounced in numerically rare species than more abundant ones.Colonization rates may also influence local species richness, and they may respond positively to the greater resource abundance in high‐energy areas.We provide the first empirical test of relationships between extinction/colonization rates and energy availability and of the influence of population size on these relationships. We use data on the changing distributions of British birds, in which positive species–energy relationships have previously been documented.We find that extinction rates are lower in high‐energy areas, but that such patterns are stronger in more abundant species. Spatial variation in colonization rates is influenced less markedly by energy availability, but such patterns are also more marked in numerically abundant species. While these results provide little overall support for the MIH, nor some of its alternatives, they add to increasing evidence that common species drive much of the spatial variation in species richness.
Density‐dependent growth of young‐of‐the‐year Atlantic salmonSalmo salarin Catamaran Brook, New Brunswick
Authors: IMRE I. , GRANT J. W. A. , CUNJAK R. A. 
Published: September 2010

SummaryWhile density‐dependent mortality and emigration have been widely reported in stream salmonid populations, density‐dependent growth is less frequently detected. A recent study suggests that density‐dependent growth in stream salmonids occurs at low densities, whereas density‐dependent mortality and emigration occur at high densities.To test the hypothesis that density‐dependent growth occurs primarily at low rather than at high densities, we examined the relationship between average fork length and population density of young‐of‐the‐year (YOY) Atlantic salmon at the end of the growing season using a 10‐year data set collected on Catamaran Brook, New Brunswick. We tested whether (1) average body size decreases with increasing density; (2) the effect of density on average body size is greatest at low densities; (3) growth rate will decrease most rapidly at low effective densities [Σ(fork length)2]; (4) density‐dependent growth is weaker over space than over time; and (5) the strength of density‐dependent growth increases with the size of the habitat unit (i.e. spatial scale) when compared within years, but not between years.There was a strong negative relationship between the average body size and population density of YOY Atlantic salmon in the autumn, which was best described by a negative power curve. Similarly, a negative power curve provided the best fit to the relationship between average body size and effective density. Most of the variation in average body size was explained by YOY density, with year, location and the density of 1+ and 2+ salmon accounting for a minor proportion of the variation.The strength of density‐dependent growth did not differ significantly between comparisons over space vs. time. Consistent with the last prediction, the strength of density‐dependent growth increased with increasing spatial scale in the within‐year, but not in the between‐year comparisons.The effect of density on growth was strongest at low population densities, too low to expect interference competition. Stream salmonid populations may be regulated by two mechanisms: density‐dependent growth via exploitative competition at low densities, perhaps mediated by predator‐induced reductions in drift rate, and density‐dependent mortality and emigration via interference competition at high densities.
Condition‐specific competition between invasive Argentine ants and Australian Iridomyrmex
Authors: THOMAS MELISSA L. , HOLWAY DAVID A. 
Published: September 2010

Summary

Biotic interactions and abiotic suitability are often emphasized as factors influencing invasion success. Here we examine how these factors might interact to affect the competitive performance of invasive Argentine ants (Linepithema humile) in Western Australia.
In standardized bait surveys Argentine ants controlled twice as many baits in the morning (ground temperatures: 18–25 °C) compared to the number they controlled in the afternoon (ground temperatures: 30–40 °C). Moreover, Argentine ants displaced native ants from baits only in the morning and were, in turn, displaced by native ants only in the afternoon.
We used a factorial field experiment to test the relative importance of interspecific competition (±) and ground temperature variation [warm (25 °C)/hot (33 °C)] as determinants of competitive performance among established colonies of Argentine ants and two species of native Iridomyrmex (I. bicknelli and I. rufoniger suchieri).
We observed a condition‐specific competitive asymmetry between I. bicknelli and L. humile. In the absence of each other as competitors, these two species responded to ground temperature variation in an opposite manner. I. bicknelli foraged more actively when ground temperatures were hot, whereas L. humile foraged more actively when ground temperatures were warm. In competition with I. bicknelli, Argentine ants monopolized two‐thirds of all baits but controlled more than twice the number of baits under warm conditions than under hot conditions. Iridomyrmex bicknelli dominated 22% of all baits but did so primarily when conditions were hot.
Linepithema humile and I. r. suchieri responded to abiotic variation in a qualitatively similar manner. Both species foraged less actively when ground temperatures were hot than when ground temperatures were warm, but L. humile showed stronger declines when ground temperatures were hot than did I. r. suchieri. In competition with I. r. suchieri, Argentine ants again monopolized two‐thirds of all baits.
Our findings suggest that physical conditions unsuitable for L. humile may combine with interspecific competition from native ants that are more tolerant to hot, dry conditions to reduce the extent to which natural areas in Australia become invaded.
Adaptive sex allocation in relation to life‐history in the common brushtail possum, Trichosurus vulpecula
Authors: ISAAC JOANNE L. , KROCKENBERGER ANDREW K. , JOHNSON CHRISTOPHER N. 
Published: September 2010

Summary

Maternal control of offspring sex remains a contentious topic in the evolutionary and behavioural ecology of vertebrates. Two models of adaptive sex allocation − the Trivers–Willard (TW) and local resource competition (LRC) hypotheses − have been supported in some studies, but in many other cases the forces shaping offspring sex ratios are unclear. One reason that past studies may not have provided clear support for either model is that the two processes interact, producing complex patterns of sex allocation in relation to the life histories of individual mothers.
The TW hypothesis predicts that in dimorphic, polygynous mammals, females in good condition should be more likely to produce male offspring. The LRC hypothesis predicts an independent effect of age on the offspring sex ratio; females should be more likely to produce sons early in their reproductive lives and daughters later, in order to minimize the duration and reproductive cost of mother–daughter competition. We tested these two predictions in a study of sex allocation in the common brushtail possum, Trichosurus vulpecula.
Offspring sex was strongly dependent on maternal age: females breeding for the first time were likely to produce sons, and at subsequent breeding attempts the sex ratio of offspring was slightly biased towards females. After the first breeding season, sex of offspring was influenced more strongly by body condition than by age, and females in good condition were more likely to have sons. Individual females that showed a between‐year gain in condition were also more likely to produce a male in the subsequent year.
Body mass of male offspring at 5 months was positively correlated with maternal condition. No relationship was found between maternal condition and mass of female offspring.
We conclude that patterns of change in sex allocation in relation to individual life histories of female common brushtail possums can be explained by the interaction of TW and LRC effects.
Association of red‐mark syndrome with a Rickettsia‐like organism and its connection with strawberry disease in the USA
Authors: Metselaar M , Thompson K D , Gratacap R M L , Kik M J L , LaPatra S E , Lloyd S J , Call D R , Smith P D , Adams A 
Published: September 2010

AbstractRed‐mark syndrome (RMS), a disease seen mostly in rainbow trout, Oncorhynchus mykiss, is of unknown aetiology. The research presented here indicates the presence of an intracellular bacterium in RMS‐affected fish. A positive reaction was observed using immunohistochemistry (IHC) with skin lesions, liver, kidney and spleen of affected fish sampled from several locations within the United Kingdom using two different polyclonal antisera raised against Piscirickettsia salmonis. The same reaction was also seen with a number of different anti‐P. salmonis monoclonal antibodies (MAbs). A disease with similar clinical signs to RMS, referred to as strawberry disease (SD), has been reported in the USA. A Rickettsia‐like organism (RLO) has recently been associated with SD based on analysis of 16S rDNA sequences. Using the same panel of anti‐P. salmonis antibodies used to screen the RMS samples, similar staining was obtained in tissue of SD‐affected fish by IHC. A polymerase chain reaction (PCR) using RLO‐specific primers was also performed on RMS‐affected fish from the United Kingdom, and the samples were positive for the RLO 16S rRNA sequence. These findings suggest that the same aetiological agent may be responsible for RMS in the United Kingdom and SD in the USA.
Motor performance of children with mild intellectual disability and borderline intellectual functioning
Authors: Vuijk P. J. , Hartman E. , Scherder E. , Visscher C. 
Published: September 2010

AbstractBackground  There is a relatively small body of research on the motor performance of children with mild intellectual disabilities (MID) and borderline intellectual functioning (BIF). Adequate levels of motor skills may contribute to lifelong enjoyment of physical activity, participation in sports and healthy lifestyles. The present study compares the motor skills of children with intellectual disability (ID) to the abilities observed in typically developing children. It also aimed to determine whether there is an association between degree of ID and motor performance.Methods  A total of 170 children between 7 and 12 years old with MID or BIF, who attended schools for special education, were examined on the test component of the Movement Assessment Battery for Children (MABC) test. Both groups were compared with the norm scores of the total score, sub‐scale scores and individual items of the MABC test.Results  Of the children, 81.8% with MID and 60.0% with BIF performed below the 16th percentile on the total score of the MABC. Both groups demonstrated a relative weakness in the area of manual dexterity. Comparisons between both groups showed small to moderate effect sizes on the total score of the MABC, as well as for all three sub‐scales, favouring the children with BIF.Conclusions  Children with ID had significantly more borderline and definite motor problems than the normative sample and there was an association between degree of ID and performance of manual dexterity, ball skills and balance skills. This study highlights the importance of improving motor skill performance in both children with borderline and mild ID, and the results support the notion that the level of motor and cognitive functioning are related in children with ID.
Adaptive behaviour in Angelman syndrome: its profile and relationship to age
Authors: Brun Gasca C. , Obiols J. E. , Bonillo A. , Artigas J. , Lorente I. , Gabau E. , Guitart M. , Turk J. 
Published: September 2010

AbstractBackground  Angelman syndrome (AS) is a neurodevelopmental disorder usually caused by an anomaly in the maternally inherited chromosome 15. The main features are severe intellectual disability, speech impairment, ataxia, epilepsy, sleep disorder and a behavioural phenotype that reportedly includes happy disposition, attraction to/fascination with water and hypermotoric behaviour.Method  We studied the level of adaptive behaviour and the adaptive behavioural profile in the areas of ‘motor skills’, ‘language and communication’, ‘personal life skills’ and ‘community life skills’ in a group of 25 individuals with genetically confirmed AS, to determine whether there is a specific adaptive behaviour profile.Results and conclusions  None of the individuals, whatever their chronological age, had reached a developmental age of 3 years. A specific adaptive behaviour profile was found, with ‘personal life skills’ emerging as relative strengths and ‘social and communication skills’ as weaknesses.
Age‐dependent antibody response to Plasmodium falciparum merozoite surface protein 2 (MSP‐2)
Authors: KHOSRAVI A. , HOMMEL M. , SAYEMIRI K. 
Published: September 2010

SummaryMerozoite surface protein 2 (MSP‐2), a very immunogenic malaria antigen, is a highly polymorphic 45–53 kDa merozoite surface protein, which is regarded as a promising vaccine candidate. The highly polymorphic nature of MSP‐2 suggests that the molecule can be involved in protective immunity against malaria. The antibody responses to MSP‐2 antigen are mostly directed against polymorphic and dimorphic regions of the protein. The current study aimed at testing the reactivity of human sera from a malaria‐endemic area of Gambia against MSP‐2 regions 2, 3 and 4 compared to crude schizont extract in a period of 20 years. The age‐dependent immunity was analysed in a manner of cross‐sectional study (the data of the first visit) and also a longitudinal study design (analysing the data at four different time points from 1960 to 1980) testing the sera of 178 individuals randomly selected from the Keneba Serum Collection by using MSP‐2 recombinant protein. The total IgG responses were measured by ELISA. Kolmogorov–Smirnov was used to check the normal distribution of OD, Hb and parasitaemia, and then Spearman correlation was applied to analyse the data. Most sera recognized, predominantly, the variable regions of the MSP‐2, particularly the domain 3. The IgG response against all the antigens increased with age. The IgG responses against domain 3 of MSP‐2 were associated with an increase in haemoglobin levels but a decrease in parasitaemia, suggesting that this immune response may be one of the most useful means for further studies on protective immunity against malaria.
The mating‐induced refractoriness of Lucilia cuprina females: manipulating the male contribution
Authors: SMITH P. H. , GILLOTT C. , BROWNE L. BARTON , GERWEN A. C. M. VAN 
Published: September 2010

Abstract Three manipulations of the male contribution to copulation were used to investigate what determines the switch‐off of female receptivity that follows mating in Lucilia cuprina.Multiple matings by males led to a reduction in their effectiveness at switching‐off females: the first twelve matings caused more than 50% of females to be switched‐off 1 day after mating, while the first four matings caused more than 50% of females to be switched‐off for 7 days after mating. Males mated up to twenty‐three times and on average ten times during 10 h of continuous access to virgin females. The number of sperm transferred declined logarithmically through a series of matings as did the quantity of material transferred from the male accessory gland (measured as radiolabeled material) through the first six matings. Overnight isolation of multiply‐mated males led to considerable recovery of their ability to switch‐off females, and to limited renewal of their ability to transfer sperm. Castrated males transferred similar quantities of accessory gland material to females as did sham‐operated males during their first five matings and in their first three matings switched‐off 95% of females for 1 day but only 48% for 7 days.When normal mating pairs were separated at increasing intervals after coupling, an increasing proportion of females were switched‐off at 1 or 7 days afterward. 7 days after 2 min matings no females were switched‐off though 40% of the number of sperm transferred in a full mating had been transferred by this time.The proposed explanation for these data is that both the initial switch‐off and its duration are determined by the quantity of a receptivity‐inhibiting substance that normally enters the female haemo‐lymph after being injected by the male into the wall of the bursa copulatrix. It is proposed that when castrated males mate, an absence of sperm results in most accessory gland secretion entering the empty spermathecae (rather than the wall of the bursa as usually occurs) and hence being unable to reach the haemolymph and exert its influence. The effective dose of the receptivity‐inhibiting substance is measured on a logarithmic scale.
On critical night lengths and temperature compensation in the photoperiodic response of two geographical clones of the black bean aphid, Aphis fabae
Authors: Nunes Marlies Vaz , Hardie Jim 
Published: September 2010

SummaryPhotoperiodic response curves were determined for two clones of the black bean aphid, Aphis fabae Scopoli, at three temperatures, 12.5, 15 and 17.5°C. Critical night lengths for the induction of winged females in an English clone (52° N) were 10.5, 11 and 11.5 h, respectively, and 10, 10.5 and 11 h in a Scottish clone (57° N). Critical night lengths for male induction were 10.5, 11 and 11 h at 12.5, 15 and 17.5°C in the English clone, and 10, 10.5 and 10.5 h, respectively, in the Scottish clone. High incidences of winged females and males were observed at all scotophases longer than the critical night length in both clones. In addition, in the English clone, the incidences of winged female and male producers in continuous darkness were 0% at 15 and 17.5°C, and 6% at 12.5°C. In the Scottish clone, however, continuous darkness resulted in high incidences of both winged female and male producers at 12.5 and 15°C, but 0% winged female producers and 6% male producers at 17.5°C. In scotophases shorter than the critical night length, including continuous light, no males or winged females were observed in either clone under the non‐crowded rearing conditions used. The results are discussed in terms of the ‘double circadian oscillator model’ for photoperiodic induction.
Variation in sperm precedence in Chorthippus grasshoppers (Caelifera: Gomphocerinae)
Authors: Reinhardt Klaus 
Published: September 2010

SummaryVariation in the proportions of offspring fathered by a second male to mate (the P2 value) has been studied in two species of grasshoppers, Chorthippus parallelus (Zetterstedt) and Ch. biguttulus (Linnaeus), by means of the sterile‐male technique. In both species the P2‐values of the first egg pods laid were in the range of 50–100%, and the temporal variation of P2‐values appeared to follow two modes. In one, the P2‐value steadily declined with time, in the other it remained constant at a high level. It is concluded that sperm is passively lost between two matings. The remaining sperm then either mixes within the spermatheca or is stratified. Further variability in sperm precedence can possibly be explained by spermatophore ejection or differential use of stored sperm.
Hormonal control of diapause and overwintering traits in a leaf beetle, Aulacophora nigripennis
Authors: Watanabe Masahiko , Tanaka Kazuhiro 
Published: September 2010

SummaryTo elucidate whether Juvenile Hormone (JH) regulates physiological status in relation to diapause and cold hardiness, we investigated various physiological and biochemical changes in diapause adults of Aulacophora nigripennis after treatment with exogenous pyriproxyfen, an analogue of JH. Topical application of pyriproxyfen at high dose (≥0.05 μg) caused the diapause adults not only to consume more oxygen and mate earlier, but also to suppress enhancement of chill tolerance at 0°C and accumulation of myo‐inositol. By contrast, a lower dose of pyriproxyfen (0.01 μg) did not, suggesting that the amount of pyriproxyfen between 0.01 and 0.05 μg is a critical dose breaking both diapause and cold hardening. Pyriproxyfen‐treated post‐diapause adults lost triacylglycerols, but not glycogen, more rapidly than the acetone control. It is suggested that triacylglycerols are the main energy resource in both diapause and post‐diapause adults, but are consumed more by the latter because of their higher metabolic rate. Glycogen may be converted mainly into myo‐inositol during diapause, but consumed as an energy fuel for basal metabolism during post‐diapause development. Thus, various physiological and biochemical traits in relation to diapause and cold tolerance in this beetle may be at least in part under the control of JH.