Rising temperature and development in dragonfly populations at different latitudes

1. For modelling the future ecological responses to climate change, data on individual species and on variation within and between populations from different latitudes are required. 2. We examined life cycle regulation and growth responses to temperature in Mediterranean and temperate populations of a widespread European odonate, Orthetrum cancellatum. In an experiment, offspring from individual females from different parts of the range were kept separately to elucidate differences between families. 3. The experiment was run outdoors at 52°N at a natural photoperiod for almost a year. We used four temperature regimes, ambient (i.e. following local air temperature) and ambient temperature increased by 2, 4 and 6 °C, to mimic future temperature rise. A mathematical model was used to categorise the type of seasonal regulation and estimate parameters of the temperature response curve. 4. Growth rate varied significantly with temperature sum, survival and geographic origin, as well as with family. Offspring of all females from the temperate part of the range had a life cycle with a 12 h day‐length threshold necessary to induce diapause (i.e. diapause was induced once day length fell below 12 h). By contrast, Mediterranean families had a 10 h threshold or had an unregulated life cycle allowing winter growth. The temperature response did not significantly differ between populations, but varied between families with a greater variation in the optimum temperature for growth in the Mediterranean population. 5. The variation in seasonal regulation leads to a diversity in voltinism patterns within species, ranging from bivoltine to semivoltine along a latitudinal gradient. Given that the type of seasonal regulation is genetically fixed, rising temperatures will not allow faster than univoltine development in temperate populations. We discuss the consequences of our results in the light of rising temperature in central Europe.     

Ambient temperature effects on photo induced gonadal cycles and hormonal secretion patterns in Great Tits from three different breeding latitudes

The present study determines how populations of Great Tits (Parus major) breeding in southern, mid and northern European latitudes have adjusted their reproductive endocrinology to differences in the ambient temperature during the gonadal cycle. A study based on long-term breeding data, using the Colwell predictability model, showed that the start of the breeding season has a high predictability (≈ 0.8-0.9) at all latitudes, and that the environmental information factor (I_e) progressively decreased from mid Italy (I_e > 4) to northern Finland (I_e < 1). The results indicate that integration of supplementary information, such as ambient temperature, with photoperiodic initial predictive information (day length), becomes progressively more important in maintaining the predictability of the breeding season with decreasing latitude. This hypothesis was verified by exposing photosensitive Great Tits from northern Norway, southern Sweden and northern Italy to sub-maximal photo-stimulatory day lengths (13L:11D) under two different ambient temperature regimes (+ 4 °C and + 20 °C). Changes in testicular size, plasma levels of LH and testosterone were measured. The main results were: (1) Initial testicular growth rate, as well as LH secretion, was affected by temperature in the Italian, but not in birds from the two Scandinavian populations. (2) Maximum testicular size, maximum LH and testosterone levels were maintained for a progressively shorter period of time with increasing latitude, regardless of whether the birds were kept on a low or a high ambient temperature. (3) In birds from all latitudes, the development of photorefractoriness, as indicated by testicular regression and a decrease in plasma levels of LH and testosterone, started much earlier (with the exception for LH Great Tits from northern Scandinavia) when kept on + 20 °C than when kept on + 4 °C. The prolonging effects of a low temperature was more pronounced in Mediterranean birds, than in birds from Scandinavia, and more pronounced in Great Tits from southern Scandinavia than in Great Tits from northern Scandinavia. Ecological implications of the results are discussed, as well as possible impact of global warming on the breeding success of European Great Tits from different breeding latitudes.     

The age dynamic of hormonal levels in children living in different latitudes in European North

An investigation simultaneously of hormonal profile in children of 10-16 years living in different latitudes and climato-ecological conditions in Russian European North (in the border of polar and middle latitudes) was performed. The increased thyrotropin level was revealed in 35% of children in the south (61 degrees North) and in 32% of children in the North (64 degrees 30' North). The thyroid hormones (thyroxin, triiodothyronine) are at low normative bound. Higher Insulin levels were observed in 28% of children living in the southen region especially in 50% of prepubertal boys. In 20% of children, higher cortisol levels were revealed mainly at the final puberty (35% of children).     

Seasonality and the scheduling of life history at different latitudes

For many ectotherms, the annual cycle is partitioned into 'growing' (summer) and 'non-growing' (winter) seasons, and the lengths of these seasons are inversely related across a latitudinal gradient. This pattern of variation has the potential to affect diverse life-history traits profoundly. A key selective agent is size-dependent winter mortality which, with increasing latitude, places an increasing premium on attainment of large body size before the first winter of life. Winter body size is determined primarily by two factors: (1) birth date, which defines the beginning of the first growing season and (2) somatic growth rate within the first season. Using examples drawn from the Atlantic silverside, Menidia menidia (L.), and other fishes, I show how latitudinal variation in the scheduling of the spawning season, countergradient variation in the capacity for growth and reproduction, and mode of sex determination (environmental v. genetic) represent adaptations to seasonality.     

Microparasite species richness in rodents is higher at lower latitudes and is associated with reduced litter size

Parasite species loads are expected to be higher in the tropics and higher parasite species richness to have cumulative effects on host physiology or demography. Despite being regularly assumed or predicted, empirical evidence on species–latitude patterns is scarce or contradictory and studies on the impacts of concomitant infections have mainly been done at host intra‐specific level. Broad generalizations are then very hard, if not spurious. By focusing on rodent species and their non‐eukaryotic microparasites (i.e. viruses and bacteria), we investigated, using a comparative approach, microparasite species richness across rodent species according to the latitude where they occur. We also explored the links between rodents’ reproductive traits, latitude and microparasite species richness. We find for the first time in rodents that virus species richness increases towards tropical latitudes, and that rodent litter size seems to decrease when microparasite species richness increases independently from the latitude. These results support the hypotheses that rodent species in the tropics effectively harbour higher parasite species loads, at least in terms of species richness for viruses, and that parasite species richness influences rodent life‐history traits. Although some other factors, such as seasonality, were not taken into account due the lack of data, our study stresses the idea that chronic microparasite infections may have detrimental effects on their rodent host reservoirs, notably by affecting litter size.     

Height and reproductive success

In Western societies, height is positively correlated with reproductive success (RS) for men but negatively correlated with RS for women. These relationships have been attributed to sexual selection: women prefer tall men, and men prefer short women. It is this success in the marriage market which leads to higher RS for tall men and short women. We have already shown that the relationship between height and RS for women is quite different in a non-Western context. In a subsistence farming community in rural Gambia, height is positively correlated with reproductive success for women, largely owing to the higher survival of the children of tall women. Here, the relationship between height and reproductive success is analyzed for men in the same community. For these Gambian men, there is no significant relationship between height and the number of children they produce, although tall men do contract more marriages than shorter men. We conclude that environmental context needs to be taken into account when analyzing human reproductive behavior.     

Central metabolism of beta-endorphin in different species of temperature acclimated rodents

The purpose of this study was to characterize the central metabolism/processing of beta-endorphin in wild, desert rodents and to study the effect of heat and cold acclimation on central metabolism/processing and beta-endorphin half-life. This report suggests that a shift occurs in the processing of beta-endorphin in desert rodents acclimated to heat and cold leading to an accumulation of gamma-type endorphins. The data support a significant difference in beta-endorphin half-life between the rodents and the laboratory white rat.     

Dominance and reproductive success in primates

Theoretical models of the relationship between competition and differential reproduction in primates share the premise that agonistic dominance hierarchies determine differential access to those limited resources which are essential to reproduction. In particular, the priority-of-access-to-estrous-female model is based on the postulate that high rank in males enhances reproductive success. Tests for a correlation between rank and reproductive success in males have produced mixed results. Problems in measuring male reproductive success and in conceptualizing dominance systems are implicated in the diversity of conclusions reached. Other attributes which affect reproductive success have been proposed, and alternative models of mating systems, based on the concepts of reproductive strategies, social skills, and life histories have also been developed. Studies of differential reproduction in female primates are fewer, but have the advantage over male studies of directly measuring infant production and offspring survival. Research on the relationship between rank and reproductive success in females has shown that under conditions of low resource availability, subordinate females sometimes suffer reduced fecundity and infant survival as a result of restricted access to food and water. Under conditions of social stress, low-ranking females may suffer from disruption of their reproductive cycles, resulting in lowered fecundity. Dominant females may also incur reproductive costs as well as benefits for their social position. Better insights into the relationship between dominance and reproduction are potentially offered by improved genetic paternity measures, new models of social and demographic processes, and the recent availability of life history data from field studies.     

Prestige and reproductive success in man

The relationship between prestige and reproductive success is explored in ten human societies. Formally, the aim is to test the hypothesis that prestige and reproductive success are positively correlated in all populations. It is concluded that in societies at or slightly above the subsistence level prestige and reproductive success are congruent, but that with the accumulation of surplus wealth sources of prestige which have no relevance for reproductive success begin to appear, their development being facilitated by the law of diminishing returns as applied to parents' nonbiological investment in offspring, a point being reached where further investment can have no beneficial effect on reproductive success. As a result sociocultural success and reproductive success may separate. In some societies, where prestige depends upon the possession of real estate, population control is embraced by wealthy families in order to keep their estates intact, thus increasing the effectiveness of the law of diminishing returns by reducing the “fixed resources” (i.e., number of offspring) available for investment. In these conditions, which may spread to the less wealthy, sociocultural success often takes precedence over reproductive success.     

Photosynthesis drives anomalies in net carbon-exchange of pine forests at different latitudes

The growth rate of atmospheric CO₂ exhibits large temporal variation that is largely determined by year‐to‐year fluctuations in land–atmosphere CO₂ fluxes. This land–atmosphere CO₂‐flux is driven by large‐scale biomass burning and variation in net ecosystem exchange (NEE). Between‐ and within years, NEE varies due to fluctuations in climate. Studies on climatic influences on inter‐ and intra‐annual variability in gross photosynthesis (GPP) and net carbon uptake in terrestrial ecosystems have shown conflicting results. These conflicts are in part related to differences in methodology and in part to the limited duration of some studies. Here, we introduce an observation‐driven methodology that provides insight into the dependence of anomalies in CO₂ fluxes on climatic conditions. The methodology was applied on fluxes from a boreal and two temperate pine forests. Annual anomalies in NEE were dominated by anomalies in GPP, which in turn were correlated with incident radiation and vapor pressure deficit (VPD). At all three sites positive anomalies in NEE (a reduced uptake or a stronger source than the daily sites specific long‐term average) were observed on summer days characterized by low incident radiation, low VPD and high precipitation. Negative anomalies in NEE occurred mainly on summer days characterized by blue skies and mild temperatures. Our study clearly highlighted the need to use weather patterns rather than single climatic variables to understand anomalous CO₂ fluxes. Temperature generally showed little direct effect on anomalies in NEE but became important when the mean daily air temperature exceeded 23 °C. On such days GPP decreased likely because VPD exceeded 2.0 kPa, inhibiting photosynthetic uptake. However, while GPP decreased, the high temperature stimulated respiration, resulting in positive anomalies in NEE. Climatic extremes in summer were more frequent and severe in the South than in the North, and had larger effects in the South because the criteria to inhibit photosynthesis are more often met.     

Variation of reproductive behaviour and success of males adopting different tactics in Atlantic salmon

  The use of video photography normally involves sub‐aqua recording via a camcorder device. The problem is that the scientist needs to be directly involved in the recording underwater or else viewing the results of the footage after the event. The system we have developed enables real time images to be relayed to a boat, satellite of shore‐based recorder. With a two‐way audio communication system, it is possible for the scientist/team to direct the camera work of the divers, remotely. The configuration of this system are discussed, and a wide range of scientific applications suggested.     

Hantavirus-specific antibodies in rodents and humans living in Kuwait

Hantaviruses are found in widely scattered areas of the world and are transmitted by inhalation of virus-contaminated aerosols of rodent excreta. The present study was undertaken in Kuwait to investigate the serological evidence for hantavirus infection in rodents and humans. Sera were collected from 283 wild rodents and 183 human subjects (46 Kuwaitis and 137 non-Kuwaitis). The rodent sera were investigated for the presence of antibodies against the Seoul and Puumala strains of the hantaviruses by enzyme-linked immunosorbent assay and immunofluorescence technique using the virus-infected Vero E6 cells. The findings showed the presence of anti-hantavirus antibodies in seven out of the 283 (2.8%) rodents. Antibodies against the Seoul strain were present in six (2.1%) and against the Puumala strain in three (1%) rodents. Further, it was observed that three out of 84 (3.6%) of the Rattus norvegicus and four out of 174 (2.3%) Mus musculus had anti-hantavirus antibodies. Two rodents belonging to species Mus musculus had antibodies against both strains of the hantaviruses. Out of 183 human sera, 13 (7%) were positive for hantavirus antibodies. Among the Kuwaitis 5/46 (11%) and among the non-Kuwaitis 8/137 (6%) were positive for the hantavirus antibodies. Antibodies to both Puumala and Hantaan strains were detected in Kuwaitis as well as in non-Kuwaitis. Although no human case of hantavirus illness has yet been reported in Kuwait, the serological evidence of infection suggests a constant vigil.     

亚热带不同纬度植物群落物种多样性分布规律

我国亚热带气候区植被资源丰富,对其典型植物群落的物种多样性分布随纬度和海拔变化规律的探索是一项非常有意义的研究工作。在亚热带区域按照纬度从高到低分别选取猫儿山、南岭和鼎湖山国家级自然保护区中的四个典型植物群落为研究对象。设立四个1hm²样地,采用国家标准方法调查和监测。通过对样地中胸径大于1cm的所有物种进行种-个体曲线分析,对优势种进行径级分布分析,以及对四个群落进行一系列α多样性和β多样性指数的比较和分析,发现四个植物群落的物种多样性随海拔和纬度变化趋势明显。研究结果显示:(1)海拔的差异对于种-个体的分布起到关键作用,个体数随海拔变化更加明显。纬度从南到北单个体种的出现频率逐渐下降,而单个体种对群落物种多样性的贡献也在低海拔地区更为显著。(2)海拔接近的南岭样地和鼎湖山样地α多样性差异显著:由于所处演替阶段不同,以及鼎湖山样地受到人为干扰大,物种多样性反而低于纬度较高的南岭样地。同一纬度不同海拔的猫儿山两块样地相比较,处于中纬度的红军亭样地α多样性高于海拔偏高的八角田样地。(3)四个群落之间由于生境的差异,物种组成明显不同。纬度和海拔对群落β多样性都有影响。...     

Alliances and reproductive success in Camargue stallions

A study of a herd of Camargue horses Equus caballus, showed that while the majority of high-ranking stallions held single-male harems, some sons of low-ranking mares, being low ranking themselves, formed alliances that could last a lifetime. The two stallions were each other's closest associate and preferential grooming partner. Alliances were based on coalitions in which either both partners confronted an intruder synchronously or the dominant of the pair tended the female(s) while the subordinate simultaneously displayed towards the rival. Alliance partners were of similar age but were not more closely related to each other than to other stallions in the herd. Long-term paternity data revealed that subordinates sired close to a quarter of the foals born into the alliance group, and significantly more foals than low-ranking stallions in the herd adopting a 'sneak'-mating strategy. The dominant appeared to benefit from the presence of his subordinate partner. Fights occurred all year round, and the subordinate stallion of each alliance pair fought outside competitors more than twice as often as the dominant. Forming short-term alliances before defending mares on their own may enhance long-term reproductive success for both partners. Other benefits to both partners include higher survivorship of their foals and increased access to proven reproductive mares. These results suggest that the relationship between alliance partners is based on mutualism, but several conditions for reciprocity seem to be fulfilled: the benefit to the dominant (assistance in fights), and the benefit to the subordinate (access to reproduction), are both costly to the other partner and delayed in time. Copyright 1999 The Association for the Study of Animal Behaviour.     

Association between adolescent idiopathic scoliosis prevalence and age at menarche in different geographic latitudes

Background

Age at menarche is considered a reliable prognostic factor for idiopathic scoliosis and varies in different geographic latitudes. Adolescent idiopathic scoliosis prevalence has also been reported to be different in various latitudes and demonstrates higher values in northern countries. A study on epidemiological reports from the literature was conducted to investigate a possible association between prevalence of adolescent idiopathic scoliosis and age at menarche among normal girls in various geographic latitudes. An attempt is also made to implicate a possible role of melatonin in the above association.

Material-methods

20 peer-reviewed published papers reporting adolescent idiopathic scoliosis prevalence and 33 peer-reviewed papers reporting age at menarche in normal girls from most geographic areas of the northern hemisphere were retrieved from the literature. The geographic latitude of each centre where a particular study was originated was documented. The statistical analysis included regression of the adolescent idiopathic scoliosis prevalence and age at menarche by latitude.

Results

The regression of prevalence of adolescent idiopathic scoliosis and age at menarche by latitude is statistically significant (p < 0.001) and are following a parallel declining course of their regression curves, especially in latitudes northern than 25 degrees.

Conclusion

Late age at menarche is parallel with higher prevalence of adolescent idiopathic scoliosis. Pubarche appears later in girls that live in northern latitudes and thus prolongs the period of spine vulnerability while other pre-existing or aetiological factors are contributing to the development of adolescent idiopathic scoliosis. A possible role of geography in the pathogenesis of idiopathic scoliosis is discussed, as it appears that latitude which differentiates the sunlight influences melatonin secretion and modifies age at menarche, which is associated to the prevalence of idiopathic scoliosis.     

Short-term effects of enhanced UV-B and CO2 on lichens at different latitudes

Interaction effects of UV-B and CO₂ on three lichens species, Cladonia arbusculo, Cetraria islandica and Stereocaulon paschale, from two latitudinal sites, 68∘N and 56∘N, were studied in a laboratory experiment. The response of the plants was recorded by measuring their chlorophyll fluorescence. All species had a similar response to enhanced UV-B depending on the latitude from which the population came and the time of the season when they were sampled. Overall, there was a significant increase in photosystem II yield (as measured by a fluorescence technique) due to UV-B and no separate effect due to enhanced CO₂, although there was a significant interaction between CO₂ and UV-B. The increase due to UV-B was at the low CO₂ level. There were also significant differences in response due to latitude. The results contradict our hypotheses that negative effects of UV-B would be larger in the North than in the South and that a negative response should be especially large during the early season.     

Anatomy of chlorenchyma cells in maize lines developed at different latitudes and grown at sub- and supraoptimal temperatures

Three inbred lines of maize ( Zea mays L.) from cool temperate regions and three from warm regions were grown at 14, 22, 30 and 38°C up to the same physiological age, the full expansion of the third leaf. The laminae of the second leaf were studied for anatomical traits of the chlorenchyma. The genotypic variation was considerable for all properties. Nevertheless, general temperature response curves existed for many properties with few deviations of single lines. The cross-sectional area of mesophyll cells and cross-sectional area and number of chloroplasts declined from 14 to 22°C, increased up to 30°C and declined again up to 38°C. The ratio of shortest to longest diameter of chloroplasts was low in mesophyll cells at intermediate temperatures, and maximum in bundle sheath cells at 30°C. Temperature response curves for other properties of the bundle sheath cells were predominantly genotype specific. Chloroplasts in bundle sheath cells were sometimes smaller than those of mesophyll cells, dependent on temperature and genotype. Values of lines from cool temperate and warm regions were mostly overlapping, but the cross-sectional area of mesophyll cells was larger in the latter than in the former lines at low temperature. The results are discussed in relation to the expression of photosynthetic properties.