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Diapause and cold tolerance are essential for temperate insects to pass the winter, with the mechanisms controlling these two traits varying considerably among insects. In the present study, diapause and cold tolerance are compared among three Leptopilina species: Leptopilina japonica Novković & Kimura, Leptopilina victoriae Nordlander and Leptopilina ryukyuensis Novković & Kimura, all larval parasitoids of frugivorous drosophilid flies, with the aim of understanding their climatic adaptations. The first species is divided into the temperate ( Leptopilina japonica japonica) and subtropical subspecies ( Leptopilina japonica formosana), and the latter two species are distributed in the tropical and subtropical regions. The temperate subspecies of L. japonica enters prepupal diapause at low temperatures (15 or 18 °C), irrespective of photoperiod, and some individuals enter diapause when exposed to 0 °C for 1 or 2 day(s) or when placed at low humidity. Leptopilina victoriae also shows signs of diapause initiation at 15 °C, although L. ryukyuensis and L. j. formosana from the subtropical regions do not. Preimaginal viability at low temperature (13, 14 or 15 °C) is usually lower in L. victoriae from the tropical regions compared with L. japonica or L. ryukyuensis from the temperate or subtropical regions. Diapausing prepupae of the temperate subspecies appear to be cold tolerant. However, the cold tolerance of nondiapausing prepupae, pupae and adult females varies little among the tropical, subtropical and temperate species or subspecies, and adult males of the temperate subspecies of L. japonica are less cold tolerant than those of the tropical or subtropical species or subspecies. Cold tolerance may be unnecessary, except for diapausing individuals of the temperate species, because nondiapausing individuals appear in warmer seasons. [ABSTRACT FROM AUTHOR]

Abstract: In the last two decades a considerable number of studies have described geographic variation in morphometric, physiological and behavioral traits of over a dozen species of wild south-Asian drosophild fruit flies. Due to strong latitudinal and altitudinal gradients this region is highly diverse with respect to climatic conditions, making it important for studies in evolutionary ecology. In this review, we examine spatial heterogeneity across the Indian subcontinent in almost all of the traits previously investigated (body weight, desiccation tolerance, pigmentation, copulation duration, fecundity, ovariole number, wing length, alcohol dehydrogenase fast allele frequency, rate of water loss and starvation resistance). We find a linear correlation between trait variation and latitude. Our data suggest that a single climatic component, the coefficient of variance of monthly temperature averages, which is strongly correlated with latitude, explains a large proportion of variation in the traits investigated. [Copyright &y& Elsevier]

The geographical variation in elytral color polymorphism in Cheilomenes sexmaculata ( Fabricius) was analyzed based on data from specimen surveys. In all, 1549 individuals collected from different latitudes throughout Indonesia to Japan were categorized into 20 morph types of elytra. Results show that the morph types have a geographical cline: dark types increased with latitude, although the light types showed higher relative frequency in lower latitudes, which suggests that the geographic variation in elytral color polymorphism in C. sexmaculata is a product of selection by climate. The darker morph types might be advantageously able to make fuller use of insolation at higher latitudes, whereas the lighter morph types were likely to reduce heat stress at lower latitudes. In most areas across Southeast and South Asia, all specimens were of the lightest type, which may imply either: (i) the saturation of genes expressing light morph types, which have less solar absorption, due to tropical climate; or (ii) an enhanced warning function of bright red against predators. On Miyako Island of Japan, a unique frequency of morph types was found compared to the adjacent areas. [ABSTRACT FROM AUTHOR]

Abstract: Tropical fruit flies (Drosophilidae) differ from temperate drosophilids in several ecophysiological traits, such as desiccation tolerance. Moreover, many species show significant differences in desiccation tolerance across geographical populations. Fruit flies from the tropical and subtropical Indian subcontinent show a clinal pattern for desiccation tolerance which is similar for more than a dozen species studied so far, suggesting adaptation to climatic differences. We performed a meta-analysis to investigate which particular climatic patterns modulate desiccation tolerance in natural populations of drosophilids. Latitude of the sampling site explained most of the variability. Seasonal thermal amplitude (fluctuations in temperature expressed as coefficient of variation) was the strongest climatic factor shaping desiccation tolerance of flies, while factors measuring humidity directly were not important. Implications for survival of flies after future climate change are suggested. [Copyright &y& Elsevier]

Abstract: We studied the effect of seed transfers on survival, yield and stem defects of silver birch (Betula pendula Roth) of North European origin in five parallel provenance trials in Finland. The trials were located at Loppi (60°39′N) in southern Finland, at Kannonkoski (62°58′N), Ilomantsi (62°58′N) and Toholampi (63°47′N) in central Finland and at Rovaniemi (66°21′N) in northern Finland. Four trials were growing on moist upland forest sites and one on agricultural land. The material consisted of altogether 38 stand seed origins from Finland, Sweden, Estonia, Great Britain and Russia ranging between latitudes 53° and 67°N. Survival, height, diameter at breast height, stem volume/ha and number of stem defects per tree were assessed when the trees were 19years old. Seed transfer distance was calculated either as latitudinal or temperature sum difference between the seed origin and the trial location. According to coefficients of determination (R 2), the latitude-based transfer models gave a slightly better fit with the data than the models based on temperature sum differences. Significant differences were found among the origins regarding all studied traits in all trials. In all traits, the pattern of variation in relation to the transfer distance was curvilinear, and the effect of transfer distance was significant. A long transfer from both directions led to a reduction in all measured traits. The optimal transfer distance and direction varied depending on the trait and covariate used in the models. According to the latitudinal model, local or slightly more northern origins had highest survival and lowest number of stem defects. Height growth and yield was at highest with the local or slightly more southern origins. A northward transfer of ca. 2° of latitude increased yield, while a southward transfer or a longer northward transfer, decreased the yield. According to the temperature sum model, origins within the limits of approximately ±200 d.d. compared to the trial location produced the highest yield. Origins with similar or slightly lower temperature sums compared to the trial locations had highest survival and best stem quality. The current seed transfer guidelines for silver birch in Finland, which recommend transfer distances of 150km or 150 d.d. at maximum in southward or northward direction, seem still valid. Because of the low gain in expected yield by even moderate northward transfers and the uncertainties in the success of more southern origins in varying future climate, we recommend no changes in seed transfer guidelines. [Copyright &y& Elsevier]

Rapid evolution has rarely been assessed in biological control systems despite the similarity with biological invasions, which are widely used as model systems. We assessed post-introduction climatic adaptation in a population of Longitarsus jacobaeae, a biological control agent of Jacobaea vulgaris, which originated from a low-elevation site in Italy and was introduced in the USA to a high-elevation site (Mt. Hood, Oregon) in the early 1980s. Life-history characteristics of beetle populations from Mt. Hood, from two low-elevation sites in Oregon (Italian origin) and from a high-elevation site from Switzerland were compared in common gardens. The performance of low- and high-elevation populations at a low- and a high-elevation site was evaluated using reciprocal transplants. The results revealed significant changes in aestival diapause and shifts in phenology in the Mt. Hood population, compared with the low-elevation populations. We found increased performance of the Mt. Hood population in its home environment compared with the low-elevation populations that it originated from. The results indicate that the beetles at Mt. Hood have adapted to the cooler conditions by life-history changes that conform to predictions based on theory and the phenology of the cold-adapted Swiss beetles. [ABSTRACT FROM AUTHOR]

The body size of a univoltine carabid beetle Carabus tosanus on Shikoku Island, Japan, was clearly smaller in higher-altitude populations (subspecies), which possibly represents incipient speciation. To explore the determinants of altitudinal differences in body size in this species, we studied the degree of phenotypic plasticity by conducting rearing experiments at two constant temperatures and examined genetic differences through interpopulation crosses. At 15 °C, C. tosanus had a longer developmental period and a shorter adult body than at 20 °C. Nevertheless, variation in body size due to temperature effects (phenotypic plasticity) was small compared to the interpopulation differences, which suggests substantial genetic differences between populations (subspecies) at different altitudes. In F1 offspring from crosses between a low-altitude (subspecies tosanus) and a high-altitude population (subspecies ishizuchianus), adult body length was affected by the genotypes of both parents, with an interaction effect of parental genotype and offspring sex. Further analyses revealed that adult body length was affected by sex-linked factors in addition to autosomal factors. These genetic differences in body size may have resulted from adaptations to different altitudes and may be important for the process of incipient speciation because body size differences could contribute to premating reproductive isolation. [ABSTRACT FROM AUTHOR]

ABSTRACT Vernalization, the induction of flowering by low winter temperatures, is likely to be involved in plant climatic adaptation. However, the genetic, molecular and ecological bases underlying the quantitative variation that tunes vernalization sensitivity to natural environments are largely unknown. To address these questions, we have studied the enhanced vernalization response shown by the Ll-0 accession of Arabidopsis thaliana. Quantitative trait locus (QTL) mapping for several flowering initiation traits in relation to vernalization, in a new L er × Ll-0 recombinant inbred line (RIL) population, identified large effect alleles at FRI, FLC and HUA2, together with two small effect loci named as Llagostera vernalization response ( LVR) 1 and 2. Phenotypic analyses of near isogenic lines validated LVR1 effect on flowering vernalization responses. To further characterize the FLC allele from Ll-0, we carried out genetic association analyses using a regional collection of wild genotypes. FLC-Ll-0 appeared as a low-frequency allele that is distinguished by polymorphism Del(-57), a 50-bp-deletion in the 5′-UTR. Del(-57) was significantly associated with enhanced vernalization responses and FLC RNA expression, as well as with altitude and minimum temperatures. These results are consistent with Del(-57) acting as a novel cis-regulatory FLC polymorphism that may confer climatic adaptation by increasing vernalization sensitivity. [ABSTRACT FROM AUTHOR]

The effect of soil water content on growth and growth cessation was studied in 18 provenances from northern Europe and 20 Danish open-pollinated families of Quercus robur in a greenhouse experiment. The objective was to study the genotypic responses, phenotypic plasticity and genotype by environment interactions, with regards to growth and to different levels of soil water content. The aim was to increase the knowledge on the genetic and adaptive potential of Q. robur to grow under different water stress conditions. Knowledge on genetic and adaptive potential can be used for practical seed zone management. Differences in growth between provenances were strongly related to latitude. Provenances of southernmost origin reacted vigorously to irrigation compared with Scandinavian provenances. For growth, the rank of provenances was the same at high and medium soil water treatments. Increased growth correlated with a higher number of secondary shoots and a prolonged growing season. Low soil water content initiated early growth cessation in all provenances. Root biomass was affected by soil water treatment and the highest root biomass was observed with medium and high soil water treatments. The results demonstrated a large evolutionary potential in relation to water treatment. The southernmost genotypes responded more strongly in growth to increased soil water level, but the local material showed a large variation and was less prone to early frost damage. The growth of Danish provenances of Q. robur was not reduced with high soil water treatment, in contrast to a study using Danish Fagus sylvatica provenances, indicating that Q. robur is well adapted to high soil water conditions. [ABSTRACT FROM AUTHOR]

Past studies have revealed that much of human craniometric variation follows a neutral model of population relationships. At the same time, there is evidence for the influence of natural selection in having shaped some global diversity in craniometrics. In order to partition these effects, and to explore other potential population-specific influences, this article analyzes residuals of craniometric distances from a geographically based neutral model of population structure. W.W. Howells' global craniometric data set was used for these analyses, consisting of 57 measurements for 22 populations around the world, excluding Polynesia and Micronesia because of the relatively recent settlement of these regions. Phenotypic and geographic distances were derived between all pairs of populations. Three-dimensional multidimensional scaling configurations were obtained for both distance matrices, and compared using a Procrustes rotation method to show which populations do not fit the geographic model. This analysis revealed three major deviations: the Buriat, Greenland Inuit, and Peru. The deviations of the Buriat and Greenland Inuit appear to be related to long-term adaptation to cold environments. The Peruvian sample is more similar to other New World populations than expected based on geographic distance alone. This deviation likely reflects the evolutionarily recent movement of human populations into South America, such that these populations are further from genetic equilibrium. This same pattern is seen in South American populations in a comparative analysis of classical genetic markers, but not in a comparative analysis of STR loci, perhaps reflecting the higher mutation rate for the latter. [ABSTRACT FROM AUTHOR]

It is commonly presumed that plant respiratory CO2 release increases with increasing temperature. However, we report on very contrasting stem CO2 release (RS)-temperature relationships of trees in a species-rich tropical montane forest of southern Ecuador under dry and wet season conditions. Rates of RS were low and completely uncoupled from the dial temperature regime during the humid season. In contrast, during the dry season, RS was generally higher and temperature sensitivity of RS differed greatly in degree and even in the direction of response, indicating that temperature might not be the only determinant of RS. In order to explain the heterogeneity of RS, we related RS to vapour pressure deficit, wind speed and solar radiation as important abiotic drivers influencing transpiration and photosynthesis. Stepwise multiple regression analyses with these meteorological predictors either were biased by high collinearity of the independent variables or could not enhance the ability to explain the variability of RS. We assume maintenance respiration to dominate under humid conditions unfavourable for energy acquisition of the tree, thus explaining the pronounced uncoupling of RS from atmospheric parameters. In contrast, the drier and hotter climate of the dry season seems to favour RS via enhanced assimilatory substrate delivery and stem respiratory activity as well as elevated xylem sap CO2 imports with increased transpiration. In addition, tree individual differences in the temperature responses of RS may mirror diverging climatic adaptations of co-existing moist forest tree species which have their distribution centre either at higher or lower elevations. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the effects of the phenotypes of body melanization on the desiccation resistance of Drosophila melanogaster. It mentions the use of regression and statistical analysis, and the Biowizard image analysis software to study physiological traits of the flies in the Indian subcontinent. Results show that darker and intermediate phenotypes have higher desiccation resistance while lighter phenotypes have lower desiccation but with higher water loss.

Abstract: In this study, we present a new analysis of the costal skeleton of the Kebara 2 Neandertal that challenges the original description of the fossil remains. In addition to correcting an erroneous rib rejoin, we document that Kebara 2 shows significant metric and morphological differences in comparison to a wide range of modern human comparative samples. Moreover, Kebara 2''s thorax is large, but it is not an isometrically scaled version of a modern human thorax. We also present updated information regarding additional Neandertal rib remains that weakens the case for previous speculations regarding marked ecogeographical patterning in the Neandertal upper thorax. From these results, in combination with various other lines of evidence, we hypothesize that the large chest of Neandertals, while different from modern humans, is not autapomorphic but instead related to a “primitive body bauplan”: wide bodies with high body mass. A large thorax in pre-modern Homo, indicating a large vital capacity, would be consistent with the idea of increased oxygen consumption derived from higher energetic demands of a larger body and higher activity levels when compared to modern industrial samples. The likely presence of larger chests in the large bodied individuals from the middle Pleistocene of Eurasia and Africa (and even from the African lower Pleistocene) calls into question cold climate adaptation as a primary force for this skeletal morphology in Neandertals. Resumen: En este estudio presentamos un nuevo análisis del esqueleto costal del Neandertal Kébara 2 que discute la descripción original de estos fósiles. Además de corregir una reconstrucción errónea de una de las costillas, documentamos que Kébara 2 muestra diferencias significativas tanto métrica como morfológicamente al comparar este individuo con una amplia serie de muestras de comparación modernas. Además, el tórax de Kébara 2 es grande, pero no es una versión isométricamente escalada de un tórax moderno. También presentamos información actualizada de otros restos de costillas de Neandertal que debilitan especulaciones previas sobre un patrón ecogeográfico en la parte superior del tórax en esta especie. A partir de estos resultados, unidos a otra serie de evidencias, hipotetizamos que el gran tórax de los Neandertales, siendo distinto del de los humanos modernos, no es autapomórfico sino que está en relación con un “modelo primitivo de cuerpo”que consiste en cuerpos anchos con gran masa corporal. Un tórax grande en las especies de Homo distintas de la nuestra, indicativo de una gran capacidad pulmonar, sería coherente con la idea de una necesidad de un gran consumo de oxígeno derivada de una mayor demanda energética de un cuerpo grande que presenta altos niveles de actividad cuando lo comparamos con las muestras modernas provenientes de sociedades industriales. La probable presencia de grandes troncos en individuos de gran tamaño del Pleistoceno Medio de Europa y África (e incluso del Pleistoceno inferior) cuestiona la adaptación al frío como el principal condicionante de esta morfología esqueletal en los Neandertales. [Copyright &y& Elsevier]

We studied variations in genetic, physiological, and ecological traits, and the phylogenetic relationship among sexual and parthenogenetic populations of Asobara japonica, a larval parasitoid of drosophilid flies, in order to understand how they adapt to local environments and have differentiated. The strain from Iriomote-jima (IR) differed from other Japanese strains in the nucleotide sequences of its cytochrome oxidase subunit I (COI) and in not undergoing diapause and having a shorter preimaginal period and a higher adult tolerance of cold. The strains other than IR showed a low level of nucleotide variation in COI but varied in their mode of reproduction; the strains from the Ryukyu Islands were sexual, whereas those from the main islands of Japan and Ogasawara were parthenogenetic. In addition, strains from higher latitudes generally showed a high incidence of diapause, although there were some exceptions. On the other hand, preimaginal period and adult cold tolerance varied little among the strains excluding IR, and pupal cold tolerance, oviposition preference and incidence of parasitism varied little among the strains including IR. Evolution and environmental adaptations in this species are discussed, particularly focusing on parthenogenetic populations. [ABSTRACT FROM AUTHOR]

Abstract: Neandertals have been characterized as possessing features indicative of cold-climate adaptation largely based on ecogeographical morphological patterning found in recent humans. Interestingly, one character that deviates from this pattern is a relatively wide nasal aperture. The ecogeographical patterning of the nasal aperture in recent humans would predict instead that Neandertals should exhibit reduced nasal breadth dimensions. To explain this apparent anomaly it has been argued that a reduction in Neandertal nasal breadth was not possible due to dentognathic constraints on their midfaces via large anterior palatal breadth dimensions, especially large intercanine distances. A complicating factor in understanding the relationship between anterior palate breadth and nasal breadth is that both measurements are also correlated with facial prognathism. It is, therefore, unknown to what degree the relationship between anterior palate breadth and nasal breadth in Neandertals is a function of the pleisiomorphic retention of a prognathic facial skeleton. We used path analysis to test for a causal relationship between intercanine breadth and nasal breadth taking into account the potential effect of facial projection and facial prognathism (i.e., basion-nasion length and basion-prosthion length) using a large sample of geographically diverse recent and fossil Homo. Additionally, we examined the ontogenetic relationship between nasal breadth and intercanine breadth using a longitudinal human growth series to determine whether these variables exhibit similar growth trajectories. The results of these analyses indicate a weaker association between intercanine breadth and nasal breadth than expected, and that more variation in nasal breadth can be explained through basion-prosthion length rather than anterior palatal breadth dimensions. Moreover, the ontogenetic development of anterior palate breadth does not correspond to the growth trajectory of the breadth of the nose. These results explain the apparent paradox of wide piriform apertures in generally cooler climate-adapted Neandertals without resorting to dentognathic constraints, and provide additional insight into both the adaptive and nonadaptive (i.e., neutral) basis for Neandertal facial evolution. [Copyright &y& Elsevier]

Abstract: Paleoanthropologists have long noted the unique “hyper-barrel-shaped” Neandertal thorax as inferred from fragmentary ribs, clavicles, and sterna. Yet scholars disagree whether the Neandertal thorax represents an adaptation to cold climates or elevated activity levels. Given the difficulties of reconstructing overall chest shape from isolated and fragmentary thoracic skeletal elements, it is worthwhile comparing Neandertals and contemporaneous early modern human fossils from the same geographic region to recent modern human skeletons that are known to have enlarged chests. This study compares thoracic skeletal morphology in two Near Eastern Neandertals (Tabūn C1 and Shanidar 3) and two early modern humans from the same region (Skhūl IV and V) with four samples of recent modern human skeletons from the Andes (n=347): two coastal groups and two groups from high altitudes. The two highland groups, similar to their living descendants, exhibit morphological evidence of anteroposteriorly deep and mediolaterally wide chests as part of respiratory adaptations to high-altitude hypoxia. I calculated the percentage of deviation of each Neandertal and early modern human fossil from the means of the four recent modern human samples for clavicle and rib lengths and curvatures. Shanidar 3 and Tabūn C1 exhibit ribs that are slightly larger and less curved than the Andean samples, indicating slightly larger thoracic skeletons than modern humans who are known to have enlarged chests in response to increased respiratory demands. Skhūl IV and V have significantly shorter ribs with greater curvature suggesting especially narrow thoracic skeletons. Comparisons with Andean populations suggest that the enlarged thoraces of Neandertals may reflect high activity levels, although results from this study do not exclude cold adaptation as an explanatory factor. [Copyright &y& Elsevier]

Photoperiodism is the ability of organisms to assess and use the day length as an anticipatory cue to time seasonal events in their life histories. Photoperiodism is especially important in initiating physiological and developmental processes that are typically irrevocable and that culminate at a future time or at a distant place; the further away in space or time, the more likely a seasonal event is initiated by photoperiod. The pervasiveness of photoperiodism across broad taxa, from rotifers to rodents, and the predictable changes of photoperiodic response with geography identify it as a central component of fitness in temperate and polar seasonal environments. Consequently, the role of day length cannot be disregarded when evaluating the mechanisms underlying life-historical events, range expansions, invasions of novel species, and response to climate change among animals in the temperate and polar regions of the world. [ABSTRACT FROM AUTHOR]

Pursuant to his major research interest in the cultural ecology of hunter-gatherers, Birdsell collected an unparalleled body of phenotypic data on Aboriginal Australians during the mid twentieth century. Birdsell did not explicitly relate the geographic patterning in his data to Australia's climatic variation, instead arguing that the observable differences between groups reflect multiple origins of Australian Aborigines. In this article, bivariate correlation and multivariate analyses demonstrate statistically significant associations between climatic variables and the body build of Australians that are consistent with the theoretical expectations of Bergmann's and Allen's rules. While Australian Aborigines in comparison to Eurasian and New World populations can be generally described as long-headed, linear in build, and characterized by elongated distal limbs, the variation in this morphological pattern across the continent evidently reflects biological adaptation to local Holocene climates. These results add to a growing body of evidence for the role of environmental selection in the development of modern human variation. [ABSTRACT FROM AUTHOR]

Variation in the incidence of diapause in local populations of Helicoverpa armigera (Hübner) and Helicoverpa assulta (Guenée) (Lepidoptera: Noctuidae) was examined in relation to changes in photoperiod and/or temperature during the larval period. Temperate zone populations of H. assulta, a native species in temperate Japan, showed a high incidence of diapause induction when only the photoperiod was decreased during the larval period, even at favorable temperatures. This photoperiod-dependent response may allow H. assulta to foresee the beginning of autumn well in advance in the temperate zone, where temperature conditions are severe. In contrast, temperate zone populations of H. armigera, an invasive and polyphagous species mainly distributed in the subtropics, showed a high incidence of diapause only when both photoperiod and temperature decreased, whereas subtropical populations showed a very low incidence of diapause under the same conditions. Furthermore, both temperate zone and subtropical populations of H. armigera enter diapause under constant low temperatures at short-day photoperiod. Thus, there is geographic variation in sensitivity to diapause-inducing stimuli (changes in photoperiod and temperature) in H. armigera. This variation may be a part of the climatic adaptation achieved by H. armigera in Japan. [ABSTRACT FROM AUTHOR]

The mane characteristics of lions Panthera leo in the greater Tsavo ecosystem (GTE) were compared with those of lions from the equatorial middle-elevation plains (EMEP). Contrary to popular belief, most full-grown GTE lions are not maneless; 87% had manes, with 49% possessing good manes. The manes of GTE lions, however, were poorer on average, relative to age, than the manes of EMEP lions. For both groups, there was a significant relationship between age and mane type. In EMEP lions, mane development started early and grew to a full mane by age 4–5. In GTE lions, mane development began later and developed more slowly. Delayed onset and a slower rate of development are correlated with the consistently hot Tsavo climate. Poorly maned but fully mature lions mated actively, showing dissociation between mane development and sexual maturity. The correlation between climate and mane development suggests that climatic adaptation results in the inhibition and/or delay in the development of a secondary sexual character without compromising reproductive viability. [ABSTRACT FROM AUTHOR]

The two major rhythms of the biosphere are daily and seasonal; the two major adaptations to these rhythms are the circadian clock, mediating daily activities, and the photoperiodic timer, mediating seasonal activities. The mechanistic connection between the circadian clock and the photoperiodic timer remains unresolved. Herein, we show that the rhythmic developmental response to exotic light : dark cycles, usually used to infer a causal connection between the circadian clock and the photoperiodic timer, has evolved independently of the photoperiodic timer in the pitcher-plant mosquito Wyeomyia smithii across the climatic gradient of eastern North America from Florida to Canada and from the coastal plain to the mountains. We conclude that the photoperiodic timing of seasonal events can evolve independently of the daily circadian clock. [ABSTRACT FROM AUTHOR]

The unusual discovery of associated cranial and postcranial elements from a single Middle Pleistocene fossil human allows us to calculate body proportions and relative cranial capacity (encephalization quotient) for that individual rather than rely on estimates based on sample means from unassociated specimens. The individual analyzed here (Jinniushan) from northeastern China at 260,000 years ago is the largest female specimen yet known in the human fossil record and has body proportions (body height relative to body breadth and relative limb length) typical of cold-adapted populations elsewhere in the world. Her encephalization quotient of 4.15 is similar to estimates for late Middle Pleistocene humans that are based on mean body size and mean brain size from unassociated specimens. [ABSTRACT FROM AUTHOR]

Larvae of the butterflyLycaena tityrus(Poda) are reared at 20 or 27 °C until adult eclosion, after which they are maintained at the same temperature or are transferred to the alternate temperature. The resulting adults are exposed to−20 °C for 8 min, returned to ambient temperature, and the recovery time to standing position is recorded. On the day of eclosion, individuals reared at 20 °C show 19% shorter recovery times than individuals reared at 27 °C. This effect of developmental temperature disappears when the same animals are tested 3 and 6 days later. However, adult temperature did not affect recovery time in these animals, presumably due to over-riding effects of previous cold shocks. This is suggested by another set of animals, not having experienced previous cold shocks, demonstrating recovery times that are 28% shorter in individuals maintained as adults for 3 days at 20 compared to 27 °C. Thus,L. tityrusappears to be capable of adapting to local temperatures. [ABSTRACT FROM AUTHOR]

We analyzed genetic variation among geographically diverse populations of Drosophila and showed that tropical flies are more tolerant than temperate ones to heat-induced male sterility, as assessed by the presence of both motile sperm and progeny production. In tropical populations, the temperature inducing 50% sterility (median threshold) is 1°C above the value for temperate populations (30.4 vs. 29.4°C). When transferred to a mild permissive temperature (21°C), males recover fertility. Recovery time is proportional to pre-adult culture temperature. At these temperatures, recovery time is greater for temperate than for tropical populations. Crosses between a temperate and a tropical strain (F1, F2 and successive backcrosses) revealed that the Y chromosome was responsible for much of the geographic variation. Sterile males exhibited diverse abnormalities in the shape and position of sperm nuclei. However, impairment of the spermatid elongation seems to be the major factor responsible for sperm inviability. Heat-induced male sterility seems to be quite a general phenomenon in Drosophilid species and variation of threshold temperatures may be important for explaining their geographic distributions. [ABSTRACT FROM AUTHOR]

Dependence of photoperiodic response of growth cessation on the stage of development was examined in seedlings of Norway spruce (Picea abies (L.) Karst.) and silver birch (Betula pendula Roth) in greenhouses with 20 °C day and 10 °C night temperatures. Different combinations of photoperiod and stage of development were created by repeating sowing five times with 2 week intervals during the summer. During the experiment light conditions were natural but the daily temperature sum accumulation was regulated to be constant. Eight origins of spruce and seven origins of birch from different latitudes (60–67°N) in Finland were used. In the first growing season both Norway spruce and silver birch seedlings from the first sowings required a longer time for growth cessation than seedlings from the later sowings. However, because the seedlings from the first sowings ceased their growth on an earlier calendar date, the night length at the time of growth cessation was shorter for the seedlings from the first sowings. The results suggest that the variation in the timing of growth cessation of Norway spruce and silver birch seedlings during the first growing season was explained jointly by night length and stage of development. Seedlings from northern origins stopped their growth with shorter night length than those from southern origins. The effects of latitude and average temperature sum of the original growing site on the critical night length of growth cessation in the first growing season were stronger in Norway spruce than in silver birch. In the second growing season the sowing time did not affect the timing of the formation of the terminal buds, but slightly affected the timing of height growth cessation of Norway spruce and silver birch seedlings. [Copyright &y& Elsevier]

Absence or long delay of budbreak, also known as prolonged dormancy, is the most important symptom during incomplete dormancy. Budbreak number was evaluated to quantify seedling response to chilling and selection on excised and intact 1-year-old apple (Malus xdomestica Borkh.) seedlings under controlled and natural environmental conditions. Indices based on: 1) the number and distribution of budbreak (prolonged dormancy grade = PDG); 2) the number of buds breaking, including shoot length with increased budbreak as part of the calculation (prolonged dormancy index = PDI); and 3) budbreak number per 100-cm shoot (NB) were tested in association with budbreak time (TB). The indices expressed the effects of cold treatments that induce earlier and higher numbers of budbreak. PDI and NB, but not PDG, identified families with increased budbreak. Seedlings with high PDG and NB were also associated with families in which high chill requiring parents were used, indicating that TB as pre-selection criterion may fail to identify seedlings with increased budbreak. Response to pre-selection for increased budbreak using PDG could be verified with the PDS and NB indices in seedlings and seedling clones. The NB of intact 1-year-old shoots under natural conditions is recommended as a pre-selection criterion against prolonged dormancy in suboptimal winter conditions. [ABSTRACT FROM AUTHOR]

Summary 1. The time required for an ectotherm to recover from cold exposure is a useful, non-lethal index of cold tolerance. We explore how recovery times are affected by exposure to low temperatures, develop statistical methodologies, and study geographic variation in recovery time in four populations of Drosophila subobscura , a cold-tolerant species. 2. We exposed flies to a low temperature (-7 °C to 1 °C) for 16 h, returned them to ambient temperature, and recorded the elapsed time (‘recovery time’) until they stood. Other flies were exposed to even colder temperatures (-11 °C to -7 °C), but for shorter times. 3. Recovery times were inversely related to exposure temperature, but had a plateau between -6 °C and -4 °C. 4. Populations had similar recovery times at ‘warm’ temperatures, but two subtropical populations had relatively long recovery times at colder temperatures. 5. Inter-population differences were also evident in a regression analysis, and recovery times were inversely related to latitude (ordered-factor analysis). Populations differed slightly in the slopes of regressions but differed strongly in their intercepts. 6. The physiological mechanisms underlying the non-linear responses are unknown, but the plateau region suggests that recovery time is governed by the interplay of two temperature-dependent processes. Two models are proposed for the interaction of these processes. [ABSTRACT FROM AUTHOR]

We analyzed the variability of a large maize ( Zea mays L.) collection of152 tropical populations for photoperiod sensitivity and grain productivityunder long-day conditions to investigate their potential adaptation to temperateconditions. A multilocal experimental design was used: one location withshort-day conditions (Guadeloupe), one location with medium-day conditions (latesowing in the south of France) and two locations with long-day conditions (earlysowing in both the North and South of France). The photoperiod sensitivity wasestimated by the slope of the regression of thermal time from sowing to 50%anthesis on photoperiod. We found highly significant effects of latitude andaltitude of the collecting site of the population on photoperiod sensitivity anda significant but small interaction between these two factors. Populationsoriginated from low altitudes and low latitudes are highly sensitive tophotoperiod, whereas highland populations never display a high photoperiodsensitivity, whatever the latitude of origin. Grain productivity under long-dayconditions was not highly correlated with photoperiod sensitivity. Andeanpopulations were little sensitive to photoperiod and exhibited poor grainproduction under long-day conditions. In contrast, some populations from theCaribbean such as populations from Cuban Flint and Early Caribbean racesexhibited a good grain production although sensitive to photoperiod. The goodadaptation of some Caribbean material to temperate conditions is consistent withthe hypothesis of the successful introduction of Caribbean germplasm in southernregions of the Old World. [ABSTRACT FROM AUTHOR]