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Population Differences (population + difference)
Selected AbstractsAtlantic salmon Salmo salar L., brown trout Salmo trutta L. and Arctic charr Salvelinus alpinus (L.): a review of aspects of their life historiesECOLOGY OF FRESHWATER FISH, Issue 1 2003A. Klemetsen Abstract ,,,Among the species in the family Salmonidae, those represented by the genera Salmo, Salvelinus, and Oncorhynchus (subfamily Salmoninae) are the most studied. Here, various aspects of phenotypic and life-history variation of Atlantic salmon Salmo salar L., brown trout Salmo trutta L., and Arctic charr Salvelinus alpinus (L.) are reviewed. While many strategies and tactics are commonly used by these species, there are also differences in their ecology and population dynamics that result in a variety of interesting and diverse topics that are challenging for future research. Atlantic salmon display considerable phenotypic plasticity and variability in life-history characters ranging from fully freshwater resident forms, where females can mature at approximately 10 cm in length, to anadromous populations characterised by 3,5 sea-winter (5SW) salmon. Even within simple 1SW populations, 20 or more spawning life-history types can be identified. Juveniles in freshwater can use both fluvial and lacustrine habitats for rearing, and while most smolts migrate to sea during the spring, fall migrations occur in some populations. At sea, some salmon undertake extensive oceanic migrations while other populations stay within the geographical confines of areas such as the Baltic Sea. At the other extreme are those that reside in estuaries and return to freshwater to spawn after spending only a few months at sea. The review of information on the diversity of life-history forms is related to conservation aspects associated with Atlantic salmon populations and current trends in abundance and survival. Brown trout is indigenous to Europe, North Africa and western Asia, but was introduced into at least 24 countries outside Europe and now has a world-wide distribution. It exploits both fresh and salt waters for feeding and spawning (brackish), and populations are often partially migratory. One part of the population leaves and feeds elsewhere, while another part stays as residents. In large, complex systems, the species is polymorphic with different size morphs in the various parts of the habitat. Brown trout feed close to the surface and near shore, but large individuals may move far offshore. The species exhibits ontogenetic niche shifts partly related to size and partly to developmental rate. They switch when the amount of surplus energy available for growth becomes small with fast growers being younger and smaller fish than slow growers. Brown trout is an opportunistic carnivore, but individuals specialise at least temporarily on particular food items; insect larvae are important for the young in streams, while littoral epibenthos in lakes and fish are most important for large trout. The sexes differ in resource use and size. Females are more inclined than males to become migratory and feed in pelagic waters. Males exploit running water, near-shore and surface waters more than females. Therefore, females feed more on zooplankton and exhibit a more uniform phenotype than males. The Arctic charr is the northernmost freshwater fish on earth, with a circumpolar distribution in the Holarctic that matches the last glaciation. Recent mtDNA studies indicate that there are five phylogeographic lineages (Atlantic, Arctic, Bering, Siberian and Acadian) that may be of Pleistocene origin. Phenotypic expression and ecology are more variable in charr than in most fish. Weights at maturation range from 3 g to 12 kg. Population differences in morphology and coloration are large and can have some genetic basis. Charr live in streams, at sea and in all habitats of oligotrophic lakes, including very deep areas. Ontogenetic habitat shifts between lacustrine habitats are common. The charr feed on all major prey types of streams, lakes and near-shore marine habitats, but has high niche flexibility in competition. Cannibalism is expressed in several cases, and can be important for developing and maintaining bimodal size distributions. Anadromy is found in the northern part of its range and involves about 40, but sometimes more days in the sea. All charr overwinter in freshwater. Partial migration is common, but the degree of anadromy varies greatly among populations. The food at sea includes zooplankton and pelagic fish, but also epibenthos. Polymorphism and sympatric morphs are much studied. As a prominent fish of glaciated lakes, charr is an important species for studying ecological speciation by the combination of field studies and experiments, particularly in the fields of morphometric heterochrony and comparative behaviour. [source] THE EVOLUTION OF SEXUAL SIZE DIMORPHISM IN THE HOUSE FINCH.EVOLUTION, Issue 6 2000Abstract Recent colonization of ecologically distinct areas in North America by the house finch (Carpodacus mexicanus) was accompanied by strong population divergence in sexual size dimorphism. Here we examined whether this divergence was produced by population differences in local selection pressures acting on each sex. In a long-term study of recently established populations in Alabama, Michigan, and Montana, we examined three selection episodes for each sex: selection for pairing success, overwinter survival, and within-season fecundity. Populations varied in intensity of these selection episodes, the contribution of each episode to the net selection, and in the targets of selection. Direction and intensity of selection strongly differed between sexes, and different selection episodes often favored opposite changes in morphological traits. In each population, current net selection for sexual dimorphism was highly concordant with observed sexual dimorphism,in each population, selection for dimorphism was the strongest on the most dimorphic traits. Strong directional selection on sexually dimorphic traits, and similar intensities of selection in both sexes, suggest that in each of the recently established populations, both males and females are far from their local fitness optimum, and that sexual dimorphism has arisen from adaptive responses in both sexes. Population differences in patterns of selection on dimorphism, combined with both low levels of ontogenetic integration in heritable sexually dimorphic traits and sexual dimorphism in growth patterns, may account for the close correspondence between dimorphism in selection and observed dimorphism in morphology across house finch populations. [source] Population differences in the International Multi-Centre ADHD Gene ProjectGENETIC EPIDEMIOLOGY, Issue 2 2008Benjamin M. Neale Abstract The International Multi-Centre ADHD Gene sample consists of 674 families from eight countries (Belgium, England, Germany, Holland, Ireland, Israel, Spain, and Switzerland) ascertained from clinics for combined-type attention definity hyperactivity disorder in an offspring. 863 SNPs were successfully genotyped across 47 autosomal genes implicated in psychiatric disorders yielding a single nucleotide polymorphism (SNP) density of approximately one SNP per 2.5,kb. A global test of heterogeneity showed 269 SNPs nominally significant (expected 43). Inclusion of the Israeli population accounted for approximately 70% of these nominally significant tests. Hardy-Weinberg equilibrium tests suggest that combining all these populations would induce stratification, but that the Northern European populations (Belgium, England, Germany, Holland, and Ireland) could be appropriate. Tag SNPs were generated using pair-wise and aggressive tagging from Carlson et al. [2004] and de Bakker et al. [2005], respectively, in each population and applied to the other populations. Cross-population performance across Northern Europe was consistent with within population comparisons. Smaller sample size for each population tended to yield more problems for the generation of aggressive tags and the application of pair-wise tags. Any case-control sample employing an Israeli sample with Northern Europeans must consider stratification. A Northern European tag set, however, appears to be appropriate for capturing the variation across populations. Genet. Epidemiol. 2008. © 2007 Wiley-Liss, Inc. [source] Population differences in behaviour are explained by shared within-population trait correlationsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2010JONATHAN N. PRUITT Abstract Correlations in behavioural traits across time, situation and ecological context (i.e. ,behavioural syndromes' or ,personality') have been documented for a variety of behaviours, and in diverse taxa. Perhaps the most controversial inference from the behavioural syndromes literature is that correlated behaviour may act as an evolutionary constraint and evolutionary change in one's behaviour may necessarily involve shifts in others. We test the two predictions of this hypothesis using comparative data from eighteen populations of the socially polymorphic spider, Anelosimus studiosus (Araneae, Theriidae). First, we ask whether geographically distant populations share a common syndrome. Second, we test whether population differences in behaviour are correlated similarly to within-population trait correlations. Our results reveal that populations separated by as much as 36° latitude shared similar syndromes. Furthermore, population differences in behaviour were correlated in the same manner as within-population trait correlations. That is, population divergence tended to be along the same axes as within-population covariance. Together, these results suggest a lack of evolutionary independence in the syndrome's constituent traits. [source] Skin reactivity to histamine and to allergens in unselected 9-year-old children living in Poland and ItalyPEDIATRIC ALLERGY AND IMMUNOLOGY, Issue 3 2003Roberto Ronchetti Several studies have shown a higher prevalence of positive skin-prick tests to airborne allergens in Western than in Eastern European countries. We have recently reported that skin histamine reactivity significantly increased in Italy over the past 15 years. Population differences in skin histamine reactivity could, at least in part, explain the reported differences in positive allergen skin tests. To test this hypothesis we compared histamine skin reactivity and the prevalence of allergen positive skin-prick tests in a sample of Italian and Polish schoolchildren. A total of 336 unselected 9-year-old-schoolchildren (198 in Italy and 138 in Poland) underwent skin-prick tests with three different histamine concentrations (10, 1 and 0.2 mg/ml) and with a panel of common airborne allergens according to the ISAAC protocol, phase two. Mean wheals elicited by skin-prick tests with the three serial concentrations of histamine were significantly larger (p < 0.001) and shifted more toward higher values (p < 0.001) in Italian than in Polish children. The differences were greater for the intermediate histamine concentration tested (1 mg/ml) than for the highest concentration (10 mg/ml). Skin-prick tests for airborne allergens were more frequently positive in Italian children: wheals ,,3 mm induced by any allergen [odds ratio (OR) 1.69; confidence interval (CI) 0.98,2.92] by Dermatophagoides pteronyssinus (OR 1.92; CI 0.97,3.80) and by D. farinae (OR 3.15; CI 1.16,8.63). Labeling as positive allergen wheal reactions half the size of the 10 mg/ml histamine wheal or larger reduced but did not abolish the Italian,Polish differences. The significantly higher skin histamine reactivity observed in Italian children could help to explain why allergen skin-test reactions differ in the East and West European populations. Moreover, differences in nonallergen-specific factors among populations should be considered in the interpretation of skin test results (e.g. cut-off points). To obtain meaningful results, epidemiological studies of allergies should include serial histamine dilutions. [source] Population differences in the testosterone levels of young men are associated with prostate cancer disparities in older menAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 4 2010Louis Calistro Alvarado Although there is evidence that greater exposure to testosterone is associated with an increased risk of prostate cancer, a recent analysis of 18 prospective studies found no relationship between levels of endogenous sex hormones and prostate cancer development. However, the reviewed studies were subject to methodological constraints that would obscure any potential relationship between prostate cancer and androgenic hormones. If prostate cancer risk is mediated by lifetime exposure to testosterone, then case-control studies that concentrate on endogenous sex hormones near the ages that prostate cancer is diagnosed would provide limited information on cumulative testosterone exposure across the lifespan. Alternately, early adulthood has been suggested as the most salient period to evaluate the influence of steroid physiology on prostate carcinogenesis. As such, an exhaustive literature search was completed to obtain testosterone values reported for study samples of younger men, along with prostate cancer incidences for the larger populations from which the study populations were sampled. A novel analytical method was developed to standardize, organize, and examine 12 studies reporting testosterone levels for 28 population samples. Study populations were generally apportioned according to ethnicity and geographic residence: Americans of African, Asian, Caucasian, and Hispanic ancestry from several different regions within the United States as well as men from China, Germany, Japan, Kuwait, New Zealand, South Korea, and Sweden. Population differences in the testosterone levels of young men were significantly associated with population disparities in the prostate cancer incidence of older men (Spearman's rho = 0.634, p = 0.002). Am. J. Hum. Biol. 2010. © 2010 Wiley-Liss, Inc. [source] The ontogeny of Holocene and Late Pleistocene human postcranial strengthAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2010Libby W. Cowgill Abstract While a wide variety of studies have focused on population variation in adult cross-sectional properties, relatively little is known about population variation in postcranial robusticity in immature individuals. Furthermore, the age at which the population differences readily detected in adults manifest during growth is also unknown. This research addresses these gaps in our current understanding through the analysis of immature humeral and femoral long bone strength. Cross-sectional geometry was used to compare the developmental trajectories of diaphyseal strength in Late Pleistocene Neandertal and modern human subadults to a sample of immature humans from seven geographically diverse Holocene populations. Population differences in size-standardized cross-sectional properties appear to be systemic and develop very early in ontogeny in the Holocene sample. In many cases, these differences are present before one year of age. In general, the Late Pleistocene fossil samples fit within the range of recent human variation in long bone strength. Population differences detected here are likely related to a combination of factors including activity patterns, genetic propensities, and nutritional status. These results highlight the complex mosaic of processes that result in adult postcranial robusticity, and suggest that further exploration of the developmental interplay between intrinsic and extrinsic influences on skeletal robusticity will likely enhance our understanding of adult postcranial morphology. Am J Phys Anthropol 2010. © 2009 Wiley-Liss, Inc. [source] Genetic, geographic, and environmental correlates of human temporal bone variationAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2007Heather F. Smith Abstract Temporal bone shape has been shown to reflect molecular phylogenetic relationships among hominoids and offers significant morphological detail for distinguishing taxa. Although it is generally accepted that temporal bone shape, like other aspects of morphology, has an underlying genetic component, the relative influence of genetic and environmental factors is unclear. To determine the impact of genetic differentiation and environmental variation on temporal bone morphology, we used three-dimensional geometric morphometric techniques to evaluate temporal bone variation in 11 modern human populations. Population differences were investigated by discriminant function analysis, and the strength of the relationships between morphology, neutral molecular distance, geographic distribution, and environmental variables were assessed by matrix correlation comparisons. Significant differences were found in temporal bone shape among all populations, and classification rates using cross-validation were relatively high. Comparisons of morphological distances to molecular distances based on short tandem repeats (STRs) revealed a significant correlation between temporal bone shape and neutral molecular distance among Old World populations, but not when Native Americans were included. Further analyses suggested a similar pattern for morphological variation and geographic distribution. No significant correlations were found between temporal bone shape and environmental variables: temperature, annual rainfall, latitude, or altitude. Significant correlations were found between temporal bone size and both temperature and latitude, presumably reflecting Bergmann's rule. Thus, temporal bone morphology appears to partially follow an isolation by distance model of evolution among human populations, although levels of correlation show that a substantial component of variation is unexplained by factors considered here. Am J Phys Anthropol 2007. © 2007 Wiley-Liss, Inc. [source] Genetic architecture of population differences in oviposition behaviour of the seed beetle Callosobruchus maculatusJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2004C. W. Fox Abstract Few studies have examined the genetic architecture of population differences in behaviour and its implications for population differentiation and adaptation. Even fewer have examined whether differences in genetic architecture depend on the environment in which organisms are reared or tested. We examined the genetic basis of differences in oviposition preference and egg dispersion between Asian (SI) and African (BF) populations of the seed beetle, Callosobruchus maculatus. We reared and tested females on each of two host legumes (cowpea and mung bean). The two populations differed in mean oviposition preference (BF females preferred cowpea seeds more strongly than did SI females) and egg dispersion (SI females distributed eggs more uniformly among seeds than did BF females). Observations of hybrid and backcross individuals indicated that only the population difference in oviposition preference could be explained by complete additivity, whereas substantial dominance and epistasis contributed to the differences in egg dispersion. Both rearing host and test host affected the relative magnitude of population differences in egg dispersion and the composite genetic effects. Our results thus demonstrate that the relative influence of epistasis and dominance on the behaviour of hybrids depends on the behaviour measured and that different aspects of insect oviposition are under different genetic control. In addition, the observed effect of rearing host and oviposition host on the relative importance of dominance and epistasis indicates that the genetic basis of population differences depends on the environment in which genes are expressed. [source] Optimal environmental and industrial policies and imperfect agglomeration effectsREGIONAL SCIENCE POLICY AND PRACTICE, Issue 2 2009Daisuke Ikazaki Agglomeration; technology; environment Abstract This paper examines a simple general equilibrium model that considers problems related to agglomeration, technology, and the environment. First, it is shown that the manufactured goods sector converts from classical technology with constant returns to scale to modern technology with increasing returns to scale as the regional population increases. The optimal pollution level might be an inverted-U shape with respect to population if optimal environmental policy is adopted. Second, the optimal population level of conversion is not attained in the market economy. The labour that is devoted to the manufactured goods sector in the market economy is too small. So, we derive the optimal subsidy rates to the manufactured goods sector to make resource allocation optimum. Third, we consider migration using the two-region model. One region becomes a large city and the other region becomes a rural area if the total population is large. The industrial policy tends to extend the population difference between city and rural areas. On the other hand, if the total population is small, a symmetric point will be stable equilibrium. [source] Conformational disorder in 4-(5,5,-dibromo-2,-chloro-4,4,-bipyridyl-2-yl)benzaldehyde: role of ,,, and halogen interactionsACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2010Mohamed Abboud The crystal packing of the title compound, C17H9Br2ClN2O, is governed by strong ,,, stacking, where molecules are tightly bound within infinite (100) planes; these planes interact mainly through non-optimal ,,, stacking where arene rings are noticeably displaced from perfect overlap, and also through halogen,halogen interactions. The aldehyde group shows conformational disorder, with a significant population difference between the two conformers; this difference is rationalized by the energetic analysis of the crystal packing using the PIXEL method, which also allows a decomposition of intermolecular interaction energy into Coulombic, polarization, dispersion and repulsion contributions. Using such an analysis, it is found that the main reason for this unequal population of the two conformers in the crystal is two hydrogen bonds that are present only for the major conformer. [source] Epidemiology of alcohol-related burden of disease among Indigenous AustraliansAUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH, Issue 2010Bianca Calabria Abstract Objective: To compare the burden of alcohol-related harm and underlying factors of this harm, by age and sex, for Indigenous and general population Australians. Methods: Population attributable fractions are used to estimate the disability adjusted life years (DALYs) for alcohol-related disease and injury. The DALYs were converted to rates per 1,000 by age and sex for the Indigenous and general populations. Results: Homicide and violence rates were much higher for Indigenous males: greatest population difference was for 30,44 years, Indigenous rate 8.9 times higher. Rates of suicide were also greater: the largest population difference was for 15,29 years, Indigenous rate 3.9 times higher. Similarly, for Indigenous females, homicide and violence rates were much higher: greatest population difference was for 30,44 years, Indigenous rate 18.1 times higher. Rates of suicide were also greater: the largest population difference was for 15,29 years, Indigenous rate 5.0 times higher. Conclusions: Alcohol consumption and associated harms are of great concern for Indigenous Australians across all ages. Violent alcohol-related harms have been highlighted as a major concern. Implications: To reduce the disproportionate burden of alcohol-related harm experienced by Indigenous Australians, targeted interventions should include the impact on families and communities and not just the individual. [source] Consistency of immigrant and country-of-birth suicide rates: a meta-analysisACTA PSYCHIATRICA SCANDINAVICA, Issue 4 2008M. Voracek Objective:, Multifaceted evidence (family, twin, adoption, molecular genetic, geographic and surname studies of suicide) suggests genetic risk factors for suicide. Migrant studies are also informative in this context, but underused. In particular, a meta-analysis of the associations of immigrant (IMM) and country-of-birth (COB) suicide rates is unavailable. Method:, Thirty-three studies, reporting IMM suicide rates for nearly 50 nationalities in seven host countries (Australia, Austria, Canada, England, the Netherlands, Sweden and the USA), were retrieved. Results:, Total-population IMM and COB suicide rates were strongly positively associated (combined rank-order correlation across 20 eligible studies: 0.65, 95% CI: 0.56,0.73, P < 10,9). The effect generalized across both sexes, host countries and study periods. Conclusion:, Following the logic of the migrant study design of genetic epidemiology, the correspondence of IMM and COB suicide rates is consistent with the assumption of population differences in the prevalence of genetic risk factors for suicide. [source] Host shifting by Operophtera brumata into novel environments leads to population differentiation in life-history traitsECOLOGICAL ENTOMOLOGY, Issue 5 2003Adam J. Vanbergen Abstract., 1. Operophtera brumata L. (Lepidoptera: Geometridae), a polyphagous herbivore usually associated with deciduous trees such as oak Quercus robur L., has expanded its host range to include the evergreen species heather Calluna vulgaris (L.) Hull and, most recently, Sitka spruce Picea sitchensis (Bong.) Carričre. 2. Phenology, morphology, and survival of O. brumata were measured at several life-history stages in populations from the three different host plant communities sampled from a range of geographical locations. The data were used to test for population differences, reflecting the marked differences in host-plant secondary chemistry, growth form, and site factors such as climate. The hypothesis that spruce-feeding populations originated from populations feeding on moorland, commonly sites of coniferous afforestation, was also tested. 3. Altitude, not host plant species, was the major influence on the timing of adult emergence. An effect of insect population independent of altitude was found, implying that additional unidentified factors contribute to this phenological variation. Larval survival and adult size varied between populations reared on different host plant species. Survival of larvae was affected negatively when reared on the novel host plant, Sitka spruce, versus the natal plant (oak or heather) but oak and heather-sourced insects did not differ in survivorship on Sitka spruce. 4. Host range extension into novel environments has resulted in population differentiation to the local climate, demonstrating that host shifts pose challenges to the herbivore population greater than those offered by the host plant alone. The hypothesis that Sitka spruce feeding populations have arisen predominantly from moorland feeding populations was not supported. [source] Assortative mating between adjacent populations of threespine stickleback (Gasterosteus aculeatus)ECOLOGY OF FRESHWATER FISH, Issue 1 2004R. J. Scott Abstract,,, The idea that sexual selection can lead to rapid evolution of premating isolation among independent populations (speciation) has been controversial, but is rapidly gaining acceptance among many evolutionary biologists as empirical examples accumulate. A survey of male signals and female preferences (mate recognition systems, MRSs) across the contact zone between divergent populations of threespine stickleback (Gasterosteus aculeatus) in Conner Creek, WA, revealed a spatial pattern of MRSs that is consistent with speciation via sexual selection. Females from locations that possessed melanic males preferred melanic males whereas females from populations possessing typical mosaic males (red chin, blue iris, and blue-green dorsum) preferred mosaic males. I argue that sensory drive sexual selection, acting through geographically varying spectral properties, is responsible for the observed population differences and premating isolation between the adjacent populations. [source] Correlation between population dynamics of mosquito larvae and their habitat qualitiesENTOMOLOGICAL RESEARCH, Issue 4 2008Lalit Mohan RANJEETA Abstract Surveillance of anopheline and culicine larvae was conducted fortnightly to determine population composition and density at seven sites in the area of the Mathura Refinery, Mathura, India during 2005,2006. The correlation between population of the vectors and their habitat quality was established. Temperature (0.978 and 0.85°C), pH (0.99 and 0.95), conductivity (0.98 and 0.98 mho) and calcium ion hardness (0.978 and 0.85 p.p.m.) were positively correlated with the populations of both larval species. In contrast, the correlation coefficients between the parameters total hardness, magnesium ion hardness, biochemical oxygen demand and chemical oxygen demand varied with the larval species. The anopheline larval population was dominant over the culicine population in the surveillance area. The distribution of anopheline mosquito larvae during the study period was found to be constant, and the average density of anopheline and culicine larvae was 84.70 and 15.30%, respectively, across all seven sites. Thus, the study demonstrated spatial and temporal population differences of mosquito larvae with respect to environmental factors, including water quality. [source] The adaptive value of personality differences revealed by small island population dynamicsEUROPEAN JOURNAL OF PERSONALITY, Issue 1 2007Andrea S. Camperio Ciani Abstract Whether differences in personality among populations really exist and, if so, whether they are only due to cultural and linguistic differences or have a genetically selected adaptive value, is a controversial issue. In this research, we compared three Italian populations living on three small archipelagos in the Tyrrhenian Sea (n,=,993), with their corresponding neighbouring mainlanders (n,=,598), i.e. sharing the same geographical origin, culture and language. We used an adjective-based Big Five questionnaire in order to measure personality traits in four categories of individuals for each archipelago/mainland population: (1) original islanders; (2) non-original islanders; (3) mainlanders and (4) immigrants to the islands. We further analysed original and non-original islanders who had or had not emigrated from the islands. We found that islanders had different personality traits from mainlanders, the former being more conscientious and emotionally stable and less extraverted and open to experience. We also found that the subgroup of islanders whose ancestors had inhabited their island for about 20 generations in isolation (original islanders, n,=,624) were less extraverted and open to experience than immigrants (n,=,193). In contrast, immigrants retained the typical personality profile of the mainland populations. Lastly, emigrants from the islands (n,=,209) were significantly more extraverted and open to experience than original and non-original islanders who had never left their island (n,=,741). We hypothesise that population differences in extraversion and openness to experience are more probably related to genetic differences which evolved rapidly, presumably through an active gene flow produced by selective emigration from the islands. Copyright © 2006 John Wiley & Sons, Ltd. [source] THE EVOLUTION OF SEXUAL SIZE DIMORPHISM IN THE HOUSE FINCH.EVOLUTION, Issue 6 2000Abstract Recent colonization of ecologically distinct areas in North America by the house finch (Carpodacus mexicanus) was accompanied by strong population divergence in sexual size dimorphism. Here we examined whether this divergence was produced by population differences in local selection pressures acting on each sex. In a long-term study of recently established populations in Alabama, Michigan, and Montana, we examined three selection episodes for each sex: selection for pairing success, overwinter survival, and within-season fecundity. Populations varied in intensity of these selection episodes, the contribution of each episode to the net selection, and in the targets of selection. Direction and intensity of selection strongly differed between sexes, and different selection episodes often favored opposite changes in morphological traits. In each population, current net selection for sexual dimorphism was highly concordant with observed sexual dimorphism,in each population, selection for dimorphism was the strongest on the most dimorphic traits. Strong directional selection on sexually dimorphic traits, and similar intensities of selection in both sexes, suggest that in each of the recently established populations, both males and females are far from their local fitness optimum, and that sexual dimorphism has arisen from adaptive responses in both sexes. Population differences in patterns of selection on dimorphism, combined with both low levels of ontogenetic integration in heritable sexually dimorphic traits and sexual dimorphism in growth patterns, may account for the close correspondence between dimorphism in selection and observed dimorphism in morphology across house finch populations. [source] A geometric morphometric study of regional differences in the ontogeny of the modern human facial skeleton,JOURNAL OF ANATOMY, Issue 3 2002Una Strand Višarsdóttir Abstract This study examines interpopulation variations in the facial skeleton of 10 modern human populations and places these in an ontogenetic perspective. It aims to establish the extent to which the distinctive features of adult representatives of these populations are present in the early post natal period and to what extent population differences in ontogenetic scaling and allometric trajectories contribute to distinct facial forms. The analyses utilize configurations of facial landmarks and are carried out using geometric morphometric methods. The results of this study show that modern human populations can be distinguished based on facial shape alone, irrespective of age or sex, indicating the early presence of differences. Additionally, some populations have statistically distinct facial ontogenetic trajectories that lead to the development of further differences later in ontogeny. We conclude that population-specific facial morphologies develop principally through distinctions in facial shape probably already present at birth and further accentuated and modified to variable degrees during growth. These findings raise interesting questions regarding the plasticity of facial growth patterns in modern humans. Further, they have important implications in relation to the study of growth in the face of fossil hominins and in relation to the possibility of developing effective discriminant functions for the identification of population affinities of immature facial skeletal material. Such tools would be of value in archaeological, forensic and anthropological applications. The findings of this study underline the need to examine more deeply, and in more detail, the ontogenetic basis of other causes of craniometric variation, such as sexual dimorphism and hominin species differentiation. [source] Population differences in behaviour are explained by shared within-population trait correlationsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2010JONATHAN N. PRUITT Abstract Correlations in behavioural traits across time, situation and ecological context (i.e. ,behavioural syndromes' or ,personality') have been documented for a variety of behaviours, and in diverse taxa. Perhaps the most controversial inference from the behavioural syndromes literature is that correlated behaviour may act as an evolutionary constraint and evolutionary change in one's behaviour may necessarily involve shifts in others. We test the two predictions of this hypothesis using comparative data from eighteen populations of the socially polymorphic spider, Anelosimus studiosus (Araneae, Theriidae). First, we ask whether geographically distant populations share a common syndrome. Second, we test whether population differences in behaviour are correlated similarly to within-population trait correlations. Our results reveal that populations separated by as much as 36° latitude shared similar syndromes. Furthermore, population differences in behaviour were correlated in the same manner as within-population trait correlations. That is, population divergence tended to be along the same axes as within-population covariance. Together, these results suggest a lack of evolutionary independence in the syndrome's constituent traits. [source] Genetic architecture of population differences in oviposition behaviour of the seed beetle Callosobruchus maculatusJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2004C. W. Fox Abstract Few studies have examined the genetic architecture of population differences in behaviour and its implications for population differentiation and adaptation. Even fewer have examined whether differences in genetic architecture depend on the environment in which organisms are reared or tested. We examined the genetic basis of differences in oviposition preference and egg dispersion between Asian (SI) and African (BF) populations of the seed beetle, Callosobruchus maculatus. We reared and tested females on each of two host legumes (cowpea and mung bean). The two populations differed in mean oviposition preference (BF females preferred cowpea seeds more strongly than did SI females) and egg dispersion (SI females distributed eggs more uniformly among seeds than did BF females). Observations of hybrid and backcross individuals indicated that only the population difference in oviposition preference could be explained by complete additivity, whereas substantial dominance and epistasis contributed to the differences in egg dispersion. Both rearing host and test host affected the relative magnitude of population differences in egg dispersion and the composite genetic effects. Our results thus demonstrate that the relative influence of epistasis and dominance on the behaviour of hybrids depends on the behaviour measured and that different aspects of insect oviposition are under different genetic control. In addition, the observed effect of rearing host and oviposition host on the relative importance of dominance and epistasis indicates that the genetic basis of population differences depends on the environment in which genes are expressed. [source] The role of predation in variation in body shape in guppies Poecilia reticulata: a comparison of field and common garden phenotypesJOURNAL OF FISH BIOLOGY, Issue 6 2009J. G. Burns The body shapes of both wild-caught and laboratory-reared male and female Trinidadian guppies Poecilia reticulata from two low-predation and two high-predation populations were studied, but predation regime did not seem to be the most important factor affecting body shape. Instead, complicated patterns of plasticity in body shape among populations and the sexes were found. In particular, populations differed in the depth of the caudal peduncle, which is the muscular region just anterior to the tail fin rays and from which most swimming power is generated. Strikingly, the direction of population differences in caudal peduncle depth observed in wild-caught individuals was reversed when P. reticulata were raised in a common laboratory environment. [source] Sexual Dimorphism in America: Geometric Morphometric Analysis of the Craniofacial Region,JOURNAL OF FORENSIC SCIENCES, Issue 1 2008Erin H. Kimmerle Ph.D. Abstract:, One of the four pillars of the anthropological protocol is the estimation of sex. The protocol generally consists of linear metric analysis or visually assessing individual skeletal traits on the skull and pelvis based on an ordinal scale of 1,5, ranging from very masculine to very feminine. The morphologic traits are then some how averaged by the investigator to estimate sex. Some skulls may be misclassified because of apparent morphologic features that appear more or less robust due to size differences among individuals. The question of misclassification may be further exemplified in light of comparisons across populations that may differ not only in cranial robusticity but also in stature and general physique. The purpose of this study is to further examine the effect of size and sex on craniofacial shape among American populations to better understand the allometric foundation of skeletal traits currently used for sex estimation. Three-dimensional coordinates of 16 standard craniofacial landmarks were collected using a Microscribe-3DX digitizer. Data were collected for 118 American White and Black males and females from the W.M. Bass Donated Collection and the Forensic Data Bank. The MANCOVA procedure tested shape differences as a function of sex and size. Sex had a significant influence on shape for both American Whites (F = 2.90; d.f. = 19, 39; p > F = 0.0024) and Blacks (F = 2.81; d.f. = 19, 37; p > F = 0.0035), whereas size did not have a significant influence on shape in either Whites (F = 1.69; d.f. = 19, 39; p > F = 0.08) or Blacks (F = 1.09; d.f. = 19, 37; p > F = 0.40). Therefore, for each sex, individuals of various sizes were statistically the same shape. In other words, while significant differences were present between the size of males and females (males on average were larger), there was no size effect beyond that accounted for by sex differences in size. Moreover, the consistency between American groups is interesting as it suggests that population differences in sexual dimorphism may result more from human variation in size than allometric variation in craniofacial morphology. [source] Associations of ALDH2 and ADH1B Genotypes With Alcohol-Related Phenotypes in Asian Young AdultsALCOHOLISM, Issue 5 2009Christian S. Hendershot Background:, Associations of ALDH2 and ADH1B genotypes with alcohol use have been evaluated largely using case,control studies, which typically focus on adult samples and dichotomous diagnostic outcomes. Relatively fewer studies have evaluated ALDH2 and ADH1B in relation to continuous drinking outcomes or at different developmental stages. This study examined additive and interactive effects of ALDH2 and ADH1B genotypes on drinking behavior in a mixed-gender sample of Asian young adults, focusing on continuous phenotypes (e.g., heavy episodic and hazardous drinking, alcohol sensitivity, drinking consequences) whose expression is expected to precede the onset of alcohol use disorders. Methods:, The sample included 182 Chinese- and Korean-American young adults ages 18 years and older (mean age = 20 years). Effects of ALDH2, ADH1B and ethnicity were estimated using generalized linear modeling. Results:, The ALDH2*2 allele predicted lower reported rates of alcohol use and drinking consequences as well as greater reported sensitivity to alcohol. There were significant ethnic group differences in drinking outcomes, such that Korean ethnicity predicted higher drinking rates and lower alcohol sensitivity. ADH1B status was not significantly related to drinking outcomes. Conclusions:, Ethnicity and ALDH2 status, but not ADH1B status, consistently explained significant variance in alcohol consumption in this relatively young sample. Results extend previous work by showing an association of ALDH2 genotype with drinking consequences. Findings are discussed in the context of possible developmental and population differences in the influence of ALDH2 and ADH1B variations on alcohol-related phenotypes. [source] Retrospective Study: Cause and clinical characteristics of rib fractures in cats: 33 cases (2000,2009)JOURNAL OF VETERINARY EMERGENCY AND CRITICAL CARE, Issue 4 2010Christine Adams DVM Abstract Objective , To characterize the clinical features and population differences among cats sustaining traumatic and nontraumatic rib fractures. Design , Retrospective clinical study. Setting , University small animal hospital. Animals , Thirty-three cats with radiographic evidence of rib fractures. Interventions , None. Measurements and Main Results , Cats with rib fractures were identified by performing a computer search of the radiology database. Thirty-three cats that sustained rib fractures were identified between January 2000 and September 2009. Seventeen cats had fractures due to trauma and 16 were deemed to occur from nontraumatic causes. A Mann-Whitney rank-sum test revealed statistically significant differences in the median ages between the 2 groups. Older cats were more likely to sustain rib fractures as a result of a presumed nontraumatic causes. A Chi-square analysis showed that nontraumatic fractures occurred significantly more often in the midbody region and involved the 9th,13th ribs. The majority of cats with presumed nontraumatic rib fracture had respiratory disease; the remaining cats had chronic renal disease or neoplasia. Cats with traumatic rib fractures had external signs of trauma. Conclusion , Rib fractures in cats may be clearly associated with trauma, or may be an incidental finding in cats with comorbidities. Cats with diseases that cause prolonged respiratory effort or coughing, metabolic diseases, or certain neoplasms, are at increased risk of spontaneous nontraumatic rib fractures. [source] Does the relationship between IgE and the CD14 gene depend on ethnicity?ALLERGY, Issue 11 2008G. Zhang This review considers the data from studies analysing associations between the CD14C,159T single nucleotide polymorphism (SNP) and asthmatic phenotypes and discusses the variability of the conclusions. By searching PubMed and EMBASE for articles on CD14C,159T -related population or family-based association studies, 47 were identified up till September 2007. Collectively, the studies reviewed herein consistently showed population differences in frequencies of the alleles of the SNP, with African descent having the highest C allele frequencies, followed by Caucasians and Asians. The T allele of the SNP was associated with increased sCD14 in some studies but not in others. Inconsistently, the C allele, or even occasionally the T allele, was associated with atopic phenotypes in a population subgroup. There are several explanations for these inconsistencies, including lack of power, linkage disequilibrium, gene,gene interactions, population admixture and gene,environment interactions. If the SNP was associated with functional changes to the coded protein and thus modulating susceptibility to allergic disease, its effect may be modest and dependent on other co-existent, ethnicity-specific, genetic or environmental risk factors. [source] Geographical variation of genetic and phenotypic traits in the Mexican sailfin mollies, Poecilia velifera and P. petenensisMOLECULAR ECOLOGY, Issue 9 2008S. J. HANKISON Abstract Comparing the patterns of population divergence using both neutral genetic and phenotypic traits provides an opportunity to examine the relative importance of evolutionary mechanisms in shaping population differences. We used microsatellite markers to examine population genetic structure in the Mexican sailfin mollies Poecilia velifera and P. petenensis. We compared patterns of genetic structure and divergence to that in two types of phenotypic traits: morphological characters and mating behaviours. Populations within each species were genetically distinct, and conformed to a model of isolation by distance, with populations within different geographical regions being more genetically similar to one another than were populations from different regions. Bayesian clustering and barrier analyses provided additional support for population separation, especially between geographical regions. In contrast, none of the phenotypic traits showed any type of geographical pattern, and population divergence in these traits was uncorrelated with that found in neutral markers. There was also a weaker pattern of regional differences among geographical regions compared to neutral genetic divergence. These results suggest that while divergence in neutral traits is likely a product of population history and genetic drift, phenotypic divergence is governed by different mechanisms, such as natural and sexual selection, and arises at spatial scales independent from those of neutral markers. [source] Prevalence of risk factors for suicide in patients prescribed venlafaxine, fluoxetine, and citalopram,PHARMACOEPIDEMIOLOGY AND DRUG SAFETY, Issue 6 2005Daniel Mines MD Abstract Purpose Three recent observational studies reported that the risk of fatal overdose is greater with venlafaxine than SSRI use. It is not clear whether patient factors could account for this finding. We evaluated whether risk factors for suicide are more prevalent among patients prescribed venlafaxine than patients prescribed fluoxetine or citalopram. Methods Using data from the UK General Practice Research Database (GPRD), we identified patients who were first prescribed any of the three drugs between January 1995 and April 2002. We ascertained risk factors for suicide documented in the 1 year before that first prescription. Separate analyses compared venlafaxine (N,=,27,096) and fluoxetine (N,=,134,996) cohorts, and venlafaxine and citalopram (N,=,52,035) cohorts. Results Previous suicidal behaviors were documented for 1.0% of the venlafaxine cohort compared to 0.4% of the fluoxetine cohort (OR 2.8, 95%CI: 2.4, 3.2) and 0.4% citalopram cohorts (OR 2.4, 95%CI: 2.0, 2.9). 72.5% of venlafaxine patients had been prescribed at least one other antidepressant compared to 27.6% of fluoxetine (OR 6.9, 95%CI: 6.7, 7.1) and 39.5% of citalopram (OR 4.0, 95%CI: 3.9, 4.2) patients. Venlafaxine patients were also four to six times as likely to have been previously hospitalized for depression. Conclusion In the UK, venlafaxine has been selectively prescribed to a patient population with a higher burden of suicide risk factors than patients prescribed fluoxetine and citalopram. Unless baseline population differences are accounted for, observational studies that compare the risk of suicide in patients receiving these agents may produce biased results. Copyright © 2005 John Wiley & Sons, Ltd. [source] Developmental adaptation: Where we go from here,AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2009A. Roberto Frisancho The concept of developmental adaptation is a powerful framework that can be used for understanding the origin of population differences in phenotypic and genotypic biological traits. There is great deal of information describing how developmental responses can shape adult biological outcomes. Specifically, current research suggest that individuals developing in stressful environments such as high altitude will attain an adult enlarged residual lung volume that contribute to the successful cardiovascular adaptation of the high-altitude Andean native. Likewise, studies on the etiology of the metabolic syndrome indicate that development under poor nutritional environments elicit efficient physiological and metabolic responses for the utilization of nutrients and energy, which become disadvantageous when the adult environmental conditions provide abundant access to food and low energy expenditure. Epigenetic research in experimental animals and retrospective research in humans confirm that environmental influences during developmental period have profound consequences on the phenotypic expression of biological and behavioral traits during adulthood. Research on epigenetics is a productive direction for human biologists concerned with understanding the origins of human biological variability. Am. J. Hum. Biol., 2009. © 2009 Wiley-Liss, Inc. [source] A comparison of anthropometric indices of nutritional status in Tukanoan and Achuar AmerindiansAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 3 2001Caley M. Orr Anthropometric data from a Tukanoan population in the Vaupes region of Colombia and an Achuar population in the Ecuadorian Amazon were compared relative to international references. The Tukanoans exploit an oligotrophic blackwater ecosystem, whereas the Achuar inhabit a resource rich montane ecosystem. Given this ecological distinction, three hypotheses regarding nutritional statuses were proposed: (1) Tukanoans are significantly shorter than the Achuar, indicating a greater degree of stunting; (2) Tukanoans are significantly leaner, indicating a greater degree of wasting; and (3) Tukanaons have significantly lower upper arm muscle area, indicating lower lean body mass. Z-scores for height, weight-for-height, and estimated upper arm muscle area were determined and significant nutritional stress was assumed at z , ,2.0. Between population differences in z-scores for height-for-age (ZHT), weight-for-height (ZWH), and upper arm muscle area (ZUMA) were examined using analysis of variance with a subsequent Scheffe's test. Between-group differences in the frequencies of individuals with low z-scores (z , ,2.0) were assessed via chi-squared analysis. Both populations showed stunting in most age groups, but neither showed low ZWH or ZUMA. Significant differences between populations were found only for ZHT in children (females 1.0,4.9 and 5.0,9.9 years, and males 5.0,9.9 years). Tukanoans have significantly higher frequencies of stunting in all age-sex groups except females and males age 30,49.9 years. There were no significant between-population differences in the frequencies of individuals with low ZWH or ZUMA. These differences in nutritional status may reflect differences in resource availability. Am. J. Hum. Biol. 13:301,309, 2001. © 2001 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||||||||