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Male Individuals (male + individual)
Selected AbstractsMathematical models for coinfection by two sexually transmitted agents: the human immunodeficiency virus and herpes simplex virus type 2 caseJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES C (APPLIED STATISTICS), Issue 4 2010S. Guy Mahiane Summary., To study the interactions between two sexually transmitted diseases without remission of the infections, we propose to use Markovian models. One model allows the estimation of the per-partnership female-to-male transmission probabilities for each infection, and the other the per-sex-act transmission probabilities. These models take into account the essential factors for the propagation of both infections, including the variability according to age of the rates of prevalence in the population of female partners for the male individuals constituting our sample. We estimate transmission probabilities and relative risks (for circumcision, usage of condoms and the effect of one infection on the infectivity of the other) by using the maximum likelihood method. Bootstrap procedures are used to provide confidence intervals for the parameters. We illustrate the new procedures with the study of the interactions between herpes simplex virus type 2 and human immunodeficiency virus by using data from the male circumcision trial that was conducted in Orange Farm (South Africa). The study shows that the probability that a susceptible male individual acquires one of the viruses is significantly higher when he is already infected with the other. Using the Akaike information criterion, we show that the per-partnership model fits the data better than the per-sex-act model. [source] The monoamine oxidase A (MAO-A) gene, family function and maltreatment as predictors of destructive behaviour during male adolescent alcohol consumptionADDICTION, Issue 3 2007Kent W. Nilsson ABSTRACT Aim To investigate possible interactions between a polymorphism in the monoamine oxidase A (MAO-A) gene promoter, family relations and maltreatment/sexual abuse on adolescent alcohol-related problem behaviour among male adolescents. Design, setting and participants A cross-sectional study of a randomized sample of 66 male individuals from a total population of 16- and 19-year adolescents from a Swedish county. Boys, who volunteered to participate answering an alcohol-related problem/behaviour questionnaire, were investigated with regard to interactions between such problems, family function, maltreatment and MAO-A genotype. Measurements MAO-A genotype, family relations history, history of being maltreated or abused and alcohol-related problem behaviour. Findings Boys with the short (three-repeat) variant of the MAO-A gene, who had been maltreated/abused or came from families with poor relations, showed significantly higher scores of alcohol-related problems. We also found that maltreatment/abuse independently showed the strongest relation to alcohol-related problems among boys in our model. Conclusions The results suggest that both maltreatment and MAO-A genotype may be useful for the understanding of male adolescent alcohol-related problem behaviour. [source] Co-morbidity of Emery,Dreifuss muscular dystrophy and a congenital myasthenic syndrome possibly affecting the phenotype in a large Bedouin kindredEUROPEAN JOURNAL OF NEUROLOGY, Issue 3 2007G. Ifergane Emery,Dreifuss muscular dystrophy (EDMD) is an X-linked humero-peroneal muscular dystrophy associated with contractures and cardiomyopathy. In a 90 member family, we found 11 affected male individuals, three of whom displayed areflexia and neurogenic electromyographic changes. Muscle biopsy performed in one case demonstrated type grouping suggestive of a neurogenic disorder. These three individuals and another family member, who suffers from mild, static limb weakness but is clinically and genetically unaffected by EDMD showed an abnormal incremental response of over 100% to tetanic stimulation. In contrast, one affected family member showed myopathic features on needle electromyography and no definite pathology in repetitive stimulation studies. The diagnosis of EDMD was established by demonstrating a 1712_1713insTGGGC mutation in the emerin gene. This family apparently expresses co-morbidity of EDMD with an exceptionally mild form of pre-synaptic congenital myasthenic syndrome resembling the Lambert,Eaton myasthenic syndrome (LEMS). The superimposed pre-synaptic disorder may have contributed to the development of the neurogenic features demonstrated in these patients. [source] Autism spectrum disorders and low body weight: Is there really a systematic association?INTERNATIONAL JOURNAL OF EATING DISORDERS, Issue 3 2002Sven Bölte Abstract Objective To examine the relationship between autism spectrum disorders and low body weight. Method The effect of maladaptive social and communicative behavior as well as stereotyped features on the normative body mass index (BMI) was analyzed in 103 subjects with autism or Asperger syndrome. Statistics were controlled for medication, neurological signs, overactivity, and general intelligence. Results Twenty-eight percent of the male individuals had a BMI in the fifth percentile or below. Except for hyperactive behavior, none of the predictors showed a significant association with BMI. None of the subjects met diagnostic criteria for anorexia nervosa. Discussion Although low body weight is often present in male subjects with autism or Asperger syndrome, results indicate that this link is inconsistent and partly mediated by hyperactivity. The co-occurrence of autism spectrum disorders and anorexia nervosa is probably due to chance. © 2002 by Wiley Periodicals, Inc. Int J Eat Disord 31: 349,351, 2002; DOI 10.1002/eat.10015 [source] A sixteenth-century warrior grave from Uppsala, Sweden: the Battle of Good FridayINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 1 2005A. KjellströmArticle first published online: 6 SEP 200 Abstract Little is known about the Battle of Good Friday in Uppsala. The historical records are scarce and of limited extent. Moreover, the more spectacular event of the Stockholm Bloodbath has drawn most of the attention from both the contemporary public and later historians. This is why the discovery of a mass grave in the steep slope of Uppsala Castle in 2001 has provoked much interest. An analysis of the osseous material showed that the remains of at least 60 male individuals, mostly between 25,34 years of age, were buried in the excavated area. The demographic profile is largely similar to other European war-related skeletal assemblages of the same era. Sharp force trauma was exhibited primarily on the skulls, with no obvious dominance to either side. The trauma distribution pattern suggests that the battle was not fought face-to-face. Blade wounds concentrated in specific regions imply a standardised technique when delivering the blows. The combination of commingled bones and articulated elements suggests that the individuals were in different stages of skeletonisation when buried. Copyright © 2004 John Wiley & Sons, Ltd. [source] Periodontal conditions in male adolescents using smokeless tobacco (moist snuff)JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 12 2006Ulrika Montén Abstract Aim: The aim of this study was to evaluate the potential association of the use of smokeless tobacco (moist snuff) on the periodontal conditions of adolescents. Material and methods: A subject sample of one hundred and three 19-year-old male individuals (33 snuff users, 70 controls) living in Göteborg, Sweden, were clinically examined with regard to oral hygiene, gingivitis, probing pocket depth (PPD), clinical attachment loss (CAL) and gingival recession. Bitewing radiographs were obtained for assessments of alveolar bone level. Information about tobacco and oral hygiene habits was obtained by a structured questionnaire. Student 's t -test, ,2 -test and logistic regression analysis were used for statistical analysis. Results: The mean plaque and gingivitis scores in snuff-users were 59% (SD 21.0) and 47% (18.6), respectively, and in controls 64% (22.4) and 50% (18.3), respectively. The average PPD and CAL in snuff-users amounted to 2.3 mm (0.3) and 0.2 mm (0.1), respectively, and in controls 2.4 mm (0.3) and 0.1 mm (0.1) (p>0.05), respectively. The mean bone level was 1.3 mm (0.2) in both groups. The prevalence of subjects showing recession was 42% among snuff-users and 17% among controls (p=0.006). In snuff users, an average of 4% (0.9) of the teeth showed recession, compared with 1% (0.3) in controls (p<0.001). Limiting the analysis to the maxillary anterior tooth region, 33% of the snuff-users and 10% of the controls presented recessions (p=0.002). The use of snuff entailed an OR=5.1 to have gingival recessions. Conclusion: In the present population sample of adolescents, the use of smokeless tobacco (moist snuff) was not associated with the presence of periodontal disease except for a significantly high prevalence of gingival recessions. [source] Allele Frequencies of 20 Y-Chromosomal Short Tandem Repeat Loci in a Tribal Population of Deccan Plateau, IndiaJOURNAL OF FORENSIC SCIENCES, Issue 2 2007G. Hima Bindu M.Sc. POPULATION: Eighty male individuals from a nomadic tribal population belonging to Dravidian and Indo-Caucasian ethnicities from Deccan Plateau, Andhra Pradesh, India (1), were analyzed in the present study. [source] Analysis of Y-STR Loci in a Population Sample from Northeast ChinaJOURNAL OF FORENSIC SCIENCES, Issue 1 2006Xiuling Wang Ph.D. POPULATION: A total of 141 unrelated Chinese Han male individuals living in Liaoning in northeast China. [source] Both Global Gray Matter Volume and Regional Gray Matter Volume Negatively Correlate with Lifetime Alcohol Intake in Non,Alcohol-Dependent Japanese Men: A Volumetric Analysis and a Voxel-Based MorphometryALCOHOLISM, Issue 6 2006Yasuyuki Taki Background: Non,alcohol-dependent heavy drinkers, as well as alcohol-dependent individuals, show brain atrophy. The purpose of this study was to evaluate whether there are correlations between global and regional gray matter volumes and the lifetime alcohol intake using volumetric analysis and voxel-based morphometry (VBM) among Japanese non-alcohol,dependent male individuals. Methods: High-resolution three-dimensional magnetic resonance images were acquired from 405 Japanese non-alcohol,dependent male individuals. The collected images were normalized, segmented for volumetric analysis, and additionally smoothed for VBM. For volumetric analysis, the partial correlation coefficient was estimated between the gray matter ratio, which represents the percentage of gray matter volume in the intracranial volume, and the lifetime alcohol intake adjusted for the age of each subject. Multiple regression analysis was performed among regional gray matter volume, lifetime alcohol intake, and age using VBM. Results: Volumetric analysis revealed that gray matter ratio showed a negative correlation with the lifetime alcohol intake adjusted for age (p=0.059, partial correlation coefficient=,0.091). The VBM revealed that the gray matter volumes of the bilateral middle frontal gyri showed a significant negative correlation with the lifetime alcohol intake adjusted for age and systolic blood pressure (left side, p=0.006, Z=4.77; right side, p=0.023, Z=4.45, and p=0.046, Z=4.27). Conclusions: Our study suggests that non-alcohol,dependent Japanese male individuals show that both global gray matter volume and regional gray matter volume have negative correlations with the lifetime alcohol intake. Our study may contribute to clarifying the mechanism underlying the brain structural changes because of alcohol influence in healthy non-alcohol,dependent individuals. [source] Mathematical models for coinfection by two sexually transmitted agents: the human immunodeficiency virus and herpes simplex virus type 2 caseJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES C (APPLIED STATISTICS), Issue 4 2010S. Guy Mahiane Summary., To study the interactions between two sexually transmitted diseases without remission of the infections, we propose to use Markovian models. One model allows the estimation of the per-partnership female-to-male transmission probabilities for each infection, and the other the per-sex-act transmission probabilities. These models take into account the essential factors for the propagation of both infections, including the variability according to age of the rates of prevalence in the population of female partners for the male individuals constituting our sample. We estimate transmission probabilities and relative risks (for circumcision, usage of condoms and the effect of one infection on the infectivity of the other) by using the maximum likelihood method. Bootstrap procedures are used to provide confidence intervals for the parameters. We illustrate the new procedures with the study of the interactions between herpes simplex virus type 2 and human immunodeficiency virus by using data from the male circumcision trial that was conducted in Orange Farm (South Africa). The study shows that the probability that a susceptible male individual acquires one of the viruses is significantly higher when he is already infected with the other. Using the Akaike information criterion, we show that the per-partnership model fits the data better than the per-sex-act model. [source] Sex-related spatial patterns of Poa ligularis in relation to shrub patch occurrence in northern PatagoniaJOURNAL OF VEGETATION SCIENCE, Issue 1 2000Mónica B. Bertiller Correa (1969,1988) Abstract. Poa ligularis is a dioecious species and a valuable forage plant which is widespread in the arid steppe of northern Patagonia (Argentina). The vegetation in these areas consists of a system of perennial plant patches alternating with bare soil areas defining contrasting micro-environments. We hypothesized that (1) male and female individuals of P. ligularis are spatially segregated in different micro-environments, (2) the intensity of spatial segregation of sexes depends on plant structure and (3) spatial segregation of sexes is enhanced by competitive interactions between the sexes within the vegetation patches. We analysed the spatial distribution of female and male individuals in relation to the spatial pattern of vegetation in two areas differing in their vegetation structure. The location of P. ligularis within patches where either male, female or both sexes occurred was also analysed. The results indicate that different patterns of spatial distribution of sexes of P. ligularis may be found at the community level depending on the dominant life forms and geometric structure of plant patches. Where patches are of a lower height, with a high internal patch cover, individuals of both sexes are concentrated within patch canopies. In sites characterized by large, tall patches and less internal patch cover suitable microsites for female and male P. ligularis occur both within and outside the patch with males located at further distances from the patch edge. Where the patch is large and tall enough to allow the establishment of males and females at relatively high numbers, males occupy the patch periphery or even colonize the interpatch bare soil. These spatial patterns are consistent with selective traits in which females better tolerate intraspecific competition than males, while males tolerate wider fluctuations in the physical environment (soil moisture, nitrogen availability, wind intensity, etc.). [source] Kinship and social structure of bobcats (Lynx rufus) inferred from microsatellite and radio-telemetry dataJOURNAL OF ZOOLOGY, Issue 4 2006J. E. Jane Abstract Kinship analysis using 12 microsatellites was compared with radio-telemetry data to examine the social structure of bobcats Lynx rufus in southern Texas. Genetically identified kinship relationships combined with capture data were used to reconstruct pedigrees. Three family groups were constructed from parent/offspring pairs identified from shared alleles. All parents identified by genetic analysis had established home ranges. Individuals with no distinct home ranges were not genetically observed to have offspring among the bobcats sampled. This suggests that establishing a home range is necessary for bobcats to breed. Of three identified male offspring and three identified female offspring, two female offspring were philopatric. These females became a part of the breeding population in their natal area. Among sibling pairs that included nine female and four male individuals, four females and one male were residents suggesting male-biased dispersal. [source] Influence of chronic alcohol abuse and ensuing forced abstinence on static subjective accommodation function in humansOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 3 2001Hugh Campbell Summary Purpose. Acute alcohol ingestion can change accommodation, but the long term effects of sustained alcohol consumption on accommodative function have not been studied in detail. This study was thus undertaken on individuals with a history of alcohol abuse. Methods. Thirty-seven male individuals aged 25,56 years (average 40 years) from an alcohol rehabilitation centre in Inverness, Scotland, were assessed on admission and after a week of forced abstinence. The results were compared to a paired age-matched set of control male subjects. The static amplitude of accommodation was measured by an RAF rule, and the pupil size measured with a pupil gauge. Results. On admission, the group mean measured amplitude of accommodation was 4.7±2.2 D (mean±SD). These values for the alcoholics were lower than age-matched controls (of5.9±2.9 D). The slope of the age-dependent decline in RAF rule accommodation measures was significantly smaller for the alcoholics compared to controls (at 0.215±0.027 D/year versus0.332±0.015 D/year, respectively; p <0.001), with the younger alcoholics showing a greater impairment. Following abstinence, there was no measurable change in accommodation measured, indicating the lower amplitude in the alcoholics was not attributable to circulatory alcohol levels. The resting pupil diameter in the alcoholics was4.37±0.63 mm compared to the controls of3.97±0.75 mm, with a higher incidence of small pupils (,3 mm) in the controls. Conclusions. The results indicate that chronic alcohol use can adversely affect subjective static accommodation, especially in younger alcoholics, as well as cause slight mydriasis. [source] A geometric morphometric approach to the quantification of population variation in sub-Saharan African craniaAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 1 2010Daniel Franklin We report here on new data examining cranial variation in 18 modern human sub-Saharan African populations. Previously, we investigated variation within southern Africa; we now extend our analyses to include a series of Central, East, and West African crania, to further knowledge of the relationships between, and variation and regional morphological patterning in, those populations. The sample comprises 377 male individuals; the three-dimensional coordinates of 96 landmarks are analyzed using Procrustes-based methods. Interpopulation variation is examined by calculating shape distances between groups, which are compared using resampling statistics and parametric tests. Phenotypic variance, as a proxy for genetic variance, is measured and compared across populations. Principal components and cluster analyses are employed to explore relationships between the populations. Shape differences are visualized using three-dimensional rendered models. Observed disparity patterns imply a mix of differences and similarities across populations, with no apparent support for genetic bottlenecks, which is likely a consequence of migrations that may have influenced differences in cranial form; supporting data are found in recent molecular studies. The Pygmy sample had the most distinctive cranial morphology; characteristically small in size with marked prognathism. These features characterized, although less strongly, the neighboring Bateke, and are possibly related to similar selective pressures in conjunction with interbreeding. Small cranial size is also involved in the considerable distinctiveness of the San and Khoikhoi. The statistical procedures applied in this study afford a powerful and robust means of quantifying and visualizing the magnitude and pattern of cranial variation between sub-Saharan African populations. Am. J. Hum. Biol., 2010. © 2009 Wiley-Liss, Inc. [source] A prospective qualitative exploration of views about attending pulmonary rehabilitationPHYSIOTHERAPY RESEARCH INTERNATIONAL, Issue 3 2009Catherine Bulley Abstract Background and Purpose.,Pulmonary rehabilitation has been found to be an effective strategy for managing chronic obstructive pulmonary disease (COPD). However, attendance at such programmes is not optimal, therefore, this study aimed to develop an in-depth understanding of views regarding attendance at pulmonary rehabilitation and experiences which may have shaped these views.,Methods.,An inductive qualitative study was carried out within the framework of Interpretative Phenomenological Analysis. Five female and four male individuals with COPD who had been referred for pulmonary rehabilitation participated in semi-structured interviews. Interviews were conducted prior to participation in pulmonary rehabilitation.,Results.,Three main themes were identified that related to views about attending pulmonary rehabilitation. The first is entitled ,Desired benefits of attending pulmonary rehabilitation', which described realistic hopes about impact on daily life. The second theme was called ,Evaluating the threat of exercise', and it encompassed both positive and negative evaluations; some interviewees described fear and avoidance of exercise, while others were determined to overcome symptoms. These attitudes extended to views about pulmonary rehabilitation. The third theme was called ,Attributing value to pulmonary rehabilitation'. Contrasting opinions about the value of attending pulmonary rehabilitation appeared to be influenced by the nature of prior interactions with health personnel and systems as well as information about the programme provided at referral. The referrer's attitude towards pulmonary rehabilitation appeared to be particularly influential.,Conclusion.,In summary, when considering rehabilitation attendance, potential participants are able to identify possible benefits, but previous experiences of symptoms and attitudes towards their condition can influence views both positively and negatively. Information and enthusiasm conveyed by the referring clinician, as well as previous interactions with health professionals can have powerful impact on views about attending. Referral practices should be informative and enthusiastic to increase the likelihood of uptake. Copyright © 2009 John Wiley & Sons, Ltd. [source] Asymmetry of the os pubis: Implications for the Suchey-Brooks methodAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009Rebecca S. Overbury Abstract Studies of skeletal development frequently document populational incidences of bilateral asymmetry. Degenerative morphological skeletal changes, attributed to age related and irregular ossification, may also progress asymmetrically, either as the result of asymmetric biomechanical factors expressed over the lifespan, asymmetric expression of physiological processes, or progressive magnification of asymmetry acquired previously during development. This study illustrates the effects of bilateral asymmetry on age at death estimates obtained from human skeletal remains. The Suchey-Brooks method, which uses the pubic symphyseal face for age estimation (Katz and Suchey, Am J Phys Anthropol 69 1986 427,435), was selected for the study based on its widespread use. Asymmetry in the Suchey-Brooks symphyseal age phases was found in over 60% of a sample composed of 20th century White male individuals from 18 to 86 years of age (N = 130). However, results suggest that the presence of asymmetry does not compromise the accuracy of the Suchey-Brooks method if the morphologically older symphyseal face of an asymmetric individual is used to estimate age at death. In addition, weak directional asymmetry and a correlation between age and asymmetry were found. This suggests that a comparison of asymmetry in this area with that in other skeletal areas, where the factors originating and influencing asymmetry are better understood, may be useful in better understanding the biological processes which underlie the age markers used in the Suchey-Brooks method. Am J Phys Anthropol 2009. © 2009 Wiley-Liss, Inc. [source] SCF and c-kit expression profiles in male individuals with normal and impaired spermatogenesisANDROLOGIA, Issue 2 2010M. Bialas Summary The transcription levels of stem cell factor (SCF) and c-kit were examined using real-time RT PCR in interstitial and intratubular cell fractions, as well as in tissue homogenates from normal, azoospermic and neoplasmic patients. Peripheral blood mononuclear cells (PBMC) were used as a systemic control. The observed level of c-kit expression in all investigated groups was generally higher than the expression of SCF. The highest (statistically significant) level of c-kit was noted in testicular tumours (the greater part of which were represented by seminomas) in contrast to SCF mRNA, which may indicate an association between c-kit overexpression and seminoma development. In Sertoli cell only syndrome, almost equal levels of SCF and c-kit transcripts were noted. These results may indicate Leydig cells as the alternative source of c-kit gene transcription. SCF transcript values were low and comparable among the analysed subgroups except that in maturation arrest at spermatocyte stage, the SCF gene expression was statistically higher than in testicular tumours. It appears from the study that c-kit has been a dynamic gene, changing its activity in a variety of testicular pathologies while being expressed in all testicular compartments but clearly overexpressed in testicular tumours of seminomatous origin. [source] Inferring Continental Ancestry of Argentineans from Autosomal, Y-Chromosomal and Mitochondrial DNAANNALS OF HUMAN GENETICS, Issue 1 2010Daniel Corach Summary We investigated the bio-geographic ancestry of Argentineans, and quantified their genetic admixture, analyzing 246 unrelated male individuals from eight provinces of three Argentinean regions using ancestry-sensitive DNA markers (ASDM) from autosomal, Y and mitochondrial chromosomes. Our results demonstrate that European, Native American and African ancestry components were detectable in the contemporary Argentineans, the amounts depending on the genetic system applied, exhibiting large inter-individual heterogeneity. Argentineans carried a large fraction of European genetic heritage in their Y-chromosomal (94.1%) and autosomal (78.5%) DNA, but their mitochondrial gene pool is mostly of Native American ancestry (53.7%); instead, African heritage was small in all three genetic systems (<4%). Population substructure in Argentina considering the eight sampled provinces was very small based on autosomal (0.92% of total variation was between provincial groups, p = 0.005) and mtDNA (1.77%, p = 0.005) data (none with NRY data), and all three genetic systems revealed no substructure when clustering the provinces into the three geographic regions to which they belong. The complex genetic ancestry picture detected in Argentineans underscores the need to apply ASDM from all three genetic systems to infer geographic origins and genetic admixture. This applies to all worldwide areas where people with different continental ancestry live geographically close together. [source] Herbivorous fishes and the potential of Caribbean marine reserves to preserve coral reef ecosystemsAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 5 2010Dorothée Kopp Abstract 1.The development of macroalgae to the detriment of corals is now one of the major threats to coral reefs. Herbivorous fishes are partly responsible for algal regulation on coral reefs and their overexploitation favours the shift from scleractinian coral-dominated systems towards macroalgae-dominated systems. 2.Marine protected areas (MPAs) that have been established worldwide may benefit coral reefs through the maintenance of high densities of herbivorous fishes which regulate algal growth. 3.The paper assesses whether small MPAs in the Caribbean are able to enhance herbivorous fish stock and by controlling macroalgae help to maintain reef ecosystems. A visual census using band-transects was undertaken around Guadeloupe island where marine reserves have been in place since 1979. The effects of MPAs on both benthic communities and herbivorous fishes are examined. 4.Inside MPAs, herbivorous fish biomass was almost twice as high as outside MPAs and macroalgal cover was significantly lower. Fish size class distributions revealed that large individuals occurred mainly inside MPAs and that few male individuals were found outside MPAs. Copyright © 2010 John Wiley & Sons, Ltd. [source] Variation in Sexual Expression in Jacaratia mexicana (Caricaceae) in Southern Mexico: Frequency and Relative Seed Performance of Fruit-Producing MalesBIOTROPICA, Issue 1 2007Armando Aguirre ABSTRACT Dioecy, the segregation of male and female structures among individuals, is widespread in tropical plants, encompassing 10,30 percent of species in some sites. In many cases, interindividual sex separation is not complete, as individual plants, although nominally dioecious, may produce both types of reproductive structures. A common form of this sexual variation is the production of female structures in otherwise male individuals, commonly referred to as fruiting males. Here we report the existence of fruiting males in the dioecious tropical tree Jacaratia mexicana (Caricaceae). We show that fruiting males can constitute up to 45 percent of all males in some populations of a tropical forest in Southern Mexico. In order to determine the functional significance of fruiting males for the breeding system of J. mexicana, we compared the relative performance of male- and female-borne seeds. Our results show that seeds from fruiting males are three times less likely to germinate and survive than seeds from female trees. Based on relative seed fitness data, and sex ratios in natural populations, we estimate that 6,15 percent of the genes contributed by fruiting males to the next generation are transmitted via ovules, meaning that morphological variation in gender is at least partially accompanied by functional gender variation. Finally, our seed fitness estimates for fruiting males suggest that fruiting males will not replace female plants in natural populations. Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp. RESUMEN El dioicismo, la distribución de estructuras masculinas y femeninas en dos tipos de individuos, es un fenómeno ampliamente distribuido en especies tropicales, llegando a abarcar 10-30 por ciento de las especies en algunos sitios. En muchos casos la separación de los sexos entre individuos no es completa, y un mismo individuo puede producir estructuras reproductivas del sexo opuesto. Una forma común de esta variación en el género es la producción de estructuras femeninas en individuos machos, los que comúnmente se denominan machos fructíferos. En este trabajo describimos la existencia de machos fructíferos en el árbol tropical dioico Jacaratia mexicana (Caricaceae). Encontramos que los machos fructíferos pueden constituir hasta el 45 por ciento de todos los árboles macho en algunas poblaciones de un bosque tropical en el Sur de México. Con el objeto de determinar el significado funcional de los machos fructíferos de J. mexicana, comparamos el desempeño relativo de semillas originadas en individuos macho y hembra. Nuestros resultados muestran que las semillas provenientes de machos fructíferos germinan y sobreviven con una probabilidad tres veces menor que las semillas provenientes de árboles hembra. Basados en la adecuación relativa de las semillas, así como en las proporciones sexuales en poblaciones naturales, estimamos que 6-15 por ciento de los genes contribuidos por los machos fructíferos a la siguiente generación son transmitidos vía óvulos, lo que significa que al menos parte de la variación en el género a nivel morfológico es acompañada por variación a nivel funcional. Finalmente, nuestras estimaciones de la adecuación de los machos fructíferos, vía semillas, sugieren que éstos no remplazarán a las plantas femeninas en poblaciones naturales. [source] | ||||||||||||||||