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1.
S. Tang  J. Ou  D. Sun  Y. Zhang  G. Xu  Y. Zhang 《Animal genetics》2011,42(1):108-112
Transforming growth factor‐beta 2 (encoded by TGFB2) is a growth factor that regulates a plethora of cellular functions. In this study, we sequenced the promoter and full‐length exon region of the chicken TGFB2 and found two mutations (g.‐640C>T and g.‐851_‐790del) within the promoter. The two polymorphisms were genotyped in 1030 pedigreed hens recorded for body weight at 7 (BW7), 9 (BW9), 11 (BW11), 13 (BW13), 17 (BW17) weeks old, egg weight at 36 weeks of age (EW36) and egg numbers from the age at first egg (AFE) to 40 weeks of age (EN40). Despite the fact that no mutations were found to have statistically significant genetic effects on egg production, the association results of growth traits showed that both g.‐640C>T and g.‐851_‐790del had significant effects on body weights and that both genotype g.‐640TT and g.‐851_‐790wt/wt were positive for body weight performance. Therefore, the polymorphisms of TGFB2, especially the g.‐851_‐790del mutation associated with body weight at almost all periods, could be potential useful genetic markers to improve the growth of Beijing You chickens.  相似文献   

2.
Risso's dolphins (Grampus griseus) are widely distributed throughout temperate to tropical pelagic waters of the world and are one of the most frequently encountered cetaceans in eastern Taiwanese coastal waters. Because their life history is poorly known, the goal of this study was to investigate the relationship between age, body length, and sexual maturity of Risso's dolphins in Taiwanese waters. Ninety‐two carcasses of dead‐stranded or fisheries bycaught dolphins (1994–2008) were measured and dissected (total body length, TBL 125–290 cm); sexual maturity was assessed in 33 dolphins; and age was estimated by counting dentinal growth layer groups in routine histologically prepared tooth sections of 28 dolphins. Sexual dimorphism in TBL was not detected. The onset of sexual maturity occurred at 240–255 cm in females and 253–265 cm in males, which was at about 10 yr of age for both sexes. Our stranding, bycatch, and previous boat survey records suggest that Risso's dolphins occur year‐round and likely have a summer‐fall calving season in Taiwanese waters. The similar life history parameters and calving season in dolphins from Taiwanese and Japanese waters suggest a common population in the northwest Pacific, which has a noticeably shorter body length than in other regions.  相似文献   

3.
Macroevolutionary patterns of sexual size dimorphism (SSD) indicate how sexual selection, natural selection, and genetic and developmental constraints mold sex differences in body size. One putative pattern, known as Rensch's rule, posits that, among species with female‐larger SSD, the relative degree of SSD declines with species' body size, whereas, among male‐larger SSD species, relative SSD increases with size. Using a dataset of 196 chelonian species from all fourteen families, we investigated the correlation in body size evolution between male and female Chelonia and the validity of Rensch's rule for the taxon and within its major clades. We conclude that male–female correlations in body size evolution are high, although these correlations differ among chelonian families. Overall, SSD scales isometrically with body size; Rensch's rule is valid for only one family, Testudinidae (tortoises). Because macroevolutionary patterns of SSD can vary markedly among clades, even in a taxon as morphologically conservative as Testudines, one must guard against inappropriately pooling clades in comparative studies of SSD. The results of the present study also indicate that regression models that assume the x‐variable (e.g. male body size) is measured without statistical error, although frequently reported, will result in erroneous conclusions about phylogenetic trends in sexual size dimorphism. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 108 , 396–413.  相似文献   

4.
Profiles of fecal progestogens and body weight from the early juvenile to the peri‐pubertal period are presented for eight captive female Nile hippopotami housed at Disney's Animal Kingdom in Florida. Average growth rate in juveniles was 0.85±0.03 kg/day (r2=0.913). Progestogen elevations were detectable as early as 16.8 months of age, and elevations indicative of ovulation and luteal activity were identified in seven of eight females by 30.3±1.6 months of age and body weight of 829.3±49.4 kg. Progestogen patterns before the onset of puberty were highly variable within and between females. Some females remained at baseline concentrations, whereas in others the progestogen pattern was characterized by infrequent, transient elevations of low amplitude and shortened duration. Four females were monitored through onset of puberty, conception, and first pregnancy. Onset of puberty was defined as the first luteal phase from the series of consecutive ovarian cycles culminating in conception and was observed at 34.9±2.2 months of age and 963.6±39.4 kg, however, the quality and number of cycles varied among females before conception. Females conceived between 2.7–3.9 years of age after attaining an approximate threshold body weight of 1,000 kg (1,070.5±39.5 kg). The age at first conception in captivity occurs at a younger age than has been reported for wild populations. Body weight may be an effective tool for approximating the state of reproductive maturity and facilitate collection management in zoos. Zoo Biol. 0:1–13, 2005. © 2005 Wiley‐Liss, Inc.  相似文献   

5.
“A primate with the skull of a Callicebus, the mandible and feet of a marmoset and the tail and teeth of Pseudocebus [=Cebus] ….” (Riberio, 1941 as cited in Hershkovitz 1 p. 866). Goeldi's monkeys are the least understood species of platyrrhine. The monkeys' small body size, black coloration, tendency to forage in the low forest understory, and cryptic nature, make them difficult to observe in the wild. Until recently, they had never been the focus of a long‐term field study and as a result, little was known of the monkeys' behavior and ecology. Goeldi's monkeys comprise only one recognized species, Callimico goeldii, and have an unusual suite of anatomical and reproductive traits. These traits have created considerable confusion for taxonomists and physical anthropologists.  相似文献   

6.
In captive Goeldi's monkeys, estrogen concentration was determined in fecal samples collected from 4 cycling/unmated females and 4 postpartum/mated females in order to ascertain the potential of fecal estrogen monitoring for providing basic information about reproductive status in this endangered Amazonian monkey. Subjects were fed an omnivorous diet and first-void feces were collected in the home cage at 1–3-day intervals for 30–50 days from the cycling females, and at 6–14-day intervals around the estimated time of the postpartum ovulation in each of the 4 mated females. Estimates for the duration of ovarian cycles (22–26 days) and the timing of ovulation were based on cyclic profiles of either blood progesterone or urinary pregnanediol-3α-glucuronide. Fecal estrogen values were normalized using these plasma or urinary profiles. HPLC analysis of estrogen from postpartum fecal samples demonstrated the presence of unconjugated estrone and estradiol-17β (“unconjugated estrogen”). Unconjugated estrogen was extracted and its fecal concentration estimated via EIA. The correlation (r) between plasma estrone conjugates and fecal unconjugated estrogen across nonconception ovarian cycles was 0.65 and measurement of the latter generated cyclic profiles. A range of 4–36-ng unconjugated estrogen g?1 feces was identified for follicular phases of nonconception cycles. Fecal unconjugated estrogen first exceeded the concentration range of the follicular phase 2–5 days after ovulation; the range was 49–402 ng g?1 feces in samples collected during the remainder of these nonconception luteal phases. Luteal phase concentrations were on average 10-fold higher than follicular phase concentrations. Each of the 4 mated females conceived at its postpartum ovulation; concentrations of fecal unconjugated estrogen excreted by 3 of these females demonstrated a marked postovulatory increase. This study demonstrates that fecal unconjugated estrogen can be applied to monitor ovarian cyclicity in Goeldi's monkey. © 1994 Wiley-Liss, Inc.  相似文献   

7.
Objective: The objective was to investigate whether calcium intake is independently associated with body fat in peripubertal girls. Research Methods and Procedures: A total of 45 healthy premenarcheal girls (initially 10.5 ± 0.6 years of age) completed a 2‐year prospective observational study. Percent body fat and trunk fat (by DXA), height, weight, maturational stage, and eating attitudes (children's Eating Attitudes Test [EAT]) were measured at baseline and at 1 and 2 years. Physical activity (by questionnaire) and calcium intake (by calcium‐specific food frequency questionnaire and 3‐day food records) were assessed at 6‐month intervals. Results: Girls with 2‐year mean calcium intake below and above the median had similar age, height, lean mass, and maturational stage at baseline, but girls below the median had significantly higher baseline percentage body fat (29.3 ± 10.3% vs. 22.0 ± 6.8%, p < 0.01) and trunk fat (24.2 ± 10.6% vs. 15.8 ± 6.8%, p < 0.01). However, differences were no longer significant when covariates (most notably children's EAT dieting score) were considered. Regression analysis revealed that dieting score was a consistent positive predictor of percentage body and trunk fat at all cross‐sectional time‐points, accounting for >20% of the variance, but did not predict 2‐year change in percentage fat. Calcium intake did not enter longitudinal regression equations for 2‐year change in percentage fat. Discussion: In this group of girls, an inverse cross‐sectional association between calcium intake and body fat appeared to result from avoidance of foods high in calcium by girls who were concerned about their body weight or shape. Calcium intake was not associated with change in fat over time.  相似文献   

8.
Objective: Mis‐reporting dietary intake is a substantial barrier to understanding the role of dietary behavior in disease. Work with adults indicates that heavier individuals under‐report dietary intake and that under‐reporting may be macronutrient‐specific. Whether weight status and macronutrient intake influence the accuracy of dietary reports among children, however, is less clear. This research evaluated children's dietary reporting accuracy as a function of their relative weight, body composition, and macronutrient intake. Research Methods and Procedures: Participants included 146 4‐ to 11‐year‐old children. Reported energy intake was determined by interviewing children in the presence of parents, using three multiple pass, 24‐hour recalls. Children were classified as having had an under‐reported, accurately reported, or over‐reported dietary intake relative to total energy expenditure, as measured by doubly labeled water. Reporting accuracy was examined as a function of children's body weight, body composition (using dual energy x‐ray absorptiometry), and macronutrient intake. Results: Average reported intake was, on average, 14% greater than children's estimated expenditure (p < 0.01). Reporting accuracy varied as a function of children's relative weight and body composition; under‐reporting tended to occur among heavier children, having the highest body fat content (p < 0.0001) and relative weight (p < 0.0001). Discussion: These findings suggest that weight status influences the accuracy of dietary reports made by children and their parents. More research is needed to address possible psychological and social factors that introduce bias in reporting children's dietary data.  相似文献   

9.
Objective: We sought to determine the role of the acute insulin secretory response to glucose (AIRg) in predicting weight gain in normoglycemic persons with no family history of diabetes, who are at low risk for development of disease. Research Methods and Procedures: One hundred five individuals (64 men and 41 women) who underwent measures of weight and AIRg and insulin sensitivity index (SI) by intravenous glucose tolerance test between 1963 and 1983 were surveyed again for weight between 1994 and 1999, with a mean follow‐up of 26 ± 4 years. Results: Mean change in weight was 8 ± 10 kg. Annualized weight change was calculated as change in kilograms divided by change in year and averaged 0.27 ± 0.04 kg/yr. Dividing the cohort by either median AIRg or median SI demonstrated no association of either AIRg or SI with total or annualized weight gain. Subgroup analysis by ideal body weight or gender did not alter the association. Furthermore, no association between AIRg and weight gain rate was seen within insulin‐sensitive or ‐resistant subgroups, although younger age at entry was associated with greater rates of weight gain. Discussion: Our data suggest that neither AIRg nor SI plays a role in predicting weight gain in normoglycemic individuals with no family history of diabetes.  相似文献   

10.
Objective: To study the impact of a weight‐loss program on sex hormones and sexual function among 38 middle‐aged obese men (BMI ≥35 kg/m2). Research Methods and Procedures: A randomized controlled clinical trial was conducted. The treatment group (n = 19) participated in a 4‐month weight‐loss program including 10 weeks on a very‐low‐energy diet (VLED) and 17 behavior modification visits. There was no intervention in the control group (n = 19). Both groups were followed for 8 months, i.e., 22 weeks after the active weight loss in the treatment group. The outcome measures (weight, sex hormones, sexual function, leptin, and metabolic variables) were obtained at baseline and at three time‐points during follow‐up. Results: The mean weight loss in the treatment group was 21 kg at the end of the 10‐week VLED. At the end of follow‐up, the maintained weight loss was 17 kg of baseline weight. The control group was weight stable throughout the study. In the treatment group, increases in sex hormone‐binding globulin, testosterone, and high‐density lipoprotein‐cholesterol, as well as decreases in insulin and leptin, were maintained until the end of follow‐up, although with VLED, the level of several hormones and metabolic variables improved transiently during the rapid weight loss. There were no significant changes in the questionnaire scores on sexual function in either group. Discussion: We conclude that obese men lose weight and increase their serum testosterone level on a weight‐loss program with VLED and behavior modification. However, they do not change their sexual function scores.  相似文献   

11.
The objective of this study was to evaluate demographic and psychosocial predictors of attendance in a family‐based behavioral weight management clinical trial. Ninety‐three children and adolescents aged 7–17 (Mean age = 11.59, s.d. = 2.6) who were either overweight or obese (Mean BMI percentile = 98.2) and their parents received either a 10‐session behavioral treatment or a three‐session brief family intervention in the context of a randomized clinical trial (10). Psychosocial and anthropometric measures were obtained before enrollment and at the end of 10 weeks for both treatment groups. Univariate linear regression and hierarchical multiple regression analyses were used to identify predictors of attendance to treatment from an a priori set of hypothesized predictors. Three variables demonstrated significant associations with the dependent variable, percent of treatment sessions attended. Specifically, distance from participant's home to treatment site, lower gross family income, and youth self‐report of depressive symptoms were each associated with lower percent attendance (all Ps < 0.05). These results corroborate (i.e., income, depressive symptoms) and expand (i.e., distance from treatment site) previous reports in the literature of potential barriers to effective treatment for pediatric obesity, and suggest the need for research on treatment delivery methods that could increase participation among low‐income families (e.g., eHealth, mHealth options). Depressive symptoms could represent an additional barrier to treatment attendance, suggesting that assessment and treatment for these symptoms may be appropriate before commencing weight management treatment.  相似文献   

12.
This study assessed the effects of resistance training (RT) on energy restriction–induced changes in body composition, protein metabolism, and the fractional synthesis rate of mixed muscle proteins (FSRm) in postmenopausal, overweight women. Sixteen women (age 68 ± 1 years, BMI 29 ± 1 kg/m2, mean ± s.e.m.) completed a 16‐week controlled diet study. Each woman consumed 1.0 g protein/kg/day. At baseline (weeks B1–B3) and poststudy (weeks RT12–RT13), energy intake matched each subject's need and during weeks RT1–RT11 was hypoenergetic by 2,092 kJ/day (500 kcal/day). From weeks RT1 to RT13, eight women performed RT 3 day/week (RT group) and eight women remained sedentary (SED group). RT did not influence the energy restriction–induced decrease in body mass (SED ?5.8 ± 0.6 kg; RT ?5.0 ± 0.2 kg) and fat mass (SED ?4.1 ± 0.9 kg; RT ?4.7 ± 0.5 kg). Fat free mass (FFM) and total body water decreased in SED (?1.6 ± 0.4 and ?2.1 ± 0.5 kg) and were unchanged in RT (?0.3 ± 0.4 and ?0.4 ± 0.7 kg) (group‐by‐time, P ≤ 0.05 and P = 0.07, respectively). Protein–mineral mass did not change in either group (SED 0.4 ± 0.2 kg; RT 0.1 ± 0.4 kg). Nitrogen balance, positive at baseline (2.2 ± 0.3 g N/day), was unchanged poststudy. After body mass loss, postabsorptive (PA) and postprandial (PP) leucine turnover, synthesis, and breakdown decreased. Leucine oxidation and balance were not changed. PA and total (PA + PP) FSRm in the vastus lateralis were higher after weight loss. RT did not influence these protein metabolism responses. In summary, RT helps older women preserve FFM during body mass loss. The comparable whole‐body nitrogen retentions, leucine kinetics, and FSRm between groups are consistent with the lack of differential protein–mineral mass change.  相似文献   

13.
In the absence of long‐term field studies, demographic and reproductive records from animals housed in zoos and research laboratories are a valuable tool for the study of life history variables relating to reproduction. In this study, we analyzed studbook records of more than 2,000 individuals born over a 40‐year period (1965–2004) to describe life history patterns of captive Goeldi's monkeys (Callimico goeldii) housed in North America and Europe. Using Kaplan–Meier survival analysis methods, we found the mean life span to be 5.5 years. The rate of infant mortality, defined as death before 30 days, was approximately 30%, with European animals being more likely to survive infancy than North American animals. When individuals surviving at least 1.5 years are considered, lifetime reproductive output averaged 3.5 offspring, yet more than one‐third of individuals did not produce any offspring. Using a smaller dataset of individuals with known pairing histories, we developed a measure of opportunity for reproduction (OFR), which represented the total time an individual was known to be housed with a potential mate. For both sexes, we found that the correlation between OFR and number of offspring produced was much higher than the correlation between life span and number of offspring produced. This result highlights the importance of taking into account an individual's OFR. As a whole, our findings help characterize the life histories of captive Goeldi's monkeys and emphasize the impact management practices may have on reproductive success. Zoo Biol 29:1–15, 2010. © 2009 Wiley‐Liss, Inc.  相似文献   

14.
Life‐history traits from four geographical populations (tropical Ledong population [LD], subtropical Guangzhou [GZ] and Yongxiu populations, and temperate Langfang population [LF]) of the Asian corn borer, Ostrinia furnacalis were investigated at a wide range of temperatures (20–32°C). The larval and pupal times were significantly decreased with increasing rearing temperature, and growth rate was positively correlated with temperature. The relationship between body weight and rearing temperature in O. furnacalis did not follow the temperature–size rule (TSR); all populations exhibited the highest pupal and adult weights at high temperatures or intermediate temperatures. However, development time, growth rate, and body weight did not show a constant latitudinal gradient. Across all populations at each temperature, female were significantly bigger than males, showing a female‐biased sexual size dimorphism (SSD). Contrary to Rensch's rule, the SSD tended to increase with rising temperature. The subtropical GZ population exhibited the largest degree of dimorphism while the temperate LF exhibited the smallest. Male pupae lose significantly more weight at metamorphosis compared to females. The proportionate weight losses of different populations were significantly different. Adult longevity was significantly decreased with increasing temperature. Between sexes, all populations exhibit a rather female‐biased adult longevity. Finally, we discuss the adaptive significance of higher temperature‐inducing high body weight in the moth's life history and why the moth exhibits the reverse TSR.  相似文献   

15.
Mycophagy has been documented in a number of species of marmosets and lion tamarins (Callitrichinae) but its effect on ranging behavior is not known. We present the results of 10 years of research on five groups of Goeldi's monkey (Callimico goeldii) at a field site in northwestern Bolivia. We studied the diet and ranging behavior of two of the groups. On average, groups contained 4.5 individuals (range 2.0–9.0), but they gradually decreased in size until only the breeding female remained in the home range. The annual diet was composed of fungi (31.1–34.9%), fruits (34.0–40.6%), prey (17.4–30.1%), and exudates (1.0–10.9%). They had large home ranges (114–150 ha) and over time individuals tended to shift their core areas of use. They used secondary and bamboo forest and forest with dense understories more than expected based on availability. We suggest that the large home ranges and shifting core areas used by C. goeldii are components of a foraging strategy to track patchy, low density, and ephemeral fungal fruiting bodies. Our results, along with data published on other callitrichines, indicate that groups of Leontopithecus, Callithrix, and Callimico that eat fungi have larger home ranges than those that do not. Mycophagy is one of the several factors that evidently affect home range size in callitrichines. Fungi are clearly an important food source for a number of populations, but additional studies are needed to determine why some eat fungi frequently while others do not. Am J Phys Anthropol, 2010. © 2010 Wiley‐Liss, Inc.  相似文献   

16.
Objective: To examine care giver perception of children's weight‐related health risk in African American families. Research Methods and Procedures: One‐hundred and eleven families (representing 48 boys and 63 girls) screened for participation in a diabetes prevention study participated. Care givers completed a health awareness questionnaire that assessed their perception of the child's weight, eating habits, appearance, exercise habits, and health risk. The care givers also reported each subject's family history of obesity, diabetes, and other chronic diseases. After a physical examination, height and weight were used to compute an age‐ and sex‐adjusted body mass index for each child. Results: Despite the fact that a substantial number of children were obese (57%) and super‐obese (12%), only 44% of the care givers perceived the child's weight to be a potential health problem. Regression analysis showed that 21% of the variance in parental perception of obesity‐related health risk could be predicted by child age, body mass index, perception of frame size, and perception of exercise habits. Discussion: A number of reasons for the apparent minimization of child health risk are discussed, including cultural differences in the acceptance of a large body habitus, lack of knowledge about the connection between childhood obesity and future health risk, and an optimistic bias in the perception of personal health risk.  相似文献   

17.
Objective: This study examined parents’ understanding of excess weight as a health risk, knowledge of healthy eating habits, and recognition of obesity in their children. Research Methods and Procedures: An anonymous questionnaire was distributed during well‐care visits involving children 4 to 8 years of age at a pediatric faculty practice. Parents indicated their level of concern about excess weight and other familiar health risks using a four‐point Likert scale, answered multiple‐choice questions concerning healthy eating patterns, and communicated their perceptions about their child's weight using a visual analog scale. A parent's perception was considered “accurate” if it deviated from the child's growth chart percentile by <30 points. Results: Of the 83 parents surveyed, 23% (19/83) had overweight children (≥95th percentile of age‐ and gender‐specific BMI growth charts). These parents did not differ from other parents in their level of concern about excess weight as a health risk or in their knowledge of healthy eating patterns, but the two groups of parents did differ in the accuracy of their perceptions about their children's weight. Only 10.5% of parents of overweight children (2/19) perceived their child's weight accurately compared with 59.4% of other parents (38/64; p < 0.001). Parents of overweight children invariably underestimated their children's weight. The median difference between their perception and the growth chart percentile was ?45 points. Discussion: Given that most parents of overweight children fail to recognize that their child has a weight problem, pediatricians should develop strategies to help these parents correct their misperceptions.  相似文献   

18.
Objective: To examine temporal trends in stature, body mass, body mass index (BMI), and the prevalence of overweight and obesity in Canada. Research Methods and Procedures: Data for adults 20 to 64 years of age were compared across eight Canadian surveys conducted between 1953 and 1998. Temporal trends in stature and body mass were examined using regression, and changes in weight‐for‐height were expressed as changes from 1953. BMI data were available from 1970 to 1972 to examine changes in overweight and obesity. Qualitative changes in the BMI distribution were examined using Tukey mean‐difference plots. Results: Significant temporal trends in stature and body mass have occurred since 1953 in Canada. Median stature increased 1.4 cm/decade in men and 1.1 cm/decade in women, whereas median body mass increased 1.9 kg/decade in men and 0.8 kg/decade in women. Increases in the 75th percentile of body mass were larger than the median. The average weight‐for‐height increased 5.1% in men and 4.9% in women from 1953. Furthermore, the prevalences of overweight and obesity have increased from 40.0% and 9.7% in 1970–1972 to 50.7% and 14.9% in 1998, respectively. The entire BMI distribution has shifted to the right since 1970–1972 and has become more skewed to the right for men than for women. Discussion: There have been significant increases in stature and body mass in Canada over the last 45 years. Body mass has increased more than stature, particularly in the upper percentiles, which has resulted in the currently observed high prevalences of overweight and obesity.  相似文献   

19.
Objective: To associate psychological status, weight‐related distress, and weight status during childhood in overweight or at‐risk‐for‐overweight children. Research Methods and Procedures: We associated self‐report of depression, trait anxiety, and weight‐related distress (body size dissatisfaction and weight‐related peer teasing after controlling for the effects of weight) in 164 children (black 35%; age 11.9 ± 2.5 years; girls 51%) who were overweight or at‐high‐risk‐for‐overweight and were not seeking weight loss. Results: Overall, heavier children reported more psychological and weight‐related distress. Black children reported more anxiety and body size dissatisfaction than white children, despite equivalent weights. However, psychological distress was not significantly associated with weight in white children. Girls reported more weight‐related distress than boys. Depression was associated with weight‐related teasing in all predictive models, except in the model using only black subjects. Trait anxiety was associated with report of peer teasing when using all subjects. Depression was also significantly associated with children's report of body size dissatisfaction in models using all subjects, only girls, or white subjects, but not in analyses using only boys or black subjects. For boys peer teasing was associated with body size dissatisfaction. In models including only black children, depression and trait anxiety were not significantly associated with either report of peer teasing or body size dissatisfaction. Discussion: Regardless of race or sex, increasing weight is associated with emotional and weight‐related distress in children. However, associations of psychological status, weight, and weight‐related distress differ for girls and boys, and for black and white children.  相似文献   

20.
Body condition is an important trait that reflects the capacity of individuals to acquire food or resist disease, eventually allowing successful reproduction and survival. We first quantified the effects of condition on life history and a secondary sexual trait using long‐term lifetime data on condition in a migratory bird species, the barn swallow, Hirundo rustica. Second, we quantified sources of individual variation in condition by separating the within‐individual from the between‐individual components of variation of environmental condition and age on body condition. Therefore, we were able to partition variation as a result of selection and phenotypic plasticity. Within‐individual variation in body condition increased in early life until middle age (i.e. 3–4 years of age) in the two sexes followed by only a slight decrease in body condition during senescence in males but not in females. After accounting for age‐dependent variation, condition could be partitioned into a within‐individual plastic response to environmental conditions during migration and a nonplastic response (i.e. a between‐individual difference) to environmental conditions experienced in the African winter quarters. Specifically, there was a within‐individual increase in body condition as environmental conditions during migration improved in both males and females, independent of age. There was a between‐individual effect of condition found in the winter quarter in body condition of females, but not in males, which was attributed to the disappearance of females in poor body condition from the study population as a result of the higher natal dispersal of low‐quality females compared to high‐quality ones during years with favourable environmental conditions in the African winter quarters. Males and females also tended to be in better body condition during the warmer springs upon arrival at the breeding grounds. There was a temporal decline in female body condition during 1991–2007, whereas no significant trend was detected in males. Therefore, both intrinsic (e.g. age and sex) and extrinsic factors (e.g. climate) affected body condition. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 420–434.  相似文献   

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