Measuring fish body condition with or without parasites: does it matter?

A fish body condition index was calculated twice for each individual fish, including or excluding parasite mass from fish body mass, and index values were compared to test the effects of parasite mass on measurement of body condition. Potential correlations between parasite load and the two alternative fish condition index values were tested to assess how parasite mass may influence the perception of the actual effects of parasitism on fish body condition. Helminth parasite mass was estimated in common bully Gobiomorphus cotidianus from four New Zealand lakes and used to assess the biasing effects of parasite mass on body condition indices. Results showed that the inclusion or exclusion of parasite mass from fish body mass in index calculations significantly influenced correlation patterns between parasite load and fish body condition indices. When parasite mass was included, there was a positive correlation between parasite load and fish body condition, seemingly indicating that fish in better condition supported higher parasite loads. When parasite mass was excluded, there was no correlation between parasite load and fish body condition, i.e. there was no detectable effect of helminth parasites on fish condition or fish condition on parasite load. Fish body condition tended to be overestimated when parasite mass was not accounted for; results showed a positive correlation between relative parasite mass and the degree to which individual fish condition was overestimated. Regardless of the actual effects of helminth parasites on fish condition, parasite mass contained within a fish should be taken into account when estimating fish condition. Parasite tissues are not host tissues and should not be included in fish mass when calculating a body condition index, especially when looking at potential effects of helminth infections on fish condition.     

Assessing vegetation condition in temperate montane grasslands

Rapid assessment techniques are commonly used for measuring vegetation condition at sites. Techniques for measuring site condition need to be quantitative, repeatable, rapid and simple. The key challenge is achieving a balance between simple techniques and adequate discrimination of condition between sites. This study compared a grassland condition index with the existing BioMetric condition index and showed that (i) the grassland index provided a strong measure of the relationship of temperate montane grassland sites with disturbance level, and differentiated condition of sites to a high degree and (ii) the simpler BioMetric index provided a strong measure of the relationship of the grassland sites with disturbance and differentiated their condition to a moderate degree. The choice of index to assess grassland condition should depend on purpose, cost and capacity.     

Body condition is associated with a shorter breeding season and reduced ovulation rate in subtropical goats

To determine the effect of body condition on the characteristics of the breeding season in female goats from subtropical Mexico, does in either greater- or lesser-body condition (n=20/group) were monitored for the expression of estrous behavior, ovulation and ovulation rate between June and April. The commencement of estrus and ovulation occurred earlier (P<0.05) in does in greater than lesser body condition. The cessation of estrus and ovulation was later (P<0.05) in female goats with greater than those with lesser body condition. Does in greater body condition had more (P<0.001) normal estrous cycles than those in lesser body condition. As consequence, does from the greater body condition group had fewer short (P<0.001) or long (P<0.05) estrous cycles than those of in the lesser body condition group. The ovulation rate was greater (P<0.01) in the greater (1.9+/-0.1) than lesser body condition does (1.6+/-0.1). In conclusion, female goats in lesser body condition have a shorter breeding season, more abnormal estrous cycles, and fewer ovulations than does in greater body condition.     

Cues of Maternal Condition Influence Offspring Selfishness

The evolution of parent-offspring communication was mostly studied from the perspective of parents responding to begging signals conveying information about offspring condition. Parents should respond to begging because of the differential fitness returns obtained from their investment in offspring that differ in condition. For analogous reasons, offspring should adjust their behavior to cues/signals of parental condition: parents that differ in condition pay differential costs of care and, hence, should provide different amounts of food. In this study, we experimentally tested in the European earwig (Forficula auricularia) if cues of maternal condition affect offspring behavior in terms of sibling cannibalism. We experimentally manipulated female condition by providing them with different amounts of food, kept nymph condition constant, allowed for nymph exposure to chemical maternal cues over extended time, quantified nymph survival (deaths being due to cannibalism) and extracted and analyzed the females’ cuticular hydrocarbons (CHC). Nymph survival was significantly affected by chemical cues of maternal condition, and this effect depended on the timing of breeding. Cues of poor maternal condition enhanced nymph survival in early broods, but reduced nymph survival in late broods, and vice versa for cues of good condition. Furthermore, female condition affected the quantitative composition of their CHC profile which in turn predicted nymph survival patterns. Thus, earwig offspring are sensitive to chemical cues of maternal condition and nymphs from early and late broods show opposite reactions to the same chemical cues. Together with former evidence on maternal sensitivities to condition-dependent nymph chemical cues, our study shows context-dependent reciprocal information exchange about condition between earwig mothers and their offspring, potentially mediated by cuticular hydrocarbons.     

Dispersal depends on body condition and predation risk in the semi‐aquatic insect,Notonecta undulata

Dispersal is the movement of organisms across space, which has important implications for ecological and evolutionary processes, including community composition and gene flow. Previous studies have demonstrated that dispersal is influenced by body condition; however, few studies have been able to separate the effects of body condition from correlated variables such as body size. Moreover, the results of these studies have been inconsistent with respect to the direction of the relationship between condition and dispersal. We examined whether body condition influences dispersal in backswimmers (Notonecta undulata). We also tested whether an interaction between body condition and predation risk (another proximate factor that influences dispersal) could contribute to the previously observed inconsistent relationship between condition and dispersal. We imposed diet treatments on backswimmers in the laboratory, and measured the effects of food availability on body condition and dispersal in the field. We found that dispersal was a positive function of body condition, which may have important consequences for population characteristics such as the rate of gene flow and population growth. However, the effects of body condition and predation risk were additive, not interactive, and therefore, our data do not support the hypothesis that the interaction between condition and predation risk contributes to the inconsistency in the results of previous condition‐dependent dispersal studies.     

Extreme sex ratio variation in relation to change in condition around conception

Adaptive theory predicts that mothers would be advantaged by adjusting the sex ratio of their offspring in relation to their offspring's future reproductive success. Studies investigating sex ratio variation in mammals have produced notoriously inconsistent results, although recent studies suggest more consistency if sex ratio variation is related to maternal condition at conception, potentially mediated by changes in circulating glucose level. Consequently, we hypothesized that change in condition might better predict sex ratio variation than condition per se. Here, we investigate sex ratio variation in feral horses (Equus caballus), where sex ratio variation was previously shown to be related to maternal condition at conception. We used condition measures before and after conception to measure the change in condition around conception in individual mothers. The relationship with sex ratio was substantially more extreme than previously reported: 3% of females losing condition gave birth to a son, whereas 80% of those females that were gaining condition gave birth to a son. Change in condition is more predictive of sex ratio than actual condition, supporting previous studies, and shows the most extreme variation in mammals ever reported.     

Influence of recruit condition on food competition and predation risk in a coral reef fish

Settlement rate is considered to be a major determinant of the population structure of coral reef fishes. In this study, the effects of larval physiological condition on survival, predation risk and competitive ability are assessed for a small damselfish, Pomacentrus moluccensis. New settlers were collected and fed for 5 days to produce high and low condition (measured as lipid) treatment fish. In a field experiment, pairs (one high and one low condition fish) were transplanted to corals. Persistence over 2 weeks was much higher (100% vs. 25%) in high condition fish. In mixed groups in the laboratory, high condition fish were both aggressively dominant and consumed more of a limiting prey source than low condition fish. In addition, low condition fish were shown to be at much higher risk of predation. All of the low condition fish but only 33% of high condition fish in mixed groups were consumed by fish predators, and in a separate experiment, 73% of feeding strikes by predators were directed at low condition fish. Quality of new settlers can have an important influence on subsequent juvenile survival. The mechanisms for this effect are likely to include a combination of effects of condition on food competition and predation risk.     

Body condition during pregnancy and lactation and reproductive efficiency of mares

In Experiment I, 32 mares were equally allotted to the following treatments: mares fed to A) high body condition from 90 days prepartum to foaling and maintained in high body condition to 90 days postpartum, B) high body condition from 90 days prepartum to foaling and allowed to lose body condition to 90 days postpartum, C) lose body condition from 90 days prepartum to foaling and maintained in low body condition to 90 days postpartum, and D) lose body condition from 90 days prepartum to foaling and allowed to gain weight after foaling to attain a high level of body condition by 90 days postpartum. After three cycles, pregnancy rate at 30 days postovulation was lower (P<0.05) in C mares (50%) than in those in the other three groups (100%). Maintenance of pregnancy to 90 days was also reduced (P<0.05) in C mares (25%) when compared with A, D (both 100%) and B mares (88%). Foal growth to 90 days of age was similar in all treatments. In Experiment II, 927 mares were evaluated for body condition and monitored for reproductive performance. Pregnancy rate was lower (P<0.05) and number of cycles/conception was higher (P<0.05) for barren and maiden mares entering the breeding season in thin condition and for pregnant mares foaling in thin condition (condition score less than 5.0) when compared with mares with a higher level of condition. Also, onset of estrus and ovulation appeared to be delayed in barren and maiden mares entering the breeding season in thin condition. Breeding efficiency was enhanced in mares entering the breeding season or foaling at a condition of 5.0 or above. Initial excess stores of body fat enhanced fertility. There were no detrimental effects of excess body fat stored in late gestation.     

Changes in the condition factor have an impact on metabolic rate and swimming performance relationships in Atlantic cod (Gadus morhua L.)

In the field, Atlantic cod face seasonal changes in food availability that in turn lead to changes in condition. To examine the physiological consequences of these changes in condition, we measured routine metabolic rate (RMR) to estimate standard metabolic rate (SMR), active metabolic rate (AMR), aerobic scope, critical swimming speed (Ucrit), cost of transport, sprint performance, time to exhaustion, and postexhaustion metabolic rate (EMR) for 24 Atlantic cod from the Gulf of St. Lawrence. Cod were measured at their initial condition (condition factor of 0.676+/-0.076) and after 9 wk of feeding (condition factor of 0.923+/-0.096). These levels of condition are representative of wild cod in the Gulf of St. Lawrence during the spring and during the fall-early winter, respectively. The improved condition did not change mass-specific SMR. However, mass-specific AMR, aerobic scope, and EMR decreased with the improvement in condition. The various measures of swimming performance were affected differently. Ucrit increased and cost of transport at 1.3 and 1.5 body lengths s(-1) decreased with improved condition, but the cost of transport at 0.3, 0.9, 1.1, 1.7, and 1.9 body lengths s(-1), sprint performance, and time to exhaustion did not change. Hierarchies for the speed at first burst-coast, the proportion of Ucrit supported by burst-coasts, and time to exhaustion were maintained with the improvement in condition. The relationships between metabolic rates and swimming performance differed with condition level, with stronger correlations apparent in the cod at their initial condition. Given the low condition of wild cod stocks, these responses indicate that reduced performance, due to both maintenance of metabolic expenditures and modified swimming capacities, may impair survival under conditions of reduced food availability.     

Maternal Condition Does Not Influence Birth Sex Ratios in Anubis Baboons (Papio anubis)

Trivers and Willard predicted that when parental condition has differential effects on the fitness of male and female offspring, parents who are in good condition will bias investment toward the sex that benefits most from additional investment. Efforts to test predictions derived from Trivers and Willard''s model have had mixed results, perhaps because most studies have relied on proxy measures of parental condition, such as dominance rank. Here, we examine the effects of female baboons condition on birth sex ratios and post-natal investment, based on visual assessments of maternal body condition. We find that local environmental conditions have significant effects on female condition, but maternal condition at conception has no consistent relationship with birth sex ratios. Mothers who are in poorer condition at the time of conception resume cycling significantly later than females who are in better condition, but the sex of their infants has no effect on the time to resumption of cycling. Thus, our findings provide strong evidence that maternal condition influences females'' ability to reproduce, but females do not facultatively adjust the sex ratio of their offspring in relation to their dominance rank or current condition.     

Brain Activation of Identity Switching in Multiple Identity Tracking Task

When different objects switch identities in the multiple identity tracking (MIT) task, viewers need to rebind objects’ identity and location, which requires attention. This rebinding helps people identify the regions targets are in (where they need to focus their attention) and inhibit unimportant regions (where distractors are). This study investigated the processing of attentional tracking after identity switching in an adapted MIT task. This experiment used three identity-switching conditions: a target-switching condition (where the target objects switched identities), a distractor-switching condition (where the distractor objects switched identities), and a no-switching condition. Compared to the distractor-switching condition, the target-switching condition elicited greater activation in the frontal eye fields (FEF), intraparietal sulcus (IPS), and visual cortex. Compared to the no-switching condition, the target-switching condition elicited greater activation in the FEF, inferior frontal gyrus (pars orbitalis) (IFG-Orb), IPS, visual cortex, middle temporal lobule, and anterior cingulate cortex. Finally, the distractor-switching condition showed greater activation in the IFG-Orb compared to the no-switching condition. These results suggest that, in the target-switching condition, the FEF and IPS (the dorsal attention network) might be involved in goal-driven attention to targets during attentional tracking. In addition, in the distractor-switching condition, the activation of the IFG-Orb may indicate salient change that pulls attention away automatically.     

Sexual selection, genetic architecture, and the condition dependence of body shape in the sexually dimorphic fly Prochyliza xanthostoma (Piophilidae)

The hypothesis that sexual selection drives the evolution of condition dependence is not firmly supported by empirical evidence, and the process remains poorly understood. First, even though sexual competition typically involves multiple traits, studies usually compare a single sexual trait with a single "control" trait, ignoring variation among sexual traits and raising the possibility of sampling bias. Second, few studies have addressed the genetic basis of condition dependence. Third, even though condition dependence is thought to result from a form of sex-specific epistasis, the evolution of condition dependence has never been considered in relation to intralocus sexual conflict. We argue that condition dependence may weaken intersexual genetic correlations and facilitate the evolution of sexual dimorphism. To address these questions, we manipulated an environmental factor affecting condition (larval diet) and examined its effects on four sexual and four nonsexual traits in Prochyliza xanthostoma adults. As predicted by theory, the strength of condition dependence increased with degree of exaggeration among male traits. Body shape was more condition dependent in males than in females and, perhaps as a result, genetic and environmental effects on body shape were congruent in males, but not in females. However, of the four male sexual traits, only head length was significantly larger in high-condition males after controlling for body size. Strong condition dependence was associated with reduced intersexual genetic correlation. However, homologous male and female traits exhibited correlated responses to condition, suggesting an intersexual genetic correlation for condition dependence itself. Our findings support the role of sexual selection in the evolution of condition dependence, but reveal considerable variation in condition dependence among sexual traits. It is not clear whether the evolution of condition dependence has mitigated or exacerbated intralocus sexual conflict in this species.     

Body condition and reproductive capacity of three‐spined stickleback infected with the cestode Schistocephalus solidus

The relationship between reproductive ability and the residual index of body condition in three‐spined stickleback Gasterosteus aculeatus from a population infected with the cestode macroparasite Schistocephalus solidus in Walby Lake, Alaska, was examined. In general, reproductive activities resulted in significantly lower levels of body condition in three‐spined stickleback during the latter part of the breeding season, and relatively high levels of S. solidus infection intensified the energetic drain. Although female body condition did not differ significantly due just to the presence of S. solidus , increased parasite index did have a significant negative effect on female body condition. Males showed significantly lower levels of body condition in response to S. solidus infection alone and in association with a greater parasite index. Males had greater mean parasite indices than females. Females had significantly lower body condition than males, which may be due to discrepancies in energy expenditure between the sexes during reproduction. Females with greater body condition were significantly more likely to produce a clutch of eggs than those with lower condition, suggesting a threshold effect of body condition on reproductive capacity.     

A reliable body condition scoring technique for estimating condition in African buffalo

Evaluating animal body condition is a necessary component of many ecological studies. Although many methods for assessing animal body condition have been developed, relatively few can be used for estimating condition on live animals. Noninvasive body condition scoring techniques have been developed for assessing condition in livestock and more recently such techniques have been applied to wild ungulates. In this study, we examined the reliability of a body condition scoring technique for assessing condition in African buffalo (Syncerus caffer caffer). We compared a body condition score (BCS) based on visual assessment and manual palpation of an animal’s body to two standard metrics of condition widely used in mammals: kidney fat index (KFI) and haematocrit (HCT). Across all buffalo, BCS was significantly and positively correlated with both KFI and HCT. For HCT, this pattern was observed among adults, juveniles, males and females; and in the wet season but not in the dry season. For KFI, BCS was significantly and positively correlated with KFI among adults, juveniles and males, but not in females. Overall, our results suggest that the BCS technique can serve as a useful method for estimating body condition in buffalo.     

Somatosensory cortex excitability changes due to differences in instruction conditions of motor imagery

Purpose Vivid motor imagery appears to be associated with improved motor learning efficiency. However, the practical difficulties in measuring vivid motor imagery warrant new analytical approaches. The present study aimed to determine the instruction conditions for which vividness in motor imagery could be more easily seen and the excitability of the sensory cortex as it relates to the motor image. Materials and methods In total, 15 healthy, right-handed volunteers were instructed to imagine grasping a rubber ball under a verbal-only instruction condition (verbal condition), a verbal?+?visual instruction condition (visual condition), and a verbal?+?execution (physically grasping a real ball) condition (execution condition). We analyzed motor imagery-related changes in somatosensory cortical excitability by comparing somatosensory-evoked potentials in each condition with the rest (control) condition. We also used a visual analogue scale to measure subject-reported vividness of imagery. Results We found the N33 component was significantly lower in the execution condition than in the rest condition (p?Conclusions These data suggest that experiencing a movement through actual motor execution immediately prior to performing mental imagery of that movement enhances the excitability of motor-related cortical areas. It is suggested that the excitability of the motor-related region increased as a result of the motor imagery in the execution condition acting on the corresponding somatosensory cortex.     

Effect of the amount of body condition loss from the dry to near calving periods on the subsequent body condition change, occurrence of postpartum diseases, metabolic parameters and reproductive performance in Holstein dairy cows

We investigated the effect of body condition loss from the dry to near calving periods on the subsequent body condition change, the occurrence of postpartum diseases, the serum metabolic parameters total cholesterol, triglyceride, glucose, and urea nitrogen and the number of days to first breeding after calving in Holstein dairy cows. Body condition scoring (using a 5-point scale with quarter-point divisions) was performed on 67 pregnant Holstein dairy cows. Cows were scored once for body condition during the dry period (prepartum day 35 +/- 16), near calving (postpartum day 5 +/- 4), and subsequently at months 1 (+/- day 4), 2 (+/- day 5), 3 (+/- day 5), and 4 (+/- day 4) of lactation. At the same time, blood samples were collected to evaluate serum total cholesterol, triglyceride, glucose and urea nitrogen concentrations. Cows were categorized based on body condition loss from the dry to near calving periods into two groups: the moderate condition loss group (0-0.75 points, n=41), or the marked condition loss group (1.0-1.5 points, n=26). Regular reproductive health examination was conducted by the same investigator once a week. The marked condition loss group lost more body condition (P<0.01) than the moderate condition loss group consistently until month 1 of lactation. The recovery of body condition in the marked condition loss group was more delayed (P<0.01) than in the moderate condition loss group from months 1 to 4 of lactation. The occurrence of metritis and metabolic diseases (including abomasal displacement, milk fever, ketosis) was greater (P<0.01) in the marked condition loss group (62 and 23%) than in the moderate condition loss group (27 and 2%), respectively. The total cholesterol concentration was lower (P<0.05) in the marked condition loss group (167 +/- 5.3 mg/dl) than in the moderate condition loss group (183 +/- 5.8 mg/dl) at month 1 of lactation, however, the cholesterol levels at the other periods were not different (P>0.05) between the two groups. The triglyceride, glucose, and urea nitrogen concentrations were not different (P>0.05) from the dry period to month 4 of lactation between the two groups. The number of days to first breeding after calving was longer (P<0.05) in the marked condition loss group (103 +/- 7.8 day) than in the moderate condition loss group (87 +/- 5.3 day). We conclude that marked body condition loss from the dry to near calving periods results in the increased occurrence of postpartum metabolic and reproductive diseases, decreased serum total cholesterol concentrations at month 1 of lactation and a longer interval to first breeding after calving in Holstein dairy cows, probably due to the more severe energy deficit reflected by unfavorable body condition score change during early lactation.     

Lifetime individual plasticity in body condition of a migratory bird

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.     

American alligator (Alligator mississippiensis) weight gain in captivity and implications for captive reptile body condition

The body condition of an animal is an indicator of health status and is dependent upon many factors, some of which can vary between wild and captive settings. Despite this, there have not been many studies on how captivity affects body condition relative to wild animal populations. This study explores the body condition of captive and wild American alligators (Alligator mississippiensis) because reptiles are frequently overlooked in studies of captive animal health and because alligators are well-represented in captivity. We collected body condition data from 209 captive alligators and 935 wild alligators throughout Florida and southeastern Georgia and compared the relationships between body condition and body length for each group. We found that captive alligators exhibited significantly higher body condition values as they aged, and that this result was driven by the difference between captive and wild males. Body condition values for captive juveniles did not differ from wild juveniles, but they differed when comparing adults. Our results suggest that factors such as diet and movement rates play major roles in determining alligator body condition and that body condition may be an important metric for monitoring captive alligator health, especially for older adult males.     

Preferential Induction of Alcohol Dehydrogenase in Coleoptiles of Rice Seedlings Germinated in Submergence Condition

Difference in the growth response to submergence between coleoptiles and roots of rice (Oryza sativa L.) was investigated in 9-d-old rice seedlings. The coleoptile length in the submergence condition was much greater than that in aerobic condition, whereas the root length in the submergence condition was less than that in the aerobic condition. Alcohol dehydrogenase (ADH) activity in the coleoptiles in the submergence condition was much greater than that in the aerobic condition, but ADH activity in the roots in the submergence condition increased slightly. These results suggest that the preferential ADH induction in rice seedlings may contribute to the difference in the growth response between the coleoptiles and roots under low oxygen conditions.