Craniodental body mass estimators in the dwarf bushbaby (Galagoides)

This study reports data on 17 craniodental body mass estimators in a sample (n = 38) of dwarf galagos (Galagoides). Correlation coefficients (r) range from a high of 0.64 for bizygomatic breadth and body mass to a low of 0.10 for M(3) length and body mass. Of the 17 variables studied, 7 exhibit significant (P < 0.05) correlation coefficients, with 5 of the 7 being multitooth (i.e., tooth row) or cranial variables. In contrast to the correlation coefficients of greater than 0.90 (e.g., Martin [1980] Z Morphol Anthropol 71:115-124; Steudel [1981] Int J Primatol 2:81-90; Gingerich et al. [1982] Am J Phys Anthropol 58:81-100; Conroy [1987] Int J Primatol 8:115-137) published for higher taxonomic level analyses (i.e., all-primate or prosimian) for many of the same variables studied here, the current data indicate weaker relationships when analyzed at the generic level. Possible explanations for the contrast in correlation coefficients between the current and many previous studies include the following: 1) individual variation due to a geographically dispersed sample, 2) individual body mass fluctuations due to seasonal food availability, and 3) individual variation within the sample due to variation in life-history parameters. Because the overall size range of the individuals in a specific or generic level analysis is smaller than that in an ordinal or subordinal sample, the individual variation normally masked when using species means represents a larger proportion of the total variation in a more limited sample. This may then be a cause of these weaker correlations.     

Regulation of cache stores and body mass in Carolina chickadees (Panes carolinensis)

Here I report the results of laboratory experiments on cachingbehavior of Carolina chickadees (Parus carolinensis) designedto test the following predictions from a recent dynamic optimizationmodel: under limited resources, small birds, when fat, shouldcache food instead of eating it, but they should eat insteadof caching when lean; when resources are abundant, birds shouldcache less when fat and more when lean. In addition, when resourcesare abundant the amount of time spent in foraging-related activityshould decrease with an increase in body mass. Chickadees weretested for 2 weeks in either a poor-quality environment (wherethey were given four 5-min periods per day of access to a feederfilled with sunflower seeds) or a richer environment (wherethey were given four 10-min access periods); they were thenswitched to the alternative environment for an additional 2weeks. The entire experiment lasted from October through June.Within-individual comparisons showed that birds in both thepoor and rich environments exhibited the predicted correlationsbetween the probability that a seed was cached and body massmeasured at dawn. The number of seeds already stored had a weakand variable effect on caching decisions. Time budgets changedas predicted; birds spent less time with food-related behaviorswhen their energy stores were high compared to when they werelow, and overall spent a higher fraction of their time foragingin the poor-quality environment compared to the rich environment.Two other variables also affected caching behavior: experienceand season. Individuals were more likely to cache in the poorenvironment when they had been tested in the rich environmentthe previous 2 weeks, as compared with birds started in thepoor environment. However, this was true only for tests donein the winter. In late spring, all birds stopped caching orreduced caching rates when faced with limited food availability,irrespective of previous experience. The birds harvested seedsfaster when they cached instead of eating seeds; as a result,long-term weight regulation in the poor environment was affectedby caching decisions. Birds tested in late spring lost weightin the poor environment, whereas those tested in the wintermaintained a stable weight when switched from the rich to thepoor environment. Thus, annual endogenous cues directly affectcaching decisions and indirectly influence the long-term regulationof body mass     

Fruit quantity of invasive shrubs predicts the abundance of common native avian frugivores in central Pennsylvania

Aim Biological invasions pose one of the most severe threats to global biodiversity. Still, invasions can create positive ecological relationships and services, which can sometimes result in challenges for conservation efforts. A case in point is the invasion of alien plants that form mutualisms with native frugivorous birds. Here, we examined the correlation between honeysuckles (Lonicera spp.) and the bird communities in a landscape of central Pennsylvania during the fall months. Location State College area in central Pennsylvania, USA. Methods We conducted point counts to quantify the abundance of birds and fleshy‐fruited plant species within a 187.5 km² landscape that included forested, urban and agricultural lands. We also compared fruit‐removal rates for a native fruiting plant under low and high Lonicera densities. Results The abundance of birds showed a strong positive association with Lonicera fruits, with the abundance of Turdus migratorius and Dumetella carolinensis showing the strongest correlations. We also found that fruit‐removal rates were 30% larger for a native plant species in areas of high Lonicera density compared to a site with low density of Lonicera. Main conclusions Our results suggest that Lonicera may currently serve as a main axis for the organization of bird communities and the networks of frugivore–plant interactions in central Pennsylvania. Since populations of key bird frugivores may be currently depending on Lonicera resources, we argue that control measures should account for the negative effects that the loss of this fruit resource could have on populations of native consumers in highly invaded regions.     

Estimating body mass of wild pigs (Sus scrofa) using body morphometrics

Wild pigs (Sus scrofa) are invading many areas globally and impacting biodiversity and economies in their non‐native range. Thus, wild pigs are often targeted for eradication efforts. Age‐ and sex‐specific body measurements are important for informing these eradication efforts because they reflect body condition, resource availability, and fecundity, which are common indicators of population trajectory. However, body mass is often difficult to collect, especially on large individuals that require specialized equipment or multiple people to weigh. Measurements that can be rapidly taken by a single land or wildlife manager on any size wild pig without aid from specialized equipment would be beneficial if they accurately infer wild pig body mass. Our goals were to assess whether morphometric measurements could accurately predict wild pig body mass, and to provide tools to directly input these measures and estimate wild pig body mass. Using linear models, we quantified the relationship between body mass and morphometric measurements (i.e., body length, chest girth, ear length, eye to snout length, hindfoot length, shoulder length, and tail length) from a subset (n = 102) of wild pigs culled at the Mississippi Alluvial Valley, Mississippi, USA. We evaluated separate models for each individual morphometric measurement. We then used the model coefficients to develop equations to predict wild pig body mass. We validated these equations predicting body mass of 1592 individuals collected across eight areas in Australia, Guam, and the USA for cross‐validation. Each developed equation remained accurate when cross‐validated across regions. Body length, chest girth, and shoulder length were the morphometrics that best predicted wild pig body mass. Our analyses indicated it is possible to use the presented equations to infer wild pig body mass from simple metrics.     

Age and body mass index associations with body segment parameters

Body segment parameters (BSPs) such as segment mass, center of mass, and radius of gyration are required in many ergonomic tools and biomechanical models to estimate injury risk, and quantify muscle and joint contact forces. Currently, the full effects of age and obesity have not been taken into account when predicting BSPs. The goal of this study is to quantify the impact of body mass index (BMI) and age on BSPs, in order to provide more representative measures necessary for modeling inputs. A whole body dual energy X-ray absorptiometry (DXA) scan was collected for 280 working men and women with a wide range of BMI and aged 21 to 70 years. Established DXA processing methods were used to determine in-vivo estimates of the mass, center of mass, and radius of gyration for the upper arm, forearm, torso, thigh, and shank for males and females. Regression models were used to determine if age and BMI terms, as well as their interactions, were associated with these BSPs. The variability in BSPs explained by BMI alone ranged from 4 to 51%, and age explained an additional 3–19%. Thus, BMI and age are significant correlates of BSPs, and need to be taken into account when predicting certain BSPs in order to obtain accurate and representative results in biomechanical models.     

Fitness costs and benefits of cowbird egg ejection by gray catbirds

Gray catbirds (Dumetella carolinensis) eject over 95% of brown-headedcowbird (Molothrus ater) eggs placed into their nests. Ejectionbehavior could be maintained by selection from either: (1) cowbird parasitism, if the costs of accepting a cowbird egg outweighthe costs of ejecting it, or (2) conspecific parasitism, ifsuch parasitism occurs naturally and results in ejection. Thisstudy tested the above hypotheses by measuring the cost ofacceptance of cowbird parasitism (n= 38 experimentally introducedcowbird chicks) and of cowbird egg ejection (n = 94 experiments),as well as the frequency of natural conspecific parasitismamong 229 catbird nests observed and the frequency of conspecific egg ejection (n = 27 experiments). The conspecific parasitism hypothesis was not supported because catbirds accepted all foreignconspecific eggs placed into their nests, and no natural conspecificbrood parasitism was detected at any nests. The cowbird parasitismhypothesis was strongly supported because the cost of acceptinga cowbird chick (0.79 catbird fledglings) is much greater thanthe cost of ejecting a cowbird egg (0.0022 catbird fledglingsper ejection).     

Genetic parameters of body weight and prolificacy in pigeons

Genetic parameters of body weight at weaning and of prolificacy were estimated in three commercial lines of pigeons selected by BLUP (Best Linear Unbiased Prediction) on both traits. The model of analysis took into account the direct genetic effects for both traits and the effect of parental permanent environment for body weight. Depending on the line considered, body weight varied from 556.7 g to 647.6 g and prolificacy ranged from 12.5 to 16.8 pigeons weaned per couple of parents per year. Heritability of body weight was high, varying between 0.46 and 0.60, and permanent environment was responsible for 6% to 9% of the total variability. On the contrary, prolificacy was poorly heritable (0.04 to 0.12). They were highly and negatively correlated (-0.77 to -0.82). Body weight showed significant genetic trends in lines B and C. No significant genetic difference could be observed between males and females for both traits.     

Heat production and body temperature during cooling and rewarming in overweight and lean men

Objective: To compare overweight and lean subjects with respect to thermogenesis and physiological insulation in response to mild cold and rewarming. Research Methods and Procedures: Ten overweight men (mean BMI, 29.2 ± 2.8 kg/m²) and 10 lean men (mean BMI, 21.1 ± 2.0 kg/m²) were exposed to cold air for 1 hour, followed by 1 hour of rewarming. Body composition was determined by hydrodensitometry and deuterium dilution. Heat production and body temperatures were measured continuously by indirect calorimetry and thermistors, respectively. Muscle activity was recorded using electromyography. Results: In both groups, heat production increased significantly during cooling (lean, p = 0.004; overweight, p = 0.006). The increase was larger in the lean group compared with the overweight group (p = 0.04). During rewarming, heat production returned to baseline in the overweight group and stayed higher compared with baseline in the lean group (p = 0.003). The difference in heat production between rewarming and baseline was larger in the lean (p = 0.01) than in the overweight subjects. Weighted body temperature of both groups decreased during cold exposure (lean, p = 0.002; overweight, p < 0.001) and did not return to baseline during rewarming. Discussion: Overweight subjects showed a blunted mild cold‐induced thermogenesis. The insulative cold response was not different among the groups. The energy‐efficient response of the overweight subjects can have consequences for energy balance in the long term. The results support the concept of a dynamic heat regulation model instead of temperature regulation around a fixed set point.     

Niche variation and the maintenance of variation in body size in a burying beetle

1. In burying beetles (Nicrophorinae), body size is known to provide both a fecundity advantage (in females) and successful resource defence (in males and females). Despite this, considerable variation in body sizes is observed in natural populations. 2. A possible explanation for the maintenance of this variation, even with intra‐ and inter‐specific resource competition, is that individuals might assort according to body size on different‐sized breeding resources. 3. We tested prediction that ‘bigger is always better’, in the wild and in the laboratory, by experimentally manipulating combinations of available breeding‐resource size (mouse carcasses) and competitor's body size in Nicrophorus vespilloides (Herbst 1783). 4. In the field, large female beetles deserted small carcasses, without breeding, more often than they did larger carcasses, but small females used carcasses indiscriminately with respect to size. In the laboratory, large beetles reared larger broods (with more offspring) on larger carcasses than small beetles, but on small carcasses small beetles had a reproductive advantage over large ones. Offspring size covaried with carcass size independently of parental body size. 5. The present combined results suggest breeding resource value depends on an individual's body size, and variation in body size is environmentally induced: maintained by differences in available carcass sizes. This produces a mechanism by which individual specialisation leads to an increase in niche variation via body size in these beetles.     

No evidence of juvenile body mass affecting dispersal in male red deer

Dispersal is an important mechanism in population dynamics with a sparse empirical basis. Environmental causes of dispersal may work directly or indirectly. In a population with documented negative density-dependent male dispersal, we investigated if the effect of density on dispersal was indirectly mediated through body mass. We analysed the probability of dispersal in 170 juvenile red deer males in Snillfjord municipality, Norway, during a 20-year period of rapid population growth (1977–1997). Body mass and dispersal propensity were not related. Thus, changes in population density act directly on dispersal and are not affected by body mass. Body mass-dependent dispersal occurs in species with strong antagonistic interactions and a high cost of dispersal. Our result suggests that the cost of dispersal in male red deer is low in terms of energy expenditure and survival. We conclude that the effect of body mass on dispersal is likely to vary with mating system and cost of dispersal.     

Influence of age,body weight and body condition score before mating start date on the pubertal rate of maiden Holstein–Friesian heifers and implications for subsequent cow performance and profitability

The aim of this study was to assess the influence of age, body weight (BW) and body condition score (BCS) of maiden Holstein–Friesian heifers before mating start date (MSD) on the rate of puberty, subsequent production and longevity and their implications with regard to farm profitability. Data were available on 871 Holstein–Friesian heifers from 48 herds. BW was recorded electronically and BCS was recorded by a single operator on a scale of 1 to 5. Heifer age was calculated as the number of days from birth to the day of visit. All of the independent variables of interest were grouped into three or four categories. Three age categories (thirtiles), four BW categories (quartiles) and four BCS categories (⩽2.75, 3.00, 3.25 and ⩾3.50) were formed. Heifers with an identifiable corpus lutuem (CL) in the presence or absence of large follicles and peri-ovulatory signs and with a plasma progesterone (P4) concentration ⩾1 ng/ml were classified as pubertal. In addition, heifers without an identifiable CL in the presence or absence of large follicles and peri-ovulatory signs but with a P4 concentration ⩾1 ng/ml were also classified as pubertal. Age, BW and BCS at MSD were all found to be significantly associated with pubertal rate (P < 0.05). Age was shown to have no practical implications on subsequent cow performance. BW at MSD was favourably associated with subsequent calving date (P < 0.05), subsequent cow BW (P < 0.001) and potential (305 days) milk fat plus protein yield (P < 0.001). BCS at MSD was found to be favourably associated with milk fat plus protein yield potential (P < 0.05) and BCS (P < 0.001) during lactation. The economic analysis undertaken indicated that larger, well-grown heifers will be more profitable because of superior production potential, all else being equal. However, because of the finding of poorer reproductive efficiency in heifers grown to more than 343 kg at MSD, heifers at ∼330 kg at MSD are deemed optimal. This will correspond to mature cow BW of ∼550 kg.     

The relative body weights of Bornean and Sumatran orangutans.

Although original field data suggested that the average Bornean orangutan weighed twice as much as the Sumatran ones, this is shown to be an error. The only statistically significant difference in weight is between males and females, regardless of geographical area or data source.     

Variation in the effects of larval history on juvenile performance of a temperate reef fish

For organisms with complex life cycles, the transition between life stages can act as a significant demographic and selective bottleneck. Variation in developmental and growth rates among individuals present in one stage (e.g. larvae), due to initial differences in parental input and/or environmental conditions experienced, can propagate to future stages (e.g. juveniles), and such ‘carry‐over effects’ can shape fitness and phenotypic distributions within a population. However, variation in the strength of carry‐over effects between life stages and the intensity of selective mortality acting on intrinsic variation, and how these might be mediated by environmental variability in natural systems, is poorly known. Here, we evaluate variation in the strength to which larval growth histories can mediate juvenile performance (growth and survival), for a reef fish (Forsterygion lapillum) common to rocky reefs of New Zealand. We used otoliths to reconstruct demographic histories of recently settled fish that were sampled across cohorts, sites and microhabitats. We quantified sources of variation in the strength of carry‐over effects and selective mortality that operate on larval growth histories. We found overall that individuals that grew fast as larvae tended to experience proportional growth advantages as juveniles. However, the strength of growth advantages being maintained into the juvenile period varied among cohorts, sites and microhabitats. Specifically, a stronger growth advantage was found on some microhabitats (e.g. mixed stands of macroalgae) relative to others (e.g. monocultures of Carpophyllum maschalocarpum) for some cohorts and sites only. For other cohorts and sites, the degree of coupling between larval and juvenile growth rates was either indistinguishable between microhabitats or else not evident. Similarly, the intensity of growth‐based selective mortality varied among cohorts, sites and microhabitats: for the cohort and site where carry‐over effects differed between microhabitats, we also observed difference in the intensity to which fish with rapid larval growth rates were favoured. Overall, our results highlight how this spatial and temporal patchiness in extrinsic factors can interact with intrinsic variation of recruiting individuals to have a major influence on the resulting distribution of juveniles and their phenotypic traits.     

Evaluating cetacean body condition; a review of traditional approaches and new developments

The ability to accurately gauge the body condition of free‐swimming cetaceans is invaluable in population and conservation biology, due to the direct implications that this measure has on individual fitness, survival, and reproductive success. Furthermore, monitoring temporal change in body condition offers insight into foraging success over time, and therefore the health of the supporting ecosystem, as well as a species’ resilience. These parameters are particularly relevant in the context of widespread and accelerated, climate‐induced habitat change. There are, however, significant logistical challenges involved with research and monitoring of large cetaceans, which often preclude direct measure of body condition of live individuals. Consequently, a wide variety of indirect approaches, or proxies, for estimating energetic stores have been proposed over past decades. To date, no single, standardized, approach has been shown to serve as a robust estimation of body condition across species, age categories, and in both live and dead individuals. Nonetheless, it is clear that streamlining and advancing body condition measures would carry significant benefits for diverse areas of cetacean research and management. Here, we review traditional approaches and new applications for the evaluation of cetacean energetic reserves. Specific attention is given to the criteria of measure performance (sensitivity and accuracy), level of invasiveness, cost and effort required for implementation, as well as versatility e.g. applicability across different species, age groups, as well as living versus deceased animals. Measures have been benchmarked against these criteria in an effort to identify key candidates for further development, and key research priorities in the field.     

Seasonal variation of 1,25-dihydroxyvitamin D and its association with body mass index and age

Under most normal conditions the serum level of 1,25-dihydroxyvitamin D is constant throughout the year, due to tight biochemical regulation. In contrast to this, the level of 25-hydroxyvitamin D is variable through the year, being largest in late summer, due to photosynthesis in the skin. The vitamin D status is usually assessed by measuring the level of the latter vitamin D derivative, rather than that of the presumably most active derivative 1,25(OH)₂ vitamin D.We here show that for persons with a high body mass index (BMI) there is a significant seasonal variation, not only of 25(OH) vitamin D, but also of 1,25(OH)₂ vitamin D. The variation seems to be largest for those with the poorest vitamin D status. Furthermore, there seems to be a correlation between the levels of the two vitamin D metabolites, indicating that the regulation of 1,25(OH)₂ vitamin D is not always tight, notably in persons with high BMI.     

Population characteristics predict responses in moose body mass to temporal variation in the environment

1. A general problem in population ecology is to predict under which conditions stochastic variation in the environment has the stronger effect on ecological processes. By analysing temporal variation in a fitness-related trait, body mass, in 21 Norwegian moose Alces alces (L.) populations, we examined whether the influence of temporal variation in different environmental variables were related to different parameters that were assumed to reflect important characteristics of the fundamental niche space of the moose. 2. Body mass during autumn was positively related to early access to fresh vegetation in spring, and to variables reflecting slow phenological development (low June temperature, a long spring with a slow plant progression during spring). In contrast, variables related to food quantity and winter conditions had only a minor influence on temporal variation in body mass. 3. The magnitude of the effects of environmental variation on body mass was larger in populations with small mean body mass or living at higher densities than in populations with large-sized individuals or living at lower densities. 4. These results indicate that the strongest influence of environmental stochasticity on moose body mass occurs towards the borders of the fundamental niche space, and suggests that populations living under good environmental conditions are partly buffered against fluctuations in environmental conditions.     

Heritability and genetic correlation of body weight and Kleiber ratio in Limousin and Charolais beef cattle breeds

Reducing the environmental impact of livestock production is now indispensable and genetic selection can be of great support for this purpose. Measures that can identify high body growth at low maintenance costs in production animals are particularly useful since resources have been increasingly limited. Therefore, the goal of this study was to estimate genetic parameters for BW and Kleiber ratio (KR) in 210-day-old and 365-day-old Charolais and Limousin breeds. A database comprising animals born from 1999 to 2018 was used in a multitrait model applying Bayesian inference. The heritability for BW is high in Charolais (0.39 and 0.42 for BW210 and BW365, respectively) and moderate in Limousin (0.22), indicating possible genetic gains for BW in both breeds. The genetic variability of KR should also allow satisfactory genetic gains. In addition, the genetic correlation between BW and KR ranged from low to moderate. Thus, selection over KR should have no effects on BW, showing that high body growth can be obtained without changes in efficiency.