The effects of posterolateral spine length and body length on feeding rate in the rotifer,Brachionus calyciflorus

The length of the posterolateral spines in the rotifer, Brachionus calyciflorus, is variable. The effect of the length of these spines on the clearance rates of B. calyciflorus was examined under laboratory conditions using radioactively-labelled yeast (Rhodotorula) and bacteria (Aerobacter). The hypothesis that individuals with longer spines have higher clearance rates than those of similarly-sized individuals with shorter spines was rejected. The effect of body length (L) on the clearance rates (C) of short-spined and long-spined animals was also examined. Statistically significant linear regressions of the form log₁₀ C = aL + b, were derived for both types. The slopes of both regressions were similar and suggest that clearance rate in B. calyciflorus increases as a cube function of body length.     

GENETIC AND SOCIAL INHERITANCE OF BODY AND EGG SIZE IN THE BARNACLE GOOSE (BRANTA LEUCOPSIS)

We present heritability estimates for final size of body traits and egg size as well as phenotypic and genetic correlations between body and egg traits in a recently established population of the barnacle goose (Branta leucopsis) in the Baltic area. Body traits as well as egg size were heritable and, hence, could respond evolutionarily to phenotypic selection. Genetic correlations between body size traits were significantly positive and of similar magnitude or higher than the corresponding phenotypic correlations. Heritability estimates for tarsus length obtained from full-sib analyses were higher than those obtained from midoffspring-midparent regressions, and this indicates common environment effects on siblings. Heritabilities for tarsus length obtained from midoffspring-mother regressions were significantly higher than estimates from midoffspring-father regressions. The results suggest that this discrepancy is not caused by maternal effects through egg size, nor by extra-pair fertilizations, but by a socially inherited foraging site fidelity in females.     

Predicting home range size from the body mass or population densities of feral pigs,Sus scrofa (Artiodactyla: Suidae)

Telemetry studies of feral pigs (Sus scrofa, L.) in different habitats were used to predict home range size, from (i) body mass and (ii) population density. Geometric mean regressions of the log_e transformed data indicated that body mass of male and female feral pigs and mean population density were good predictors of the home range size of feral pigs (r² = 0.81, 0.77 and 0.85 respectively). There were no sexual differences in home range size of feral pigs once the effect of body mass was taken into account. Use of these variables in models that incorporate spatial aspects along with the practical application of the results to the management of feral pig populations are briefly discussed.     

Predictive Length–Dry Mass Regressions for Freshwater Invertebrates in a Pre‐Alpine Lake Littoral

To date, no regressions for invertebrates from lentic environments are available to facilitate biomass estimation. Predictive length–dry mass regressions for 20 freshwater invertebrate taxa from a pre‐alpine lake littoral in Central Europe are presented here. Regressions were calculated by fitting a power function to body‐length parameters. For Gammarus roeseli, the head height, an easily measurable length parameter, was used. Differences between regressions of different taxa were confirmed by analyses of covariance. Equations for invertebrates grouped at a higher taxonomic level had lower coefficients of determination; therefore, the use of regression equations at the lowest possible taxonomic level is indicated. A comparison of regressions with those published for related taxa in streams revealed significant differences, supporting the opinion that equations should be applied carefully and their use restricted to waterbodies with similar abiotic conditions.     

Allometry of thermal variables in mammals: consequences of body size and phylogeny

A large number of analyses have examined how basal metabolic rate (BMR) is affected by body mass in mammals. By contrast, the critical ambient temperatures that define the thermo‐neutral zone (TNZ), in which BMR is measured, have received much less attention. We provide the first phylogenetic analyses on scaling of lower and upper critical temperatures and the breadth of the TNZ in 204 mammal species from diverse orders. The phylogenetic signal of thermal variables was strong for all variables analysed. Most allometric relationships between thermal variables and body mass were significant and regressions using phylogenetic analyses fitted the data better than conventional regressions. Allometric exponents for all mammals were 0.19 for the lower critical temperature (expressed as body temperature ‐ lower critical temperature), ?0.027 for the upper critical temperature, and 0.17 for the breadth of TNZ. The small exponents for the breadth of the TNZ compared to the large exponents for BMR suggest that BMR per se affects the influence of body mass on TNZ only marginally. However, the breadth of the TNZ is also related to the apparent thermal conductance and it is therefore possible that BMR at different body masses is a function of both the heat exchange in the TNZ and that encountered below and above the TNZ to permit effective homeothermic thermoregulation.     

Paleobiology of the oligopithecines,the earliest known anthropoid primates

Anthropoid primates of the subfamily Oligopithecinae are late Eocene in age, and have a known distribution of Northeast Africa and the Arabian Peninsula. Body sizes of the three known oligopithecine species are estimated from allometric molar size regressions to be 700–1000 g forOligopithecus savagei, 600–900 g forCatopithecus browni, and 500 g for the least well-known and smallest species,Proteopithecus sylviae. Occlusal features of the molar teeth, considered in conjunction with body size, suggest that all three species were frugivorous and insectivorous. The orbital size ofCatopithecus indicates a diurnal activity cycle. A relatively broad interobital region in this species may indicate prosimian-like or callitrichid-like olfactory adaptations. Structural features of the crushed skull suggest thatCatopithecus had a smaller cranial capacity than those of extant anthropoids with a similar body size. Fossil plants and birds from localities yielding oligopithecines suggest a wet, warm, tropical, forested, swampy environment. These paleobiological inferences about the extinct oligopithecines are discussed in relation to questions about primate adaptations near the prosimian-anthropoid transition.     

Which body condition index is best?

Body condition indices are widely used by ecologists, but many indices are used without empirical validation. To test the validity of a variety of indices, we compared how well a broad range of body condition indices predicted body fat mass, percent body fat and residual fat mass in mice Mus musculus. We also compared the performance of these condition indices with the multiple regression of several morphometric variables on body fat mass, percent body fat and residual fat mass. In our study population, two ratio based condition indices – body mass/body length and log body mass/log body length – predicted body fat mass as well as or better than other ratio and residual indices of condition in females. In males one ratio based condition index (log body mass/log body length) and one residual index (residuals from a regression of pelvic circumference on body length) were best at predicting body fat mass. All indices were better at estimating body fat mass, and residual fat mass than at estimating percent body fat. The predictions of body fat were much better for females than for males. Multiple regressions incorporating pelvic circumference (i.e. girth at the iliac crests) were the best predictors of body fat mass, residual fat mass, and percent body fat, and these multiple regressions were better than any of the condition indices. We recommend 1) that condition be precisely defined, 2) that predictors of condition be empirically validated, 3) that pelvic circumference be considered as a potential predictor of fat content, and 4) that, in general, multiple regression be considered as an alternative to condition indices.     

Tree mortality of five major species on Hokkaido Island, northern Japan

The mortality rates of five major tree species (Abies sachalinensis, Acer mono, Magnolia obovata, Quercus crispula, Tilia japonica) on Hokkaido Island, northern Japan were modeled using logistic regressions based on the long-term observation of 8929 individuals in 65 permanent plots. Individual size, recent growth, one-sided and two-sided interactions with neighbors, climatic and topographic factors were used as independent variables in the logistic regressions, and relevant variables were selected using the stepwise method. For all species analyzed, the final models significantly explained tree mortality rates. The regression analyses indicated that individual size and/or recent growth had effects on tree mortality. A significant effect of one-sided interaction on tree mortality was detected for three species, and a significant effect of two-sided interaction was detected for two species. The interactions with neighbors were not necessarily competitive. For all species analyzed, climatic and topographic factors affected tree mortality. The mortality models obtained can be used for forest dynamics simulations. One ecological question was examined using these models. Species that can grow fast in forest stands with smaller basal areas tended to have high mortality rates in forest stands with larger basal areas. Some ecological characteristics of the analyzed species are described based on the results of the regressions.     

Competition, coexistence, and adaptation amongst rodent invaders to Pacific and New Zealand islands

Variation in skull size was investigated for three species of rats (kiore –Rattus exulans Peale; ship rat –R. rattus L.; Norway rat –R. norvegicus Berkenhout) which were introduced by humans to various islands in New Zealand and other Pacific islands. Data from seventy-one islands and 882 specimens are examined for evidence of the effects of latitude, island size and interspecific competition among rats and the house mouse (Mus musculus L.) on skull size, using multiple regressions. For R. exulans, skull size increases with latitude as predicted by Bergmann's rule, but no such effect occurs for the other two rats. There was a positive relationship between island size and the number of species inhabiting it, and some species combinations were more likely to occur than others. For example, R. exulans and R. norvegicus were more likely to occur together, while R. rattus and R. exulans were rarely sympatric. R. exulans and R. rattus skull size was negatively correlated with the number of other rodents on the same island. R. exulans skull size increased on smaller islands in some island groups, perhaps because increased density and consequent increased intraspecific competition on smaller islands favours increased body size. This effect is more pronounced in tropical islands (Solomon islands), than in subtropical ones (Hawaiian islands) and less so in temperate New Zealand. Collectively the data demonstrate that rapid evolution of body size in predictable directions can follow within 150 years of the introduction of species to new receiving communities.     

Body Mass Estimates for Eocene Eosimiid and Amphipithecid Primates Using Prosimian and Anthropoid Scaling Models

We estimated body masses for middle to late Eocene East Asian eosimiids and amphipithecids from the crown areas of cheek teeth. First, we calculated body mass estimate equations via an extant primate sample of 11 prosimian and 30 anthropoid species, and compared the reliability of the resulting body mass estimate regressions. M ^1–2 and M _1–2 are better body mass estimators, especially for fossils with few samples, because of their low intraspecific variations in dimensions. Moreover, body masses derived from M _1–2 tend to indicate lower estimate error than those from other cheek teeth. The relationships between tooth crown areas and body mass differ between prosimians and anthropoids; the estimated body mass from crown area of P ⁴ or any molar will be larger if anthropoids, instead of prosimians, are used as a reference taxon. Second, We applied the regressions to the fossil primates. The estimated body masses in kg are as follows: Eosimias centennicus, 0.16; E. sinensis, 0.14; Eosimiidae indet. from the Pondaung Formation, 0.41; Bahinia pondaungensis, 0.57; Myanmarpithecus yarshensis, 1.8; Amphipithecus mogaungensis, 6.8; Pondaungia cotteri, 5.9; Pondaungia savagei, 8.8; Siamopithecus eocaenus, 5.9. Eosimiids fit the prosimian model better than the anthropoid model. Amphipithecids do not fit one model particularly better than the other, as the estimates vary considerably according to the tooth used and the reference taxon. The anthropoid model gives smaller differences between upper- and lower-molar-based body mass estimates, but premolars are relatively much smaller in amphipithecids than in extant prosimians and anthropoids.     

EXPRESSION OF GENETIC VARIATION IN BODY SIZE OF THE COLLARED FLYCATCHER UNDER DIFFERENT ENVIRONMENTAL CONDITIONS

Heritability of body size in two experimentally created environments, representing good and poor feeding conditions, respectively, was estimated using cross-fostered collared flycatcher Ficedula albicollis nestlings. Young raised under poor feeding conditions attained smaller body size (tarsus length) than their full-sibs raised under good feeding conditions. Parent-offspring regressions revealed lower heritability (h²) of body size under poor than under good feeding conditions. Hence, as the same set of parents were used in the estimation of h² in both environments, this suggests environment-dependent change in additive genetic component of variance (V_A), or that the genetic correlation between parental and poor offspring environment was less than that between parental and good offspring environment. However, full-sib analyses failed to find evidence for genotype-environment interactions, although the power of these tests might have been low. Full-sib heritabilities in both environments tended to be higher than estimates from parent-offspring regressions, indicating that prehatching or early posthatching common environment/maternal effects might have inflated full-sib estimates of V_A. The effect of sibling competition on estimates of V_A was probably small as the nestling size-hierarchy at day 2 posthatch was not generally correlated with size-hierarchy at fledging. Furthermore, there was no correlation between maternal body condition during the incubation and final size of offspring, indicating that direct maternal effects related to nutritional status were small. A review of earlier quantitative genetic studies of body size variation in birds revealed that in eight of nine cases, heritability of body size was lower in poor than in good environmental conditions. The main implication of this relationship will be a decreased evolutionary response to selection under poor environmental conditions. On the other hand, this will retard the loss of genetic variation by reducing the accuracy of selection and might help explain the moderate to high heritabilities of body-size traits under good environmental conditions.     

Larval nutritional environment determines adult size in Japanese horned beetles <Emphasis Type="Italic">Allomyrina dichotoma</Emphasis>

The effects of larval nutrition and parental size on offspring horn (male) and body size (male and female) were examined in the Japanese horned beetle Allomyrina dichotoma L. (Coleoptera: Scarabaeidae). Offspring-parent regressions for both horn size and body size of males show no heritable effect, and the magnitudes of these traits were primarily determined by the larval nutritional condition. Male Allomyrina dichotoma also displayed dimorphic horn size-body size allometry, that is, larger males had longer horns relative to their body size and vice versa. Because it has been suggested that males of different body sizes adopt different reproductive tactics, the dimorphic horn size–body size allometry and male reproductive tactics are also a result of the larval environment. Similarly, female body size was determined by larval nutrition, and, thus, larval condition might influence future female fecundity. Females under low nutrition treatment spent longer duration of the third larval instar than females under high nutrition. Females under poor nutrition treatment probably attempted to be as large as possible by the extent of larval duration. Since horn and/or body sizes of males and females affect their fitness, this suggests the evolution of female choice for better oviposition site.     

Deep phylogeny,net primary productivity,and global body size gradient in birds

Body size is evolutionarily constrained, but the influence of phylogenetic relationships on global body size (i.e. body mass) gradients is unexplored. We quantify and map the family‐level phylogenetic and non‐phylogenetic structure of the global gradient of birds, evaluating the extent to which it is influenced by phylogenetic inertia in contrast to heat conservation, resource availability, starvation resistance, niche conservatism, or interspecific competition. Phylogenetic eigenvector regression (PVR) partitioned the global bird body size gradient into phylogenetically autocorrelated (PA) and phylogenetically independent (PI) components. Simple, piecewise, and partial regressions were used to investigate associations between the PA and PI components of body size and environmental correlates, and to quantify independent and overlapping contributions of environment, phylogenetic autocorrelation, and species richness to the body size gradient. Two‐thirds of the geographic variation in bird body size can be explained by phylogenetic relationships at the family level. The global variation in body size, independent of phylogenetic relationships, is most strongly associated with net primary productivity, which is consistent with ‘starvation resistance’. However, the New and Old worlds have very different patterns. We found no independent association of species richness with body size. Despite major unresolved regional differences, deep phylogenetic relationships, heat conservation, and starvation resistance probably operate in concert in shaping the global bird body size gradient in different parts of the world. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??.     

Ontogenetic Diet Shifts of a Neotropical Catfish, Pimelodus maculatus (Siluriformes, Pimelodidae): An Ecomorphological Approach

This study analyses the ontogenetic diet shifts of a Neotropical catfish, Pimelodus maculatus (Siluriformes, Pimelodidae), from an ecomorphological standpoint. We collected 241 individuals in the Piracicaba River (Brazil) and, in the laboratory, seven morphometric variables were recorded from each specimen: standard length (SL), body depth, head length, snout length, eye diameter, mouth height and mouth width. After standardizing these measurements (as a proportion of SL), linear regressions were run to determine whether their growth was isometric or allometric in relation to SL. The diet analysis shows that the main food item for fish in the smaller size classes is aquatic insects, while the largest individuals feed mainly on other fish. As the great majority of the morphometric variables analyzed showed isometric growth as a function of SL – which means that these fish do not change their shape significantly during their lives – the ontogenetic diet shifts may be seen as a consequence of the absolute size increment of their mouth gape, which allows individuals to maximize their energetic gain by ingesting larger prey with a higher caloric content.     

Patterns of sexual size dimorphism in stingless bees: Testing Rensch’s rule and potential causes in highly eusocial bees (Hymenoptera: Apidae,Meliponini)

Eusocial insects offer a unique opportunity to analyze the evolution of body size differences between sexes in relation to social environment. The workers, being sterile females, are not subject to selection for reproductive function providing a natural control for parsing the effects of selection on reproductive function (i.e., sexual and fecundity selection) from other kinds of natural selection. Patterns of sexual size dimorphism (SSD) and testing of Rensch's rule controlling for phylogenetic effects were analyzed in the Meliponini or stingless bees. Theory predicts that queens may exhibit higher selection for fecundity in eusocial taxa, but contrary to this, we found mixed patterns of SSD in Meliponini. Non‐Melipona species generally have a female‐biased SSD, while all analyzed species of Melipona showed a male‐biased SSD, indicating that the direction and magnitude of the selective pressures do not operate in the same way for all members of this taxon. The phylogenetic regressions revealed that the rate of divergence has not differed between the two castes of females and the males, that is, stingless bees do not seem to follow Rensch's rule (a slope >1), adding this highly eusocial taxon to the various solitary insect taxa not conforming with it. Noteworthy, when Melipona was removed from the analysis, the phylogenetic regressions for the thorax width of males on queens had a slope significantly smaller than 1, suggesting that the evolutionary divergence has been larger in queens than males, and could be explained by stronger selection on female fecundity only in non‐Melipona species. Our results in the stingless bees question the classical explanation of female‐biased SSD via fecundity and provide a first evidence of a more complex determination of SSD in highly eusocial species. We suggest that in highly eusocial taxa, additional selection mechanisms, possibly related to individual and colonial interests, could influence the evolution of environmentally determined traits such as body size.     

Body mass estimation for †Cyonasua (Procyonidae,Carnivora) and related taxa based on postcranial skeleton

Procyonidae were the first northern placental carnivorans that reached the Neotropics. They are represented by two extinct genera: ?Cyonasua and ?Chapalmalania (late Miocene – early Pleistocene). Postcranial elements are only known for ?Cyonasua and related taxa (?Parahyaenodon argentinus and ?Tetraprothomo argentinus). To obtain highly reliable allometric equations for body mass estimations of fossil procyonids, we performed least squares regressions (multiple and bivariate lineal models) using 51 postcranial linear measurements. The extant sample included 124 taxa corresponding to nine families of Carnivora, with body mass data from the literature. We obtained about 63 equations from diverse combinations of postcranial measurements; 14 of them were selected using several reliability indexes as criteria. Our results show that body masses calculated for ?Cyonasua range between 12.63 and 28.45 kg, ?P. argentinus was estimated at 14.41 kg, while ?T. argentinus at 25.31 kg. Thus, the body mass of ?Cyonasua would have been at least twice as high as the mean of the extant procyonid Procyon cancrivorus. ?Cyonasua was probably able to fend off predators and quite capable of climbing slowly on thick-enough branches. Other palaeoecological and palaeobiological inferences are discussed.     

Density,biomass, and guild structure of arboreal arthropods as related to their inhabited tree size in aCryptomeria japonica plantation

Arboreal arthropods in a 15-year-old plantation ofCryptomeria japonica were surveyed using the smoking method under open conditions and also in the enclosed condition in which the whole above-ground part of a tree was covered by a cloth bag. Per tree, the number of individuals collected was 8200–14000, with a biomass of 340–1700 mg d.wt. Collembola and Acarina were major components in number, while Diplopoda, Collembola, and Araneae occupied the larger part of the biomass. About 60–70% of total numbers of individuals dropped within two hours after the open fumigation. Clear power-form regressions between total numbers of individuals and biomasses of all animals and their host tree size (stem diameter at clear length,D _B ) showed they were approximately proportional toD _B ². The guilds of scavengers and tourists demonstrated the most significant correlations between their numbers and biomasses and the tree size. Numbers and biomasses of Collembola, Diptera, and Araneae revealed remarkable dependence on the tree size. From these regressions, numbers of individuals and biomasses per unit ground area were estimated for all arthropods to be 3755/m² and 165.87 mg d.wt./m², respectively. Power-form regressions were observed between numbers and biomasses of prey and predators. The number-and biomass ratios of all predators to all prey tended to decrease with increasing tree size. A similar trend was observed in the corresponding ratios of parasitic Hymenoptera to lepidopteran larvae, while those of Araneae to Collembola were almost constant, irrespective of tree size.     

A bioenergetic study of a benthic nematode,Plectus palustris de man 1880, throughout its life cycle

Summary Respiration rates of the bacterivorous freshwater nematode Plectus palustris were measured during the whole life cycle of the species and for animals grown at two food densities. Covariance analysis showed that small, but significant differences exist in the elevation of the respiration rate—body weight regressions (R=aW ^b, in nl O₂/ind·h and g wet weight) for different food densities. At a food density of 6–9·10⁸ bacterial cells/ml the level of respiration is 14% lower compared to rates of animals cultured at a ten times higher food density. However, the allometric function, R-aW ^b, adequately describes the relationship of respiration and body weight only during the larval growth phase and for young females, while respiration rates of newly hatched larvae and mature females at maximal egg production have lower metabolic rates. Cumulated metabolic costs to attain a certain age, size and stage of development have been determined and are used in a subsequent paper (Schiemer et al., 1979) to calculate the energy budgets of the species.     

Relationships between length and weight of freshwater macroinvertebrates in Japan

Relationships between weight (W; dry weight) and length (L; head capsule width, total body length or head carapace length) were examined in 31 Japanese freshwater macroinvertebrate taxa, using the form W = aL ^b . The relationships were expressed as data of the lowest taxonomic level and data of higher taxonomic levels. The length–weight relationships obtained in this study were similar to those obtained in North America and Europe at the lowest taxonomic level, whereas they could be different from those obtained in North America and Europe at the higher taxonomic levels. We suggest that researchers should make their own regressions for a target taxon or use the regression for the same taxon as possible lower taxonomic level in the local area.     

Gonads annual development of Kelee shad, <Emphasis Type="Italic">Hilsa kelee</Emphasis> (Cuvier, 1829) from the coastal waters of Pakistan and its spawning ecology

Annual reproductive cycle and spawning ecology of Kelee shad, Hilsa kelee were studied. The sex ratios did not exhibit as 1: 1; whereas 69.19% were females. On the basis of histological examination, the maturity of female gonads of H. kelee was categorized in eight developmental stages: immature, developing, fully developed, hydrated, running ripe, partially spent, spent and post spawning. Whereas males of this species were categorized in five developmental stages: immature, developing, ripe, partially spent and spent. This fish is repeatedly spawner and spawns twice per year: in April to June and August to October. The values of exponent b in the length weight regressions (W = al ^b ) slightly varied in males b = 3.133, R ² = 0.96 and P < 0.01 and females b = 3.143, R ² = 0.95 and P < 0.001. The linear regressions of length-weight relationships were significant for both males and females.