Does body size affect the response to exercise in shortnose sturgeon (Acipenser brevirostrum)?

The effect of body size on various hematological variables was examined in juvenile shortnose sturgeon (Acipenser brevirostrum) ranging in mass from 38 to 730 g. The blood was examined for differences in plasma ionic composition (Na⁺, K⁺, Cl^?), blood oxygen carrying capacities (hemoglobin, hematocrit), and plasma metabolite concentrations (lactate, glucose), before and following a standard 5‐min chasing stress. All measured resting hematological variables were size independent in shortnose sturgeon. After exercise, levels of plasma lactate, potassium, and hemoglobin increased in all fish. Only post‐exercise levels of chloride and hemoglobin changed in a size‐dependent manner; however, the relationships were weak. The general lack of a relationship between body size and hematological variables might reflect the narrow range of fish sizes used in the present study. From a practical perspective, the results suggest that when examining the hematological stress response in juvenile shortnose sturgeon, a range of fish sizes could be used. This is important considering the variability in the growth rates of juvenile shortnose sturgeon under laboratory conditions.     

Tadpole–odonate larvae interactions: influence of body size and diel rhythm

Several studies have shown that prey and predator body size may affect the outcome of predator–prey interactions. However, few studies have taken in account the changes on predator–prey interactions over 24 h. In a tropical freshwater system I evaluated how predator and prey size, and their diel rhythm in activity influenced the interaction between Physalaemus pustulosus tadpoles and dragonfly larvae. Tadpoles of different size classes were exposed to two size classes of the dragonfly larvae Rhionaeschna spec. Feeding trials were conducted during day and night. Tadpole activity showed a diel rhythm and affected size-selective predation of the smallest dragonfly larvae, but not of the larger ones. Predator and prey size had a significant effect on the prey survivorship and prey size had a significant effect on the preference of the predator. The interaction between both factors was significant, indicating that they did not operate independently. I conclude that the predator–prey interactions between odonate larvae and anuran tadpoles were mainly affected by the size of the prey and the predator, and less by the diel activity pattern of the prey.     

Does education influence the results of the Amsterdam Dementia-Screening Test (ADS)?

The goal of this study was to explore the correlation between education and the results of five dementia screening tests. In a study of 551 consecutively enrolled psychogeriatric day care attendants individual differences in education explained only very small portions of variance (< or = 0.63%) in four tests (visual recognition memory, orientation, category fluency and alternating sequences) of the Amsterdam Dementia Screening Test, a standard neuropsychological battery. The only exception was graphical copying of two- or three-dimensional geometric designs, where education explained 6.25% of the variance in copying accuracy. The more education participants had (from incomplete or complete primary education, through extended primary education, lower technical and vocational training, and secondary to higher education), the better their copying performance was. There was however one exception, in that participants with secondary education copied designs significantly less accurately than participants with lower technical and vocational training. Differences in copying accuracy of subjects with higher versus lower educational attainment were largest for participants matched for high levels of cognitive function. More severe cognitive impairment attenuated education effects. Higher education did not protect against decline of copying performance as a consequence of increasing cognitive impairment. For each of three educational levels, premorbid copying performance was estimated by constructing a regression equation using an independent measure of cognitive functioning (in terms of visual recognition memory, orientation and category fluency) as the predictor variable. The results support the clinical utility of controlling for educational level when interpreting individual copying performance.     

What are the maximum size and live body coloration of opah (Teleostei: Lampridae: Lampris species)?

Validity of the largest size accounts is not well documented and most published accounts of body coloration describe dead specimens lacking scales instead of the color of freshly caught opah. Maximum length is at least 163?cm fork length and maximum weight about 89?kg. The body color of fresh specimens is vermilion with white spots.     

Can shifts in metabolic scaling predict coevolution between diet quality and body size?

Larger species tend to feed on abundant resources, which nonetheless have lower quality or degradability, the so‐called Jarman‐Bell principle. The “eat more” hypothesis posits that larger animals compensate for lower quality diets through higher consumption rates. If so, evolutionary shifts in metabolic scaling should affect the scope for this compensation, but whether this has happened is unknown. Here, we investigated this issue using termites, major tropical detritivores that feed along a humification gradient ranging from dead plant tissue to mineral soil. Metabolic scaling is shallower in termites with pounding mandibles adapted to soil‐like substrates than in termites with grinding mandibles adapted to fibrous plant tissue. Accordingly, we predicted that only larger species of the former group should have more humified, lower quality diets, given their higher scope to compensate for such a diet. Using literature data on 65 termite species, we show that diet humification does increase with body size in termites with pounding mandibles, but is weakly related to size in termites with grinding mandibles. Our findings suggest that evolution of metabolic scaling may shape the strength of the Jarman‐Bell principle.     

Conservation genetics of Boelen’s python (Morelia boeleni) from New Guinea: reduced genetic diversity and divergence of captive and wild animals

Boelen’s python (Morelia boeleni) is a montane New Guinea endemic found in highlands above 1000 m and below the tree line. The ecology, natural history, distribution, population size, and conservation status of this species are largely unknown. It has a protected status in Papua New Guinea but not in Indonesian Papua and several US and European zoos have active captive breeding programs that have been largely unsuccessful. To understand the degree of genetic diversity in wild and captive animals we undertook a genetic analysis of 90 M. boeleni for which we sequenced two mtDNA loci and one nuclear locus for a total of 1,418 bp of sequence data per individual. All 16 wild-caught M. boeleni from Indonesia and all captive M. boeleni are genetically uniform for all three loci. The single wild-caught animal from Papua New Guinea showed extremely low levels of genetic divergence and diversity from the Indonesian and captive samples. Data from two congeners, M. amethistina and M. viridis, suggests that M. boeleni have reduced genetic variation with a small effective population size possibly due to historical bottlenecks. These data demonstrate the need for further studies of genetic diversity of M. boeleni from across its range and raise particular concern for the limited genetic diversity of M. boeleni used captive breeding programs in zoological parks.     

Are hummingbirds facultatively ammonotelic? Nitrogen excretion and requirements as a function of body size

Most birds are uricotelic. An exception to this rule may be nectar-feeding birds, which excrete significant amounts of ammonia under certain conditions. Although ammonia is toxic, because it is highly water soluble its excretion may be facilitated in animals that ingest and excrete large amounts of water. Bird-pollinated plants secrete carbohydrate- and water-rich floral nectars that contain exceedingly little protein. Thus, nectar-feeding birds are faced with the dual challenge of meeting nitrogen requirements while disposing of large amounts of water. The peculiar diet of nectar-feeding birds suggests two hypotheses: (1) these birds must have low protein requirements, and (2) when they ingest large quantities of water their primary nitrogen excretion product may be ammonia. To test these hypotheses, we measured maintenance nitrogen requirements (MNR) and total endogenous nitrogen losses (TENL) in three hummingbird species (Archilochus alexandri, Eugenes fulgens, and Lampornis clemenciae) fed on diets with varying sugar, protein, and water content. We also quantified the form in which the by-products of nitrogen metabolism were excreted. The MNR and TENL of the hummingbirds examined were exceptionally low. However, no birds excreted more than 50% of nitrogen as ammonia or more nitrogen as ammonia than urates. Furthermore, ammonia excretion was not influenced by either water or protein intake. The smallest species (A. alexandri) excreted a significantly greater proportion (>25%) of their nitrogenous wastes as ammonia than the larger hummingbirds ( approximately 4%). Our results support the hypothesis that nectar-feeding birds have low protein requirements but cast doubt on the notion that they are facultatively ammonotelic. Our data also hint at a possible size-dependent dichotomy in hummingbirds, with higher ammonia excretion in smaller species. Differences in proportionate water loads and/or postrenal modification of urine may explain this dichotomy.     

Does the timing of attainment of maturity influence sexual size dimorphism and adult sex ratio in turtles?

The attainment of sexual maturity has been shown to affect measures of sexual size dimorphism (SSD) and adult sex ratios in several groups of vertebrates. Using data for turtles, we tested the model that sex ratios are expected to be male‐biased when females are larger than males and female‐biased when males are larger than females because of the relationship of each with the attainment of maturity. Our model is based on the premise that the earlier‐maturing sex remains smaller, on average throughout life, and predominates numerically unless the sexes are strongly affected by differential mortality, differential emigration, and immigration, or biased primary sex ratios. Based on data for 24 species in seven families, SSD and sex ratios were significantly negatively correlated for most analyses, even after the effect of phylogenetic bias was removed. The analyses provide support for the model that SSD and adult sex ratios are correlated in turtles as a result of simultaneous correlation of each with sexual differences in attainment of maturity (bimaturism). Environmental sex determination provides a possible mechanism for the phenomenon in turtles and some other organisms. © 2014 The Authors. Biological Journal of the Linnean Society published by John Wiley & Sons Ltd on behalf of The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 142–149.     

Does size matter? Relating consumed prey sizes and diet composition of otters in South Iberian coastal streams

We analysed seasonal changes in the sizes of prey [grey mullets (Mugilidae), flatfish (Soleidae), eelAnguilla anguilla and crayfishProcambarus clarkii] consumed by ottersLutra lutra Linnaeus, 1758 in a Mediterranean-climate coastal area and relate them to the frequencies of occurrence of each prey species in otter diet. The sizes of over 1500 otter prey were estimated from measurements of key pieces found in 814 otter spraints, which were collected in lower stream stretches in a sandy coastal area. Clear relationships between mean prey size and frequency of occurrence were observed for the four prey types. These relationships were positive for grey mullets, flatfish and crayfish (ie they occurred more in otter diet when more large individuals were predated), but was negative in the case of eels. Results suggest that these patterns could be related to seasonal changes in habitat use. Previous works in the study area showed that otter concentrate its predation efforts in freshwater stream stretches during spring and summer, when more and larger crayfish are available. Freshwater stretches have neither grey mullets nor flatfish, while eels are larger and scarcer there than near streams’ mouths, where crayfish is absent.     

Does troop size of wild Japanese macaques influence birth rate and infant mortality in the absence of predators?

For the wild Japanese macaques of Yakushima and Kinkazan Islands, we analyzed the relationship between the troop size or the number of adult females of each troop, infant/adult female ratio (IFR; crude birth rate), and infant mortality (IM) in habitats with no predators. In Yakushima, IFR was positively correlated to troop size and the number of adult females. In Kinkazan, however, IFR tended to decrease with the number of adult females. This difference may be due to the difference in troop size; i.e. in Yakushima, where troop size was small, IFR may increase with that of troop size, because a relatively larger troop is likely to the advantage in intertroop competition. In Kinkazan, where troop size was large, however, IFR is likely to decrease with troop size, because intratroop competition may increase. Thus, the present data roughly supportWrangham's model of the social structure of female-bonded primates, and suggests that there is an optimal troop size for birth rate (BR). On the other hand, there was no clear correlation between IM and the troop size or number of adult females of each troop.     

Does macrophyte fractal complexity drive invertebrate diversity,biomass and body size distributions?

Habitat structure is one of the fundamental factors determining the distribution of organisms at all spatial scales, and vegetation is of primary importance in shaping the structural environment for invertebrates in many systems. In the majority of biotopes, invertebrates live within vegetation stands of mixed species composition, making estimates of structural complexity difficult to obtain. Here we use fractal indices to describe the structural complexity of mixed stands of aquatic macrophytes, and these are employed to examine the effects of habitat complexity on the composition of free-living invertebrate assemblages that utilise the habitat in three dimensions. Macrophytes and associated invertebrates were sampled from shallow ponds in southwest England, and rapid digital image analysis was used to quantify the fractal complexity of all plant species recorded, allowing the complexity of vegetation stands to be reconstructed based on their species composition. Fractal indices were found to be significantly related to both invertebrate biomass–body size scaling and overall invertebrate biomass; more complex stands of macrophytes contained a greater number of small animals. Habitat complexity was unrelated to invertebrate taxon richness and macrophyte surface area and species richness were not correlated with any of the invertebrate community parameters. The biomass–body size scaling relationship of lentic macroinvertebrates matched those predicted by models incorporating both allometric scaling of resource use and the fractal dimension of a habitat, suggesting that both habitat fractal complexity and allometry may control density–body size scaling in lentic macroinvertebrate communities.     

Does wing reduction influence the relationship between altitude and insect body size? A case study using New Zealand's diverse stonefly fauna

Researchers have long been intrigued by evolutionary processes that explain biological diversity. Numerous studies have reported strong associations between animal body size and altitude, but insect analyses have often yielded equivocal results. Here, we analyze a collection database of New Zealand's diverse endemic stonefly fauna (106 species across 21 genera) to test for relationships between altitude and plecopteran body size. This insect assemblage includes a variety of wing‐reduced (26 spp) and fully winged (80 spp) taxa and covers a broad range of altitudes (0–2,000 m). We detected significant relationships between altitude and body size for wing‐reduced, but not fully winged, stonefly taxa. These results suggest that, while the maintenance of flight apparatus might place a constraint on body size in some fully winged species, the loss of flight may free insects from this evolutionary constraint. We suggest that rapid switches in insect dispersal ability may facilitate rapid evolutionary shifts across a number of biological attributes and may explain the inconsistent results from previous macroecological analyses of insect assemblages.     

Does the colonization of new biogeographic regions influence the diversification and accumulation of clade richness among the Corvides (Aves: Passeriformes)?

Regional variation in clade richness can be vast, reflecting differences in the dynamics of historical dispersal and diversification among lineages. Although it has been proposed that dispersal into new biogeographic regions may facilitate diversification, to date there has been limited assessment of the importance of this process in the generation, and maintenance, of broad‐scale biodiversity gradients. To address this issue, we analytically derive biogeographic regions for a global radiation of passerine birds (the Corvides, c. 790 species) that are highly variable in the geographic and taxonomic distribution of species. Subsequently, we determine rates of historical dispersal between regions, the dynamics of diversification following regional colonization, and spatial variation in the distribution of species that differ in their rates of lineage diversification. The results of these analyses reveal spatiotemporal differences in the build‐up of lineages across regions. The number of regions occupied and the rate of transition between regions both predict family richness well, indicating that the accumulation of high clade richness is associated with repeated expansion into new geographic areas. However, only the largest family (the Corvidae) had significantly heightened rates of both speciation and regional transition, implying that repeated regional colonization is not a general mechanism promoting lineage diversification among the Corvides.     

Does the size of small objects influence chemical reactivity in living systems?

Previous theoretical works showed that chemical reactions in micro- and nano-droplets, bubbles and solid particles were strongly affected by their confinement. In particular, the smallness of the systems leads to high internal pressure compared to the external pressure, which then significantly modifies the values of chemical equilibrium and kinetic constants. In addition, surface tension or surface stress, reactional dilatation and surface charge play also a major role on the chemical reactivity. As living systems are also made of very complex dispersed subsystems, i.e. organelles, it seemed obvious to illustrate our theory by some biological actual examples encountered in pulmonary alveolae, in vacuolae and in medical applications, such as dissolution of gallstones.     

Does reservoir trophic status influence the feeding and growth of the sharptooth catfish,Clarias gariepinus (Teleostei: Clariidae)?

The diet and growth of sharptooth catfish, Clarias gariepinus, in an oligotrophic system (Kat River Reservoir, Eastern Cape, South Africa) were compared to those in a eutrophic system (Laing Reservoir, Eastern Cape) to determine if the trophic status of a waterbody had an effect on the growth rate of the species. In order of importance, the diet of catfish in Kat River Reservoir consisted of fish, insects, zooplankton, plant material and other items, while the diet of catfish in Laing Reservoir consisted of fish, plant material, zooplankton, other vertebrates and insects. The diets of catfish in the two reservoirs had a similarity index of 68.1% and there was no significant difference in their nutritional value. Fish prey was the most important dietary component in both reservoirs. Temperature regime and zooplankton and zoobenthos density were similar in both systems. However, fish prey density was significantly higher in the eutrophic Laing Reservoir and catfish grew significantly faster in that system. The slower growth rate in Kat River Reservoir was attributed to the higher energy costs associated with the capture of fish prey, which was less abundant than in Laing Reservoir. Trophic status therefore had an indirect effect on catfish growth by influencing the availability of fish prey.     

Does zinc concentration in the substrate influence the onset of flowering in Arabidopsis arenosa (Brassicaceae)?

We investigated the impact of low zinc (Zn) concentrations in the substare on the onset of flowering in Arabidopsis arenosa (Brassicaceae). Experiments were carried out in controlled conditions using plants from four different populations. The research was aimed to verify experimentally the following hypotheses: (1) Zn content in the growth medium promote the onset of flowering in A. arenosa, (2) Changes in the onset of flowering induced by Zn depend on Zn concentration employed; (3) Zn-induced early onset of flowering is an universal plant response present within the species and is not an effect of stress or physiological adaptation to high Zn content in the environment. Investigated plants were subjected to four different Zn concentrations: 0.4 (control), 155, 775 and 1,550???M Zn²⁺. To asses stress level in investigated plants we calculated biomass accumulation and employed fluorometric methods. Zn content was estimated in shoots using atomic absorption spectroscopy. Differences in the onset of flowering were assessed using Kaplan?CMeier curves. Our results showed that Zn was transported form growth medium to roots and shoots of investigated plants and that the content of Zn increased with the increase of Zn concentration in the growth medium. We evidenced that apart from one (1,550???M Zn²⁺) applied Zn concentrations did not caused stress in investigated plants what was confirmed by two independent experimental approaches: measurement of biomass accumulation and chlorophyll a fluorescence. Flowering curves obtained on the basis of calculation of Kaplan?CMeier estimator showed that: (1) control plants originating from four different populations did not differ in terms of the onset of flowering, (2) plants from each population tested tends to enter flowering phase earlier in response to applied Zn concentrations than control plants, (3) plants treated with the lowest tested Zn concentration (155???M Zn²⁺) tend to flower earlier than plants treated with the higher concentration (775???M Zn²⁺), (4) the impact of Zn on the onset of flowering did not depend on the origin on the plant material used (Zn-rich or Zn-poor soils). Our results indicate that Zn ions present in the growth medium promote early flowering in A.arenosa and that this effect may depend on Zn concentration used. Zn-induced early flowering in A. arenosa seems to be an universal plant response present within the species and is not an effect of stress or physiological adaptation to high Zn content in the environment.