Correlates of Research Effort in Carnivores: Body Size,Range Size and Diet Matter

Given the budgetary restrictions on scientific research and the increasing need to better inform conservation actions, it is important to identify the patterns and causes of biases in research effort. We combine bibliometric information from a literature review of almost 16,500 peer-reviewed publications on a well-known group of 286 species, the Order Carnivora, with global datasets on species'' life history and ecological traits to explore patterns in research effort. Our study explores how species'' characteristics influenced the degree to which they were studied (measured as the number of publications). We identified a wide variation in intensity of research effort at both Family and Species levels, with some of the least studied being those which may need protection in future. Our findings hint at the complex role of human perspectives in setting research agendas. We found that better-studied species tended to be large-bodied and have a large geographic range whilst omnivory had a negative relationship with research effort. IUCN threat status did not exhibit a strong relationship with research effort which suggests that the conservation needs of individual species are not major drivers of research interest. This work is the first to use a combination of bibliometric analysis and biological data to quantify and interpret gaps in research knowledge across an entire Order. Our results could be combined with other resources, such as Biodiversity Action Plans, to prioritise and co-ordinate future research effort, whilst our methods can be applied across many scientific disciplines to describe knowledge gaps.     

华西蟾蜍年龄结构、体长和生长率的研究

本研究利用骨龄学方法研究了青藏高原东缘横断山脉区一个华西蟾蜍种群的年龄结构、体长、年生长率及性成熟年龄。采集的74个成体个体中(雄性47只,雌性27只),均能够在趾骨切片中观察到受抑制生长线。结果表明:两性的体长和年龄都成正相关关系(雌性:F1,26=4.87,r=0.40,P=0.04,雄性:F1,46=4.48,r=0.30,P=0.04)。雌性初始繁殖年龄为4龄,寿命至少为11龄;雄性分别为3龄和11龄。雌性和雄性的平均年龄存在显著差异(Z=2.27,P<0.01),雌性为(8.4±1.8)龄,雄性为(6.2±1.8)龄。雌性平均体长大于雄性(t=2.348,P<0.01),雌性为91.9 mm±7.2 mm,雄性为74.8 mm±5.5 mm。另外,雌性和雄性具有不同的生长模式,雌性生长率(r=2.48)大于雄性(r=2.32)。年龄和生长率对华西蟾蜍的性二型的解释有重要意义。     

Timing of Recruitment Events, Residence Periods and Post-Settlement Growth of Juvenile Fish in a Seagrass Nursery Area, South-Eastern Australia

We sampled juvenile fish approximately fortnightly using a fine mesh beach seine net to determine the recruitment patterns of Sillago ciliata, Centropogon australis and Girella tricuspidata to seagrass, Zostera capricorni, habitats in Botany Bay, south-eastern Australia. We used trends in the length frequency distributions of juveniles to estimate the timing of recruitment events, rates of post-settlement growth and the residence time of each species in seagrass. We detected discrete pulses of recruitment by each species. The timing of recruitment events by S. ciliata reflected the timing of spawning events. Recruitment by G. tricuspidata reflected lunar or tidal cycles. The factors influencing the timing of recruitment by C. australis were unclear. The growth rate of S. ciliata length cohorts varied and was positively related to estuarine water temperature. The timing of emigration from seagrass of C. australis and G. tricuspidata juveniles appeared to be length-dependant.     

Herbivory and Body Size: Allometries of Diet Quality and Gastrointestinal Physiology,and Implications for Herbivore Ecology and Dinosaur Gigantism

Digestive physiology has played a prominent role in explanations for terrestrial herbivore body size evolution and size-driven diversification and niche differentiation. This is based on the association of increasing body mass (BM) with diets of lower quality, and with putative mechanisms by which a higher BM could translate into a higher digestive efficiency. Such concepts, however, often do not match empirical data. Here, we review concepts and data on terrestrial herbivore BM, diet quality, digestive physiology and metabolism, and in doing so give examples for problems in using allometric analyses and extrapolations. A digestive advantage of larger BM is not corroborated by conceptual or empirical approaches. We suggest that explanatory models should shift from physiological to ecological scenarios based on the association of forage quality and biomass availability, and the association between BM and feeding selectivity. These associations mostly (but not exclusively) allow large herbivores to use low quality forage only, whereas they allow small herbivores the use of any forage they can physically manage. Examples of small herbivores able to subsist on lower quality diets are rare but exist. We speculate that this could be explained by evolutionary adaptations to the ecological opportunity of selective feeding in smaller animals, rather than by a physiologic or metabolic necessity linked to BM. For gigantic herbivores such as sauropod dinosaurs, other factors than digestive physiology appear more promising candidates to explain evolutionary drives towards extreme BM.     

Growth and Life Span of the Commercial Gastropods of Buccinidae Family in Peter the Great Bay, Sea of Japan

Patterns with of body size and mass age variation in five gastropod species of Buccinidae family from Ussuriisky Bay (Peter the Great Bay, Sea of Japan) were studied. Equations of body size and mass correlation were obtained for each species, Bertalanffy's equations of group growth were estimated, and specifics of rates of linear growth and of body mass with age variation were considered. It was determined that in the survey area, the life span for Buccinum bayani bayani was nine years; for B. verkruzeni, 11; for Neptunea constricta, 17; for N. lyrata lyrata 18; and for N. polycostata, 16.     

Life Span,Distribution and Radiosensitivity of the Large Lymphocyte

ALTHOUGH little is known about the origin or functions of the larger lymphocytes in the blood, a relationship to the small lymphocytes has been inferred, chiefly from similarities in gross morphology, staining characteristics and from the fact that lymphocytes exhibit a range of sizes which makes a distinction between large and small cells seem arbitrary. We have been studying lymphocyte kinetics by establishing cross-circulation between pairs of syngeneic rats, in which the lymphocytes of one member had been labelled in vivo by repeated injections of tritiated thymidine (³H-TdR) and we found that some time after the period of labelling, most of the isotope in blood leucocytes resided in the large lymphocytes. This suggested a way of studying a class of lymphocyte which has received scant attention so far.     

Demography of the Giant Otter (Pteronura brasiliensis) in Manu National Park,South-Eastern Peru: Implications for Conservation

The giant otter (Pteronura brasiliensis) is an endangered semi-aquatic carnivore of South America. We present findings on the demography of a population inhabiting the floodplain of Manu National Park, south-eastern Peru, arising from 14 annual dry season censuses over a 16 year period. The breeding system of territorial groups, including only a single breeding female with non-reproductive adult ‘helpers’, resulted in a low intrinsic rate of increase (0.03) and a slow recovery from decades of hunting for the pelt trade. This is explained by a combination of factors: (1) physiological traits such as late age at first reproduction and long generation time, (2) a high degree of reproductive skew, (3) small litters produced only once a year, and (4) a 50% mortality between den emergence and age of dispersal, as well as high mortality amongst dispersers (especially males). Female and male giant otters show similar traits with respect to average reproductive life-spans (female 5.4 yrs., male 5.2 yrs.) and average cub productivity (female 6.9, male 6.7 cubs per lifetime); the longest reproductive life spans were 11 and 13 years respectively. Individual reproductive success varied substantially and depended mainly on the duration of dominance tenure in the territory. When breeding females died, the reproductive position in the group was usually occupied by sisters or daughters (n = 11), with immigrant male partners. Male philopatry was not observed. The vulnerability of the Manu giant otter population to anthropogenic disturbance emphasises the importance of effective protection of core lake habitats in particular. Riverine forests are the most endangered ecosystem in the Department of Madre de Dios due to the concentration of gold mining, logging and agricultural activities in floodplains, highlighting the need for a giant otter habitat conservation corridor along the Madre de Dios River.     

Water deficits in timberline trees in the Snowy Mountains of South-Eastern Australia

Summary Leaf water potential (), leaf diffusion resistance (r ₁) and net photosynthesis of leaves of Eucalyptus pauciflora Sieb at timberline (2,040 m) were measured in winter and spring in the Snowy Mountains area of southeastern Australia. Four treatments were established in a 2×2 factorial design involving exposure to direct sunlight, screening to reduce solar radiation by approximately 50%, exposure to direct radiant cooling at night, and screening to reduce radiant cooling. A less comprehensive set of measurements was also made in summer.No significant water deficits developed in any of the treatments, water potentials remaining above =-14 bars in winter, and above =-10 bars in spring, well above the levels needed to cause tissue damage in this species. These results contrast with the extreme desiccation reported in trees at timberline in other regions and suggest that winter dehydration is not an important factor in limiting tree distribution in the Snowy Mountains.Tissue damage was observed in all treatments and was most pronounced in those exposed to natural radiation frosts, in which shoot die-back occurred. Although factors other than frost incidence may have been influenced by the treatments, the results suggest that low temperatures, possibly associated with periods of clear weather and cold nights in the spring, when the tissue was no longer winter-hardy, may have been the main factors responsible.     

Life history and distribution of the small south-western Atlantic octopus, Octopus tehuelchus

Although this species has been reported from shallow waters down to 90 m depth, knowledge is almost entirely based on intertidal samples. In this study both intertidal and subtidal samples were taken during 1982–1987, in northern San Matias Gulf (41° S, 63° 30' W). This is a large-egged (eggs: 9–12 mm long ×–5 mm wide, stack of 4–6 mm long) and small-sized (up to 150 g) octopus. Egg laying occurs between autumn and winter. Embryonic development takes about four months (water temperature:–19°C). Large hatchlings (DML: 5·64 mm, TL: 14·23 mm, TW: 0·139 g) emerge over spring and early summer, and development is direct. Maximum size is reached after 17–18 months; mating takes place in summer. Females reduce their feeding activity when they reach maturity, and cease eating while brooding. Mean life-span is two years, but some individuals (mostly females) may live up to three years. Females approaching the beginning of the brooding period move to the subtidal zone, where males outnumber females until the end of summer and females (mostly brooders) then outnumber males. In the intertidal zone sex ratio was 1:1 from December to late March, but in April males outnumber females.
These life-history traits are compared with those of other large-egged octopuses and are discussed in relation to environmental conditions prevailing in the San Matias Gulf.     

The Edible Dormouse (<Emphasis Type=Italic>Glis glis</Emphasis>, Gliridae,Rodentia) in the Periphery of Its Distribution Range: Body Size and Life History Parameters

The body size, longevity, growth rate, and the intensity of breeding in a peripheral population of the edible dormouse from the Zhiguli Mountains are analyzed from the standpoint of life cycle theory. A breeding peculiarity of the species lies in periodically repeated years of reproductive failure, i.e., the total absence of young, seen throughout the species range. In reproductively successful years, anticipatory reproduction is observed, when the birth of posterity precedes a period of maximum food abundance. In the optimum of the distribution range, in Central and Western Europe, the mechanism of reproductive control in unfavorable years is based on the suppressing of the male reproductive activity at the beginning of the active season. In the Zhiguli population, natality regulation is rooted in mass resorption of embryos in the vast majority of females. In that population, the body size and weight are the minimum, while the difference from individuals from other populations studied may reach three times. The peculiarities of the edible dormouse biology in the peripheral population are related to the life cycle parameters. In contrast to the Central European populations, reproduction in the Zhiguli occurs every year, but in pregnant females, the death of embryos is observed in lean years. In males of that population, which are reproductively active every year, no significant costs of reproduction related to weight loss have been identified. The lower growth rate in comparison with more western European populations is shown in four age groups conventionally distinguishable based on morphometric parameters. In yearling males whose growth is not yet finished, the onset of the mating period depends on the body mass. Typically, the lifespan in the study population does not exceed four years, this being much shorter than in other populations where it lasts seven to nine years.     

Plant communities of the Stirling Range,Western Australia

The Stirling Range is a mountain system of Proterozoic origin in the southern part of Western Australia, reaching an altitude of 1000 m; it consists of acid rocks and has a mediterranean climate with a rainfall of 500 - 550 mm/yr. It is the only extensive mountain system of this portion of the continent and presents a rich endemic flora. The vegetation of the area was investigated from 1984 to 1992; 68 phytosoci-ological releves, ecological observations and extensive floris-tic collections were made. On the basis of multivariate analysis eight communities have been distinguished: Eucalyptus woodland, mallee, evergreen shrubland (plain, mountain and slope), and herbaceous communities of wet sands, springs and rocks. The Stirling Range is the only area in the south of Western Australia where vegetation belts can be recognised.     

Female Preferences for Sailfin and Body Size in the Sailfin Molly, Poecilia latipinna

We tested the mating preference of female sailfin mollies (Poecilia latipinna) by presenting them with pairs of dummy males differing in: (I) sailfin and body size together (holding sailfin : body size ratio constant); (II) body size alone (holding sailfin size constant); (III) sailfin size alone (holding body size constant); and (IV) sailfin : body size ratio (holding total lateral projection area constant). Females spent more time near dummies of greater sailfin or greater body size. The preference functions based on the first three sets of stimuli showed a similar pattern: the preference between any two simultaneously presented dummies increased with the magnitude of the discrepancy in lateral projection area (LPA) between them. However, when LPA was held constant in expt (IV), neither body size, sailfin size, nor any particular dummy (i.e. any particular sailfin + body size combination) was preferred. These findings suggest that increased LPA is more stimulating to sexually receptive females and that females consequently prefer larger males. The sailfin may therefore have evolved as a way for males to exploit this sensory bias and appear larger to prospective mates.     

Relationship between Body Mass Index and Percent Body Fat in Vietnamese: Implications for the Diagnosis of Obesity

BackgroundThe burden of obesity in Vietnam has not been well defined because there is a lack of reference data for percent body fat (PBF) in Asians. This study sought to define the relationship between PBF and body mass index (BMI) in the Vietnamese population.MethodsThe study was designed as a comparative cross-sectional investigation that involved 1217 individuals of Vietnamese background (862 women) aged 20 years and older (average age 47 yr) who were randomly selected from the general population in Ho Chi Minh City. Lean mass (LM) and fat mass (FM) were measured by DXA (Hologic QDR 4500). PBF was derived as FM over body weight.ResultsBased on BMI ≥30, the prevalence of obesity was 1.1% and 1.3% for men and women, respectively. The prevalence of overweight and obesity combined (BMI ≥25) was ~24% and ~19% in men and women, respectively. Based on the quadratic relationship between BMI and PBF, the approximate PBF corresponding to the BMI threshold of 30 (obese) was 30.5 in men and 41 in women. Using the criteria of PBF >30 in men and PBF >40 in women, approximately 15% of men and women were considered obese.ConclusionThese data suggest that body mass index underestimates the prevalence of obesity. We suggest that a PBF >30 in men or PBF >40 in women is used as criteria for the diagnosis of obesity in Vietnamese adults. Using these criteria, 15% of Vietnamese adults in Ho Chi Minh City was considered obese.     

Ecological and Evolutionary Aspects of Integumentary Respiration: Body Size, Diffusion, and the Invertebrata

SYNOPSIS. Most animal phyla lack specialized respiratory surfacesand all phyla contain groups that, for some part of their lifehistory, depend entirely upon integumental diffusion of respiratorygases. Animals that are diffusion-limited, yet function aerobicallyare generally small with large surface areas and there has beenconvergence for this among all phyla including the coelomateinvertebrates. Acoelomates lack specialized respiratory structuresbut have highly modified integuments, functional specializations,and features ranging from symbioses to air gulping that compensatefor diffusion limitation. The diversity of structures functioningfor integumentary respiration is much greater among invertebratesthan vertebrates. Among the higher invertebrates with respiratorysurfaces, accessory integumentary O₂ uptake is usually 20 to50% of total respiration. The high diffusion constant of O₂in air minimizes boundary effects on gas transfer and permitslarger body size, although this is limited by dry conditions.Terrestrial annelids and flatworms, both confined to moist habitats,are larger than aquatic forms which often have accessory gills.Size differences between terrestrial forms in these two phylareflect the presence of a circulation in the annelids. Ontogenetictransitions from skin breathing to other respiratory structuresoccur among marine invertebrates and vertebrates. Vertebratesapparently exercise greater integratory control over integumentalrespiration through adjustment of ventilation and perfusion;however, it is not known if these processes occur in some invertebrates.