Physiological,Behavioral and Maternal Factors That Contribute to Size Variation in Larval Amphibian Populations

Size variance among similarly aged individuals within populations is a pattern common to many organisms that is a result of interactions between intrinsic and extrinsic traits of individuals. While genetic and maternal effects, as well as physiological and behavioral traits have been shown to contribute to size variation in animal populations, teasing apart the influence of such factors on individual growth rates remain a challenge. Furthermore, tracing the effects of these interactions across life stages and in shaping adult phenotypes also requires further exploration. In this study we investigated the relationship between genetics, hatching patterns, behaviors, neuroendocrine stress axis activity and variance in growth and metamorphosis among same-aged larval amphibians. Through parallel experiments we found that in the absence of conspecific interactions, hatch time and to a lesser extent egg clutch identity (i.e. genetics and maternal effects) influenced the propensity for growth and development in individual tadpoles and determined metamorphic traits. Within experimental groups we found that variance in growth rates was associated with size-dependent foraging behaviors and responses to food restriction. We also found an inverse relationship between glucocorticoid (GC) hormone levels and body mass and developmental stage among group-reared tadpoles, which suggests that GC expression plays a role in regulating differing within-population growth trajectories in response to density-dependent conditions. Taken together these findings suggest that factors that influence hatching conditions can have long-term effects on growth and development. These results also raise compelling questions regarding the extent to which maternal and genetic factors influence physiological and behavioral profiles in amphibians.     

Allelopathy Among Prairie Grasses and its Possible Ecological Significance

The phytotoxic effect of four kinds of litter and three kindsof fresh material extracts of blue grama and western wheatgrasson seed germination of blue grama, western wheatgrass and buffalograss was tested. The four kinds of litter were collected fromthe Ecosystem Stress Area at the native shortgrass prairie site.These included litter from control, fertilized, irrigated, andfertilized plus irrigated plots. The three kinds of fresh materialswere harvested from blue grama and western wheatgrass growingunder growth chamber conditions at three distinct phenologicalstages. Results indicated that the fresh material extracts weremore phytotoxic than the litter extracts and among the formerthe fresh material harvested at the earlier phenological stagewas more phytotoxic than those collected at the advanced phenologicalstage. Chemical composition of litter and fresh material indicatedthat the fresh materials contained comparatively more phenolicsubstances than that of litter materials.     

Behavioral and Physiological Thermoregulation of Crocodilians

Crocodilians, like other reptiles, regulate their body temperaturesby a combination of behavioral and physiological mechanisms.Behaviorally, they seek warm surface water or bask when cooland avoid overheating by the evaporation of water from theirdorsum, evaporation of water by gaping or by retreating to deep,cool water. Physiologically, crocodilians increase cutaneousthermal conductance by increasing blood flow to the skin (andsubdermal musculature) during warming. This hastens the warmingprocess. Cutaneous blood flow is reduced during general coolingand locally if the body temperature exceeds skin temperature.This enables crocodilians to increase body temperature significantlywhile basking in cool shallow water. Large crocodilians appearto be able to alter their rates of heat exchange to a largerextent than small ones and they can do so with less cardiovascularinvolvement. Large crocodilians, with their lower surface/volumeratio, are capable of producing sufficient metabolic heat toelevate their body temperature above water temperature.     

Intrinsic Differences between Oral and Skin Keratinocytes

Keratinocytes cover both the skin and some oral mucosa, but the morphology of each tissue and the behavior of the keratinocytes from these two sites are different. One significant dissimilarity between the two sites is the response to injury. Oral mucosal wounds heal faster and with less inflammation than equivalent cutaneous wounds. We hypothesized that oral and skin keratinocytes might have intrinsic differences at baseline as well as in the response to injury, and that such differences would be reflected in gene expression profiles.     

Differences in Vegetative Characteristics Among Four Populations of Senecio vulgaris L. Possibly Due to Interspecific Hybridization

Leaf vegetative characteristics of Senecio vulgaris plants wereexamined for evidence of introgression by Senecio squalidus.S. vulgaris plants are shown to be more similar to S. squalidusin an area of high S. squalidus frequency than elsewhere, butthe expected greater similarity of the radiate form of S. vulgaristo S. squalidus is seen only in one of the three characteristicsstudied. A possible explanation for these latter results isgiven.     

Anatomical and Behavioral Differences Among Threespine Sticklebacks: the Marine Form,the Landlocked Form and Their Hybrids

In order to elucidate the mechanisms and degree of isolation in the landlocked form of the threespine stickleback, Gasterosteus aculeatus (L.), inhabiting the Shinano and Agano Rivers that flow into the Japan Sea, comparative studies on the morphology, behavior and histology were made of the marine form, the landlocked form and their hybrids reared in the laboratory. The body shape, coloration and behavior of reciprocal hybrids were almost intermediate between the two parent forms. From January to February, the testis of the hybrid between the female marine form and the male landlocked form is occupied exclusively by spermatocytes and some spermatids. However, a small number of large cells, identified as macrophages, are found invading the seminiferous tubules, indicating the occurrence of phagocytosis. On the other hand, ripe functional eggs appear in the ovary in May, i.e. the breeding season. The eggs deposited into the nest do not develop even when the hybrids display the same mating behavior as their parents. Functional sperms are found in the testis of the hybrid between female landlocked and male marine forms at the period of breeding. However, only a single female lived until March. In the ovary of this female, all eggs reaching vitellogenesis (= primary yolk globule stage) are collapsed, while the younger oocytes appear in healthy condition. The hybrid female of this pairing seemed also to be sterile.     

Neural and Behavioral Evidence for an Intrinsic Cost of Self-Control

The capacity for self-control is critical to adaptive functioning, yet our knowledge of the underlying processes and mechanisms is presently only inchoate. Theoretical work in economics has suggested a model of self-control centering on two key assumptions: (1) a division within the decision-maker between two ‘selves’ with differing preferences; (2) the idea that self-control is intrinsically costly. Neuroscience has recently generated findings supporting the ‘dual-self’ assumption. The idea of self-control costs, in contrast, has remained speculative. We report the first independent evidence for self-control costs. Through a neuroimaging meta-analysis, we establish an anatomical link between self-control and the registration of cognitive effort costs. This link predicts that individuals who strongly avoid cognitive demand should also display poor self-control. To test this, we conducted a behavioral experiment leveraging a measure of demand avoidance along with two measures of self-control. The results obtained provide clear support for the idea of self-control costs.     

Aggressive and Foraging Behavioral Interactions Among Ruffe

The ruffe, Gymnocephalus cernuus, is a nonindigenous percid in the Great Lakes. Ruffe are aggressive benthivores and forage over soft substrates. Laboratory studies in pools (100cm diameter, 15cm water depth) were conducted to determine whether fish density (low=2, medium=4, high=6 ruffe per pool) changed foraging and aggressive behaviors with a limited food supply of chironomid larvae. All fish densities demonstrated a hierarchy based on aggressive interactions, but ruffe were most aggressive at low and high fish densities. Time spent in foraging was lowest at the low fish density. The best forager at the low fish density was the most aggressive individual, but the second most aggressive fish at the medium and high fish density was the best forager and also the one chased most frequently. A medium fish density offered the best energetic benefits to ruffe by providing the lowest ratio of time spent in aggression to that spent foraging. Based on our results, ruffe should grow best at an intermediate density. With high ruffe densities, we would also expect disparity in size as the more aggressive fish are able to garner a disproportionate amount of the resources. Alternatively, as the Great Lakes are a fairly open system, ruffe could migrate out of one area to colonize another as populations exceed optimal densities.     

人参不同栽培群体遗传关系的RAPD分析

用随机扩增多态ＤＮＡ（ＲＡＰＤ）标记法对４个人参（Ｐａｎａｘ ｇｉｎｓｅｇ Ｃ．Ａ．Ｍｅｙｅｒ）栽培群体中存在较丰富的遗传多样性。分析一路参、三路参、系选品系５９号、北京参等４个人参栽培群体和１个西洋参（Ｐ．ｑｕｉｎｑｕｅｆｏｌｉｕｍ Ｌ．）群体的遗传分化指数值表明,三路参变异量最大（０．４１６９）,一路参降为０．２５６５,边条参系选品系５９号最低为０．１８８１,表明选择方式和选择代数的纯化作用十分     

On the Evolution of Behavioral Heterogeneity in Individuals and Populations

A wide range of ecological and evolutionary models predict variety in phenotype or behavior when a population is at equilibrium. This heterogeneity can be realized in different ways. For example, it can be realized through a complex population of individuals exhibiting different simple behaviors, or through a simple population of individuals exhibiting complex, varying behaviors. In some theoretical frameworks these different realizations are treated as equivalent, but natural selection distinguishes between these two alternatives in subtle ways. By investigating an increasingly complex series of models, from a simple fluctuating selection model up to a finite population hawk/dove game, we explore the selective pressures which discriminate between pure strategists, mixed at the population level, and individual mixed strategists. Our analysis reveals some important limitations to the ESS framework often employed to investigate the evolution of complex behavior.     

实验室繁育树鼩生理指标的检测分析

对实验室繁育的22只成年树鼩进行生理指标的检测,并与正常人参考值进行对比分析。结果显示,树鼩红细胞数8.19×1012/L,高于人参考值上限;白细胞数2.21×109/L,低于人参考值下限;肌酐16.63μmol/L,低于人参考值下限;丙氨酸氨基转移酶77.92U/L和天门冬氨酸氨基转移酶179.9U/L,都高于人参考值上限;HBsAg均为阴性0.022ng/ml±0.005。表明树鼩作为更接近人类的低等灵长类动物,适合应用于研究人类疾病的动物模型。     

Variation in Intergroup Relationships Among Species and Among and Within Local Populations of African Apes

International Journal of Primatology - Although many animals typically defend key resources from conspecifics during encounters, tolerant encounters also occur frequently in some primate species....     

Susceptibility to Development of Central Adiposity Among Populations

There is good evidence that central (visceral) adiposity is important in the development of the insulin resistance or metabolic syndrome (obesity, hyperinsulinemia, dyslipidemia, glucose intolerance, hypertension, and coronary heart disease). It is proposed that some non-Caucasian populations are especially susceptible to development of this syndrome, and that lifestyle changes may play important etiologic roles. We postulate that this is due to the presence in these populations of a genetic predisposition to weight gain, perhaps related to a “thrifty” genotype, leading to the concentration of weight gain in visceral fat depots, when there is exposure to conditions associated with westernization.     

Rh系统单倍型在中国人群中的分布

对中国已发表的125个人群Rh血型系统表型分布频率数据进行了收集和整理。用累积计算法（Counting method)重新计算单倍型频率,通过各单倍型的分布差异分析中国不同地区不同种族、人群的遗传差异,分组比较了不同地区汉族和少数民族人群的基因多样度和基因分化度,结果表明南方少数民族和北方少数民族民族亚群体基因多样度有明显差异,用不同方法计算中小组遗传距离并进行聚类分析。最后,计算了除维吾尔族和哈萨克族外的68个人群间的遗传距离并聚类比较,结果表明Rh基因单倍型的分布与地理分布基本相符。     

Analysis of Geographic and Pairwise Genetic Distances Among Sheep Populations

This study assessed the usefulness of geographic and pairwise genetic distances in the characterization of five sheep populations using 15 microsatellite markers. The average F statistics across loci were F _IT = 0.523 ± 0.140, F _ST = 0.363 ± 0.131, and F _IS = 0.263 ± 0.092. The average heterozygosity was 0.716 ± 0.069, polymorphism information content was 0.691 ± 0.070, and effective number of alleles was 3.736 ± 0.998. Sheep populations clustered into group 1 (Hu and Tong breeds) and group 2 (small-tailed Han, Wadi, and Tan breeds). Reynolds’ distance varied from 0.0062 to 0.0499, and the range of gene flow (N _m) was 4.8834–40.0726 among the sheep populations. The results showed that the genetic structure of the five populations was not consistent with their genetic distances, and the population genetic divergence was not linearly related to geographic distance as indicated by a Mantel test (P = 0.7936).     

Behavioral Indexes of Poor Welfare in Laboratory Rats

A study compared the behavior of rats kept under standard conditions with the behavior of those from enriched, semi-enriched, and single-housed conditions to determine whether standard conditions have detrimental effects on nonhuman animal welfare. The subjects were 35 female Hooded Norway rats. Using an emergence box, open field, and Hebb-Williams maze, the study measured the subjects' behaviors. Housing conditions significantly affected the behavior of the rats as measured by all 3 procedures. The results of the rats from standard conditions were intermediate between those of the single-housed and the more enriched groups. Thus, enrichng the standard environment would ameliorate behavioral deficits in rats kept under standard conditions.     

Transmission of Herpetomonas in Laboratory Populations of Drosophila melanogaster

Methods of transmission and the effects of temperature and mites on ageledeme development of Herpetomonas were examined in populations of Drosophila melanogaster maintained in the laboratory. Herpetomonas was observed in feces of infected adults taken from population cages and in the vomitus of clean flies shortly after feeding on a saline suspension of flagellates. Free-swimming flagellates were found in the moist areas of food cups. Adult D. melanogaster became infected when they fed on flagellates taken from the endoperitrophic space, the ectoperitrophic space or the Malpighian tubules. At 25°C the flagellates infected approximately 90% of the host population within 20 days. The high transmission rate was prematurely disrupted if host populations were subjected to changes in temperature. Free-swimming flagellates did not appear to be affected at these temperature changes. Food mites (Tyrophagus) established in the growth media of the fly nearly eliminated the Herpetomonas from Drosophila populations.     

Measurement of Intrinsic Physiological Membrane Noise in Cultured Living Cells

An experimental technique and some preliminary observations are reported here for the measurement of electric noise and potentials intrinsic to the physiological function of living cells, using an in vitro yeast cells (Saccharomyces cerevisiae) model. The design and working of technique is based on a micro-electrode-based sensor working in a modified patch-clamp configuration. We present recordings of intrinsic noise and cellular electric potentials in living and aerobically respiring cells (in an electromagnetically shielded environment). An important observation of the effect of aerobic respiration on the studied cells is discussed, whereby conspicuously higher magnitude potentials were seen with aerobically respiring active yeast cells, as compared to anaerobic or dead cells. Recorded noise potentials from aerobically respiring cells are found to have a magnitude on the order of a few microVolts/cm and fall within the range of 140– in the low-frequency (LF) band.     

Concurrent Multiple Paternity in Natural and Laboratory Populations of DROSOPHILA MELANOGASTER

Electrophoretic analysis of two or three linked enzyme loci in progenies of homozygous females from cage and natural populations demonstrates frequent concurrent multiple paternity in both cases.