Histoplasmosis in purebred mice: Influence of genetic susceptibility and immune depression on treatment

These experiments demonstrate that susceptibility to Histoplasma infection of the mouse is dramatically influenced by genetic and immunologic factors, and that these factors appear to exert little influence on response to therapy. They further demonstrate that such influence may vary in different visceral organs. The explanation for these observations remains to be elucidated.Supported in part by NIH-GRSG Grant RRO5374-13     

Experimental study of young fish distribution and behaviour under combined influence of baro-, photo- and thermo-gradients

The complex influence of baro-, photo- and thermo-gradients on distribution and behaviour of young physostomous Leuciscus leuciscus L., leaciscus idus L. and physoclistous fish Perca fluviatilis L. was investigated. 40 different combinations consisting of 4 types of photogradients, 3 types of termo gradients and 4 types of baro-gradients were tested. All considered factors influenced the distribution of physostomous and physoclistous fish with high degree of significance. Under a multi-factorial experiment fish behaviour and distribution are determined not only by a separately taken environmental factor but by the presence of other accompanying factors. Under different combinations of imposed factors, the reaction of fish to an individual factor and the character of the response (positive or negative) may change. Hydrostatic pressure is one of the strongest factors which influence fish distribution. The presence of its gradient may change the character of response of perch Perca fluviatilis to light (a changing of a sign of its photoreaction). Water temperature influences fish distribution more than illumination. However, the definite value of water temperature at which most fish prefer to stay may be changed depending on both the intensity of illumination and the value of hydrostatic pressure.     

Biological and Environmental Influences on Parturition Date and Birth Mass of a Seasonal Breeder

Natal features (e.g. Julian birth date and birth mass) often have fitness consequences and can be influenced by endogenous responses by the mother to seasonal fluctuations in nutritional quality and photoperiodic cues. We sought to further understand the biological and environmental factors that influence the natal features of a polytocous species in an environment with constant nutritional resources and limited seasonal variation. During a 36-year study we assessed the influence of biological factors (maternal age and litter type [i.e., litter size and sexual composition]) and environmental factors (total precipitation and mean maximum temperature during months encompassing conception, the last trimester of gestation, and the entire length of gestation) on Julian birth date and birth mass using linear-mixed effects models. Linear and quadratic functions of maternal age influenced both natal features with earliest Julian birth dates and heaviest birth masses occurring at prime-age and older individuals, which ranged from 5–9 years of age. Litter type influenced Julian birth date and birth mass. Interestingly, environmental factors affected Julian birth date and birth mass even though mothers were continuously allowed access to a high-quality diet. Random effects revealed considerable variation among mothers and years. This study demonstrates that, in long-lived polytocous species, environmental factors may have a greater influence on natal features than previously supposed and the influence from biological factors is also complex. The documented responses to environmental influences provide unique insights into how mammalian seasonal reproductive dynamics may respond to current changes in climate.     

Paternal levels of DNA damage in spermatozoa and maternal parity influence offspring mortality in an endangered ungulate

Understanding which factors influence offspring mortality rates is a major challenge since it influences population dynamics and may constrain the chances of recovery among endangered species. Most studies have focused on the effects of maternal and environmental factors, but little is known about paternal factors. Among most polygynous mammals, males only contribute the haploid genome to their offspring, but the possibility that sperm DNA integrity may influence offspring survival has not been explored. We examined several maternal, paternal and individual factors that may influence offspring survival in an endangered species (Gazella cuvieri). Levels of sperm DNA damage had the largest impact upon offspring mortality rates, followed by maternal parity. In addition, there was a significant interaction between these two variables, so that offspring born to primiparous mothers were more likely to die if their father had high levels of sperm DNA damage, but this was not the case among multiparous mothers. Thus, multiparous mothers seem to protect their offspring from the deleterious effects of sperm DNA damage. Since levels of sperm DNA damage seem to be higher among endangered species, more attention should be paid to the impact of this largely ignored factor among the viability of endangered species.     

Factors affecting offspring survival and development in a cooperative bird: social, maternal and environmental effects

1. In many noncooperative vertebrates, maternal effects commonly influence offspring survival and development. In cooperative vertebrates, where multiple adults help to raise young from a single brood, social effects may reduce or replace maternal effects on offspring. 2. Factors affecting offspring survival and development at different stages (fledging, nutritional independence and adulthood) were tested in the cooperatively breeding Arabian babbler to determine the relative importance of social, maternal and environmental factors at each stage. An influence of maternal effects was found during the nestling stage only. 3. Social factors affected the survival and development of young at all stages. The amount of food received from helpers influenced post-fledging weight gain, development of foraging skills, and survival to reproductive age. Environmental effects were also important, with groups occupying high-quality territories more likely to produce young that survived to maturity. 4. The strong influence of helper contributions on the survival and development of young at all stages from hatching to maturity suggests social factors may have important long-term effects on offspring fitness in cooperative societies. Traditional measures of offspring survival in cooperative birds, which commonly measure survival to fledging age only, may underestimate the significant benefit of helper contributions on the survival and development of young.     

Influence of voltine ecotype and geographic distance on genetic and haplotype variation in the Asian corn borer

Diapause is an adaptive dormancy strategy by which arthropods endure extended periods of adverse climatic conditions. Seasonal variation in larval diapause initiation and duration in Ostrinia furnacalis may influence adult mating generation number (voltinism) across different local environments. The degree to which voltine ecotype, geographic distance, or other ecological factors influence O. furnacalis population genetic structure remains uncertain. Genetic differentiation was estimated between voltine ecotypes collected from 8 locations. Mitochondrial haplotypes were significantly different between historically allopatric univoltine and bivoltine locations, but confounded by a strong correlation with geographic distance. In contrast, single nucleotide polymorphism (SNP) genotypes show low but significant levels of variation and a lack of influence of geographic distance between allopatric voltine locations. Regardless, 11 of 257 SNP loci were predicted to be under selection, suggesting population genetic homogenization except at loci proximal to factors putatively under selection. These findings provide evidence of haplotype divergent voltine ecotypes that may be maintained in allopatric and sympatric areas despite relatively high rates of nuclear gene flow, yet influence of voltinism on maintenance of observed haplotype divergence remains unresolved.     

Influence of local-scale abiotic and biotic factors on stress and nutrition in invasive silver carp

Community structure and dynamics in aquatic ecosystems are influenced by a variety of abiotic and biotic factors including productivity, species composition, and temperature. These factors may also affect local-scale community resilience to nonnative species invasions. We used habitat characteristics, zooplankton concentrations, fish abundances, and species composition and richness data collected by two fish population monitoring programs to define relationships that influence stress and nutrition in invasive silver carp (Hypophthalmichthys molitrix). We collected blood samples and quantified nutritional (alkaline phosphatase, cholesterol, protein, and triglycerides) and stress metrics (cortisol and glucose) from individuals across three distinct time periods. Nutritional patterns in silver carp were explained by temperature and food resources, indicating elevated feeding in warmer months. Patterns in blood-based stress parameters were most strongly driven by environmental characteristics, elevating with high water temperatures and increased turbidity. Nutrient levels and community richness parameters did not influence the stress or condition of silver carp, likely due to the absence of limiting resources or competition for this species. Together, our results provide insights into the factors that may influence the spread and distribution of silver carp, as well as the characteristics of habitats that could be vulnerable to future silver carp invasion.     

广东鼎湖山马尾松年轮元素含量及其相关性研究

马尾松 (Ｐｉｎｕｓｍａｓｓｏｎｉａｎａ)是我国目前造林数量最多的树种之一 ,研究其体内各种矿质元素的含量变化及相关性关系有助于了解该物种的选择性吸收、积累和分配各种元素的能力 ;而且对年轮元素含量的分析使我们有可能研究树木生命史中内外因子的变化对树木的元素吸收和积累的影响 ;同时 ,植物元素的含量又不可避免地打上了区域的烙印 ,因此 ,此类研究对区域植物地球化学的研究具有重要意义。1　材料和方法鼎湖山自然保护区位于广东省肇庆境内 ,距广州市 86ｋｍ ,位于 2 3°0 8′Ｎ ,112°35′Ｅ ,地处南亚热带的南缘。马尾松采自…     

广东鼎湖山马尾松年轮元素含量及其相关性研究

The concentrations of the elements in the annual rings of Pinus massoniana reflect the influence of both regional factors and species characteristics in absorbing,accumulating and distributing elements.The changes of environmental factors may result in concentration changes of elements in tree rings.Therefore,variations of tree ring element concentration may provide some clue in studying environmental changes.Some of eight elements studied are strongly correlated with others,the reason of which might be their similar structural and enzymatic functions in the plant cell,similar chemical properties and similar or opposite reaction to variations in some environment factors.     

Influence of cisco (Coregonus artedi,Lesueur) on muskellunge (Esox masquinongy,Mitchill) mean length,population size structure,and maximum size in northern Wisconsin lakes

Population size structure and maximum size of managed sportfish populations are dictated by abiotic, biotic, ecosystem, and anthropogenic influences. In their native ranges of northern Wisconsin, muskellunge (Esox masquinongy) and cisco (Coregonus artedi) are co-adapted cool- and cold-water species where cisco presence may influence population size structure and maximum size of muskellunge. We tested whether muskellunge size structure indices (length-frequency distributions, proportional size distribution), mean length, and mean maximum length of muskellunge differed when cisco were present or absent in Ceded Territory of Wisconsin (CTWI) lakes during 2015–2018. Cisco presence had a positive influence on size structure and mean length of individual muskellunge within populations. In contrast, cisco presence had no influence on the mean maximum length of muskellunge observed in CTWI populations suggesting that other factors may be better predictors of this metric than cisco presence. In cisco lakes, mean muskellunge length was negatively correlated with mean cisco length suggesting that gape limitation may be a factor influencing population size structure and individual growth rates. Therefore, cisco populations with primarily large individuals may be unavailable to muskellunge as forage. Our results suggest that cisco are an important forage species for some aspects of muskellunge population ecology; however, other factors may also contribute to muskellunge population size structure and maximum size outcomes. As such, conservation of remaining cisco populations in Wisconsin is critical because they influence muskellunge population ecology in lakes where the species coexist. Future research is needed to better understand the interactions of cisco, abiotic and biotic factors, and anthropogenic influences on muskellunge growth dynamics.     

气候因子对橘小实蝇生长发育及地理分布的影响

文章概述橘小实蝇Bactrocera dorsalis(Hendel)生活史、地理分布和生态要求的基础上,分析温度、湿度、降雨以及气候因子与橘小实蝇生长发育的关系,以及对橘小实蝇地理分布的影响。综述结果表明:喜湿热,厌干冷是橘小实蝇主要的生态学特征,低温与干旱不利于其生长发育;温度是橘小实蝇纬度分布中最主要的影响因子,冬季低温是中高纬度分布的主要限制因子,夏季高温是低纬度地区的限制因素之一,降雨影响橘小实蝇在经度上的分布范围。     

On the regulation of sex-hormone-binding globulin--a challenge of an old dogma and outlines of an alternative mechanism

In this review, the different factors known to affect SHBG levels are discussed with respect to their possible significance in the physiological regulation of this protein: Sex steroids, puberty, nutritional status, thyroid hormones and liver disease. It is concluded that the serum levels of SHBG are related to general metabolic factors, nutritional status, growth and ageing than to the estrogen/androgen balance. The authors suggest that SHBG is regulated primarily by growth hormone, somatomedin-C and possibly other growth factors. Growth hormone may promote SHBG synthesis in the liver while somatomedin-C may stimulate its extravasation and uptake in target tissues. It is suggested that sex steroids merely have an indirect, modulating influence.     

Effects of landscape and patch-level attributes on regional population persistence

Species responses are influenced by processes operating at multiple scales, yet many conservation studies and management actions are focused on a single scale. Although landscape-level habitat conditions (i.e., habitat amount, fragmentation and landscape quality) are likely to drive the regional persistence of spatially structured populations, patch-level factors (i.e., patch size, isolation, and quality) may also be important. To determine the spatial scales at which habitat factors influence the regional persistence of endangered Ord's kangaroo rats (Dipodomys ordii) in Alberta, Canada, we simulated population dynamics under a range of habitat conditions. Using a spatially-explicit population model, we removed groups of habitat patches based on their characteristics and measured the resulting time to extinction. We used proportional hazards models to rank the influence of landscape and interacting patch-level variables. Landscape quality was the most influential variable followed by patch quality, with both outweighing landscape- and patch-level measures of habitat quantity and fragmentation/proximity. Although habitat conservation and restoration priorities for this population should be in maximizing the overall quality of the landscape, population persistence depends on how this goal is achieved. Patch quality exerted a significant influence on regional persistence, with the removal of low quality road margin patches (sinks) reducing the risk of regional extinction. Strategies for maximizing overall landscape quality that omit patch-level considerations may produce suboptimal or detrimental results for regional population persistence, particularly where complex local population dynamics (e.g., source-sink dynamics) exist. This study contributes to a growing body literature that suggests that the prediction of species responses and future conservation actions may best be assessed with a multi-scale approach that considers habitat quality and that the success of conservation actions may depend on assessing the influences of habitat factors at multiple scales.     

Effect of acclimation temperature and substrate type on selected temperature,movement and activity of juvenile spiny softshell turtles (Apalone spinifera) in an aquatic thermal gradient

In some turtle species, temperature selection may be influenced by environmental conditions, including acclimation temperature and substrate quality. These factors may be particularly important for softshell turtles that are highly aquatic and often thermoregulate by burying in the substrate in shallow water microhabitats. We tested for effects of acclimation temperature (22 °C or 27 °C) and substrate type (sand or gravel) on the selected temperature and movement patterns of 20 juvenile spiny softhshell turtles (Apalone spinifera; Reptilia: Trionychidae) in an aquatic thermal gradient of 14–34 °C. Among 7–11 month old juvenile softshell turtles, acclimation temperature and substrate type did not influence temperature selection, nor alter activity and movement patterns. During thermal gradient tests, both 22- and 27 °C-acclimated turtles selected the warmest temperature (34 °C) available most frequently, regardless of substrate type (sand or gravel). Similarly, acclimation temperature and substrate type did not influence movement patterns of turtles, nor the number of chambers used in the gradient tests. These results suggest that juvenile Apalone spinifera are capable of detecting small temperature increments and prefer warm temperatures that may positively influence growth and metabolism, and that thermal factors more significantly influence aquatic thermoregulation in this species than does substrate type.     

Legal and ethical aspects of new wildlife food sources

The production of animals for new sources of food may be affected by a variety of laws relating to the keeping, trading, health, welfare and movement of animals. Other legislation, such as that applicable to wildlife and to human safety, are also relevant. Religious, cultural and ethical considerations may also influence attitudes towards a new food product. It is important that these factors are taken into account during the planning and progress of an enterprise since they may have a substantial impact on its viability.     

Influence of hybridization on animal space use: a case study using coyote range expansion

Hybridization between animal species is likely to increase as distributional and reproductive barriers continue to break down due to anthropogenically driven changes in habitat and climate. Yet, the influence of hybridization on ecological interactions and ecosystem function remains understudied. Animal space use, an important component of ecosystem dynamics, is a complex relationship between intrinsic factors, which hybridization can influence, and extrinsic factors, such as environmental heterogeneity. Using the coyote Canis latrans, a well‐studied species with a long history of hybridization with wolves and dogs Canis spp., we sought to assess the influence of hybridization relative to environmental factors in determining animal space use. We conducted a meta‐regression analysis of 67 datasets on coyote home range size across North America and generated models to predict coyote home range size. Climate (latitude) and environmental variability played important roles in determining patterns of coyote space use, likely through their influence on availability of prey resources. However, we found hybridization to be the preeminent factor driving variation in coyote space use, with non‐introgressed populations having considerably smaller home ranges than those from within the Canis hybrid zone of eastern North America. This pattern was upheld despite the variation in environmental factors between areas inside and outside the Canis hybrid zone. Our findings suggest that hybridization may serve as an important factor affecting ecosystems, as hybrids may have altered space requirements, and presumably different niche dimensions, compared to parental species. This, in turn, may influence the role that particular species play within communities. Synthesis Hybridization between animal species is likely to increase due to anthropogenically driven changes in habitat and climate. We used a meta‐regression analysis (n = 67) to examine the relationship between hybridization and coyote Canis latrans space use across North America. We found that independent of environmental factors, introgressed coyotes had larger home ranges. Our findings suggest that hybridization may serve as an important factor affecting ecosystems, as hybrids may have altered space requirements, and presumably different niche dimensions, compared to parental species. This, in turn, may influence the role that particular species play within communities.     

Risk Perception and Risk-Taking Behaviour during Adolescence: The Influence of Personality and Gender

This study investigated the influence of personality characteristics and gender on adolescents’ perception of risk and their risk-taking behaviour. Male and female participants (157 females: 116 males, aged 13–20) completed self-report measures on risk perception, risk-taking and personality. Male participants perceived behaviours as less risky, reportedly took more risks, were less sensitive to negative outcomes and less socially anxious than female participants. Path analysis identified a model in which age, behavioural inhibition and impulsiveness directly influenced risk perception, while age, social anxiety, impulsiveness, sensitivity to reward, behavioural inhibition and risk perception itself were directly or indirectly associated with risk-taking behaviour. Age and behavioural inhibition had direct relationships with social anxiety, and reward sensitivity was associated with impulsiveness. The model was representative for the whole sample and male and female groups separately. The observed relationship between age and social anxiety and the influence this may have on risk-taking behaviour could be key for reducing adolescent risk-taking behaviour. Even though adolescents may understand the riskiness of their behaviour and estimate their vulnerability to risk at a similar level to adults, factors such as anxiety regarding social situations, sensitivity to reward and impulsiveness may exert their influence and make these individuals prone to taking risks. If these associations are proven causal, these factors are, and will continue to be, important targets in prevention and intervention efforts.     

Sex Ratio and Sex‐specific Latitudinal Variation in Floral Characteristics of Gynodioecious Kallstroemia grandiflora (Zygophyllaceae) in Mexico

In species with broad distribution, geographic variation could be associated to particular environmental factors that may affect plant reproduction. In dimorphic species, environmental factors may influence evolutionary processes governing sex ratio variation and floral traits evolution. Kallstroemia grandiflora is an annual insect‐pollinated gynodioecious herb with broad distribution from the Sonoran desert to the semiarid west coast of Mexico. In this study, we explored if female frequency increases in harsh environments and the associated changes in floral morphology in female and hermaphrodite plants. We selected 23 populations along the pacific coast of Mexico where we estimated female frequency and in eight of them we also measured flower size in hermaphrodite and female plants. The average decrease in precipitation was correlated with the increase in female frequency, and a reduction in the flower size of hermaphrodite plants. Our results support the idea that harsh environments may influence female frequency, but also flower size and possibly breeding system evolution.     

Day-night patterns in bronchial patency and dyspnea: basis for once-daily and unequally divided twice-daily theophylline dosing schedules

Asthma typically worsens overnight. Although 24-hr variation in environmental conditions may contribute to the worsening of dyspnea at night, this does not fully explain day-night patterns of this disease. Circadian (about 24-hr) rhythms in bioprocesses which influence airways patency constitute major contributory factors. The nighttime exacerbation of asthma may represent the influence of circadian bioperiodicities in bronchial patency, airways hyperreactivity to acetylcholine, histamine and house dust, and altered levels of several plasma constituents such as cortisol, epinephrine, histamine and cyclic AMP.     

Food, reproduction and survival in mice on sub-Antarctic Marion Island

The house mouse Mus musculus is the most widespread introduced mammal on sub-Antarctic islands, where it may alter ecosystem function. Ambient temperature and food availability affect reproduction and survival for mice. It is unclear how these factors influence mouse demography in the sub-Antarctic, and we tested the influence of food experimentally on Marion Island. Using food supplementation trials, we did not alter reproduction or overwinter survival. Alternatively, we argue ongoing climatic change on Marion could increase mouse densities through summer, while increased winter survival may reduce population growth rates the following summer through density dependence. The overall influence of these apposing forces depends on their relative strengths but may limit changes in mouse numbers with ongoing changes in climate in the sub-Antarctic.