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The evolution of copulation frequency and the mechanisms of reproduction in male Anolis lizards
The evolution of many morphological structures is associated with the behavioral context of their use, particularly for structures involved in copulation. Yet, few studies have considered evolutionary relationships among the integrated suite of structures associated with male reproduction. In this study, we examined nine species of lizards in the genus Anolis to determine whether larger copulatory morphologies and higher potential for copulatory muscle performance evolved in association with higher copulation rates. In 10--12 adult males of each species, we measured the size of the hemipenes and related muscles, the seminiferous tubules in the testes, and the renal sex segments in the kidneys, and we assessed the fiber type composition of the muscles associated with copulation. In a series of pbylogenetically-informed analyses, we used field behavioral data to determine whether observed rates of copulation were associated with these morphologies.We found that species with larger hemipenes had larger fibers in the RPM (the retractor penis magnus, a muscle that controls hemipenis movement), and that the evolution of larg- er hemipenes and RPM fibers is associated with the evolution of higher rates of copulatory behavior. However, the sizes of the seminiferous tubules and renal sex segments, and the muscle fiber composition of the RPM, were not associated with copulation rates. Further, body size was not associated with the size of any of the reproductive structures investigated. The results of this study suggest that peripheral morphologies involved in the transfer of ejaculate may be more evolutionarily labile than internal structures involved in ejaculate production.Michele A. JOHNSON,Mafia Veronica LOPEZ,Tara K. WHITTLE,Bonnie K. KIRCHER,Alisa K. DILL,Divina VARGHESE,Juli WADE - 动物学报(英文版)文章来源: 万方数据 -
Evolution of deceit by worthless donations in a nuptial gift-giving spider
Paolo Giovanni GHISLANDI,Mafia J. ALBO,Cristina TUNI,Trine BILDE - 动物学报(英文版)文章来源: 万方数据 -
Age of maturation and behavioral tactics in male yellow ground squirrel Spermophilus fulvus during mating season
Life-history theory predicts that in hibemators age of maturation is related positively to body size and negatively to the duration of active season aboveground. Yellow souslik is a large-sized ground squirrel with long hibernation, which suggests late maturation. We used four-year field observations of marked individuals to determine the age of maturation in males through analysis of age-dependent variation in body size, mass, androgen status, timing of spring emergence, ranging patterns and social behavior during the mating season. Yearling males were smaller, lighter, had lower level of fecal testosterone, emerged later and had smaller home ranges than older males. Social activity and the number of females encountered did not differ between age classes. After the second hibernation none of the studied parameters varied with age. Cluster analysis revealed two behavioral tactics: "active" males (adults only) emerged earlier, ranged more widely, initiated more contacts, encountered more females and were heavier than "passive" males (both yearling and adult). Thus, males of S. fulvus reached adult size and matured after two hibernations, which is relatively fast for such a big species with short active period. Indirect evidence for copulations and high variation among yearlings in all parameters suggest that some of them might successfully compete with adults. Active tactic of wandering and searching for females is energetically costly, and probably only adult males in good physical condition can afford it, whereas passive tactic of residing is energy saving and good for adults in poor condition and for yearlings that are continuing to grow.Nina A. VASILIEVA Ekaterina V. PAVLOVA Sergey V. NAIDENKO Andrey V.TCHABOVSKY - 动物学报(英文版)文章来源: 万方数据 -
2002和2010年中国南部经济快速增长地区的健康调查数据系列横断面分析:高血压的患病率、知晓率、治疗率、控制率及相关因素
该研究调查居住于过去30年问经济发展速度位于世界领先地位的中国南部地区,高血压人群的分布情况,患病率、知晓率、治疗率以及控制率的变化趋势.方法:2002和2010年在广东省一个包括85000000人口的人群进行4次标准化横断面调查.采用多阶段整群抽样方法抽取代表性人口样本.数据通过现场健康体检和面对面访谈获得.结果:调查期间,- 中华高血压杂志文章来源: 万方数据 -
Endocrine correlates of mate choice and promiscuity in females of a socially monogamous avian mating system with alternative male reproductive phenotypes
While our understanding of male reproductive strategies is informed by extensive investigations into endocrine mechanisms, the proximate mechanisms by which females compete for mates and adjust reproduction to social environment remains enigmatic. We set out to uncover endocrine correlates of mate choice, social environment, and reproductive investment in female red-backed fairy-wrens Malurus melanocephalus. In this socially monogamous, yet highly sexually promiscuous species, females experience discrete variation in the phenotype of their mates, which vary in both plumage signals and level of paternal care, and in the composition of their breeding groups, which consist of either the pair alone or with an additional cooperative auxiliary; fe- male investment varies according to these social parameters. We found that androgen, estrogen, and glucorticoid levels varied with reproductive stage, with highest androgen and estrogen concentrations during nest construction and highest corticosterone concentrations during the pre-breeding stage. These stage-dependent patterns did not vary with male phenotype or auxiliary presence, though androgen levels during pre-breeding mate selection were lower in females obtaining red/black mates than those obtaining brown mates. We found no evidence that androgen, estrogen, or corticosterone levels during the fertile period were re- lated to extra-pair young (EPY) frequency. This study demonstrates clear changes in steroid levels with reproductive stage, though it found little support for variation with social environment. We suggest hormonal responsiveness to social factors may be physiologically constrained in ways that are bypassed through exogenous hormone manipulations.Hubert SCHWABL,Willow R. LINDSAY,Douglas G. BARRON,Michael S. WEBSTER - 动物学报(英文版)文章来源: 万方数据 -
饮酒与冠心病
大量的研究表明,饮酒与冠心病之间呈J型曲线关系,少量饮酒可以降低冠心病发病风险.随着研究的深入,发现不仅饮酒的量与冠心病风险相关,饮酒的方式对冠心病的影响也十分重要.饮酒对不同人群的影响以及对冠心病的作用机制也进行了较多的研究,本文将对近期的研究进展作一综述.张玉英,孙永乐 - 临床心血管病杂志文章来源: 万方数据 -
Animal behavior can inform conservation policy, we just need to get on with the jobor can it?
1?Conservation?Behavior?as?an??Emerging?Discipline?on?the?Brink?of??Success,?or?Unrealistic?Ideal?
?It?seems?intuitively?sensible?that?an?understanding?of?the?behavioral?characteristics?of?animals,?such?as?their?home?ranges,?diets,?mating?systems,?and?dispersal?me-?chanisms,?may?be?useful?to?inform?conservation?efforts?in?determining,?for?example,?suitable?reintroduction?areas,?or?the?design?of?dispersal?corridors.Ximena J. NELSON, Editor - 动物学报(英文版)文章来源: 万方数据 -
运用二分法求解内含报酬率
一、内含报酬率的通常计算方法1.内含报酬率的含义.内含报酬率是一个项目本身能达到的实际报酬率,使用内含报酬率作为项目现金流的折现率,该项目的未来现金流入量现值等于未来现金流出量现值.内含报酬率大于期望报酬率则方案可行,且内含报酬率越高方案越优.刘姝蕙,陈锦辉 - 财会月刊文章来源: 万方数据 -
宁夏人民医院脑卒中治疗再创佳绩
脑卒中发病率高、致残率高、死亡率高、复发率高.2012年第三次全国死因调查显示,脑卒中致死率排名第一,高达22.45%,我国脑卒中发生率正以每年8.7%的速度上升,脑卒中已经成为我国重大的公共卫生问题.因此,国家卫生计生委实施了"脑卒中筛查与防治"工程,宁夏人民医院承担着"脑卒中筛查与防治"基地医院的责任.脑卒中既是一种突然起病的脑血液循环障碍性疾病,也是脑血管疾病最严重的并发症.血管内介入技术是近年来发展起来的防治脑血管病的新方法,宁夏人民医院为落实基地医院在脑卒中防治技术方面的要求,积极开展脑血管介入诊疗工作.工作中严格掌握适应症,规范手术流程,- 宁夏医学杂志文章来源: 万方数据

