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1.
湖南宁乡县乡村汉族体型分析   总被引:1,自引:0,他引:1  
 运用Heath-Carter体型法,对湖南宁乡县乡村418例(男197例,女221例)汉族成人体型进行了分析.研究发现:① 湖南宁乡县乡村汉族男性平均体型值为3.5-5.3-1.8,属于偏内胚层的中胚层体型;女性平均体型值为4.9-4.9-1.4,属于内胚层中胚层均衡体型.② 男性以30岁为体型分界点,30岁前男性肌肉较发达而体脂相对菲薄,30岁后随年龄增长皮下脂肪积累量增加但体型变化不大;女性以40岁为体型分界点,40岁前随年龄增长肌肉渐趋发达,身体线性度下降.40岁后肌肉和脂肪含量呈下降趋势但体型变化不明显.③ 湖南宁乡县乡村汉族成人体型性别间存在显著性差异.与其他群体相比,宁乡县男性平均体型与鄂温克族(SAD=0.36)和山东乡村汉族(SAD=0.37)最为接近,女性平均体型与鄂温克族(SAD=0.59)最接近.  相似文献   

2.
普通刺猬的解剖学研究(一) 被皮   总被引:1,自引:1,他引:0  
对28 只( ♀16 ,♂12) 成年普通刺猬( Erinaceuseuropaeus) 的被皮进行了解剖学研究,结果表明,普通刺猬被皮有丰厚的皮下脂肪和发达的皮下肌,雄性被皮重占体重的38-02 % ,雌性占44-29 % ;雄性皮下脂肪占体重的6-88 % ,雌性占12-04 % ,雌性皮肤重和皮下脂肪重均显著高于雄性( P< 0-05 或0-01) ,皮肌和刺重无性别差异。除面部、四肢和腹部外,全身披有粗而硬的针刺,针刺长16-36 ±1-30 m m ,直径0-95 ±0-15 m m ,重3-55 ±0-43 mg。每只普通刺猬有针刺5434 ±475 根。按颜色分针刺有五种类型,不同个体身上这五种针刺的分布比例不等。普通刺猬有乳腺5 对,前后足各5 指( 趾) ,指( 趾) 端具爪。普通刺猬皮肤的特殊结构,具有重要的生理保护意义  相似文献   

3.
Populations of red deer that are limited by food, like those of many other ungulates, commonly include more females than males. We assessed the contribution of variation in sex- and age-specific rates of mortality and emigration to density-dependent changes in the adult sex ratio, using long-term observations and demographic experiments involving the red deer population on Rum, Scotland. We incorporated these effects in a stochastic model of local populations under different management regimes to show here that, when female numbers are allowed to increase to more than 60% of the ecological carrying capacity, the sustainable annual harvest of males from local deer populations will fall. Because males are typically culled by fee-paying hunters and generate more income than females, income will decrease as the male harvest falls. Because numbers of female deer throughout much of the Highlands probably exceed the threshold at which male density starts to be affected, many managers might be able to raise income from local deer populations by reducing female numbers, with potential benefits to the vegetation of Scottish Highland environments.  相似文献   

4.
运用Heath-Carter法对俄罗斯族体型的研究   总被引:2,自引:0,他引:2  
采用Heath-Carter人体测量体型法对336例(男186,女150)俄罗斯族成人的体型进行了研究,并将俄罗斯族的体型与我国部分少数民族以及部分国外群体体型进行了比较.结果:男性的平均体型为偏内胚层型的中胚层型(3.3-5.8-1.7),女性为内胚层-中胚层均衡型(5.7-6.2-1.1).随年龄增长,两性的内、中因子值增大,外因子值减小.但二者体型具有极显著性别差异.俄罗斯族男性的体型最接近于因纽特人;女性体型相对接近于乌孜别克族.结论:俄罗斯族成人的体型具有其自身的特征:骨骼宽大,身材魁梧健壮,皮下脂肪较多,身体线性度欠佳,尤其是女性,其中因子成分明显占优.  相似文献   

5.
通过长期观察、试验和研究认为,性成熟的棕色田鼠与双亲或雌亲相处或与兄妹鼠相处都不能发情,从而体现亲缘关系对棕色田鼠发情所具有的明显抑制作用。同母喂养的非同胞异性鼠相处能够动情,说明遗传识别在棕色田鼠亲缘识别中起重要作用。非同母喂养的非同胞异性鼠和同母喂养的异性非同胞鼠中的雄性睾丸下降率显大于异性同胞鼠相处时的雄鼠,说明亲缘关系对雄性睾丸下降表现出明显的抑制作用。  相似文献   

6.
Höner OP  Wachter B  East ML  Streich WJ  Wilhelm K  Burke T  Hofer H 《Nature》2007,448(7155):798-801
Dispersal has a significant impact on lifetime reproductive success, and is often more prevalent in one sex than the other. In group-living mammals, dispersal is normally male-biased and in theory this sexual bias could be a response by males to female mate preferences, competition for access to females or resources, or the result of males avoiding inbreeding. There is a lack of studies on social mammals that simultaneously assess these factors and measure the fitness consequences of male dispersal decisions. Here we show that male-biased dispersal in the spotted hyaena (Crocuta crocuta) most probably results from an adaptive response by males to simple female mate-choice rules that have evolved to avoid inbreeding. Microsatellite profiling revealed that females preferred sires that were born into or immigrated into the female's group after the female was born. Furthermore, young females preferred short-tenured sires and older females preferred longer-tenured sires. Males responded to these female mate preferences by initiating their reproductive careers in groups containing the highest number of young females. As a consequence, 11% of males started their reproductive career in their natal group and 89% of males dispersed. Males that started reproduction in groups containing the highest number of young females had a higher long-term reproductive success than males that did not. The female mate-choice rules ensured that females effectively avoided inbreeding without the need to discriminate directly against close kin or males born in their own group, or to favour immigrant males. The extent of male dispersal as a response to such female mate preferences depends on the demographic structure of breeding groups, rather than the genetic relatedness between females and males.  相似文献   

7.
摘要:目的 探讨应用生物阻抗分析仪测量不同性别Wistar大鼠体液成分和脂肪分布情况。 方法 利用生物阻抗分析仪检测Wistar大鼠身体组份,包括体液总量(TBW)、细胞内液(ICF)、细胞外液(ECF)、脂肪量(FM)、除脂肪量(FFM)、体液总量/ 体质量(TBW/BW)、细胞外液量/ 体质量(ECF/BW)、细胞内液量/ 体质量(ICF/ BW)、脂肪量/ 体质量(FM/BW)和除脂肪量/ 体质量(FFM/BW)。雄性组13只,雌性组,13只分别检测各项指标改变,以证明不同性别正常成年Wistar大鼠身体组份构成。 结果 不同性别两组间比较,雄性Wistar大鼠体液总量、细胞内外液含量、TBW/BW、ECF/BW、ICF/BW高于雌性Wistar大鼠,P值均小于0.05,差异有显著性。 FM/BW、FFM/BW比较,P值均小于0.05,两组差异有显著性。 雌性Wistar大鼠的脂肪含量高于雄性Wistar大鼠。 结论 正常雄性成年Wistar大鼠的体液含量高于雌性Wistar大鼠,而雌性Wistar大鼠脂肪百分比高于雄性。  相似文献   

8.
Female mimicry in garter snakes   总被引:4,自引:0,他引:4  
R T Mason  D Crews 《Nature》1985,316(6023):59-60
In many diverse taxa, males of the same species often exhibit multiple mating strategies. One well-documented alternative male reproductive pattern is 'female mimicry', whereby males assume a female-like morphology or mimic female behaviour patterns. In some species males mimic both female morphology and behaviour. We report here female mimicry in a reptile, the red-sided garter snake (Thamnophis sirtalis parietalis). This form of mimicry is unique in that it is expressed as a physiological feminization. Courting male red-sided garter snakes detect a female-specific pheromone and normally avoid courting other males. However, a small proportion of males release a pheromone that attracts other males, as though they were females. In the field, mating aggregations of 5-17 males were observed formed around these individual attractive males, which we have termed 'she-males'. In competitive mating trails, she-males mated with females significantly more often than did normal males, demonstrating not only reproductive competence but also a possible selective advantage to males with this female-like pheromone.  相似文献   

9.
对成年棕色田鼠 (Microtusmandarinus)的社会行为进行了实验室观察 .结果发现 ,当陌生的两只雄鼠相遇时 ,优势雄鼠和从属雄鼠间的社会行为有明显的区别 ,优势鼠接近、攻击、追赶对方的频次和持续时间明显的多于从属鼠 ,而从属鼠逃离和防御行为多于优势鼠 ;优势鼠的体重明显的大于从属鼠 ,而且攻击行为和社会探究行为的频次与体重呈正相关 ,非社会行为无明显的差别 .但当两只熟悉的雄鼠相遇时 ,则比陌生雄鼠相遇表现出较多的喜好行为和较少的攻击行为 .观察还发现 ,单独生活的异性个体相遇时表现出较少的攻击行为和较多的喜好行为 ;相反 ,和其它家庭成员生活的两个陌生异性个体相遇时表现出较多的攻击行为 .两个雌性相遇和两个雄性相遇表现出相似的行为模式 .以上结果表明 ,熟悉性、性别、个体大小、接触近况是影响棕色田鼠社会行为的重要因子 .  相似文献   

10.
为了解怀化市成人身体形态与身体成分现状及特点,揭示不同年龄段间各项指标的变化规律,对怀化市20~59岁成年人,共计4 880人(男2 480,女2 400)进行了测试与分析.结果表明,身高随年龄增长呈逐年下降趋势,体重、腰臀比等指标随年龄的增长呈缓慢增加趋势;体脂率随年龄的增长呈缓慢增加趋势,与2005年相比较,男子身高和体脂率分别低于湖南省平均水平(P<0.05,P<0.01),男子克托莱指数和女子体脂率分别高于湖南平均值(P<0.05).  相似文献   

11.
C S Price  K A Dyer  J A Coyne 《Nature》1999,400(6743):449-452
Females in almost all animal groups copulate with multiple males. This behaviour allows different males to compete for fertilization and gives females the opportunity to mediate this competition. In many animals and most insects, the second male to copulate with a female typically sires most of her offspring. In Drosophila melanogaster, this second-male sperm precedence has long been studied but, as in most species, its mechanism has remained unknown. Here we show, using labelled sperm in doubly mated females, that males can both physically displace and incapacitate stored sperm from earlier-mating males. Displacement occurs only if the second male transfers sperm to the female, and in only one of her three sperm-storage organs. Incapacitation can be caused by either fertile or spermless second males, but requires extended intervals between matings. Sperm from different males are not 'stratified' in the storage organs but mix freely. Many animal species may have multiple mechanisms of sperm competition like those observed here, and revealing these mechanisms is necessary to understand the genetic and evolutionary basis of second-male sperm precedence in animals.  相似文献   

12.
The newly emerged adult females of Schistocerca gregaria were separated and kept in the rearing conditions without males to examine the detailed developmental characteristic of the no mating females and carefully observed the developmental progress of non-fertilised eggs laid by virgin females. The results showed that the females kept without males survived in average 43 d, i.e. 58% of the life span of mated controls, and laid correspondingly fewer egg pods. The size of egg batches, the weight of eggs, and their content of ecdysteroids were normal but the hatch rate was reduced to 18.27%. Blocks of early embryogenesis (58.43%) and hatching failures (23.29%) were the major causes of death. Moreover, most of the hatched insects died during the postembryonic development and only a few females reached the adult stage. All insects that developed until the penultimate or last larval instar or reached the adult stage were females.  相似文献   

13.
广西玉林地区青少年纵向体质发育指标分析   总被引:1,自引:0,他引:1       下载免费PDF全文
用随机分层抽样方法,对7岁-16岁广西玉林地区博白,陆川两县1135名中,小学生质发育23项指标测量调查,选身高,躯干长,上肢长,下肢长进行男女学生对比,结果男女生的发育趋势一致,但突增期不同,(男10岁~11岁,女12岁~13岁)对上肢长/身高指数分型,发现男女生的上胀长/身高指数均集中在短型(分别为98.0%,98.2%)对下肢长/身高指数分型,发现男女生的下肢长/身高指数多在长型(男58.5  相似文献   

14.
Egg investment is influenced by male attractiveness in the mallard   总被引:36,自引:0,他引:36  
Cunningham EJ  Russell AF 《Nature》2000,404(6773):74-77
Why females prefer to copulate with particular males is a contentious issue. Attention is currently focused on whether females choose males on the basis of their genetic quality, in order to produce more viable offspring. Support for this hypothesis in birds has come from studies showing that preferred males tend to father offspring of better condition or with increased survivorship. Before attributing greater offspring viability to a male's heritable genetic quality, however, it is important to discount effects arising from confounding sources, including maternal effects. This has generally been addressed by comparing offspring viability from two different breeding attempts by the same female: one when offspring are sired by a preferred male, and one when offspring are sired by a less preferred male. However, here we show that individual female mallard (Anas platyrhynchos) lay larger eggs after copulating with preferred males and smaller eggs after copulating with less preferred males. As a result, females produced offspring of better body condition when paired with preferred males. After controlling for these differences in maternal investment, we found no effect of paternity on offspring condition. This shows that differences between half-sibs cannot always be attributed to paternal or maternal genetic effects.  相似文献   

15.
Liu Y  Jiang Y  Si Y  Kim JY  Chen ZF  Rao Y 《Nature》2011,472(7341):95-99
Although the question of to whom a male directs his mating attempts is a critical one in social interactions, little is known about the molecular and cellular mechanisms controlling mammalian sexual preference. Here we report that the neurotransmitter 5-hydroxytryptamine (5-HT) is required for male sexual preference. Wild-type male mice preferred females over males, but males lacking central serotonergic neurons lost sexual preference although they were not generally defective in olfaction or in pheromone sensing. A role for 5-HT was demonstrated by the phenotype of mice lacking tryptophan hydroxylase 2 (Tph2), which is required for the first step of 5-HT synthesis in the brain. Thirty-five minutes after the injection of the intermediate 5-hydroxytryptophan (5-HTP), which circumvented Tph2 to restore 5-HT to the wild-type level, adult Tph2 knockout mice also preferred females over males. These results indicate that 5-HT and serotonergic neurons in the adult brain regulate mammalian sexual preference.  相似文献   

16.
Female feral fowl eject sperm of subdominant males   总被引:11,自引:0,他引:11  
Pizzari T  Birkhead TR 《Nature》2000,405(6788):787-789
Paternity is often determined by competition between the ejaculates of different males. Males can also use particular behaviours or structures to manipulate how females use sperm. However, the ability of females to bias sperm utilization in favour of preferred males independently of male manipulation has not been demonstrated. Females are predicted to respond differentially to the sperm of different males when the reproductive interests of the sexes differ and when females are coerced into copulating. Here we show that in female feral fowl most copulations are coerced, and that females consistently bias sperm retention in favour of the preferred male phenotype. Females prefer to copulate with dominant males, but when sexually coerced by subordinate males, they manipulate the behaviour of dominant males to reduce the likelihood of insemination. If this fails, females differentially eject ejaculates according to male status in the absence of any male manipulation and preferentially retain the sperm of dominant males.  相似文献   

17.
为了探讨布里亚特蒙古族成人身体围度特征,对310名(男152,女158)布里亚特蒙古族成人的9项身体围度进行测量,计算了6项围度指数值,比较了性别间的差异性,分析了围度值随年龄变化的规律,并将布里亚特蒙古族与我国其他14个人群的围度值进行了u检验.结果表明:男性围度的总体均数中,臀围明显低于女性,腹围和大腿围略低于女性,其余均高于女性;随着年龄增长,女性围度变化幅度大于男性,且女性多数围度值在50岁以后明显下降;男性上、下肢近端部与远端部围度发育较匀称,而女性较粗壮;布里亚特蒙古族成人的多数围度值都大于其他人群,是蒙古族中身材较为粗壮魁梧的人群.  相似文献   

18.
对2008年10月到2009年2月采于嘉陵江南充段的117尾兴凯鱊进行形态测量,单因素方差分析显示:兴凯鱊比例性状在雌雄鱼之间无显著差异;体长质量关系和肥满度分析表明,体长大于8em时;雌鱼体质量增长快于雄鱼;相同体长组中,雌鱼肥满度指数稍大于雄鱼.  相似文献   

19.
P Hutter  M Ashburner 《Nature》1987,327(6120):331-333
Post-mating mechanisms are central to the establishment of reproductive isolation between different, but closely related, species. Post-mating isolation mechanisms include hybrid breakdown, hybrid sterility and hybrid lethality and may, in some cases, be reinforced by pre-mating mechanisms such as ethological differentiation. In the Drosophila melanogaster species sub-group post-mating reproductive isolation is ensured by both the inviability and the sterility of hybrids. For example when D. melanogaster females are crossed to D. simulans males the hybrid progeny are normally all female; the hybrid males die as third instar larvae. The viable hybrid females are totally sterile. Little is known of the genetic basis for either hybrid sterility or hybrid inviability, although Coyne and others have begun a genetic analysis of the sterility of hybrids within this species sub-group. We have discovered a single gene difference that rescues the otherwise inviable male hybrids from the cross between D. melanogaster females and males of its three closest relatives. The study of this locus may shed light on the genetic control of both speciation and development.  相似文献   

20.
为了探讨用皮褶厚度、体脂率法评价江淮地区汉族肥胖的标准,于2010年在安徽滁州和江苏淮安调查了1 426例(城市男性309例,乡村男性414例,城市女性312例,乡村女性391例)江淮汉族成年人的身高、体重、肱三头肌皮褶、肩胛下皮褶,通过身高、体重来计算身体质量指数(BMI),通过肱三头肌皮褶、肩胛下皮褶来计算体密度,采用Brozek公式计算体脂率.用BMI、皮褶厚度、体脂率分别评价江淮汉族成年人的肥胖率.结果表明:(1)江淮汉族男性BMI值为(24.1±3.6)kg/m2,女性BMI值为(23.8±3.6)kg/m2.用BMI法判断,江淮汉族超重率男性为34.7%,女性为30.7%;肥胖率男性为14.4%,女性为13.2%.(2)随年龄增长,肱三头肌皮褶、肩胛下皮褶值、BMI、体脂率增大,身高下降.(3)用长岭晋吉皮褶厚度法判断,江淮汉族肥胖率男性为39.8%,女性为30.4%.皮褶厚度法得出的肥胖率远远高于BMI法,两种方法存在较大矛盾.本研究认为用肱三头肌皮褶与肩胛下皮褶之和来判断中国人群肥胖的标准,男性应该在35~45 mm之间,女性应该在45~55 mm之间选取.(4)用长岭晋吉体脂率法作为判断肥胖的标准,肥胖率男性为43.3%,女性为5.3%.用体脂率和BMI法判断江淮汉族成年人的肥胖存在较大矛盾.长岭晋吉体脂率法男性标准定得太低;女性标准定得太高.本研究认为用体脂率来判断江淮地区汉族肥胖,男性以大于24%、女性以大于28%为宜.  相似文献   

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