CORRELATED EVOLUTION OF SEXUAL DIMORPHISM AND MALE DIMORPHISM IN A CLADE OF NEOTROPICAL HARVESTMEN

Secondary sexual traits increase male fitness, but may be maladaptive in females, generating intralocus sexual conflict that is ameliorated through sexual dimorphism. Sexual selection on males may also lead some males to avoid expenditure on secondary sexual traits and achieve copulations using alternative reproductive tactics (ARTs). Secondary sexual traits can increase or decrease fitness in males, depending on which ART they employ, generating intralocus tactical conflict that can be ameliorated through male dimorphism. Due to the evolutionary forces acting against intralocus sexual and tactical conflicts, male dimorphism could coevolve with sexual dimorphism, a hypothesis that we tested by investigating these dimorphisms across 48 harvestman species. Using three independently derived phylogenies, we consistently found that the evolution of sexual dimorphism was correlated with that of male dimorphism, and suggest that the major force behind this relationship is the similarity between selection against intralocus sexual conflict and selection against intralocus tactical conflict. We also found that transitions in male dimorphism were more likely in the presence of sexual dimorphism, indicating that if a sexually selected trait arises on an autosome and is expressed in both sexes, its suppression in females probably evolves earlier than its suppression in small males that adopt ARTs.     

金丝猴肩带和前肢的性二型

本文研究了两种金丝猴(Rhinopitheous bieti和R.brelichi)肩带及上肢的62项线性变量及指数的性二型,其中64.5%达到了显著性差异水平。结果表明,两性在运动行为上存在一些差异。在所分析的变量中,性别间的差异主要由于成熟时间的不同所引起(雄性比雌性具更长的生长时期),其次是生长速率的不同(雄性比雌性具有更明显的正异速生长率)。对一些指数及不同部位的性二型分析表明,在上肢利用和尺、桡骨的前旋及后旋活动方面,两性也具一些不同。     

中国兔猴的单一物种及其两性差别

观察到以前描述的中国兔猴不同种的特征在禄丰的全部中国兔猴标本中交叉地存在、并通过连续的中间表现型而衔接,本文建议石灰坝中国兔猴是厚齿中国兔候的同种异名,因而前一名称应予取消。以犬齿和下第四前臼齿为材料研究了中国兔猴的两性差别。本文使用双变量分布确定两性重叠分布的测量性状的性别差异取得较好的效果。     

蜘蛛的性二型现象及其进化

对蜘蛛的性二型现象进行了初步的概括,并试图以食物对种群繁衍的影响为线索说明其进化机制。蜘蛛的性二型现象主要表现在体形大小上,一般雌性大于雄性;食物的数量和分布制约着蜘蛛性二型现象的进化。     

SEXUAL DIMORPHISM IN CYPRAEIDAE

EVIDENCE of sexual dimorphism has been found in two species,Cypraeagracilis Gaskoin and Umbilia hesitata Iredale. In theformer the observed difference lies in the colour of the livinganimals, and in the latter in the length of the shell, the malebeing the longer. (Received 10 June 1960;     

SEXUAL DIMORPHISM IN MAMMALS

1. Life expectancy and mortality rates from diseases arising in various organs vary with sex because of differential exposure to external hazards and because of essential differences between males and females in aspects not directly connected with reproduction. This review attempts to collate data about the structural and functional dimorphism of mammals exclusive of the genital organs and psychological aspects. 2. The primary sex ratio is not certain and like the secondary and tertiary may vary with species. In many mammals more males are aborted and born than females. Later a higher mortality of males, due to sex-linked congenital diseases and greater exposure to external hazards, shifts the balance in favour of females at the time of sexual maturity. The average life span of females is longer than that of males, except in hamsters and in inbred strains of mice with a high incidence of mammary tumours. 3. Chromosomes as well as gonadal hormones are responsible for the development of male and female characteristics. The Y-chromosome initiates the differentiation of the testis, but gonadal hormones control the subsequent differentiation of the genital tract and other organs. In embryos the testicular secretion precedes that of the ovary. The Y-chromosome is devoid of, but the X-chromosome retains structural genes. The random heterochromatization of a paternal or a maternal X-chromosome in the somatic cells of female embryos equalizes the genetic information for both sexes and produces a mosaicism of female somatic cells except in the kangaroo where the paternal X-chromosome is selectively inactivated. Deficient genes on the X-chromosome become manifest in hemizygous males, in homozygous females and can be detected in heterozygous women in half of the somatic cell population in some conditions. 4. The testis grows faster than the ovary and starts to secrete earlier, but the maturation of female gonocytes precedes that of males. Spermatogenesis starts at puberty and is maintained throughout life, while multiplication of oogonia ceases in the perinatal period (except in lemurs), when the stage of the first meiotic division is reached. The stock of oocytes dwindles during life. 5. In many mammals the male grows faster than the female before and after birth, but is less mature. Puberty tends to start earlier in females and the associated growth spurt does not last as long as in males. Testosterone has a direct anabolic effect, promotes growth and delays differentiation. Oestrogens are considered katabolic, but promote growth indirectly by stimulating the production of growth hormone in the pituitary. Progesterone has an anabolic and slight androgenic effect. 6. A female pattern of differentiation of the hypothalamus, the pituitary and the pineal gland, manifested at puberty by cyclical activities of the reproductive organs requires the absence of androgens during a critical phase of ante- or perinatal development. Oestrogens given to males at that period produce effects similar to castration. Antiandrogens induce in males a cyclical pattern of function in the hypothalamus and the pituitary, enlargement of the breasts and formation of nipples in the rat and a female type of sexual behaviour. There is no complete sex reversal in mammals comparable to that of fish and amphibians. 7. With some exceptions (hamsters, rabbits, guinea-pigs) males are larger than females. Gender differences in weight of organs and in other parameters must be assessed as proportion to male or female weight, surface and activities. The relatively greater amount of fat in female and of connective tissue in male organs in relation to the active parenchyma complicate comparisons. 8. The head and shoulder region is proportionately larger in males and the pelvic region in females. Men and male mice have heavier bones, muscles, hearts, lungs, salivary glands, kidneys and gonads in proportion to body weight, while females have proportionately heavier brains, livers, spleens, adrenals, thymus, stomach and fat deposits. 9. The basal metabolic rate in women is lower than in males. A great variety of metabolic parameters, levels of enzyme activity, location of fat deposits, sensitivity to drugs is sexually dimorphic and responsive to the action of androgens, oestrogens and progestagens. 10. Males tend to have more red blood corpuscles, haemoglobin and erythropoietin per unit volume of blood than women, cows, mares, sows, bitches, female cats and hamsters, but there is no sex difference in this respect in rats, rabbits, goats or sheep. Females tend to have more granulocytes and a proportionately larger lymphomyeloid complex (bone marrow, spleen, thymus, lymph nodes and lymphoepithelial tissues) and greater immunological competence than males. The cortical epithelium of the thymus in mice and rats is sexually dimorphic, responsive to castration and treatment with sex hormones and varies with the oestrous cycle. 11. The kidney is proportionately larger in male mice, rats, cats and dogs, is reduced by castration and enlarged by treatment with testosterone. The kidneys of hamsters and guinea-pigs do not differ in size with sex, nor do they respond to castration or to androgens. The proportion of tubules to glomeruli is greater in the male than the female kidney. The tubular mass increases with androgenic medication, but not the juxtaglomerular apparatus. The parietal epithelium of Bowman's capsule, the histochemistry of the kidney and the composition of the urine vary with gender and respond to sex hormones according to species and strain. The bladder of male mice is proportionately larger than that of females. Some pheromones are present in the bladder urine of intact male mice and of spayed females given testosterone, but absent from that of castrated males. 12. Boars, male elephants, mastodons, horses, deer and monkeys have larger canines than the females. The submaxillary gland of male mice, rats and pigs is proportionately larger than in females, but smaller in hamsters. The proportion of mucous to serous acinar cells in female rodents is greater than in males; female hamsters produce more sialic acid. The secretory tubules of male rats and mice are larger than in females and produce a nerve- and an epidermal-growth factor. Apart from amylase the levels of enzyme activity vary with sex. The liver is sexually dimorphic as regards size, content and metabolism of glycogen, fat, vitamin A, levels of enzymatic activity, phagocytic activity and in its response to castration, sex hormones, to toxic agents, drugs and carcinogens. Sex hormones affect the production of insulin by the pancreas in vivo and in vitro. 13. The male larynx which enlarges and induces voice changes in many mammals at puberty or the onset of the breeding season, is affected by castration and by sex hormones. Male lungs are proportionately larger than female ones with a greater vital and maximal respiratory capacity. Breathing rate and manner varies with sex and is related to differences in the muscular development of the diaphragm. 14. The epidermis and dermis of males are thicker, but the subcutis thinner than in females. The skin is sexually dimorphic in respect of dermatoglyphics, the replacement of vellus by terminal hair and pigmentation of specific regions, the colour of the face and of the sexual skin in monkeys, the development of antlers and horns. The synchrony of the hair cycle and the growth wave of the hair coat in mice and rats depend on the sex of the animals. The X-chromosome mosaicism in the hair follicles of female mice accounts for the mosaicism in pigmentation. Apart from a genetic disorder, the sweat glands are not sexually dimorphic, but the apocrine, the sebaceous glands and their specialized forms are. The embryonic development of mammary glands depends on the absence of androgens and can be induced in male rats and guinea-pigs by antiandrogens. 15. An intact cerebral cortex is necessary for the performance of reproductive functions in male, but not in female rats, cats, rabbits and guinea-pigs. Removal of the olfactory bulb impairs reproduction in female, but not in male mice. Pinealectomy prevents the testicular atrophy of hamsters kept in the dark. The reproductive cycles in females are regulated by the hypothalamus through the control of the ratio of FSH to LH release in the pituitary. This in turn acts on the ovary and thus affects the activity of the thyroid, thymus and lung. In males FSH and LH act synergistically and their secretion is not controlled separately. Oestrogens are more effective than androgens in inhibiting pituitary functions. Sexual dimorphism in cytology, enzyme levels and oestrogen-binding is manifest in the preoptic area, the hypothalamus and the nucleus medialis amygdalae. The female brain is proportionately larger than the male with equal relative amounts of grey and white matter, but a bigger hypothalamic-pituitary-pineal complex. The pineal gland is more prone to tumour formation in boys than in girls and retains its cellularity longer in women than in men. Colour blindness is manifested less in heterozygous women than in hemizygous men. Mature women are more sensitive to the smell of synthetic musk than girls or men. Male rats and mice are more susceptible to audiogenic seizures than females. 16. The activity of the thyroid gland varies at different phases of the oestrous cycle in rats, mice and guinea-pigs. Female mice release more thyroid hormone into the blood than males or spayed animals. Oestrogens increase the level of thyroxin-binding protein. The concentration of TSH in the blood of mature women is double that of men and of menopausal women. The incidence of non-endemic thyroid disorders in women considerably exceeds that in men. 17. The adrenals of females are much larger than those of males except in hamsters. The gland of the female mouse contains more lipid than that of the male. The juxtamedullary X-zone of mice involutes at puberty in males and during the first pregnancy in females. Castration induces an X-zone in male mice, voles, hamsters and cats and an enlargement without stratification in rats. ACTH controls the secretion of glucocorticoids and since its formation is promoted by oestrogens and inhibited by androgens, sex hormones influence indirectly the size and activity of the adrenal cortex. Hepatic inactivation of glucocorticoids is 3 to 10 times greater in intact females than in males. 18. The implications of species variations in sexual dimorphism for the survival and the evolution of mammals are discussed.     

腾格里沙漠人工固沙植被中油蒿的生长及生物量分配动态

植物的资源分配模式反映了对环境的生态适应对策。2007年整个生长季, 采用生物量法对腾格里沙漠东南缘固沙植被区半灌木油蒿(Artemisia ordosica)地上部分各器官的生长及资源分配格局动态进行了研究。结果表明: 不同时期各器官的生长速率不同, 光合产物在各器官中的分配也不是等量的, 而是按一定的顺序在不同时期有不同的分配中心; 2007年油蒿的营养生长、繁殖输出、生殖枝大小都显著大于年降水量不足其一半的年份, 而繁殖分配和头状花序大小没有差异; 营养器官生物量大的油蒿总的繁殖输出也大, 但生殖期内营养生长和生殖生长既不同时也不等速, 表明资源分配的权衡(Trade-off)是存在的; 固沙植被建立以后, 随着时间延长, 油蒿的当年总生物量、繁殖输出、繁殖器官生物量分配有减小的趋势, 但不显著。     

禄丰古猿的两性差别

本文首先讨论了粗壮池猿化石标本的性别判断问题,然后把粗壮池猿和禄丰西瓦古猿分别与有关的现生猿类的两性差别进行比较研究,得出这两个进化系统性别差异的时代变化的结论。这样的结论支持禄丰西瓦古猿的系统地位的论证。     

Fus在斑马鱼生长发育及两性生长异形中的功能

为研究肉瘤融合基因(fus)在鱼类中的功能, 在斑马鱼中利用CRISPR/Cas9基因突变技术使fus基因产生移码突变。fus-/-纯合突变体斑马鱼发育正常并且完全可育, 但体长和体重在幼鱼和成年阶段都小于野生型斑马鱼。此外, 相较于野生型斑马鱼, fus-/-纯合突变体斑马鱼不存在雌鱼身体比例大于雄鱼的性别异形现象。在fus-/-纯合突变体斑马鱼早期幼鱼发育阶段, 一些生长相关基因包括gh1、ghra、igf1、igf2a、stat5.1和socs6的表达水平显著低于野生型斑马鱼但其运动能力并未受到影响。因此, 不同于fus基因在哺乳动物中的功能, 它在斑马鱼中不参与运动神经元的发育, 但在调节鱼类躯体生长发育与两性生长异形方面有着重要的功能。     

不同放牧强度下冷蒿(Artemisia frigida )、星毛委陵菜(Potentilla acaulis)的形态可塑

 研究了不同放牧强度下（不放牧、轻牧(1.33只羊/hm2)、中牧(4.00只羊/hm2)、重牧(6.67只羊/hm2)）冷蒿 (Artemisia frigida)、星毛委陵菜 (Potentilla acaulis)的克隆形态（间隔子长度、分枝强度）可塑性以及生物量分配格局。两种植物的间隔子长度、分枝强度沿放牧梯度具有显著的可塑性反应。冷蒿间隔子长度：不放牧>轻牧>重牧>中牧;分枝强度：重牧>中牧>轻牧>不放牧。星毛委陵菜间隔子长度:轻牧>不放牧>中牧>重牧;分枝强度:重牧>中牧>轻牧>不放牧。冷蒿种群     

SEXUAL SIZE DIMORPHISM AND EGG-SIZE ALLOMETRY IN BIRDS

We tested the hypothesis that egg size should evolve in sexually dimorphic birds to reduce costs associated with more rapid growth by nestlings of the larger sex. Consistent with this hypothesis, we found that in species in which males were larger, females laid proportionately larger eggs as sexual size dimorphism increased. However, this result was also consistent with the hypothesis that egg size varied allometrically with both male and female body size. Furthermore we found that in species in which females were larger, relative egg size decreased as size dimorphism increased, which is consistent with the “allometry hypothesis” but not the “cost-reduction hypothesis. That male body size contributes to the allometric relationship between egg size and body size suggests that the basis for the allometric relationship is not wholly a mechanical one stemming from the physical requirements of developing, transporting, and laying an egg of a particular size. Rather, the relationship seems likely to be tied more directly to body size itself the tact that male body size influences a female trait suggests that egg size–body size relationships otter some scope for investigating the basis for allometric relationships in general.     

STRUCTURE OF CLONES OF NORTHERN PRICKLY ASH (XANTHOXYLUM AMERICANUM)

Clones of northern prickly ash (Xanthoxylum americanum) were excavated to expose their horizontal root structure and pattern of vegetative spread; stems and horizontal roots were mapped. Most of the root system was very shallow (< 10 cm deep). Stems and roots were aged from annual rings. The four clones studied ranged in age from 26 to 33 yrs. All root connections between shoots were maintained for the life of the clone. Clones were found to be single individuals in a physical as well as a genetic sense. There was virtually no overlap of adjacent clones; horizontal roots turned away or stopped growing when the border of another clone was encountered. No differences were found between male and female clones in above- or below-ground morphology. There was, however, a great deal of intrasexual variation among clones.     

克隆植物的无性与有性繁殖对策

许多植物同时具有克隆生长与有性繁殖,两种繁殖方式间的平衡在不同物种间以及同一物种内不同种群间变化很大。旺盛的克隆生长可能会从多方面影响生活史进化。首先,许多克隆植物的有性繁殖与更新程度都很低,甚至有一些植物由于克隆生长而几乎完全放弃了有性过程,从而影响到克隆植物对局域环境的适应和地理范围进化。其次,克隆生长增大花展示进而增加了对传粉者的吸引,同时也增加了同株异花授粉的风险,而同株异花授粉往往会导致植物雄性和雌性适合度的下降。因此,克隆植物的空间结构与交配方式间可能存在着协同进化关系。最后,克隆生长与有性繁殖间可能存在着权衡关系:对克隆生长的资源投入将会减少对有性繁殖的资源投入。这种权衡关系可能是由环境条件、竞争力度、植物寿命和遗传等因素决定的。如果不同的繁殖方式是植物在不同环境下采取的适应性对策,那么我们可以预期:在波动和竞争力度大的生境中,植物应将大部分的繁殖资源分配给有性繁殖;而在相对稳定的环境中,克隆繁殖应该占据优势地位。但是自然选择对两种繁殖方式的选择结果是什么,以及控制这两种方式间平衡的生态和遗传因子究竟有哪些,到底是克隆生长单向地影响了植物的有性繁殖,还是与有性过程相伴随的选择压力同时塑造了植物的克隆习性?目前尚不清楚。同时从无性与有性繁殖两个方面综合考察克隆植物的繁殖对策是今后亟待加强的工作。     

银鹊树群落生物量和能量的分配

 本文研究了安徽大别山天然林内16年生银鹊树和引种于南京的银鹊树幼苗及人工幼林的生物量,分析了光能利用率。研究结果表明：(1)常规芦蒹遮光,一龄苗的生物量为1777.5kg／ha。以一层塑料纱遮光处理的幼苗生物量最大,全光照的幼苗生物量居第二、三层纱遮光生物量最小。(2)天然林内16年生单株银鹊树地上部分干重为107.77kg。(3)8年生人工银鹊树林总生物量为80.63t／ha,其中乔木层平均净生产量为9.563t／ha·a,高于湖南会同、朱亭及江苏南部的杉木林。(4)银鹊树林总初级生产量为1219.18g／m2·a;其中乔木层为956.25g／m2·a,草本及天然幼苗为161.10g／m 2·a,枯枝落叶为101.83g／m2·a．光能利用率为0.527%,其中乔木层的光能利用率为0.417%。     

NATURAL SELECTION AND SEXUAL SIZE DIMORPHISM IN RED-WINGED BLACKBIRDS

Patterns of overwinter mortality in the sexually dimorphic red-winged blackbird (Agelaius phoeniceus) were examined to test the predictions of the sexual-selection hypothesis that male size is limited by directional selection favoring small males and that female size is maintained by stabilizing selection wherein extreme phenotypes experience higher mortality. Museum specimens collected from Ontario over a 95-yr period were used to compare the sizes of males and females collected in fall and spring. In a separate field study, body sizes of returning and nonreturning male and female red-winged blackbirds were compared over a 6-yr period. Overall, there was no evidence of higher overwinter mortality among larger males. Among adult (ASY) males, large individuals appeared to have higher survival than small individuals, although among subadult (SY) males, large size may have been disadvantageous. Weak evidence of stabilizing selection on female body size was found. Among adults, sexual size dimorphism seemed more pronounced after winter than before winter. Our results do not support the hypothesis that body size in male red-winged blackbirds is limited by selective mortality outside the breeding season. It is possible that size selection occurs earlier in life, when males are still in the nest. Our results suggest that caution should be exercised when interpreting interspecific evidence showing higher adult male than female mortality in sexually dimorphic species. Such patterns could arise as a cost to males of sexual selection and yet provide no insight into how natural selection opposes sexual selection for increased male size.