Fluctuating asymmetry and age in children: evolutionary implications for the control of developmental stability

Fluctuating asymmetry (FA) is small deviations from perfect symmetry which reflect one component of fitness, i.e. developmental stability. There is accumulating evidence that low FA is important in inter- and intra-sexual selection in humans. However, there is little information on the pattern of FA in children. Data from cross-sectional studies of 680 participants from 2–18 years suggests that (1) both absolute and relative FA reduces with age until 10 years (2) there is an increase in FA in adolescents (11–15 years) with a peak at 13 years for males and 14 years for females (3) after 15 years there is reduction in FA which is maintained until 18 years. The importance of growth rate, metabolic maintenance and sex steroids on developmental stability is discussed.     

Parasites differentially increase the degree of fluctuating asymmetry in secondary sexual characters

The degree of fluctuating asymmetry has been demonstrated to reflect the ability of individuals to cope with different kinds of environmental stress (Parsons 1990). Parasites and diseases are one kind of environmental stress which most individuals encounter during their lifetime. Parasites have also been suggested to play an important role in sexual selection and the development of ornaments, since the full expression of ornaments may reflect the ability of hosts to cope with the debilitating effects of parasites. Here I report for the first time that a parasite, the haematophagous tropical fowl mite Ornithonyssus bursa (Macronyssidae, Gamasida), directly affects the degree of fluctuating asymmetry in a secondary sexual character of its host, the elongated tail of the swallow Hirundo rustica (Aves: Hirundinidae). I experimentally manipulated the mite load of swallow nests during one season by either increasing or reducing the number of mites, or keeping nests as controls. The degree of fluctuating asymmetry was measured in the subsequent year after the swallows had grown new tail ornaments under the altered parasite regime. The degree of fluctuating asymmetry was larger at increasing levels of parasites for male tail length, but not for the length of the shortest tail feather or wing length or for tail and wing length in females. These results suggest that the degree of fluctuating asymmetry in tail ornaments, but not in other feather traits, reliably reveals the level of parasite infestation. This has important implications for the ability of conspecifics to use the size and the expression of ornaments in assessment of phenotypic quality and thus in sexual selection.     

红原鸡全基因组中微卫星分布规律研究

本文对红原鸡Gallus gallus全基因组中微卫星数量及分布规律进行了分析,查找到l～6个碱基重复类型的微卫星序列共282728个,约占全基因组序列(1.1Gb)的0.49%,分布频率为1/3.89kb,微卫星序列的长度主要在12～70个碱基长度范围内。第1、2、3条染色体上微卫星分布频率较高,而32号染色体上无微卫星分布。不同类型微卫星中,单碱基重复类型数目最多,为184192个,占总数的65.1%;其次是四、二、三、五、六碱基重复单元序列,分别占到总数的12.8%、9.7%、7.2%、4.6%、0.8%。T、A、AT、GTTT、AAAC、G、C、ATTT、AC、GT、AAAT、ATT、AAC、AAT、GTT、AG、CT、CTTT、AAAG、GTTTT、AAACA、AAGG、CCTT是红原鸡基因组中最主要的微卫星重复类型。本研究为红原鸡微卫星标记的分离筛选、遗传多样性的研究以及不同物种微卫星的比较分析奠定了基础。     

The effect of avermectin B1 on developmental stability in the bush fly, Musca vetustissima, as measured by fluctuating asymmetry

Fluctuating asymmetry is used as an indicator of developmental stability to assess the effect of exposure to Avermectin B₁ on normal developmental processes in the bush fly, Musca vetustissima Walker (Diptera: Muscidae). Flies breeding in dung from cattle treated with Avermectin B₁ were found to be significantly more asymmetric for two morphometric characters (wing vein lengths), than those breeding in dung from either untreated cattle or cattle treated with Levamisole-HCl at times when fly survival was not affected by the treatments. Fluctuating asymmetry is shown to be a valuable means of defining developmental stress in situations where conventional estimates such as survival show no response.

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Résumé La fluctuation de l'asymétrie a été utilisée comme indice de la stabilité du développement pour mettre en évidence l'effet de l'exposition à l'avermectine B₁ au cours du développement de M. vetustissima. Les mouches élevées sur bouses de vaches traitées à l'avermectine B₁ sont devenues significativement plus asymétriques pour 2 caractères morphométriques (longueurs des veines de l'aile) que celles élevées sur bouses de vaches témoins ou de vaches traitées au Levamisole-HCl, même quand la survie des mouches n'était pas affectée par le traitement. La fluctuation de l'asymétrie s'est avérée un bon critère pour définir des stress pendant le développement, alors que des critères conventionnels comme la survie ne permettent pas de déceler quoi que ce soit.

     

原鸡采精技术与精液品质研究

以原鸡滇南亚种为研究对象,利用性欲反射强度、精液采集量等评判指标,探索适合于原鸡的人工采精技术.通过对精液感官评定和显微镜检,构建精液常规生理指标;在精液中,分别添加NaCl(0.9%、1%)、葡萄糖(5%、5.7%)、卵黄液(10%、13%)、蔗糖液(11%、13%)等4种稀释液,测量不同处理精子的活力、畸形率、质膜完整性、存活时间和生存指数,探讨稀释液、不同季节及二者交互作用对精液品质的影响,筛选新鲜精液的最优稀释液.结果表明:改进后的人工采精技术可使采精量增至0.16 ml、成功率达96%以上.精液中性微偏酸性(pH∶ 6.7～7.0),呈现\"有云雾状\"特性、春秋季较明显,呈乳白色或乳黄色,略带腥味.精液量为(0.13±0.02) ml (0.10～0.16 ml),精子密度为(15.03±4.46)×10~8个/ml(11.61×10~8～22.16×10~8个/ml),活力为(93.91±0.08)%(93.20%～95.00%),质膜完整性为(93.75±2.71)%(91.60%～95.64%),畸形率为(5.53±1.59)%(4.55%～6.48%).NaCl(0.9%、1%)、葡萄糖(5%、5.7%)和11%蔗糖液均可作为新鲜精液稀释液,其总存活时间达32 h以上,考虑对畸形率、活力和质膜完整性等影响,以1%NaCl处理效果相对最佳.就精子活力和质膜完整性而言,原鸡采精的季节(月份)对稀释液具有一定选择性.     

Left–right asymmetries and shape analysis on Ceroglossus chilensis (Coleoptera: Carabidae)

Bilateral symmetry is widespread in animal kingdom, however most animal can deviate from expected symmetry and manifest some kind of asymmetries. Fluctuating asymmetry is considered as a tool for valuating developmental instability, whereas directional asymmetry is inherited and could be used for evaluating evolutionary development. We use the method of geometric morphometrics to analyze left/right asymmetries in the whole body, in two sites and totally six populations of Ceroglossus chilensis with the aim to infer and explain morphological disparities between populations and sexes in this species. In all individuals analyzed we found both fluctuating asymmetry and directional asymmetry for size and shape variation components, and a high sexual dimorphism. Moreover a high morphological variability between the two sites emerged as well. Differences in diet could influence the expression of morphological variation and simultaneously affect body sides, and therefore contribute to the symmetric component of variation. Moreover differences emerged between two sites could be a consequence of isolation and fragmentation, rather than a response to local environmental differences between sampling sites.     

Asymmetry of the mandibular condyle in Haida Indians

The condyles of 72 aged and sexed Haida Indians were measured for anteroposterior and mediolateral diameter and their approximate areas calculated. Dental wear was assessed for the same individuals. Asymmetry of condyle size did not appear to change with age. In a pair-wise analysis, no relationship was found between the largest of a pair of condyles and the most worn side of the dentition. The difference in size between each pair of condyles (normalized for individual size) was plotted as a histogram and found to have a normal distribution with a mean of 0 and no skewness. Condyle asymmetry does not appear to be related to differential chewing forces but more closely fits the model of fluctuating asymmetry.     

Insect preference for symmetrical artificial flowers

An insect preference for floral symmetry may be maintained because plants with symmetrical flowers, which are able to control developmental processes under given environmental conditions, also are able to provide more pollinator rewards than plants with asymmetrical flowers. Alternatively, insects may have an inherent preference for symmetrical structures and thereby impose selection for the maintenance of symmetry in flowers even in the absence of any pollinator rewards. We tested for an insect preference for radially symmetrical flowers by using horizontally placed units of four circular coloured flower models varying in size and symmetry. The shape and colour of the model flowers did not resemble any naturally occurring flowers in the environment. Insects and Hymenoptera, respectively (five species of Diptera and one species of Coleoptera) that visited the flower models clearly preferred symmetrical models over asymmetrical ones, and the ranking of visits to the models reflected a preference for large, symmetrical flowers. These results provide evidence for a preference for symmetrical flower models, even in the absence of pollinator rewards. Received: 11 September 1997 / Accepted: 2 November 1997     

先天性心脏病患者皮纹波动不对称性的研究

本文采用随机整体抽样的方法分析了先天性心脏病患者129例(男性59例, 女性70例) 和正常对照人群133例(男性69例, 女性64例) 13项皮纹波动不对称性(Fluctuating asymmetry, FA)的分布特征。结果表明: (1)先天性心脏病患者组与正常对照组在13项皮纹波动不对称性指标中均未出现显著性别差异; (2)先天性心脏病患者组与正常对照组在FAⅥ(P<0.05)和FAⅦ(P<0.01)两项有显著性差异, 表现为患者组明显增高, 提示先天性心脏病患者在胚胎发育早期易受到环境因素影响, 具有较高的发育不稳定性。     

精神分裂症患者皮纹a-b嵴线数波动性不对称的研究

本文分析了精神分裂症患者134例(男性70例,女性64例)和正常对照人群331例(男性170例,女性161例)皮纹a-b嵴线数波动性不对称的分布特征。结果表明:⑴精神分裂症患者双手皮纹a-b嵴线数明显低于正常对照组(P<0.01),表现出明显增高。     

鸡内金中氨基酸及营养元素含量的测定

采用日立 835 - 5 0型氨基酸自动分析仪和岛津Z - 80 0 0型原子吸收分光光计。测定了鸡内金中氨基酸和营养元素的含量 ,结果表明 :鸡内金中营养元素钾、钙、镁、铜、锌、铁、锰含量分别为 36 9.5 0、12 0 .5 6、470 .77、31.89、32 .42、5 5 9.6 4、8.11mg/kg ;氨基酸总量为 86 .92 4% ,必需氨基酸占氨基酸总量的 30 .2 6 4%。     

Fluctuating asymmetry in bank vole populations (Rodentia, Arvicolinae) reflects stress caused by landscape fragmentation in the Mont-Saint-Michel Bay

In intensively farmed, reclaimed areas (polders) of Mont-St-Michel Bay, France, bank voles ( Clethrionomys glareolus ) live in fragmented hedgerows, where populations are small and dispersal rates and genetic diversity are low. These small populations are likely to have been exposed to potential environmental and/or genetic stress. The sensitivity of development to stress can be measured by fluctuating asymmetry (FA). FA was calculated for three samples from a disturbed area and one sample from an adjacent, more connected and undisturbed landscape. Size FA was estimated from 16 measurements of the skull and teeth whilst shape asymmetry was estimated from the skull alone. Bank voles in fragmented hedgerows of the disturbed area had a higher degree of FA than bank voles from the more extensive and more connected hedges of the undisturbed area. These results were confirmed by the study of shape asymmetry, body mass and centroid size of the skull. There were no differences in FA between the three disturbed area samples. We conclude that FA does not reveal differences in the development of bank voles living in isolation under different local conditions in the various parts of the disturbed area. However, FA may allow differentiation between populations from greatly contrasting landscapes.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80, 37–44.     

Interpopulation variation in fluctuating asymmetry of the palmar A-B ridge-count

Fluctuating asymmetry was measured by the Pearson correlation coefficient between a-b ridge-counts of the right and left hands. Such data were available for 38 samples, which were grouped by major geographical regions. Significant heterogeneity exists within some of the geographical groups but the between geographical group component is highly significant in both sexes. Our results show that a sizable fraction of variation in fluctuating asymmetry is related to geographical race. There is no evidence that it follows environmental or ecological lines. The variation between geographical races suggests that there is a genetic component in the magnitude of fluctuating asymmetry.     

广东省原鸡种群数量、分布及栖息地现状的初步调查

广东原鸡栖息地分布在徐闻,雷州,信宜,高州,阳春5个县（市）,为孤立的三块,呈岛屿状分布,总面积2501.62km^2,总体数量680-750只,原鸡数量最多,面积最大的一块栖息地是由信宜,高州,阳春3块小栖息地组合而成,成为广东原鸡的主要栖息和分布地。