山地麻蜥的雌性繁殖和孵出幼体特征

山地麻蜥年产多窝卵。窝卵数、窝卵重和卵重与雌体体长呈正相关,卵重与窝卵数无关。窝卵数、窝卵重和卵重不存在明显的季节变化。卵长径与卵短径呈正相关,卵长径、卵短径与窝卵数无关。雌体通过增加窝卵数和卵大小增加繁殖输出。孵出幼体的体重、体长、尾长、躯干干重、刺余卵黄不存在季节差异,但5月份孵出幼体的脂肪体高于4月份。     

浙江舟山五种卵生游蛇科动物个体大小、窝卵数和卵大小之间的关系

阐明五种游蛇科动物雌体大小、窝卵数和卵大小之间的关系和雌性繁殖特征的种间差异。５种蛇均产单窝卵,产卵高峰期为６月下旬至７月,窝卵数与雌体大小（ＳＶＬ）呈显著的正相关,相对窝卵重与雌体ＳＶＬ无关,卵理与窝卵数无关。灰鼠蛇卵重与雌体ＳＶＬ呈正相关,赤链蛇、王锦蛇、黑眉锦蛇和乌梢蛇的卵重与雌体ＳＶＬ无关,黑眉锦蛇卵长径与窝卵娄呈负相关,其余４种蛇卵长径与窝卵数无关。５种蛇卵长径与短径无关。黑眉锦蛇卵短径     

蓝尾石龙子的生长、两性异形及雌性繁殖

报道蓝尾石龙子（Eumeces elegans)的生长、两性异形和雌性繁殖,性成熟个体体色的两性差异显著,成年雄性体长、头长和头宽显著大于成年雌性,幼体体长生长率无显著的两性差异。成年雄体体长生长率显著大于成年雌体,因此,个体大小的两性异形是性成熟后发生的,体长小于50mm的幼体,头长和头宽无性差异;当体长大于50mm。雄性头长和头宽随体长的生长率显著大于雌性。并导致头部大小的两性异形,并随个体发育变得越来越显著,蓝尾石龙子产卵雌体的最小体长为69.3mm,大于此体长的雌体均年产单窝卵。窝卵数、窝卵重和平均卵重均与雌体体长呈正相关,平均值分别为6.4、2.783和0.554g。窝卵数与雌体产后状态无关,蓝尾石龙子雌体主要通过增加窝卵数和卵大小来增加繁殖输出。     

宁波滑蜥两性异形和雌性繁殖

蜥蜴的雌性繁殖特征对理解两性异形的进化原因起着重要作用。于2011年4月在安徽滁州采集宁波滑蜥(Scincella modesta),定量研究该种形态特征的两性异形和雌性繁殖特征,检验成体形态特征两性异形与雌性繁殖的相关性。研究共采集43条(17♀♀,26♂♂)宁波滑蜥,雄性和雌性个体的最大体长分别为47.4 mm和46.6 mm。雌雄两性在体长和头宽上没有差异,而在腹长和头长上差异显著,雄性有较大的头长,雌性有较大的腹长。宁波滑蜥年产单窝卵。窝卵数和窝卵重与雌体体长及腹长呈正相关,卵重与雌体体长无相关性。窝卵数及卵重的变异系数分别为0.20和0.12。卵长径与窝卵数呈负相关,而卵短径与窝卵数无关。雌体主要通过增加窝卵数来增加繁殖输出。这些结果表明,宁波滑蜥是雌雄个体大小同形的两性异形模式,性选择使得雄性有着较大的头长,以具有较高的交配成功率,生育力选择使得雌性有着较大的腹长,以具有较大的生育力和繁殖输出。     

圈养尖吻蝮雌体大小、窝卵数和卵大小之间的关系

尖吻蝮(Deinagkistrodon acutus)野生资源日益枯竭,食用和药用压力巨大,亟需开展人工养殖。目前尖吻蝮的人工养殖技术还不够成熟,大多数养殖场采用半地下室饲养尖吻蝮,有关该条件下尖吻蝮的繁殖特性报道较少。为促进尖吻蝮的人工养殖,2010年4—9月,在湖南永州市对半地下室圈养的尖吻蝮成体的体型指标、窝卵数、窝卵重、卵重等繁殖特征之间的关系进行了研究。结果表明:圈养尖吻蝮成年雌体产单窝柔性卵,平均窝卵数为23.0±7.8(13—37)枚(n=23);将产后雌体体重和窝卵重相加记为产前雌体体重,采用SPSS 13.0软件处理数据,设置α=0.05和α=0.01,发现产前雌体体重分别与窝卵数、窝卵重、卵重均呈显著相关性;产前雌体体长分别与窝卵数、窝卵重、卵重无显著相关性;窝卵数与卵重无显著相关性,卵重分别与卵短径、卵长径均呈显著相关性。产前体重在1000—1200 g之间的雌蛇所产窝卵数和单枚卵重的数值均较大且最集中,这保证了雌体繁殖输出后代的生存优势,对尖吻蝮人工养殖挑选雌性种蛇有一定的指导意义。     

草晰属两种蜥蜴卵和幼体特征的比较研究

比较研究了南草蜥实验条件下的卵及幼体特征。南草蜥产卵雌体的体长、最大窝卵数、平均卵重小于北草蜥,相对放重与北草蜥相似。两种蜥蜴均通过增加卵长径和卵短径来增加卵重,但卵处形明显不同,南草蜥的卵孵化过程中均吸水增重。相同孵化温度（２６℃）条件下,南草蜥的孵化期明显比北草蜥长。南草蜥幼体的体重、体长、头长和头宽的实测值小于北草蜥,尾长实测值与是蜥显著差异。南草晰幼体的体重、头长和头宽的矫正平均值小于北草     

草蜥属两种蜥蜴卵和幼体特征的比较研究

比较研究了南草蜥和北草蜥实验条件下的卵及幼体特征。南草蜥产卵雌体的体长、最大窝卵数、平均卵重小于北草蜥 ,相对窝卵重与北草蜥相似。两种蜥蜴均通过增加卵长径和卵短径来增加卵重 ,但卵外形明显不同 ,南草蜥的卵较长。两种蜥蜴卵孵化过程中均吸水增重。相同孵化温度 ( 2 6℃ )条件下 ,南草蜥的孵化期明显比北草蜥长。南草蜥幼体的体重、体长、头长和头宽的实测值小于北草蜥 ,尾长实测值与北草蜥无显著差异。南草蜥幼体的体重、头长和头宽的矫正平均值小于北草蜥 ,尾长矫正平均值大于北草蜥 ,体长矫正平均值与北草蜥无显著差异。     

赤链华游蛇的雌性生殖输出和初生幼体特征

研究浙江舟山产赤链华游蛇窝仔数,幼体大小和雌 大小之间的关系以及初生幼体特征,产仔雌体的最小体长（SVL）为486mm,大于最小SVL的雌体均年产单窝仔,产仔期为8月30日09月30日,窝仔数与雌体SVL呈正相关,平均值为11．7,初生幼仔重与雌体SVL和窝仔数无关,窝仔数与产后雌体的状态无关,赤链华游蛇主要通过增加窝仔仔数来增加繁殖输出,初生幼仔湿重,干重,SVL和尾长平均值分别为4．37g,1.18g,171.0mm和44.mm,幼体躯干,剩余卵黄和脂肪体的干重有显著的窝间差异,偏相关分析显示,幼体躯干干重与剩余卵黄及脂肪体干重呈负相关,剩余卵黄干重与脂肪体干重无关。     

两种麻蜥卵和孵出幼体的特征

研究了山地麻蜥和丽斑麻蜥实验条件下的卵及孵出幼体的特征.山地麻蜥产卵雌体的体长大于丽斑麻蜥,窝卵重小于丽斑麻蜥,但平均卵重和相对窝卵重与丽斑麻蜥相似.两种蜥蜴均通过增加卵长径和卵短径来增加卵重,但卵的外形不同,山地麻蜥卵较长.两种蜥蜴卵孵化过程中均吸水增重.相似孵化条件(波动温度、-12 kPa)下,山地麻蜥的孵化期明显比丽斑麻蜥长.山地麻蜥幼体的尾、头部大于丽斑麻蜥,但体重和SVL相似.     

yan蜓头、体大小的两性异形和雌体繁殖

报道了yan蜓(Sphenomorphus indicus)头、体大小的两性异形和雌性繁殖。性成熟雌体大于雄体。雄性成体头长大于雌性成体，但头宽与雌性成体无显著差异。初生幼仔的头长和头宽无两性差异。雄性幼体头长和头宽大于雌性幼体。设置SVL恒定时，雄性幼体和雄性成 体的头长和头宽无显著差异，雌性幼体的头长和头宽大于雌性成体。初生幼仔具有相对较大的头部。产仔雌体的最小SVL为67.7 mm，大于此SVL的雌体均年产单窝仔。平均窝仔数、窝仔重和幼仔重分别为7.2(3-11)、3.34(1.30-5.19)和0.48(0.36-0.58)g。用卵黄沉积卵巢卵和输卵管计数的窝仔数比用幼仔计数的窝仔数多约1.0个后代。幼仔体重与雌体SVL无关。相对窝仔重与雌体SVL边缘性地呈正相关。窝仔数、窝仔重与雌体SVL呈正相关，幼仔体重与窝仔数呈负相关。窝仔数与雌体状态无关。     

浙江丽水中国石龙子的食性、两性异形和雌性繁殖

丽水分布的中国石龙子（Ｅｕｍｅｃｅｓ ｃｈｉｎｅｎｓｉｓ）摄入的食物均为无脊椎动物,分别属于环节、软体和节肢动物,涉及３０余科,成体和幼体的食物生态位宽度分别为７．２６和６．６９,成体的幼体的食物生态们重叠度为０．５９。性成熟雄性个体大于雌体。成雄和幼体的头长和头宽随体长ＳＶＬ的增长速率大于成雌,成雄头长随ＳＶＬ的增长速度显著大于幼体,成雌和幼体的头长随ＳＶＬ的增长速率无显著差异。成雄头部大于成雌     

A comparative study of egg mass and clutch size in the Anseriformes

The factors explaining interspecific differences in clutch investment in precocial birds are poorly understood. We investigated how variations in clutch characteristics are related to environmental factors in a comparative study of 151 extant species of ducks, geese and swans (Anseriformes). Egg mass was negatively related to clutch size in a phylogenetic regression, a relationship that was much stronger when controlling for female mass. Nest placement was related to both egg size and clutch size, with cavity-nesting species laying more but smaller eggs. Egg size was positively correlated with incubation period and with female mass, and also with sexual size dimorphism (i.e. male mass relative to that of the female). Clutch size was not related to female mass. Species with long term pair bonds laid smaller clutches and larger eggs. The size of the breeding range was strongly positively correlated with clutch size and clutch mass, and its inclusion in multivariate models made other biogeographical variables (hemisphere, breeding latitude or insularity) non-significant. The small clutches in insular species appear to be a product of small range size rather than insularity per se. Our results suggest there is an evolutionary trade-off between clutch and egg size, and lend support to Lack’s resource-limitation hypothesis for the waterfowl.     

蜡皮蜥的两性异形和繁殖输出

为研究蜡皮蜥(Leiolepis reevesii)两性异形和繁殖输出,于2002、2003年4月下旬从海南乐东一种群捕获423头蜡皮蜥。经检测得到繁殖雌体的最小体长为89．0mm,据此判定≥89．0mm的个体为性成熟。研究结果表明：①蜡皮蜥具有两性异形,雄性大于雌性且具有较大的头部。成体雄性头长和头宽随体长的增长速率大于雌性,幼体头长和头宽随体长的增长速率无显著的两性差异。以性别和年龄(成、幼体)为因子的双因子ANOVA比较两性头长和头宽与体长的回归剩余值发现,雄性头部大于雌性,幼体头部相对大于成体。②饲养于实验室的母体中有42头于2002、2003年5月22日～7月16日产出正常卵,这些繁殖雌体具有年产多窝卵的潜力。窝卵数和卵重的变异系数分别为0．18和0．13,前者变异度大于后者。窝卵数、窝卵重和卵重均与母体体长无关。卵重与相对生育力之间无显著的负相关性,表明蜡皮蜥缺乏卵数量与卵大小之间的权衡。相对窝卵重与母体体长呈显著的负相关,表明较小的母体具有相对较大的繁殖输出。因雌体繁殖会滞缓其生长,小母体具有相对较大的繁殖输出,至少部分地解释了雌性蜡皮蜥的成体为什么个体较小。     

Life-history variation within a three-spined stickleback population in the Camargue

Among individuals of female three-spined sticklebacks Gasterosteus aculeatus from a population in the Camargue, southern France, studied in 12 successive years, adult L _T ranged from 31–64 mm, clutch size ranged from 33–660 eggs, and mean egg diameter per clutch ranged from 1.15–1.67 mm. Because the population was strictly annual, inter-annual variation corresponded to variation among generations having experienced different environmental conditions. Body mass varied significantly among years, suggesting an effect of varying environmental conditions. Gonad mass and clutch size increased with body mass, but mean egg diameter was not correlated to body mass. Body mass-adjusted gonad mass, interpreted as reproductive effort per clutch, did not vary significantly among years, suggesting that this trait was not influenced by environmental conditions. Body mass-adjusted clutch size and egg size varied significantly among years. Inter-annual variation in body length at breeding, clutch size and egg size was of the same order of magnitude as inter-population variation reported by other authors for this species. During the breeding season, reproductive effort and clutch size tended to increase. Egg size tended to decrease during the breeding season but this seasonal pattern varied among years. Observed life-history variation is discussed both in terms of its evolutionary significance and methodological implications in the study of life-history variation among populations.     

Reproductive dynamics of a tropical freshwater crocodilian: Morelet's crocodile in northern Belize

Morelet's crocodile Crocodylus moreletii has not been well-studied and many aspects of its life history are unknown. In particular there is a notable paucity of information on nesting and reproductive ecology. We studied the nesting ecology of Morelet's crocodile in northern Belize from 1992 through 1995. Nesting occurs at the onset of the wet season in mid-June and continues through mid-July (mean oviposition date =1 July±10 days). Eggs hatch from mid-August through mid- to late September. Nesting effort at our primary study site remained relatively constant during 1992, 1993 and 1995, but nearly doubled in 1994; this appeared to reflect a regional trend. Natural and man-made islands are heavily used as nesting sites. Nesting success in 1993 and 1994 was consistently higher on natural islands when compared with man-made islands or shoreline sites. Nest losses were primarily due to flooding and raccoon Procyon lotor predation. Losses from predation were greatest in 1994 when unseasonably low water levels facilitated predator access to nests. Females probably reach sexual maturity in 7–8 years after attaining a total length of 150 cm. Mean clutch size (25.0±7.6; range=9–42; n =73) did not differ among years. Mean clutch size, egg width (EW), egg length, egg mass (EM) and clutch mass were positively correlated with female snout–vent length (SVL). Mean EW was the best predictor of female SVL. A partial correlation analysis of egg and clutch attributes found that independent of female SVL, EM increases with increasing clutch size.     

Controlling resource acquisition to reveal a life history trade-off: egg mass and clutch size in an iteroparous seed predator, Prostephanus truncatus

1. A trade-off constraining egg production was investigated and the consequences of egg mass for the offspring life history in Prostephanus truncatus investigated. Fresh egg mass was found to vary between 0.065 and 0.109 mg (about 20% of fresh body mass at emergence) and was correlated both with dry egg mass ( r = 0.8) and with the mass of first-instar larvae ( r = 0.8).
2. There was a negative correlation between egg mass and clutch size: doubling clutch size from eight to sixteen eggs resulted in a reduction in egg mass from 0.09 to 0.07 mg. Resource allocation per clutch was not constant but increased with clutch size. After allowing for the relationship between egg mass and clutch size, heavier females were found to oviposit both heavier eggs and more eggs in a clutch.
3. By placing eggs in prepared seeds that minimized variation in resource acquisition, it was discovered that development period of females, but not of males, was negatively correlated with egg mass. Egg size was not correlated with body size at emergence in either sex.
4. The results are interpreted as revealing a resource-allocation trade-off in egg production.     

Geographical variation in egg size of the Great Tit Parus major: a new perspective

A recent study on geographical variation in egg size of Great Tits Parus major concluded that: (1) mean egg size tended to increase with increasing latitude; and (2) mean egg size was positively correlated with mean clutch size. Including new data on both egg and clutch size, we reanalysed the relationships between egg size, clutch size and latitude, and investigated the possible effects of habitat type, female body size and egg shape on these relationships. We found that (1) egg volume showed minimum values around 51°N, increasing both north and southwards; (2) female body size increased linearly with increasing latitude; (3) female body size was positively correlated with egg breadth, but not with egg length or egg volume; (4) the sphericity index of the eggs (breadth to length ratio) was largest at medium latitudes, and eggs were more elongated towards the north and the south; (5) the relationship between clutch size and latitude was curvilinear, with the largest clutch sizes at intermediate latitudes; (6) egg size was not correlated with clutch size when the complete latitudinal range was considered, but egg size was negatively correlated with clutch size between 40 and 51°N; and (7) egg size did not differ among habitat types. We suggest that female body size (which probably limits egg breadth), and the pressure for producing large eggs (which in turn increases the reproductive success) are the main determinants of geographical variation in egg size and shape. Populations of small-bodied Great Tits seem to escape from the limits of their size, producing relatively elongated eggs, so that from a certain latitude southwards, egg volume does not decrease in spite of a decrease in female body size. Moreover, the negative relationship between egg and clutch size at low latitudes suggests that energetic trade-offs may also contribute to determine egg size in the south.