蝘蜓和蓝尾石龙子幼体食物同化的热依赖性

用采自安徽滁州琅琊山的蝘蜓(Sphenomorphus indicus,头体长42．8～54．4mm,n=12)和蓝尾石龙子(Eumeces elegans,头体长43,9～57．3mm,n=10)幼体,研究温度(24～32℃)对蝘蜓和蓝尾石龙子幼体食物通过时间、摄食量、表观消化系数(ADC)、同化效率(AE)和生长的影响。结果显示,24～30℃范围内,蝘蜓和蓝尾石龙子幼体的食物通过时间随温度的升高而缩短,超过30℃则基本不变。蝘蜓幼体：30和32℃摄食量和生长小于24～28℃;24～30℃．ADC、AE随温度升高而下降,但32℃时又升高。蓝尾石龙子幼体：24～26℃摄食量随温度升高而增加,26℃后随温度升高显著下降;24～28℃ADC、AE大于30和32℃,呈现出随温度升高而下降的趋势;26℃生长最快。结果表明,蝘蜓和蓝尾石龙子幼体的摄食和同化能力均低于相应的成体。     

四川雉鹑育雏早期雌体与幼体夜栖地的选择

开展鸟类幼体夜栖生境的研究,对于确定物种的生存策略并实施生境保护具有重要的参考价值。四川雉鹑Tetraophasis szechenyii是我国Ⅰ级重点保护物种。利用无线电遥测和直接跟踪的方法,对育雏早期(幼体孵化后大约2周内)雌体与幼体的夜栖生境进行研究。研究发现,在幼体孵化后1周内,雌体与幼体夜栖于地上(n=3);在第2周,它们开始上树夜栖(n=12)。当树栖时,偏好选择鳞皮冷杉-大果红杉林,并使用乔木盖度和坡度较大的地方。与育雏后期的正常夜栖生境相比,本阶段雌体与幼体的夜栖地的乔木盖度更大,但夜栖树胸径较小且靠近道路。基于本研究,建议在生境保护方面应该维持一定区域的乔木盖度,并适当注意保留一些中小型乔木。     

镇海棘螈早期个体发育研究

根据野外观察和室内实验 ,对镇海棘螈的早期个体发育过程进行了研究。结果显示 ,镇海棘螈早期发育过程与琉球棘螈的个体发育过程非常相似 ,它们的平衡枝均不发达且在前肢芽晚期迅速消失。温度和湿度对胚胎发育具有显著影响。室温下 ,从受精卵到孵化需 2 9d左右。孵化幼体体长呈配合对数曲线增长 ,其体全长 (S)与日龄 (T)的关系可表示为S =1 2 974 9+6 2 398lnT(Sig.F <0 0 1 )。水生生活阶段为 58～ 88d。室内幼体的水生发育时间和变态个体大小与野外的情况有较大的差异 ,可能与营养条件和自然条件下的持续干旱有关。变态前的外鳃萎缩期是镇海棘螈早期个体发育过程中的死亡高峰期。     

蝘蜒消化管内分泌细胞的免疫组织化学定位

目的阐明爬行动物蝘蜒消化管各段内分泌细胞的类型、局部分布、分布密度和形态学特征。方法应用免疫组织化学技术中链霉卵白素一过氧化物酶（S-P）法。结果在蝘蜒消化管内鉴别出5种内分泌细胞,即：5—羟色胺（5-hydroxytryptamine,5-HT）、生长抑素（somatostatin,SS）、胃泌素（gastrin,GAS）、高血糖素（glucagon,GLU）、P-物质（substance P,SP）免疫活性（immnoreactive,IR）细胞。5-羟色胺免疫活性细胞是消化管中最主要的内分泌细胞类型,以不同密度分布于消化管各段,其中胃幽门部位分布密度最高。生长抑素免疫活性细胞在消化管内仅局限分布于胃部。胃泌素免疫活性细胞仅见于幽门和十二指肠部位。高血糖素免疫活性细胞仅分布于回肠和直肠。P-物质免疫活性细胞仅出现在直肠部位。蝘蜒消化管内分泌细胞形态多样：圆形、椭圆形、纺锤形、梭形、楔形、锥形以及不规则形。胃部多数内分泌细胞分布于胃腺中,食管和肠管中多数内分泌细胞则分布于上皮细胞间。结论蝘蜒和其它爬行动物胃肠内分泌细胞的分布存在一定共同特征,然而也存在着一些特有的差异。     

蓝尾石龙子的头部两性异形和食性

通过测量头、体大小和胃检研究浙江泰顺产蓝尾石龙子 (Eumeceselegans)个体发育过程中两性异形和食性的变化。蓝尾石龙子成体个体大小和头部大小的两性差异显著 ,雄性大于雌性。不同发育阶段雌性头长与SVL的线性回归斜率无显著差异 ,头宽与SVL线性回归斜率的差异显著 ,成体和SVL <5 0mm幼体头宽随SVL的增长速率显著小于SVL为 5 0 - 6 9mm的幼体。雄性头部相对于SVL呈加速式异速生长。两性比较发现 :雌雄幼体头长和头宽随SVL的增长速率无显著差异 ,SVL <5 0mm幼体特定SVL的头长和头宽无显著的两性差异 ,但SVL为 5 0 - 6 9mm的雄性幼体头长和头宽大于SVL相同的雌性幼体 ;雄性成体头长和头宽随SVL的增长速率显著大于雌性。SVL <5 0mm的雌性幼体头部相对小于SVL为 5 0 - 6 9mm的同性幼体 ,性成熟雌体头部相对小于SVL为 5 0 - 6 9mm的同性幼体。雌性幼体、雄性幼体、雌性成体和雄性成体食物生态位宽度分别为 12 3、 12 5、 4 8和 14 4。雌雄幼体食物生态位重叠度最高 ,雌雄成体食物生态位重叠度次之 ,成体与幼体食物生态位重叠度较小。成体摄入食饵的大小 (用胃内完整食物长度的平均值表示 )和变化范围大于幼体。两性成、幼体摄入的食饵大小差异显著。两性个体摄入的食饵大小均与其SVL呈正相关 ,表明较大     

孵化温度对赤链蛇胚胎代谢和幼体行为的影响

研究了赤链蛇(Dinodon rufozonatum)在孵化过程中卵的生长、孵化期、胚胎代谢和孵出幼体行为表现的热依赖性。结果显示:孵化温度对孵化期、卵增重、孵化过程中消耗的总能量和孵出幼体的运动表现有显著影响,但不影响胚胎代谢率、孵化成功率和幼体吐信频次。孵化期随着孵化温度的升高而缩短,孵化过程中,24℃终末卵重和胚胎代谢率显著大于30℃,而27℃与其他两个温度没有差异;27℃孵出幼体游速较24℃快,30℃孵出幼体与其他两个温度孵出幼体的游速无显著差异。上述结果显示:24—30℃是赤链蛇适合的孵化温度范围,与赤链蛇所处的生境温度相近。     

艾美尔球虫防治高原鼠兔实验及对其胚胎发育的影响

高原鼠兔是青藏高原地区危害高寒草甸植被的主要有害小哺乳动物。生物控制为有害动物防治的主要发展方向,但存在防治效果见效慢的缺点。艾美尔球虫是高原鼠兔肠道内的主要寄生物,并对宿主具有专一性寄生的特点。为将艾美尔球虫研发成新型的高原鼠兔无公害生物防治制剂,本文测定了球虫毒饵对高原鼠兔致死率并在野外进行了灭鼠实验。结果表明,添加增效剂的300 万球虫毒饵在室内可导致63. 6% 的成年个体死亡,在野外可导致54. 9% 成体和71. 0% 幼体死亡。灭鼠后残存高原鼠兔的球虫感染率和感染强度显著大于对照个体,且妊娠雌体的胚胎重较对照显著降低。上述结果说明,艾美尔球虫防治高原鼠兔具有较好的速效性,并能影响残存妊娠雌体的胚胎发育。     

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６７．７ｍｍ,大于此ＳＶＬ     

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。     

人工繁育与野外鳄蜥幼体及亚成体形态和健康状况的比较

人工繁育是濒危物种保护的重要手段,但是也会改变物种的表型。为了探究人工繁育对于鳄蜥(Shinisaurus crocodilurus)形态和健康状况的影响,本研究比较了人工繁育鳄蜥与野外鳄蜥新生幼体及亚成体形态特征与细菌感染率。结果发现,人工繁育鳄蜥与野外鳄蜥的新生幼体体型无显著差异,而人工繁育鳄蜥亚成体体型显著大于野外鳄蜥;两个年龄段的人工繁育鳄蜥断尾率均显著低于野外鳄蜥;人工繁育鳄蜥亚成体细菌感染率最高,但是各年龄组种群间的差异不显著。本研究表明,人工环境促进了鳄蜥的生长,减少了鳄蜥被捕食的风险,但有增加鳄蜥感染疾病的可能性,因此在鳄蜥的饲养管理中需要加强疾病防治。     

The ontogeny of escape behavior,locomotor performance,and the hind limb in Sceloporus woodi

Flight initiation distance describes the distance at which an animal flees during the approach of a predator. This distance presumably reflects the tradeoff between the benefits of fleeing versus the benefits of remaining stationary. Throughout ontogeny, the costs and benefits of flight may change substantially due to growth-related changes in sprint speed; thus ontogenetic variation in flight initiation distance may be substantial. If escape velocity is essential for surviving predator encounters, then juveniles should either tolerate short flight initiation distances and rely on crypsis, or should have high flight initiation distances to remain far away from their predators. We examined this hypothesis in a small, short-lived lizard (Sceloporus woodi). Flight initiation distance and escape velocity were recorded on an ontogenetic series of lizards in the field. Maximal running velocity was also quantified in a laboratory raceway to establish if escape velocities in the field compared with maximal velocities as measured in the lab. Finally a subset of individuals was used to quantify how muscle and limb size scale with body size throughout ontogeny. Flight initiation distance increased with body size; larger animals had higher flight initiation distances. Small lizards had short flight initiation distances and remained immobile longer, thus relying on crypsis for concealment. Escape velocity in the field did not vary with body size, yet maximum velocity in the lab did increase with size. Hind limb morphology scaled isometrically with body size. Isometric scaling of the hind limb elements and its musculature, coupled with similarities in sprint and escape velocity across ontogeny, demonstrate that smaller S. woodi must rely on crypsis to avoid predator encounters, whereas adults alter their behavior via larger flight initiation distance and lower (presumably less expensive) escape velocities.     

Nuptial Coloration and Mate Guarding Affect Escape Decisions of Male Lizards Psammodromus algirus

Males of many species show conspicuous breeding colours that are important for status signalling, but that may decrease crypsis and increase predation risk. However, prey may adjust their escape response, such that the optimal distance at which an animal starts to flee (approach distance) would be the point where the costs of staying exceed the cost of fleeing. We examined in the field the escape response of Psammodromus algirus lizards, to test the hypothesis that more conspicuous old males, showing orange nuptial coloration on most of the head, which presumably have a higher probability of being detected (i.e. increased costs of staying), have longer approach distances, independent of other environmental variables. As predicted, old brightly coloured males had significantly longer approach and flight distances than young dull males, and young males had longer ones than females. In contrast, neither the distance to the nearest refuge nor the air temperature when the lizards escaped were significantly different. In addition, although male and female lizards differed in their use of microhabitats, old and young males did not differ. We also found that old males guarding a female (i.e. increased costs of fleeing) had shorter approach distances than old males that were found alone.     

Grouping increases the ability of the social rodent,Octodon degus,to detect predators when using exposed microhabitats

We examined the hypothesis that a main benefit of group‐living in the hystricognath rodent, Octodon degus (common degu), is to decrease individual risk of predation. During a first series of field observations, we contrasted group size of degus when using covered microhabitats with that of degus using exposed patches. During a second set of field observations, we assessed how distance to detection and to escape by degus varied with group size upon the approach of a potential human predator. Degus in exposed patches formed larger groups than degus in covered microhabitats. After excluding the influence of nearest burrow to focal subjects, we found that degus of larger groups detected an approaching human predator at a greater distance than degus of smaller groups. Likewise, degus of larger groups escaped to nearby burrows at a greater distance from the approaching predator than degus of smaller groups. All these pieces of evidence support the predatory risk hypothesis according to which group‐living in degus functions to reduce the risk of predation.     

Impact of dispersal on population growth: the role of inter-patch distance

Dispersal can play a key role in the dynamics of patchy populations through patch colonization, and generally this leads to distance-dependent colonization. Less recognised are the roles of dispersal and inter-patch distance on the growth of a population after colonization. We use a laboratory mite model system in which both juveniles and adults can disperse to explore the impact of dispersal, and particularly inter-patch distance, on population dynamics. We examine the dynamics of patches after colonization by manipulating the presence of a dispersal corridor to a source patch at two inter-patch distances. Consistent with many field studies, the results show colonization was slower in more distant patches. Following colonization, the effect of the dispersal corridor on dynamics was dependent on inter-patch distance. In patches near the source, the number of adults tended to increase at a faster rate, and juveniles at a slower rate when connected with a dispersal corridor. In contrast, adult numbers grew slower and juveniles tended to grow faster when connected with a corridor in more distant patches. In the long-term, equilibrium adult numbers were lower in patches connected to the source patch at both distances. These results are likely to be driven by the effects of inter-patch distance on dispersal mortality, and the effects of dispersal on patch abundance and within-patch competition. These results confirm that distance is important for patch colonization and also show that distance can affect population density after colonization. The effects of dispersal and distance on local dynamics could be important in the dynamics of patchy populations in increasingly fragmented landscapes.     

Testicular thermoregulation in Bos indicus, crossbred and Bos taurus bulls: relationship with scrotal, testicular vascular cone and testicular morphology, and effects on semen quality and sperm production

Mechanisms of testicular thermoregulation, the relationship of scrotal, testicular vascular cone (TVC), and testicular morphology with thermoregulatory capability, and their effects on semen quality and sperm production were studied in 20 Bos indicus, 28 crossbred, and 26 Bos taurus bulls. The ratio of testicular artery length and volume to testicular volume were larger (P<0.05) in B. indicus and crossbred bulls than in B. taurus bulls (1.03 and 0.94 cm/cm3 versus 0.48 cm/cm3; 0.034 and 0.047 ml/cm3 versus 0.017 ml/cm3, respectively). Testicular artery wall thickness (average 192.5, 229.0, and 290.0 microm, respectively) and arterial-venous blood distance in the TVC (average 330.5, 373.7, and 609.4 microm, respectively) were smallest in B. indicus, intermediary in crossbred, and greatest in B. taurus bulls (P<0.05); the proximity between arterial and venous blood was consistent with the estimated decrease in arterial blood temperature after passage through the TVC (5.9, 5.0, and 2.9 degrees C, in B. indicus, crossbred, and B. taurus bulls, respectively). In crossbred and B. taurus bulls, there was a positive top-to-bottom scrotal temperature gradient and a negative testicular subtunic temperature gradient. However, in B. indicus bulls, both scrotal and testicular subtunic temperatures gradients were positive. Differences in the vascular arrangement, characteristics of the artery (e.g. wall thickness) or thickness of the tunica albuginea may have affected the testicular arterial blood and subtunic temperatures in B. indicus bulls. Better testicular thermoregulatory capability was associated with increased scrotal shape (pendulosity), testicular artery length and volume, and top-to-bottom gradient of the distance between the artery wall and the veins in the TVC. Increased semen quality was associated with increased testicular volume and scrotal subcutaneous (SQT) temperature gradient, and with decreased scrotal surface and testicular temperatures. Increased sperm production was associated with increased testicular artery volume, testicular volume, and SQT temperature gradient, and with decreased testicular artery wall thickness, scrotal circumference (SC), and scrotal surface, testicular subtunic, and epididymal temperatures. In conclusion, morphology of the TVC may contribute to the greater resistance of B. indicus bulls to high ambient temperatures by conferring a better testicular blood supply and by facilitating heat transfer between the testicular artery and veins. Testicular thermoregulation was associated with opposing scrotal and testicular subtunic temperatures gradients only in crossbred and B. taurus bulls. Scrotal, TVC, and testicular morphology influence testicular thermoregulatory capability and were associated with differences in semen quality and sperm production.     

Escape tactics and effects of perch height and habituation on flight initiation distance in two Jamaican anoles (Squamata: polychrotidae)

Escape by Anolis lizards is influenced by microhabitats and fight initiation distance increases with predation risk. Differences in microhabitat use among ecomorphs affect escape behavior, but only two studies have reported ecomorphological differences in flight initiation distance among Greater Antillean species. I studied effects of predation risk and microhabitats on escape behavior by conducting field experiments using two species of anoles, Anolis lineatopus and A. grahami, on the campus of the University of the West Indies at Mona, Jamaica. Because ecomorphological variation of anoles has evolved independently within each island of the Greater Antilles, but relationships between ecomorphs and escape behaviors are poorly known, I characterized microhabitat use and escape tactics, and determined relationships between flight initiation distance and two risk factors, habituation to human presence and perch height, in Anolis lineatopus, a trunk-ground anole and A. grahami, a trunk-crown anole. Sample sizes for A. lineatopus and A. grahami were 214 and 93, for microhabitat use and escape destinations, 74 and 34 for human presence and 125 and 34 for perch height. The two species occurred in similar microhabitats and exhibited similar escape tactics, but exhibited key differences expected for their ecomorphs. Both species were sighted frequently on the ground and on trees, but A. lineatopus were more frequently on ground and were perched lower than A. grahami. Both species escaped from ground to trees and when on trees hid on far sides and escaped without changing climbing direction with equal frequency. The frequency of fleeing upward was greater for A. grahami than A. lineatopus. Both species exhibited habituation by having shorter flight initiation distances in areas with more frequent exposure to people. In both species flight initiation distance increased as perch height decreased because, lizards had to climb farther to be out of reach when perched lower. The relationship between flight initiation distance and perch height may apply to other anole ecomorphs that flee upward when low perched on trees.     

Effects of temperature on hatching time and hatchling proportions in a poecilogonous population of Haminoea zelandiae

Poecilogony is a relatively uncommon life-history strategy that results in the production of two different larval forms from the same egg mass (e.g., free-swimming lecithotrophic larvae and post-metamorphic, crawling juveniles). In this study, a population of the opisthobranch gastropod Haminoea zelandiae from Pauatahanui Inlet, New Zealand, was found to exhibit poecilogony. Further, differences in development, hatching times and proportion of hatchlings that were veligers or juveniles were examined for egg masses in two temperature regimes in the laboratory: cool (15-17 °C), and warm (21-23 °C). Hatching proportions were also examined for egg masses collected from the field (where temperatures ranged from 21-23 °C) for varying lengths of time (1 d, 5 d, and 10 d post-spawning). Hatchlings from egg masses in warmer temperatures developed faster and hatched earlier than those in cool temperatures. In the laboratory, egg masses in warm conditions hatched a greater proportion of post-metamorphic juveniles (45.4%) compared to egg masses in cool conditions (24.6%) Further, egg masses that had been in the field 10 d before hatching (i.e., more days at warmer temperatures) exhibited a greater proportion of post-metamorphic juveniles (67.9%) than those that were collected after only 1 d in the field (25.1%). Together these results suggest that temperature may have an important role in mediating dispersal strategies in this poecilogonous species.     

Growth and morphological development of chub, Leuciscus cephalus (L.), during the first year of life

The growth and the morphological development of larvae and juveniles of chub, Leuciscus cephalus (L.), from a small stream of western Greece is described, based on field samples and laboratory-raised fish. In the laboratory, size hierarchy was developed and morphological differentiation occurred at a younger age in the fastest growing larvae. Growth was faster in the field and differentiation of fins and scales began at a larger size, but apparently at a younger age, than in the laboratory.     

Thermal parameters and locomotor performance in juvenile of Pleurodema nebulosum (Anura: Leptodactylidae) from the Monte Desert

We studied a combination of thermal parameters (critical thermal maximum, selected body temperature, and field body temperature) and locomotor performance capacities (laboratory and field conditions) of juveniles of Pleurodema nebulosum. We found that field body temperature was determined largely by the temperature of the micro-environment. Field body temperatures of juveniles of P. nebulosum were below selected body temperature. The locomotor performance curve was maximized and reaches a plateau between 30 and 35 °C, with 35 °C being the temperature at which maximum performance was obtained for analyzed individuals. The plateau values were close to the selected body temperature (T_sel) obtained for the studied frogs. In field conditions the locomotor performance was determinated by the substrate temperature. Apparently, juveniles of P. nebulosum show thermal coadaptation because the selected body temperature and the optimum temperature for locomotion had close values. We believe that the temperatures prevailing during the early hours of activity would allow frogs to explore the micro-environment, covering larger areas in search of food.     

Social influences on the acquisition of sex-typical foraging patterns by juveniles in a group of wild tufted capuchin monkeys (Cebus nigritus)

Foraging traditions in primates are becoming the subject of increasing debate. Recent evidence for such a phenomenon was recently provided for wild Cebus capucinus [Fragaszy & Perry, 2003]. To better understand the bases of animal traditions, one should examine intrapopulation behavioral variability and the influence of social context on within-group transmission of specific foraging patterns. We studied the variability of foraging patterns across age and sex classes, and the proximity patterns of juveniles to adults of both sexes in a group of wild tufted capuchin monkeys (Cebus nigritus) living in the Iguazu National Park, Argentina. Foraging activity was examined for a period of 9 months in terms of proportions of focal samples devoted to foraging on certain food targets, microhabitats, and supports, and using specific foraging patterns. Proximity analyses were performed to reveal patterns of association between juveniles and adults. Sex differences in foraging behavior were present and overrode age differences. Overall, males ate more animal foods, foraged more for invertebrates on woody microhabitats (especially large branches), palms, and epiphytes, and used lower and larger supports than females. Females ate more fruits, foraged more on leaves and bamboo microhabitats, and used smaller supports than males. Juveniles were similar to adults of the same sex in terms of food targets, foraging substrates, and choice of supports, but were less efficient than adults. Proximity patterns indicated that juvenile males stayed in close spatial association with adult males and preferentially focused their "food interest" on them. This phenomenon was less evident in juvenile females. The degree to which juveniles, especially males, showed some of the sex-typical foraging patterns correlated positively with their proximity to adults of the same sex. These findings suggest that the acquisition of foraging behaviors by juvenile males is socially biased by their closeness to adults of the same sex.