松墨天牛成虫雌雄体型差异及蛹和成虫大小与越冬幼虫体重的关系

【目的】本研究旨在明确松墨天牛 Monochamus alteratus 成虫及越冬幼虫体型大小的差异,探讨该虫越冬后成虫体型大小和越冬幼虫体重大小关系及原因。【方法】于2014年5月1日至10月31日在浙江富阳野外诱捕松墨天牛,通过测量野外诱捕到的松墨天牛成虫体长、体宽,确定林间松墨天牛成虫体型的差异;松墨天牛越冬幼虫的采集和称重测量明确越冬幼虫的组成和体重大小差异;进而通过对越冬幼虫单头跟踪饲养至化蛹、羽化,确定越冬幼虫体重大小与发育所得蛹和成虫大小的关系,阐明林间松墨天牛成虫体型差异的原因。【结果】浙江富阳野外诱捕发现,松墨天牛的活动期间很长,从5月中旬到10月初一直能诱捕到松墨天牛成虫,高峰期在6和7月份。松墨天牛雌雄成虫体型差异很大,雌虫平均体长和体宽分别为20.59±0.19和6.59±0.06 mm;雄虫平均体长和体宽分别为19.90±0.26 和6.44±0.08 mm; 雌虫的平均体长明显高于雄虫,但二者体宽没有显著差异;并且雌雄成虫体长和体宽呈显著正相关。越冬幼虫的头宽测定表明头宽的变化很大,最小为2.20 mm,最大为4.24 mm,经比对越冬幼虫由4龄和5龄幼虫组成;幼虫体重差异大,平均体重为304.2 mg, 介于71.6~858.0 mg之间,其中5龄越冬幼虫显著重于4龄越冬幼虫。进一步将越冬幼虫单管饲养跟踪研究发现,越冬幼虫体重大小决定蛹和羽化后的成虫的大小,二者存在显著的正相关,并且由4龄越冬幼虫发育所得的蛹和成虫显著轻于由5龄幼虫发育所得的蛹和成虫。【结论】松墨天牛成虫体型差异很大,这与越冬幼虫体重差异相关;越冬幼虫的体重大小决定了其化蛹后的蛹重和羽化后成虫的体型和体重的大小;造成越冬幼虫体重差异的可能原因包括松墨天牛成虫扬飞周期长导致的产卵期长而使得天牛发育进度不一致以及寄主不同部位营养的差异。     

扬子鳄的越冬管理

扬子鳄(Ａｌｌｉｇａｔｏｒｓｉｎｅｎｓｉｓ)是我国特有的珍稀爬行动物。安徽省扬子鳄繁殖研究中心经过20年的发展,现有扬子鳄8000余条,是国内外驯养、繁殖扬子鳄的最大种群基地。冬眠是扬子鳄适应寒冷气候的一种生理现象,其越冬管理的好坏直接影响到幼鳄的成活率和成鳄的繁殖率,故其越冬技术一直很受重视,并不断得以完善,现将其总结,供引种扬子鳄饲养者参考。由于不同年龄扬子鳄的生理特点和管理要求不同,所以将扬子鳄的越冬管理分成当年孵出鳄、2-6龄鳄和成鳄3个年龄段来叙述。1　当年孵出鳄的越冬管理当年孵出的幼鳄,身体各器官的功能尚…     

影响扬子鳄产蛋量的因素分析

1997～2006年对安徽省扬子鳄繁殖研究中心内的扬子鳄亲本、F1代和F2代繁殖鳄群体在冬眠环境条件、采食量、年龄等方面进行观察,对各代繁殖鳄的年产蛋数量进行统计。用SPSS11.0软件中的one-way ANOVA方法分析比较人工饲养鳄各代群体之间及人工饲养鳄与野生鳄群体之间年产蛋数量的变化关系,结果显示区域内扬子鳄所建造的洞穴数量和其所建造洞穴的质量决定着圈养鳄的冬眠质量,鳄的冬眠质量影响到鳄体内的性腺系统正常发育,最终影响扬子鳄次年能否参加产蛋;年采食量影响鳄的产蛋数量。通过第1、2、5年间产蛋量F值检验(F值=4.866,P=0.009<0.05),得出圈养条件下扬子鳄的产蛋数量是随着产龄的增加而呈增长的趋势。     

多疣狭口蛙昆明种群雌雄配对行为及形态适应选择

测量和比较采自昆明东北郊的24对抱对多疣狭口蛙(Kaloulaverrucosa)标本,同时野外观察其繁殖行为。配对雌雄蛙的体长、体重和头宽3个形态特征的Pearson相关系数大于0·5;择体长和体重作回归分析,结果表明,雌雄蛙体长选择和雌雄蛙体重配对都呈良好的线性关系。雌蛙选择雄蛙体长为自身体长的(81·8±5·7)%、体重为自身体重的(53·1±10·7)%的个体为最适配偶。雌蛙选择体长较长而体重较轻的雄蛙作为配偶,这样有利于形成较好的空间(雄性胸腹部皮肤腺长度,雌雄抱对时泄殖孔位置等)配对关系。多疣狭口蛙属于雌性选择模式,即雄蛙鸣叫,雌蛙受吸引,主动接近雄蛙,如果雄蛙条件适合则形成配对。     

东方田鼠两亚种幼体生长特征参数的比较

在相同驯养条件下同步测定东方田鼠(Microtus fortis)指名亚种和长江亚种幼体的生长特征参数。两亚种初生幼体表型特征无明显差异。采用Von Bertalanffy生长模型对两亚种幼体的体重、体长和尾长,以Logistic生长方程对后足长生长过程进行拟合与描述。指名亚种雄体渐近体重、体长和尾长均大于或显著大于长江亚种,雌体前者小于后者;两亚种在17~20 d体重均已产生性二型分化,长江亚种两性个体渐近体重、体长和尾长差值大于指名亚种。两亚种雌体体重、体长、尾长和后足生长速率均相应地大于雄体,体重生长曲线拐点出现时间、瞬时生长率曲线拐点出现时间较体长、尾长和后足长明显迟缓。两亚种两性个体的后足长生长速率要大于其体重、体长和尾长。结果表明,(1)雌体较雄体早熟;(2)雄性体重指名亚种大于长江亚种,雌体相反,指名亚种性二型现象较长江亚种明显;(3)后足长较体重、体长和尾长较早地达到成熟时的大小;(4)两亚种幼体性二型分化时间早于其性成熟过程。     

冬眠期温度和扬子鳄疾病发生的关系

分析5～8年龄段的扬子鳄在不同环境条件下越冬出现的发病死亡结果,表明越冬期内空气温度的昼夜剧烈变化,使得越冬池内的水温发生较大的波动,导致处在越冬中的扬子鳄生理功能紊乱,使鳄患病甚至死亡,当年的室外饲养质量影响鳄的发病时间.     

人工条件下越冬扬子鳄的繁殖

2003年11月~2004年9月在安徽省扬子鳄繁殖研究中心,观察了人工养殖的成年扬子鳄(Alligatorsinensis)在饲养池和模拟自然生态环境的繁殖区中越冬后的繁殖行为。结果表明,在与扬子鳄自然洞穴的温度和水分条件相似但其他条件相差很大的人工环境中冬眠的扬子鳄具有繁殖能力。越冬后,这些鳄只能在具备其栖息地环境特点的场地成功繁殖,但不能在不具备这种环境特点的场地成功繁殖。本研究拓展了扬子鳄的人工繁殖技术,为扬子鳄人工繁殖场地的兴建提供参考资料。     

养殖美洲鲥的生长特性

通过对各周年生长阶段的养殖美洲鲥(Alosa sapidissima)体长、体重的测量与分析,研究了工厂化养殖美洲鲥的周年生长特性。养殖美洲鲥雌雄鱼的体长与体重关系均呈幂函数增长相关,其方程分别为,雌:W=0.8062×10~(-5) L~(3.1113)(n=122,R~2=0.997 5,P0.01);雄:W=1.0047×10~(-5) L~(3.0574)(n=125,R~2=0.997 5,P0.01),b均接近于3,呈等速生长;雌雄鱼生长均可分快速生长期(0~+龄)、稳定生长期(1~+龄)、生长衰老期(2~+龄)三个时期,雌鱼生长快于雄鱼。拟合出von Bertallanffy生长方程,雌:Lt=467.92(1﹣e~(-0.5748(t+0.1710))),Wt=1637.72(1﹣e~(-0.5748(t+0.1710)))~(3.1113);雄:Lt=389.21(1﹣e~(-0.7374(t+0.1975))),Wt=834.08(1﹣e~(-0.7374(t+0.7189)))~(3.0574)。雌雄鱼体重生长拐点分别位于1.517 8 a和1.224 7 a,属性成熟拐点,拐点前生长较快;拐点后,特别是性成熟后(2龄),2~+龄鱼的生长速度明显降低;同时,2龄鱼繁殖季节过后会出现大量死亡。建议商业化工厂化养殖美洲鲥以2龄前上市为宜。     

北京地区宽鳍(魚巤)的生长及食性

2004-2006年,作者对分布于北京市怀柔水库上游入库河流怀沙河和怀九河宽鳍鱲的生物学进行了研究。结果显示:北京地区宽鳍鱲年龄组成较小,雄鱼最大3龄,雌鱼最大2龄。体长和体重相关关系式为:W=9×10-6L3.1947(r=0.9784),其种群呈异速增长。1龄组雌雄鱼体长和体重无显著差异,2龄组雄鱼体长和体重显著大于雌鱼,可能与雌鱼性成熟后生长速度减慢有关。雄鱼VonBertalanffy生长方程为:Lt=121.56×(1-e-0.3718(t 0.6272)),最大体长121.56mm;Wt=41.16×(1-e-0.3718(t 0.6272))3,最大体重41.16g;生长拐点tr=2.41龄;雌鱼最大为2龄,未能拟合VonBertalanffy生长方程。丰满度和饱食指数均呈周年变化,这可能与水温变化和繁殖期的影响有关。北京地区的宽鳍鱲为植食性,主要摄食硅藻,取食具选择性,且获得的食物量与藻类的多度一定程度上正相关。雌雄性比接近1∶1,1冬龄性成熟;繁殖期5-7月,5月份成熟系数最高。与嘉陵江种群相比,北京种群体长、体重均小于嘉陵江种群;食性上,前人研究认为嘉陵江种群为肉食性,但经我们重新鉴定,嘉陵江种群也为植食性,个别肉食性食物成分可能是随摄食的藻类带入的;在年龄组成、种群增长方式、性比及繁殖特性上,未发现二者有明显差异。基于北京地区宽鳍鱲的生物学特性,结合该地区的环境特点,我们建议通过控制捕捞数量、选择最适捕捞时间、保护原有生境来维持北京地区宽鳍鱲资源的可持续利用。     

多疣狭口蛙昆明种群雌雄配对行为及形态适应选择

测量和比较采自昆明东北郊的24对抱对多疣狭口蛙(Kaloula verrucosa)标本，同时野外观察其繁殖行为。配对雌雄蛙的体长、体重和头宽3个形态特征的Pearson相关系数大于0.5；择体长和体重作回归分析，结果表明，雌雄蛙体长选择和雌雄蛙体重配对都呈良好的线性关系。雌蛙选择雄蛙体长为自身体长的(81.8±5.7)%、体重为自身体重的(53.1±10.7)%的个体为最适配偶。雌蛙选择体长较长而体重较轻的雄蛙作为配偶，这样有利于形成较好的空间(雄性胸腹部皮肤腺长度，雌雄抱对时泄殖孔位置等)配对关系。多疣狭口蛙属于雌性选择模式，即雄蛙鸣叫，雌蛙受吸引，主动接近雄蛙，如果雄蛙条件适合则形成配对。     

扬子鳄胚胎发育分期

本文基于150例不同胎龄的扬子鳄胚胎,将扬子鳄胚胎发育过程分成28个时期。早期胚胎主要以外部形态如体节、体曲程度、脑泡、感觉器官、附肢、鳃弓、颜面部突起、心脏、皮肤等作为分期标准;晚期胚胎主要以器官发育的组织学指标为分期依据。发现在前20个时期中,每个时期的胎龄与密河鳄的很一致,后8个时期的胎龄与密河鳄有差异。分析认为,鳄类晚期胚胎的分期依据应增加器官发育的组织学指标,以便使不同鳄类的胚胎发育有一致的分期标准,为鳄类发育生物学后续研究提供基础资料。     

Chronic incidental lead ingestion in a group of captive-reared alligators (Alligator mississippiensis): possible contribution to reproductive failure

An American alligator (Alligator mississippiensis) breeding facility using male and female alligators raised from artificially incubated eggs was established in 1975. These alligators first reproduced at 6 years of age as compared to 10-12 years in wild alligators, but the eggs produced showed a lower hatching rate than those collected from the wild. By age 21 reproduction had failed almost completely. The alligators were sacrificed and tissues collected at necropsy from 44 captive and 15 wild animals and assayed for metals. Results showed that captive alligators had significantly higher tissue levels of lead than wild alligators. Cadmium did not differ between wild and captive and selenium was 50% higher in wild than captive alligator kidneys. Bone lead in captive alligators was 252,443 +/- 20,462 ng/g. High yolk lead was suggested as a probable cause for early embryonic death in alligator eggs. The high tissue lead levels in captive alligators was attributed to long-term consumption of nutria (Myocastor coypus) meat contaminated with lead shot. Liver, ovary, and testis were assayed for lipid peroxidation using the thiobarbituric acid (TBA) test. Captive alligators had 3.6 fold increased TBA-reactive materials in the liver tissue compared to wild. Lipid peroxidation was strongly suspected as having been enhanced by consumption of rancid nutria meat containing lead.     

American alligator (Alligator mississippiensis) weight gain in captivity and implications for captive reptile body condition

The body condition of an animal is an indicator of health status and is dependent upon many factors, some of which can vary between wild and captive settings. Despite this, there have not been many studies on how captivity affects body condition relative to wild animal populations. This study explores the body condition of captive and wild American alligators (Alligator mississippiensis) because reptiles are frequently overlooked in studies of captive animal health and because alligators are well-represented in captivity. We collected body condition data from 209 captive alligators and 935 wild alligators throughout Florida and southeastern Georgia and compared the relationships between body condition and body length for each group. We found that captive alligators exhibited significantly higher body condition values as they aged, and that this result was driven by the difference between captive and wild males. Body condition values for captive juveniles did not differ from wild juveniles, but they differed when comparing adults. Our results suggest that factors such as diet and movement rates play major roles in determining alligator body condition and that body condition may be an important metric for monitoring captive alligator health, especially for older adult males.     

Evaluation of Effects of Harvest on Alligator Populations in Louisiana

Biologists with the Louisiana Department of Wildlife and Fisheries, Louisiana, USA, have managed statewide annual harvest of alligators (Alligator mississippiensis) for 35 years (1981–present). We collected and analyzed harvest data for Louisiana alligators to determine the effects of harvest on the population structure, focusing on the larger size classes (≥274 cm) of this slow-growing species. Linear regression analyses revealed that body size-class structure, based on overall average size and the percentage of animals harvested in the larger size classes was relatively stable. Annual aerial alligator nest counts indicated a continual growth of the population, and over time harvested alligators maintained a constant average size. Analyses of population size (based on number of nests and population modeling) indicated that the current annual harvest represents approximately 3% of the population. Linear regression analysis showed that annual hunter success declined only slightly during the study period, and the scheduling of the hunt season after the hatch period and recommended hunting in areas not frequented by breeding females provides economic opportunities for hunters to participate in a sustainable harvest that preserves the larger size classes of alligators in the population. Strict enforcement of existing laws was a key factor responsible for the success of this harvest program. Comparison of alligator population size and number of harvest-related citations indicated that illegal harvest did not have a negative effect on population size, and linear regression analyses revealed that the rate of increase in citations was lower than the increase in populations over the study period. The results of this harvest program indicated that alligators can be hunted in a sustainable manner if hunting is conducted after the hatch period and occurs in areas that primarily exclude the harvest of adult females, and strict law enforcement curbs illegal activities that negatively affect populations. © 2021 The Authors. The Journal of Wildlife Management published by Wiley Periodicals LLC on behalf of The Wildlife Society.     

Nest Site Preference and Fidelity of Chinese Alligator(Alligator sinensis)

Oviparous female reptiles select nesting sites with optimal ecological factors that contribute to egg development. Chinese alligator(Alligator sinensis), an oviparous reptile, is a critically endangered crocodilian with temperature-dependent sex determination. Research on its nesting behavior may facilitate the protection of this species. In this study, we monitored nesting behavior over eight years. We compared selected frequency of nest sites, distance from nest site to water, height from nest site top to the water surface, distance from nest site to human activity region, and canopy density between nest sites on the island and bank. The results showed that 45 nest sites were used by female alligators over eight years and each site was selected from one to 10 times. The selected frequency of nest site occurrence on the island was higher than that on the bank(P 0.001). We observed that 88% of the individual alligators(15/17) showed different degrees of nest site fidelity. However, Chinese alligators might not always be loyal to only one nest site because of environmental changes or interspecific competition at nest sites. Our findings suggest that female alligators prefer to nest at island, which might be because of the nests on the island had a higher canopy density(P = 0.010) and were further from the human activity region(P 0.001) than those on the bank did. It would be beneficial to reduce human activities during the breeding season and protect the vegetation of Chinese alligator habitats in the future. of the beach(Ali et al., 2005; Kamel and Mrosovsky, 2005; Turkozan et al., 2012). Other species such as snakes and lizards select nest sites with more moist substrates, which significantly increases their body size at hatching(Brown and Shine, 2004; Reedy et al., 2013). Nest site preference may be maintained for one or more breeding seasons(Janzen and Morjan, 2001; Kamel et al., 2006). When female chose the same site or area during different years, it is called nest site fidelity(Switzer, 1993). This nest choice behavior may influence offspring survival(Lindeman, 1992) and nest site fidelity has been documented in numerous species such as birds(Lindberg and Sedinger, 1997), turtles(Mitrus, 2006; Walde et al., 2007), tuatara(Refsnider et al., 2010), and crocodilians(Elsey et al., 2008).Chinese alligator(Alligator sinensis) is a critically endangered freshwater crocodilian endemic to China(Thorbjarnarson and Wang, 1999). Recent investigations show that there are no more than 130 Chinese alligators     

Growth rates of Chinese and American alligators

Growth rates in two closely related species, Alligator mississippiensis (American alligator) and Alligator sinensis (Chinese alligator), were compared under identical conditions for at least 1 year after hatching. When hatched, Chinese alligators were approximately 2/3 the length and approximately 1/2 the weight of American alligator hatchlings. At the end of 1 year of growth in captivity in heated chambers, the Chinese alligators were approximately 1/2 as long and weighed approximately 1/10 as much as American alligator yearlings. When the animals were maintained at 31 degrees C, Chinese alligator food consumption and length gain rates dropped to near zero during autumn and winter and body weights decreased slightly, apparently in response to the change in day length. At constant temperature (31 degrees C), food consumption by American alligators remained high throughout the year. Length gain rates in American alligators decreased slowly as size increased, but were not affected by photoperiod. Daily weight gains in American alligators increased steadily throughout the year. In autumn, provision of artificial light for 18 h a day initially stimulated both length and weight gain in Chinese alligators, but did not affect growth in American alligators. Continuation of the artificial light regimen seemed to cause deleterious effects in the Chinese alligators after several months, however, so that animals exposed to the normal light cycle caught up to and then surpassed the extra-light group in size. Even after removal of the artificial light, it was several months before these extra-light animals reverted to a normal growth pattern. These findings may be of interest to those institutions engaged in captive growth programs intended to provide animals for reintroduction to the wild or to protected habitat.     

2龄前扬子鳄肠道的年龄结构变化

光镜下,用组织学和组织化学的方法对四个不同年龄段扬子鳄不同肠段进行了研究。扬子鳄肠道长度随年龄增大而增加,相对长度从初生至８月龄逐减,从８月龄至２龄增大。肠道各项组织学参数绝对值均年龄增长而增加,相对值从初生至５月龄变化很大,５月龄至２龄变化不明显。     

使用SSR和mtVNTR分子标记识别扬子鳄个体

扬子鳄是中国特有的濒危物种,为有效避免种群衰退,最大限度地保持该物种现有的遗传多样性,有必要对种群的个体进行个体识别研究,以便重建遗传谱系,指导现有繁育工作。应用SSR(Simple sequence repeats)与mtVNTR(Variable number tandem repeats on mitochondrial DNA)两种分子标记对扬子鳄39个个体进行了个体识别分析,结果显示：8个SSR座位的累计个体识别率与累计父权排除率分别达0．9968、0．7697,mtVNTR的个体识别率为0．9146,联合SSR与mtVNTR两种分子标记的累计个体识别率理论值达0．9997,并在实际分析中将39个扬子鳄个体完全区分开,其区分能力较RAPD(Random amplified polymorphic DNA)、AFLP(Amplified fragment length polymorphism)及mtDNA控制区5’端序列分析等分子标记要高。此外,SSR和mtvNTR还可对某些低频等位基因及其携带个体做有效的筛查,这对今后进行大量扬子鳄个体的分子标记识别和群体的遗传谱系建立等工作将具有一定实际意义[动物学报51(3)：501—506,2005]。     

绥芬河大麻哈鱼个体生物学研究

研究以2012至2017年在绥芬河东宁段采集的447尾大麻哈鱼(Oncorhynchus keta Walbaum)为材料,对其年龄与生长及繁殖特性等个体生物学特征进行研究分析。结果表明:绥芬河大麻哈鱼种群由1~+-5~+龄5个年龄组构成,其中雌性个体以3~+龄为主,雄性个体以2~+龄为主。大麻哈鱼雌、雄个体的体长-体重关系分别为:W=0.0082×L~(3.0604);W=0.0076×L~(3.0746),均属匀速生长类型;采用Von Bertalanffy生长方程拟合得到3~+龄大麻哈鱼雌、雄个体的叉长生长方程分别为:L_(t,F)=141.64×e~(-0.11)·(t+1.55));L_(t,M)=119.51×e~(-0.13·(t+1.45))。利用逻辑斯蒂方程估算大麻哈鱼雌、雄个体初次性成熟叉长(L_(50))分别为51.53和42.15 cm。ARSS分析显示雌、雄个体的L_(50)差异显著;大麻哈鱼的绝对繁殖力(F)、相对叉长繁殖力(F_L)和相对体重繁殖力(F_W)分别为3412粒、52.42粒/cm和1.17粒/g;F与叉长、体重、性腺重呈显著正相关关系,GSI与叉长、体重、F成显著负相关关系;F与叉长、体重的幂函数关系方程式分别为:F=0.0311×L~(2.7745)(R~2=0.638)和F=1.946×W~(0.9374)(R~2=0.704)。本研究为绥芬河大麻哈鱼资源保护工作提供基础资料。