一条扬子鳄在岩洞越冬的尝试

扬子鳄是原产于中国长江中下游的珍稀爬行动物,其越冬问题一直受到关注。2009~2013年,桂林动物园尝试把扬子鳄装入铁笼放入石山岩洞里越冬。结果表明:岩洞的几项环境因素与原产地土洞穴的环境因素相近,扬子鳄可在岩洞中进行越冬,这是一种经济可行的越冬方式。     

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…     

冬眠期温度对扬子鳄繁殖的影响

本文报道了扬子鳄在人工越冬环境条件下,深眠期的温度值对越冬后繁殖的影响.6年的研究表明扬子鳄在深眠期的温度处在5～8℃时,扬子鳄越冬后能够成功繁殖产卵.     

扬子鳄的起源

介绍了现存鳄彼此间的亲缘关系、扬子鳄起源的时间和地点。主要结论可归纳如下：①现存鳄类在科、属、种分类上都存在不同意见;②扬子鳄与密河鳄被分在同一属内,但两者之间的亲缘关系存在争议,两者在形态、生化、细胞、分子生物学上差异很大;③Stell认为扬子鳄在中新世开始出现,作者认为它可能起源于渐新世或中新世早期;④Stell认为分布于北美的汤氏鳄（A.thomsoni)可能是扬子鳄的祖先类型,而另一些学者认为扬子鳄起源于亚洲的可能性更大些。     

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。     

建议开展扬子鳄保护遗传学和开发利用研究

扬子鳄是一种人工饲养繁殖成功的濒危野生动物。１９９２年获ＣＩＴＥＳ成员大会批准,允许子二代鳄的商业性开发利用。作者分析了我国扬鳄保护、养殖现状和扬子鳄群体的跗特征,认为一方面扬子鳄野生资源仍受到威胁,另一方面随着饲养各群数量的增加,养殖费用不断增长,扬子鳄在潜在经济价值也示能实现。鉴于此,提出加强动用现代生物技术对扬鳄保护遗传学和开发利用研究的建议。     

野放前候选扬子鳄泄殖腔的细菌鉴定

扬子鳄(Alligator sinensis)是中国濒危的物种,野生鳄种群已濒临灭绝。通过放归工程,将挑选饲养鳄放养到野外去扩大野生种群。本文的研究目的是通过检测扬子鳄的健康状况为扬子鳄的筛选提供依据。从 25 条准备进行野放的扬子鳄泄殖腔中筛选出 13 种形态不同的菌株。应用细菌学和分子生物学方法,鉴定它们分别属于 6个属的 8 个种和一个未分类的菌;从扬子鳄生活的水体中筛选出 8 种形态不同的菌株,鉴定它们分别属于 1 个属的 4 个种。经分析,除了未分类的菌之外,从扬子鳄泄殖腔中分离得到的菌株都是非致病性的且不同于扬子鳄生活水体中分离的菌株,因此可以认为这些扬子鳄是健康的,可以野放。由于从标记为 AS12 的扬子鳄体内分离到一个分类地位尚未确定的菌,对它的生理生化特征进行了检测,但这种菌的致病性方面特征尚不清楚,建议不考虑野放标记为 AS12 的扬子鳄个体。     

野放前候选扬子鳄泄殖腔的细菌鉴定(英文）

扬子鳄(Alligator sinensis)是中国濒危的物种,野生鳄种群已濒临灭绝。通过放归工程,将挑选饲养鳄放养到野外去扩大野生种群。本文的研究目的是通过检测扬子鳄的健康状况为扬子鳄的筛选提供依据。从25条准备进行野放的扬子鳄泄殖腔中筛选出13种形态不同的菌株。应用细菌学和分子生物学方法,鉴定它们分别属于6个属的8个种和一个未分类的菌;从扬子鳄生活的水体中筛选出8种形态不同的菌株,鉴定它们分别属于1个属的4个种。经分析,除了未分类的菌之外,从扬子鳄泄殖腔中分离得到的菌株都是非致病性的且不同于扬子鳄生活水体中分离的菌株,因此可以认为这些扬子鳄是健康的,可以野放。由于从标记为AS12的扬子鳄体内分离到一个分类地位尚未确定的菌,对它的生理生化特征进行了检测,但这种菌的致病性方面特征尚不清楚,建议不考虑野放标记为AS12的扬子鳄个体。     

人工驯养下扬子鳄的生长规律

研究结果表明扬子鳄在饲养条件下的生长具有一定的规律性。饲养群体中,5龄以前的鳄生长速率较快,其中在2龄前生长速率最快,在5龄至7龄间生长速率明显减慢;鳄体长与体重之间呈正相关,两者在体长小于50cm时呈直线相关,体长大于50cm时呈曲线相关。不同性别的扬子鳄年生长状况不同,从5龄开始雌雄鳄体重出现显著差异,雄鳄重于雌鳄;从6龄开始雌雄鳄在体长方面的生长速率出现差异,雄鳄生长明显快于雌鳄;达到10龄后,雌雄鳄在体长和体重方面的增长均明显减慢,达到15龄时两者的体形已相差悬殊,雄性大于雌性。由von Berta-lanffy生长模型分析,雌鳄达到25龄而雄鳄达到35龄后,各自的体长几乎停止生长,雌鳄平均最大体长为173cm,雄鳄平均最大体长为219cm。在人工越冬下,除第一次越冬外,扬子鳄在越冬室内的冬眠中体况无明显变化,体能明显消耗出现在户外冬眠过程中。本研究为扬子鳄的科学化饲养提供理论依据。     

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。     

Late-born intermittently fasted juvenile garden dormice use torpor to grow and fatten prior to hibernation: consequences for ageing processes

Torpor is thought to slow age-related processes and to sustain growth and fattening of young individuals. Energy allocation into these processes represents a challenge for juveniles, especially for those born late in the season. We tested the hypothesis that late-born juvenile garden dormice (Eliomys quercinus) fed ad libitum (‘AL’, n = 9) or intermittently fasted (‘IF’, n = 9) use short torpor bouts to enhance growth and fat accumulation to survive winter. IF juveniles displayed more frequent and longer torpor bouts, compared with AL individuals before hibernation. Torpor frequency correlated negatively with energy expenditure and water turnover. Hence, IF juveniles gained mass at the same rate, reached similar pre-hibernation fattening and displayed identical hibernating patterns and mass losses as AL animals. We found no group differences in relative telomere length (RTL), an indicator of ageing, during the period of highest summer mass gain, despite greater torpor use by IF juveniles. Percentage change in RTL was negatively associated with mean and total euthermic durations among all individuals during hibernation. We conclude that torpor use promotes fattening in late-born juvenile dormice prior to hibernation. Furthermore, we provided the first evidence for a functional link between time spent in euthermy and ageing processes over winter.     

华北地区扬子鳄室内控温冬眠的初步研究

扬子鳄(Alligator sinensis),属于我国Ⅰ级重点保护野生动物,华北地区养殖条件下未见降温冬眠报道.本次于2020年11月至2021年5月对北京动物园饲养的5尾扬子鳄开展人工降温冬眠实验,观察冬眠各期个体的环境选择和行为变化,建立冬眠期间的行为谱,分析冬眠前后行为指标和形态指标(全长、体重和围度)变化,监...     

Characteristics of American alligator bites on people in Florida

Human–American alligator (Alligator mississippiensis) conflict in Florida, USA, has increased since the early 1970s, along with the recovery of the American alligator population. To better understand factors contributing to the risk of people being bitten by free-ranging alligators in Florida, we evaluated the trend of alligator bites during 1971–2014 and examined characteristics associated with bites on people documented during 1948–2014. We classified 372 bites as either unprovoked or unintentionally provoked and used these in further analyses. Major injuries to victims occurred in 247 bite incidents. The estimated annual number of bites resulting in major injury to the victim increased from 3.5 to 7.0 during 1971–2014. The number of bites per Florida resident did not show a significant trend during 1971–2014. No significant change occurred in the frequency of fatal attacks during 1971–2014. Monthly frequency of bites was positively correlated with both mean maximum and mean minimum air temperatures but was not significantly correlated with testosterone concentration in adult male alligators, suggesting that bites are more likely related to feeding rates associated with seasonal fluctuations in ambient temperature than to aggression by male alligators during the breeding season. A high percentage of bites (41.8%) occurred in unnamed water bodies, which were generally small or man-made. Most (93.7%) victims were Florida residents, and 58.7% resided close to the incident site. Victims were predominantly male (81.4%), and adults were more frequently victims than were adolescents or children. Most victims (93.9%) were in the water or near the shore when bitten. Victims were more likely to sustain major injuries if the bite occurred in deeper water. Male alligators were more frequently (76.9%) responsible for bites. We found only 1 instance in which a bite was associated with defense of eggs or young by an adult female alligator. Evidence of people feeding alligators before the bite was documented in 34.7% of bite incidents. Twenty-two fatalities were attributed to alligator attacks, but we could not discern a pattern in the ages of victims. Alligators responsible for severe or fatal bites were predominantly in good condition with few deformities or injuries. Most alligator bites in Florida appeared to be attempts at feeding, although 36.8% of incidents entailed a single bite followed by immediate release, suggesting that alligators were unsure about their prey or were biting in defense. The risk of alligator bites can be reduced by educating people likely to interact with alligators and by selectively removing problem alligators in human residential areas and water bodies used regularly by people for swimming, wading, and shoreline activities. © 2019 The Wildlife Society.     

Low mitochondrial DNA variation among American alligators and a novel non-coding region in crocodilians

We analyzed 1317-1823 base pairs (bp) of mitochondrial DNA sequence beginning in the 5' end of cytochrome b (cyt b) and ending in the central domain of the control region for 25 American alligators (Alligator mississippiensis) and compared these to a homologous sequence from a Chinese alligator (A. sinensis). Both species share a non-coding spacer between cyt b and tRNA(Thr). Chinese alligator cyt b differs from that of the American alligator by 17.5% at the nucleotide level and 13.8% for inferred amino acids, which is consistent with their presumed ancient divergence. Only two cyt b haplotypes were detected among the 25 American alligators (693-1199 bp surveyed), with one haplotype shared among 24 individuals. One alligator from Mississippi differed from all other alligators by a single silent substitution. The control region contained only slightly more variation among the 25 American alligators, with two variable positions (624 bp surveyed), yielding three haplotypes with 22, two, and one individuals in each of these groups. Previous genetic studies examining allozymes and the proportion of variable microsatellite DNA loci also found low levels of genetic diversity in American alligators. However, in contrast with allozymes, microsatellites, and morphology, the mtDNA data shows no evidence of differentiation among populations from the extremes of the species range. These results suggest that American alligators underwent a severe population bottleneck in the late Pleistocene, resulting in nearly homogenous mtDNA among all American alligators today.     

Pathology of experimental mycoplasmosis in American alligators.

Mycoplasma alligatoris was the suspected etiology of an epidemic of acute multisystemic inflammatory disease which emerged in captive American alligators (Alligator mississippiensis) in Florida (USA) in 1995. In an experimental inoculation study conducted from April through October 1999, 18 alligators were inoculated with 10(2), 10(4), or 10(6) colony forming units (CFU) of M. alligatoris by instillation into the glottis. As early as 1 wk post-inoculation (PI), mycoplasma were cultured from blood of three of six alligators inoculated with 10(6) CFU. Two of those died and the third was euthanatized within 4 wk PI. Necropsy gross findings included fibrinous polyserositis and polyarthritis. Histopathologic changes in affected individuals included pulmonary edema, interstitial pneumonia, pericarditis, myocarditis, meningitis, and synovitis. Mycoplasma were cultured quantitatively in high numbers from trachea, lung, coelomic cavity, liver, spleen, interior of pericardial sac, heart, blood, brain, and limb joints. In alligators inoculated with 10(6) CFU, heterophilia and moderate hyperglycemia peaked about 4 wk PI, and seroconversion occurred by 6 to 8 wk PI. Necropsy gross and histologic findings were generally unremarkable for the surviving alligators inoculated with 10(6) CFU, alligators inoculated with 10(2) or 10(4) CFU, and four uninoculated control alligators. Mycoplasma were not cultured at any time point from those alligators. The findings confirm that M. alligatoris can cause fulminant inflammatory disease and rapid death of alligators.     

Microsatellite analysis of genetic diversity in the Chinese alligator (<Emphasis Type="Italic">Alligator sinensis</Emphasis>) Changxing captive population

Chinese alligator (Alligator sinensis) is a critically endangered species endemic to China. In this study, the extent of genetic variation in the captive alligators of the Changxing Reserve Center was investigated using microsatellite markers derived from American alligators. Out of 22 loci employed, 21 were successfully amplified in the Chinese alligator. Sequence analysis showed loci in American alligators had a bigger average size than that of the Chinese alligators and the longest allele of an individual locus almost always existed in the species with longer stretch of repeat units. Eight of the 22 loci were found to be polymorphic with a total of 26 alleles present among 32 animals scored, yielding an average of 3.25 alleles per polymorphic locus. The expected heterozygosity (H _E) ranged at a moderate level from 0.4385 to 0.7163 in this population. Compared to that in the American alligators, a lower level of microsatellite diversity existed in the Changxing population as revealed by about 46% fewer alleles per locus and smaller H _E at the homologous loci. The average exclusion power and the ability to detect shared genotypes and multiple paternity were evaluated for those markers. Results suggested that when the polymorphic loci were combined, they could be sensitive markers in genetic diversity study and relatedness inference within the Chinese alligator populations. The level of genetic diversity present in the current Changxing population indicated an important resource to complement reintroductions based on the individuals from the other population. In addition, the microsatellite markers and their associated diversity characterized in this population could be utilized to further investigate the genetic status of this species.     

Does variation in movement tactics and trophic interactions among American alligators create habitat linkages?

1. Highly mobile top predators are hypothesized to spatially and/or temporally link disparate habitats through the combination of their movement and feeding patterns, but recent studies suggest that individual specialization in habitat use and feeding could keep habitats compartmentalized. 2. We used passive acoustic telemetry and stable isotope analysis to investigate whether specialization in movement and feeding patterns of American alligators (Alligator mississippiensis) in an oligotrophic subtropical estuary created habitat linkages between marine and estuarine/freshwater food webs. 3. Individual alligators adopted one of the three relatively distinct movement tactics that were linked to variation in diets. Fifty-six per cent of alligators regularly travelled from the upstream (freshwater/mid-estuary) areas into the downstream (marine-influenced) areas where salinities exceed those typically tolerated by alligators. Thirty-one per cent of the alligators made regular trips from the mid-estuarine habitat into the upstream habitat; 13% remained in the mid-estuary zone year-round. 4. Stable isotopic analysis indicated that, unlike individuals remaining in the mid-estuary and upstream zones, alligators that used the downstream zone fed at least partially from marine food webs and likely moved to access higher prey abundance at the expense of salt stress. Therefore, 'commuting' alligators may link marine food webs with those of the estuary and marshes in the coastal Everglades and create an upstream vector for allochthonous nutrient inputs into the estuary. 5. This study lends further support to the hypothesis that large-bodied highly mobile predators faced with trade-offs are likely to exhibit individual specialization leading to habitat linkages, rather than compartmentalization. However, the conditions under which this scenario occurs require further investigation.