东方蝾螈Cynops orientalis(David)排精和纳精的初步观察

多年来我们在室内饲养和繁殖东方蝾螈,但是关于东方蝾螈的排精和纳精的具体情况并未看到,过去只作了一些猜测。1963年3月份我们作了较详细的观察,兹将观察方法及获得的一些结果分述如下: 用作观察的蝾螈有两种来源:1.室内雌雄分开饲养的,这些蝾螈于1962年春季采自野外,雌雄分开饲养直到本次试验(1963年3月)前为止,其中部分雌体已开始产卵但不能正常发育;2.当年野外采来的,部分雌体采回室内后已开始产卵并能正常发育。 将上述蝾螈按1雌1雄的比例配对,并按材料来源的不同分成五组:     

东方蝾螈繁殖生态的研究

本文报道东方蝾螈(Cynops orientalis)的繁殖生态,内容有精巢分叶、精子形态、怀卵量、性征、性比、求偶、交配、纳精、产卵及孵化等,并对产卵场中性比的周年变化、精包形态、精子存活力及与蓝尾蝾螈的种间差异进行了观察和讨论。     

潮汕蝾螈的求偶行为

潮汕蝾螈(Cynops orphicus)是我国特有的濒危有尾两栖类,繁殖季节始于5月中旬。对其求偶行为观察发现,该螈求偶模式表现出与东方蝾螈(C.orientalis)相似的特点,但雄性扇尾和潜行时间(25~37 s)较东方蝾螈(10~20 s)更长;雄性在一次求偶中多次排精,雌性亦可多次纳精,精子囊形态与东方蝾螈类同;雌性纳精后,雄性反转咬住其腹部,被咬雌性呈现植物态。纳精过后,雌性出现暂时的冷漠或恐惧,不再接受雄性求偶。该螈成功纳精在累次求偶行为中占比不高(2.7%),但较东方蝾螈(1.1%)成功率高。雄性之间存在求偶过程中的竞争和干扰行为。     

蓝尾蝾螈的食性和食量及耐饥时间的观察

本文观察了蓝尾蝾螈在水下的摄食行为和食性;在室内饲喂畜寓肌肉年总食量雄性为6.37克,雌性为13.29克,其食量随季节而变化,最低与最高月食量之比雄性1∶7.4,雌性1∶13.1;雄雌年平均食量为1∶2.09。蝾螈的耐饥时间雄性为102—282(197)天,死亡时体重为原体重46.6％;雌性为282—621(395)天,死亡时体重为原体重36.0％;雌螈在饥饿情况下,产卵期为35—102天,可产卵9—61粒。     

人工养殖条件下东方蝾螈的繁殖生物学

通过室内饲养观察,重点研究了东方蝾螈的产卵行为、受精卵孵化、仔螈的变态发育等繁殖生物学.东方蝾螈雌螈产卵前有明显的筑巢行为,分批产卵,产卵时间不集中,产卵期持续46～98 d,平均产卵期为78 d±14 d,产卵高峰期在5月上中旬,平均产卵量为101±56枚;温度对受精卵孵化影响十分显著,3月份产的卵平均54.1 d孵出仔螈,6月份产的卵平均11 d孵出仔螈,在15～26℃的自然水温条件下,受精卵一般需要11～30 d孵出仔螈;仔螈的变态发育与温度、饲料等因素密切相关,在24～25℃的控温养殖条件下,仔螈40 d后外鳃开始萎缩,68～79 d完成变态发育,但在自然水温下,只有78%的仔螈当年能完成变态发育.     

云南蓝尾蝾螈一新亚种

1974年,1975年,先后在云南昆明、景东无量山采到一批蓝尾蝾螈标本,被定为蓝尾蝾螈云南亚种。后被施立明等(1979,遗传,1(6):34-35)所引用。现将模式标本和鉴别特征列后。     

东方蝾螈

东方蝾螈 Cynops orientalis(David)是研究胚胎发育的良好材料,也可以作为观赏动物.它隶属于两栖纲、有尾目、蝾螈科、蝾螈属.我国福建、江西、浙江、江苏、安徽、湖南、湖北和河南等省均有分布. 形态和习性东方蝾螈分头、颈、躯干、四肢和尾五部分,成体全长6—8厘米.皮肤裸露,布有痣粒,背面黑色或灰黑色,腹面有不规则的桔红色斑块. 头部较扁,前端是宽大的咀巴,口腔顶部生有八字形的犁骨齿,是分类的重要依据.颈部不明显、躯干较扁、四肢较发达,前肢四指,后肢五趾,指(趾)间无蹼.尾侧扁而长.在水底和     

东方蝾螈幼体热耐受性和游泳表现的热驯化响应

特定物种的热驯化能力决定着其是否能成功耐受环境温度的改变,在应对未来气候变暖的趋势中扮演重要角色。为评估有尾类两栖动物的热驯化反应,在3个恒定水温(15、20℃和25℃)中驯化东方蝾螈(Cynops orientalis)幼体4周,测定驯化后幼体在不同测试温度下的运动(游泳)表现、临界低温(CT_(Min))与临界高温(CT_(Max))。结果显示:驯化与测试温度均显著影响蝾螈的游泳速度;驯化温度亦影响蝾螈的CT_(Min)和CT_(Max),但不影响可耐受温度范围(TRR)。驯化与测试温度的交互作用对蝾螈泳速的影响显著,表明驯化温度可改变其游泳表现的热敏感性。经某一温度驯化后蝾螈泳速似乎在相同测试温度下表现最好,该结果可能支持驯化有益假说。CT_(Min)和CT_(Max)随驯化温度的升高而增加,表明:低温驯化可提高动物抗低温能力,而高温驯化提高其抗高温能力。两栖类动物热耐受性与运动表现热驯化反应的种间变异可能与栖息地热环境的差异有关。     

浙江省望东垟高山湿地发现橙脊瘰螈（有尾目：蝾螈科）

2017年2月14日,在浙江省丽水市景宁畲族自治县望东垟高山湿地省级自然保护区(28°11′51.72″N,119°49′2.28″E,1 100 m)采集到瘰螈标本5号,通过形态特征测量和描述初步鉴定为橙脊蝾螈(Paramesotriton aurantius),并利用线粒体COⅠ基因序列进行分子鉴定,所采标本鉴定为蝾螈科(Salamandridae)瘰螈属橙脊蝾螈。该物种为浙江省两栖纲新记录种。     

蓝尾蝾螈早期发育的初步观察

关于有尾两栖类胚胎发育的研究,国外曾有过斑点钝口螈(Ambystoma maculatum)、红腹蝾螈(Triturus pyrrhogastre)和其他一些种类的胚胎发育资料。1960年以来,蔡堡、耿家举、曲韻芳等先后对国产种东方蝾螈(C. orientalis)的胚胎发育和胚后发育作了报道。其中,蔡堡教授的专著是研究得比较系统而详细的。但是,迄今这方面的资料仍然很少。     

Description of Hygrobates aloisii sp. nov. from Hong Kong, a new species of Hygrobates (Lurchibates) subgen. nov. (Acari, Hydrachnidia, Hygrobatidae), with data on the parasite-host relationship to the Hong Kong Newt Paramesotriton hongkongensis (Amphibia, Caudata, Salamandridae)

Adults and deutonymphs of a new water mite species of the genus Hygrobates Koch, 1837 (Acari, Hydrachnidia, Hygrobatidae) were found to parasitize the Hong Kong Newt, Paramesotriton hongkongensis Myers and Leviton, 1962 (Amphibia, Caudata, Salamandridae), endemic to Hong Kong and coastal areas of Guangdong Province: Hygrobates aloisii sp. nov. Males and females, as well as deutonymphs and larvae are described. A new subgenus - Lurchibates subgen. nov. - is defined to accommodate the species of the Hygrobates salamandrarum-group. The parasite-host association, infestation rate, attachment sites and the impact of mite infestation on the newts behaviour and body condition are investigated. These ecological aspects of the parasite-host association between freshwater mites and newts are examined for the first time in detail in their natural habitat.     

Replacement of a unique population of newts (<Emphasis Type="Italic">Taricha granulosa mazamae</Emphasis>) by introduced signal crayfish (<Emphasis Type="Italic">Pacifastacus leniusculus</Emphasis>) in Crater Lake,Oregon

The signal crayfish (Pacifastacus leniusculus) was introduced to Crater Lake in 1915 and now threatens the local extinction of an endemic salamander, the Mazama newt (Taricha granulosa mazamae). More than a century after their introduction, crayfish have expanded in distribution to occupy nearly 80% of the lakeshore. Although newts remain in uninvaded areas, they are almost entirely absent in crayfish occupied areas. Abundance of benthic macroinvertebrates was dramatically reduced in locations with crayfish compared with areas of the lake where crayfish were absent. Isotopic signatures of newt and crayfish tissue confirm overlap in the diets of the two species and demonstrate their similar position in the Crater Lake food web. Mesocosm experiments conducted with newts and crayfish revealed that crayfish prey directly on newts, displace newts from cover, and generally alter newt behavior. Combined, this evidence suggests that further crayfish expansion likely will cause additional declines in newt abundance and distribution, and could lead to extinction of the unique population of newts in Crater Lake.     

Postprandial thermophily in the Danube crested newt, Triturus dobrogicus

(1) Preferred temperatures were compared between fed and fasted newts with respect to their locomotor activity (LA) in an aquatic thermal gradient (5–32.5°C). (2) Locations and LA of 17 newts in postabsorptive phase were recorded over 24 h. (3) Nine randomly chosen newts were fed (10% of their body mass) and behaviour of all newts was recorded over the next 24 h. (4) Fasted newts preferred similar water temperatures during periods of both LA and inactivity. (5) Newts preferred 2–3°C higher water temperatures after feeding irrespective of the behavioural state.     

Skeletal Growth Marks and Testis Lobulation as Criteria for Age in Triturus spp. (Amphibia) in Central Norway

Two methods of age determination in newts. Triturus vulgaris and T. cristatus, have been examined and compared: (1) Counting growth rings in the bone tissue of humerus or femur is an accurate method, but possible supplementary rings may make the reading difficult. The innermost periosteal zone corresponds to the first year of life. Later, new zones are added each year. (2) Every second year after maturing a new lobe is developed on the testes. Knowing the juvenile life span in a population, it is possible to determine the age of male newts with a possible error of one year. The correlation between growth marks and testis lobes in T. vulgaris and T. cristatus is highly significant. The testis lobing method, however, is less applicable in older newts, since no more than three or four lobes can be developed on a testis.     

The breeding migration of Smooth and Palmate newts (Triturus vulgaris and T. helveticus) at a pond in mid Wales

The breeding population sizes of newts at Llysdinam Pond in 1981 are estimated at around 800 Palmate and 300 Smooth newts. Females were more numerous than males with sex ration of 3.0: 1 for Palamte and 2.6: 1 for Smooth newts. The movement of males of both species into the pond preceded that of females, and female Palmate newts moved out of the pond significantly later than the other classes. The number of females of both species leaving the pond was much less than the number entering, apparently as a result of mortality whilst in the pond. Females leaving the pond were significantly lighter than those entering, and for female Palmate newts the weight loss in only partly attributable to loss of egg load. Temperature and humidity were important factors influencing the number of newts active during the inward migration period, but had little effect on activity during the outward migration.     

Long day photoperiods and temperature of 20 degrees C induce spermatogenesis in blinded and non-blinded marbled newts during the period of testicular quiescence

Adult male marbled newts (Triturus marmoratus) were collected at the end of the spermatogenesis period and exposed to different photoperiods (natural-daylength-simulated photoperiod, total darkness, 8L:16D, 12L:12D, 16L:8D, and continuous light) for 3 mo. Temperature was maintained at 20 degrees C. Two additional groups of newts were blinded and exposed to either the natural-simulated photoperiod and to 16 h of light per day respectively. Quantitative histologic studies on testicular development and germ cell volume per testis were performed. The newts captured in the field at the beginning (initial controls) or at the end of the experiments (final controls) were in the period of testicular quiescence. Newts kept in total darkness or exposed to a short photoperiod (8L:16D) showed germ cell development up to primary spermatocytes, whereas germ cell development in the newts exposed to long photoperiods (12L:12D or 16L:8D) progressed to elongated spermatids. The newts exposed either to intermediate photoperiods (natural-simulated photoperiod) or to constant light showed an intermediate degree of germ cell development (up to round spermatids). No significant differences between non-blinded and blinded animals were found. These results suggest that (1) mild temperature initiates testicular development in the period of testicular quiescence, (2) long photoperiods associated with mild temperatures produce spermatogenesis in this period, (3) complete darkness or constant light are less effective than some intermediate photoperiod, and (4) the effect of photoperiod on testicular function in newts is not related to ocular photoreception.     

Fine‐scale selection by ovipositing females increases egg survival

One of the most important defenses for the eggs of ovipositing female organisms is to avoid being laid in the same habitat as their predators. However, for most organisms, completely avoiding an offspring's predators is not possible. One mechanism that has been largely overlooked is for females to partition an oviposition site into microhabitats that differ in quality for offspring survival. We conducted a series of experiments to examine whether female newts avoid microhabitats utilized by their offspring's primary predator, caddisfly larvae. Female newts avoided laying eggs near predatory caddisflies and shifted egg laying upward in the water column when provided with a vertical dimension. Caddisflies were attracted to chemical stimuli from female newts and their eggs, yet primarily used benthic areas in experimental chambers. Finally, results from a field experiment indicate that the behavioral strategy employed by female newts increases offspring survival. This subset of non‐genetic maternal effects, micro‐oviposition avoidance, is likely an important yet underexplored mechanism by which females increase offspring survival.     

Characteristics of newt breeding sites

Breeding site characteristics have been studied for the three species of newt that occur in Britain, the Palmate ( Triturus helveticus (Razoumowski)), Smooth ( T. vulgaris (L.)) and Warty ( T. cristatus (Laurenti)). The Warty newt was seldom found in the absence of the much commoner Smooth newt, but seemed to prefer sites that were relatively large and deep and that had a high proportion of open water surface. All three species tended to breed in ponds having abundant aquatic vegetation. Smooth newts, unlike Palmate newts, were rarely encountered in water with pH <6. The Smooth newt tended to be found in water with relatively high concentrations of metals, while the reverse was true for the Palmate newt. Over Britain, Smooth and Warty newts are relatively less common in soft water areas, while the Palmate is less common in hard water areas. Possible reasons for these associations are discussed.     

Differential Kin Discrimination by Red-spotted Newts (Notophthalmus viridescens) and Smooth Newts (Triturus vulgaris)

In organisms lacking parental care or when eggs of more than one female are layed together, parents preferentially tend to avoid eating their own offspring. In some species of newts (Caudata: Salamandridae), there is no parental care and cannibalism of eggs and larvae occurs when philopatric adults remain in the pond throughout the breeding season where eggs and larvae develop. Kin discrimination by both adult newts and larvae would be expected to occur during the breeding season as it would enable individuals to benefit from the nutrients obtained from eating eggs and larvae while they avoid eating close relatives. The effects of kinship on cannibalism of eggs and larvae were examined in two species of newts. In separate, but similar, paired behavioral trials adult female red-spotted newts, Notophthalmus viridescens, and smooth newts, Triturus vulgaris, were allowed to consume their own egg or an egg from another female. Female red-spotted newts, but not smooth newts, preferred to eat eggs of other females rather than their own, and overall smooth newts were ‘reluctant’ to eat conspecific eggs. To test for ontogenetic shifts in discrimination abilities, additional experiments were performed with adult female red-spotted newts paired with their own larvae and a larva from another female. In addition, the effects of kinship on the attraction or repulsion of larvae was also studied in red-spotted newts. Females showed no significant discrimination abilities during acts of cannibalism on larvae. Larvae spent similar amounts of time with siblings and non-siblings. These results suggest that the ability of adult newts to discriminate among eggs varies between species and that the elicitation of a kin-discrimination response may be context-dependent. For red-spotted newts, there was no evidence of discrimination abilities within and between other life-history stages.     

Cues from Introduced Fish Alter Shelter Use and Feeding Behaviour in Adult Alpine Newts

Amphibians are particularly affected by alien fish introductions and are declining worldwide. However, the behavioural mechanisms behind the observed cases of coexistence and exclusion patterns between adult amphibians and fish are poorly understood. In the present study, we aimed at testing the hypothesis that adult newts display different feeding and space use behaviour in the presence of fish cues (i.e. access less food resources and use more shelters than when fish cues are absent). To achieve this we measured behavioural patterns in 100 adult Alpine newts (Mesotriton alpestris) in a replicated laboratory design (20 tanks × 7 replicates across time). Half of trials involved individuals in indirect (visual and olfactory) contact with goldfish (Carassius auratus), a non‐predatory species for adult newts. In the presence of fish, significantly more newts hid under shelters than in their absence, but this difference decreased over time. A lower number of newts fed in comparison with controls. These results show that newts responded to fish presence even in the absence of direct contact, but the differences were small. Newts decreased vital activities such as exploration of open areas and feeding. They also adjusted shelter use over time, suggesting a process of habituation or a risk assessment in the absence of direct risk. These results reveal that exploring behavioural patterns can aid in understanding the causes of exclusion and coexistence patterns between fish and amphibians.