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。     

多疣狭口蛙不同繁殖时期皮肤显微结构观察

采用常规石蜡切片及HE染色,对多疣狭口蛙不同繁殖时期背腹皮肤结构进行显微观察.结果发现:多疣狭口蛙3个不同繁殖时期皮肤结构无明显变化,其背部腺体要比腹部发达.尤其是颗粒腺,比腹部丰富.背部皮肤的色素层也比腹部发达.繁殖前期、繁殖中期粘液腺含量比繁殖后期略微多.     

多疣狭口蛙皮肤分泌物中FSH和LH的分离及在不同繁殖期的表达

运用聚丙烯酰胺凝胶电泳、葡聚糖凝胶层析、酶联免疫等实验方法,对多疣狭口蛙Kaloula verrucosa繁殖前期、繁殖期、繁殖后期的皮肤分泌物进行初步的成分分离,并对其不同时期皮肤分泌物成分中卵泡刺激素(Follicle stimulating hormone,FSH)及黄体生成素(Luteinizing hormone, LH)进行了免疫检测和定量比较.结果 表明:多疣狭口蛙皮肤分泌物中FSH的含量在其繁殖前期处于三个时期中的最高,繁殖期次之,繁殖后期最低;而LH则是在繁殖期含量最高,繁殖前期含量略偏低,到繁殖后期含量最低.     

敌敌畏对多疣狭口蛙不同发育期蝌蚪的急性毒性影响

为了解农药对不同发育期蝌蚪的毒性,以多疣狭口蛙Kaloula verrucosa蝌蚪为对象,采用水生生物急性毒性试验方法,研究杀虫剂敌敌畏(DDVP)对25期、26期、35期和42期蝌蚪的急性毒性影响.结果表明,在水温19.5～22.0℃条件下,敌敌畏对各期蝌蚪96 h LC50分别为1.13、1.43、1.38和0.61 mg/L,各期蝌蚪对敌敌畏的敏感顺序为42期>25期>35期>26期.由此得出敌敌畏对25期、26期和35期蝌蚪属中等毒性,对42期蝌蚪则表现为高毒.因此建议农药施用应尽量避开蝌蚪的变态期进行.蛙类胚胎期(出膜后)随着发育对外界环境的耐受性增强,蝌蚪期随着发育对外界环境的敏感性增强.鉴于42期蝌蚪意外死亡率高的特点,认为不宜采用变态期蝌蚪进行急性毒性试验.     

北方狭口蛙消化道嗜银细胞的分布与形态

应用Grimelius银染法观察北方狭口蛙消化道嗜银细胞的形态学特点,并统计分析嗜银细胞的分布密度。结果表明,消化道嗜银细胞可分为开放型细胞和闭合型细胞,两者的比值变化范围为0.20～0.49,从食管至直肠都以闭合型细胞为主。分布密度食管和胃体最高,空肠最低。北方狭口蛙消化道嗜银细胞的形态学特点和分布密度有自身的独特性,这可能与其善于穴居掘土的生活习性有关。     

中国两栖动物新纪录--多疣棘蛙的再证实

多疣棘蛙(Paa verrucospinosa(Bourret),1939)是Bourret于1937年根据越南沙巴采集到的标本订为棘胸蛙一新亚种[1],1939年他改订为新种[2]。寇治通等人1983年10月在云南省勐腊县景飘采到一只雌性成体蛙的标本,作为我国多疣棘蛙的新纪录发表[5]。但一直未得到承认[3,4,6~9]。笔者于2003年7月在云南省景洪市勐龙乡勐宋村、2004年8月在云南省勐腊县勐远镇艺班东村进行两栖动物调查时,采集到8号蛙类标本,经鉴定为蛙科棘蛙属多疣棘蛙(Paa verrucospinosa),这是中国两栖动物新记录,标本现保存于云南大学生命科学学院脊椎动物标本室,现报道如下。…     

云南昆明地区三种蛙皮肤显微结构的比较

对昆明地区的多疣狭口蛙、昭觉林蛙及黑斑蛙的背腹皮肤切片的显微结构进行了观察和比较,尤其对它们皮肤腺体的类型和功能进行了比较分析.结果 表明:多疣狭口蛙皮肤比昭觉林蛙及黑斑蛙皮肤含有更多的腺体,尤其是颗粒腺比后两者含量更为丰富,并且在皮下存在许多腺体团,背腹皮肤较后者厚.昭觉林蛙皮肤较黑斑蛙的含有更多的颗粒腺和粘液腺.3种蛙的背部皮肤都含有色素细胞,而除了在多疣狭口蛙雌性腹部观察到少量色素细胞外,另两种蛙在腹部皮肤中均未见色素层.相比之下,昭觉林蛙和黑斑蛙皮肤结构较相似,两者同多疣狭口蛙在皮肤腺体分布及数量上差别较大,这也体现了三者不同的生态适应机制.     

中国两栖动物新纪录——多疣棘蛙的再证实（图版封3）

多疣棘蛙（Paa verrucospinosa（Bourret）,1939）是Bourret于1937年根据越南沙巴采集到的标本订为棘胸蛙一新亚种,1939年他改订为新种。寇治通等人1983年10月在云南省勐腊县景飘采到一只雌性成体蛙的标本,作为我国多疣棘蛙的新纪录发表。但一直未得到承认。     

雌性凹耳蛙生育力与体型参数间相关性及其配对模式

为了探究雌性凹耳蛙(Odorrana tormota)生育力与体型参数之间是否存在相关性,测量了黄山浮溪地区23只排卵后雌蛙的体重、体长、头长、头宽、前臂宽、前肢及指长、前肢长、后肢全长、胫长等9个体型参数,并计数每只雌蛙的窝卵数。相关性分析显示,雌蛙的窝卵数和9个体型参数值均呈正相关性(P 0.05),体长和其他8个体型参数值均呈现正相关性(P 0.05),以体长为控制变量,偏相关分析显示,窝卵数和体重呈正相关性(P 0.05),故具有较长的体长、较重的体重特征的雌蛙,可以携带更多的卵,具有更强的生育能力。不同雌蛙个体间的窝卵数差异较大,平均窝卵数为(646.5±37.6)枚(590～706枚)。大个体雌蛙具有更强的生育力、更大的繁殖输出,可能是导致凹耳蛙两性间异形程度较大(雌大雄小)的重要驱动力。为了探究抱对雌、雄凹耳蛙之间的配对模式,测量了21对抱对雌、雄蛙的上述9个体型参数,分析显示,抱对雌、雄间9个体型参数值均不存在相关性(P 0.05),未发现凹耳蛙在性选择的过程中采用选型配对模式,雌性凹耳蛙可能倾向雄蛙非体型的品质特征,比如鸣叫声等。     

不同多疣壁虎种群繁殖特征的比较

对浙江地区3个多疣壁虎(Gekko japonicus)种群的个体大小、繁殖生活史特征进行了测定。在24 ℃、28 ℃和31 ℃条件下,孵化多疣壁虎卵,并测定其孵化期和幼体特征。结果表明：多疣壁虎成体存在显著种群间变异和两性差异,即衢州和温州个体大于杭州个体,雌体大于雄体;卵平均质量和窝卵重无显著种群间差异,但杭州壁虎的相对窝卵重显著大于衢州和温州个体;孵化温度能显著影响孵化期及幼体的尾长和头宽,但不影响幼体体长、体质量及运动能力;孵化温度效应不存在种群间差异。本研究揭示了疣壁虎个体大小、繁殖输出以及卵孵化特征的微地理变异。     

Mating system in the tarantula spider Eupalaestrus weijenberghi (Thorell, 1894): evidences of monandry and polygyny

The road tarantula Eupalaestrus weijenberghi shows a strongly female-biased sex ratio since adult females live several years while adult males live only for 2 months. In this scenario selective males could be expected. However, several factors such as the rates of reproduction of each sex, degree of sexual selectivity and synchronicity of female receptiveness determine the operational sexual ratio and mating system of the species. Our objective was to determine the mating rates and mating tactics for females and males of E. weijenberghi and their variation throughout the reproductive period. Four hundred sexual encounters among 20 females and 20 males in all possible pair-wise combinations were carried out during 29 days, a brief but intense experimental period, as it also occurs in the field. Mating success differed strongly between sexes. Females mated once: five females mated at the first attempt, eight initially rejected males and copulated in subsequent attempts. Half of the males did not copulate and the others copulated 1-3 times. Mated females actively rejected males. Results indicate a mating system with monogamous females and polygamous males. Not all the females were receptive in every reproductive season. We suggest that female monogamy drastically affects the operational sex ratio, since several females were unreceptive after a single copulation, directly diminishing the male potential reproductive rate. This is the first experimental approach to estimate tarantula mating systems, their determinants and the consequences of the strategies shown by each sex.     

Sexual selection for small size in male mosquitofish (Gambusia holbrooki)

In many poeciliid fishes, large males which court females coexist with small males which sneak-copulate. It is unclear whether these two tactics represent two evolutionarily stable strategies or if sneaking is a conditional strategy adopted by small, unattractive males. We studied the success of sneaky copulation by looking for sperm in the gonoduct of females after they were kept for 48 h with a male. A logistic regression analysis showed that the probability of a female being inseminated increased with female length and decreased with male length. The length of the male relative to that of the female was the best predictor of success. This result was confirmed using virgin females, thereby excluding any possible confounding effect due to the release of sperm from previous copulations. Sperm counts suggested that large males do not compensate for their reduced copulatory success by releasing larger sperm numbers. Behavioural data indicate that the advantages to small males are twofold: they have a greater chance to approach females from behind without being detected, and manoeuvre better when inserting the gonopodium into the female''s gonoduct. The selective advantage of small size might explain male dwarfism in poeciliids. Our results also suggest that small males adopting the sneaky tactic may be as successful as large males adopting courtship, and that alternative mating strategies may be maintained by negative density-dependent selection.     

Mating system and demographic constraints on the opportunity for sexual selection

In monogamous systems the fitness difference between males due to competition for mates is limited to one female. This constraint presumably impedes the action of sexual selection relative to polygynous systems. In this paper, we use formal selection theory to show how population size and the adult sex ratio constrain the force of sexual selection and phenotypic evolution under monogamy and polygyny. The force of sexual selection is ultimately constrained by the number of males in a population and the theoretical limit to the rate of male phenotypic evolution is realized if a single male mates with one or many females. These results imply that the force of sexual selection is not strictly constrained by monogamy. The constraint on female phenotypic evolution is typically higher than the constraint on males under polygyny and similar to selection on males in monogamous systems. The sexual asymmetry in the force of selection under polygyny--not necessarily weak sexual selection on males of monogamous systems--may explain the prominence of sexual dimorphism in polygynous systems.     

Mating tactics of male feral goats (Capra hircus): risks and benefits

Intense competition between males for reproduction has led to the evolution of alternative mating tactics (AMTs). Feral goat males usually use a tactic called tending, in which they defend oestrous females from other males. Males may also use a second mating tactic called coursing, in which they gain access to oestrous females by disturbing a tending pair. Herein, we examine estimated mating success (EMS) and risks of using these tactics. Tending was only used by mature (≥4 years old), higher-ranking males and accounted for 75% of EMS. Coursing was used by males of all ages and dominance ranks, and accounted for 25% of EMS. Using coursing, male kids achieved 8% of EMS. Mature males achieved 92% of EMS. Both age and dominance rank were related to EMS, but age was not important after its relationship with dominance was controlled. Tending bouts were, on average, ca. 30 min long, while coursing bouts only averaged ca. 2 min. Males were more likely to suffer a butt while coursing than while tending, and formerly tending males were responsible for most butts. Kids that coursed had the highest risk of being butted. In most AMTs, there are reductions in the risks in relation to low fitness benefits. However, we found that the risks of butts during coursing were high, while our evidence suggests that the EMS was probably low. Nevertheless, the existence of an effective AMT in male feral goats may have an important influence on the intensity of sexual selection and the effective population size.