繁殖前期中国大鲵雄性成体的冲凉行为及其意义

为揭示和探讨中国大鲵(Andrias davidianus)繁殖前期的冲凉行为及其意义,在仿生态养殖环境条件下,采用定时定点观察法和全事件记录法,对雄性成鲵的冲凉行为过程及姿势进行了观察记录,并分析了冲凉行为与年龄、求偶行为、繁殖成功率之间的关系.繁殖前期雄性成鲵表现出冲凉行为,冲凉行为与求偶行为之间存在极显著的正相关,表现出求偶行为的6尾雄性成鲵有4尾成功参与了繁殖.冲凉行为可能促进了雄性成鲵精巢的发育,引发求偶行为,最终达到成功繁殖.     

中国大鲵的活动节律及繁殖行为描记

采用定时定点观察法,对仿生态条件下养殖的中国大鲵(Andrias davidianus)活动节律及繁殖行为进行了观察。结果表明,大鲵活动具有明显的昼夜节律变化,白天隐藏在洞穴中不活动,每天20:30时部分大鲵开始出洞活动,21:00时至次日凌晨1:00时为活动高峰期,1:00时后部分大鲵开始陆续回到洞穴,3:00时后又全部隐藏在洞穴中;大鲵的夜间活动随季节的变化而发生周期性变化,8～9月出洞活动的大鲵数量达到一年之中的最大值。大鲵尤其是雄鲵在繁殖季节表现出明显多样的繁殖行为:①推沙行为;②求偶行为,包括聚集、露头、巡视、追随、尾阴探究、亲吻、邀请和爬跨8种行为型;③冲凉行为;④护卵行为;⑤婚配行为。     

旅游干扰的水质模拟对繁殖前期中国大鲵夜间活动节律的影响

动物的日活动节律是它们对各种环境条件昼夜变化的综合适应。研究旅游干扰对繁殖前期中国大鲵(Andrias davidianus)的夜间活动节律影响,有助于探明旅游干扰是否以及如何影响大鲵繁殖行为的机理。前期研究发现旅游干扰程度与水中溶解氧(Dissolved Oxygen,DO)含量显著负相关。在大鲵繁殖前期,通过控制大鲵生态繁育池水中的进水量(主要影响DO含量)来模拟重度与轻度旅游干扰下大鲵水环境,通过监测大鲵夜间出洞与进洞时间、水温(Water Temperature,WT)、DO和大肠菌群的动态变化,比较不同旅游干扰强度下大鲵夜间活动节律的差异,以明确旅游干扰导致的水质变化对大鲵夜间活动节律的影响。结果表明,雌/雄鲵出洞时间在模拟重度旅游干扰水质下显著晚于轻度水质中,雌鲵分别为19:10±0:22与18:53±0:24,雄鲵分别在18:29±0:20与18:13±0:18。重度干扰导致水质变化分别推迟了雌/雄大鲵出洞时间约17 min与16 min。但是,雌雄大鲵进洞时间在模拟重度与轻度旅游干扰水质下,差异不显著,雌鲵分别为24:10±0:13与24:18±0:17,雄鲵分别为6:44±0:23与6:40±0:29。此外,该研究还发现,雌/雄鲵出洞时间与三种因子(WT、DO与大肠菌群)显著相关,然而,雌/雄鲵进洞时间与以上3因子不相关,可能主要由其生物钟决定。重度旅游干扰导致的水质变化对大鲵繁殖前期活动节律影响小,仅对出洞时间有一定影响。     

旅游干扰下水质对大鲵繁殖行为与繁殖力的影响

通过控制大鲵仿生态繁育池进水量模拟旅游干扰下的水质溶解氧特征,采用红外数字监控系统研究大鲵繁殖行为(产卵与护卵)及繁殖力(相对产卵量、受精率与孵化率)特点,分析它们与水质的关系,探讨旅游干扰导致的水质变化对大鲵繁殖行为及繁殖力的影响。结果表明: 与对照组相比,旅游干扰下大鲵的产卵行为与繁殖力未受到显著影响,但雄鲵护卵行为中的扇尾与搅动时间显著延长,以提高水中溶解氧浓度,满足大鲵胚胎发育需求;此外,旅游干扰下受精卵的孵化时间显著延长,但孵化率未受到显著影响。雄鲵护卵行为变化与受精卵孵化时间延长可能是大鲵对旅游干扰导致的水质变化的一种主动响应。     

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。     

郑州地区夜鹭的求偶行为

2003年及2004年3~6月在河南郑州市区对夜鹭(Nycticorax nycticorax)的求偶行为进行了观察。结果表明,3月中旬至5月底雄性夜鹭表现出占区及固定的仪式化求偶行为,主要包括伸展炫耀、扬举炫耀、炫耀羽毛和配偶形成后的相互爱抚4个方面,其中前两种行为是夜鹭主要的求偶行为。在营巢地,求偶行为从早上日出之前夜鹭觅食归来开始,一直持续至日落前后。夜鹭的配偶选择包括雄性之间对巢区的竞争、雄鹭与雌鹭的相互选择等一系列过程。     

张家界大鲵人工放流效果及其影响因素分析

大鲵(Andrias davidianus)是我国特有的两栖动物, 由于栖息地破坏和人类过度捕杀等, 种群数量急剧下降, 被列为我国II类保护野生动物。为探索大鲵人工放流的有效方法, 实现野生大鲵资源增殖, 作者对2002–2008年间在湖南张家界大鲵国家级自然保护区内进行的大鲵人工放流活动与放流效果进行了评估, 并通过对放流点的隐蔽物、水质及饵料生物等生境特点的分析, 探讨影响放流成败的因素。该保护区内共在9处大鲵原栖息地进行了11次人工放流活动, 共放流各种规格大鲵995尾, 其中4次成功。成功放流的大鲵为1–4.5 kg的性成熟个体, 雌雄比在1:1和1:1.5之间, 成功放流点均有良好的后期管理措施, 如建立保护站, 补充饵料等。虽然所选择的多数放流点生境基本能满足大鲵生长和繁殖的要求, 但由于受水质、饵料或安全某一因素的制约, 野生大鲵资源增殖效果不明显, 导致放流失败。因此我们认为依据野生大鲵繁殖的生境特征标准, 科学选择放流地点, 选择性成熟的大鲵在春季放流, 并进行完善的后期跟踪保护, 可能是大鲵人工放流成功和实现资源增殖的有效途径。     

池养大鲵的人工催产研究

本文报道了人工培育大鲵亲本的繁殖结果。在养殖条件下,大鲵的性腺可正常发育,大鲵的性成熟年龄为5龄,性周期为一年一次,群体的繁殖高峰期出现在每年的6—8月。使用LRH-A或HCG均可诱导大鲵产卵和排精。群体的性腺发育进程存在明显的个体差异,雄性比雌性的发育时间长10—20d。在繁殖盛期进行人工催产,获产率为60%左右。人工繁育的子代,在培育为亲本时,其性腺发育的个体差异仍然存在。养殖的性成熟个体,在没有受到外源激素作用时,将不会发生自然排卵现象,雄鲵不能挤出精液。在20—23℃下,雌性大鲵的效应时间约为96—120h,雄性可在80h后挤到精液。大鲵的产卵量为400—500粒,平均为430粒。多次产卵个体的产卵量多于初次产卵个体。低剂量的药物催熟,未发现对性腺发育进程和产卵结果有明显的促进作用。     

卢氏县大鲵种群年龄结构和性比的初步研究

对大鲵种群样本(n=252)及观察到的当年孵化的幼鲵进行测量,样本采自河南省卢氏县大鲵自然保护区。以大鲵体长、体重为指标,用重心法聚类划分出8个年龄组(不含当年孵化幼鲵)。在此基础上结合大鲵的生长发育特点,同时与人工养殖条件下的生长情况进行对照,根据样本聚类情况推断出大鲵5个个体年龄组及相应的体长和体重指标,对卢氏县大鲵20世纪90年代初的种群年龄结构和性比进行了分析,探讨了以大鲵体长和体重为生长指标、用聚类分析法划分大鲵年龄组的可能性。     

果蝇脑内多巴胺水平过高诱发雄性果蝇之间的“同性之恋”

求偶行为对于动物物种的繁衍和其对环境的适应都是非常重要的。果蝇的求偶行为是一个复杂的过程,它包括六个步骤：雄蝇转向雌蝇,拍打,唱求偶歌,舔雌蝇尾端,试图交尾和交尾成功。虽然求偶行为通常发生在异性之间,但某些基因的突变和异位表达可以诱发雄性果蝇间的求偶行为。     

The Influence of Pedipalp Autotomy on the Courtship and Mating Behavior of Pardosa milvina (Araneae: Lycosidae)

Male Pardosa milvina wolf spiders use their pedipalps both for copulation and courtship. Pedipalp loss is significantly more common among adult males compared to females. We measured the courtship and mating effects associated with the loss of one or both pedipalps among adult male P. milvina. Pedipalp loss significantly reduced courtship intensity, but had no influence on mounting success. Intact males were less likely to be cannibalized and suffered fewer predatory attacks by females than autotomized males. Loss of the left pedipalp resulted in significantly less intense courtship, higher female aggression levels, and delayed onset of courtship whereas loss of the right pedipalp minimally affected male and female behavior relative to intact males. Pedipalp displays may function in reducing female aggression rather than increasing female receptivity.     

The hector G-protein coupled receptor is required in a subset of fruitless neurons for male courtship behavior

Male courtship behavior in Drosophila melanogaster is controlled by two main regulators, fruitless (fru) and doublesex (dsx). Their sex-specific expression in brain neurons has been characterized in detail, but little is known about the downstream targets of the sex-specific FRU and DSX proteins and how they specify the function of these neurons. While sexual dimorphism in the number and connections of fru and dsx expressing neurons has been observed, a majority of the neurons that express the two regulators are present in both sexes. This poses the question which molecules define the sex-specific function of these neurons. Signaling molecules are likely to play a significant role. We have identified a predicted G-protein coupled receptor (GPCR), CG4395, that is required for male courtship behavior. The courtship defect in the mutants can be rescued by expression of the wildtype protein in fru neurons of adult males. The GPCR is expressed in a subset of fru-positive antennal glomeruli that have previously been shown to be essential for male courtship. Expression of 4395-RNAi in GH146 projection neurons lowers courtship. This suggests that signaling through the CG4395 GPCR in this subset of fru neurons is critical for male courtship behavior.     

Male sexual behavior does not require elevated testosterone in a lizard (Coleonyx elegans, Eublepharidae)

Male sexual behavior depends on gonadal androgens in species of all major vertebrate lineages, including reptiles. However, male sexual behavior includes distinct appetitive and consummatory phases, typically denoted as courtship and mounting, with potentially different hormonal control. Different proximate controls of courtship versus mounting could enable disconnected evolutionary losses and gains of various aspects of male sexual behavior. Male courtship display, which is activated by testosterone (T) in many species, is an ancestral trait in the lizard family Eublepharidae. However, Coleonyx elegans (Yucatan Banded Gecko) lost the courtship display, while retaining a highly simplified male sexual behavior that involves only mounting for copulation. We performed surgical manipulations (castration with and without T replacement in adult males; implantation of adult females with exogenous T) to investigate hormonal mechanisms involved in this evolutionary novelty. Our results indicate that the expression of simplified sexual behavior in C. elegans does not require elevated circulating levels of T, a finding that is previously unreported in lizards. In females, however, exogenous T induced male-like mounting. Thus, the mounting phase of sexual behavior is not activated by T in the traditional sense of this term but probably requires post-natal, maturational organization (if not periodic reorganization) by androgens. We conclude that the simplification of male sexual behavior and its independence from elevated levels of circulating androgens in C. elegans evolved via 1) evolutionary loss of the androgen-activated courtship display and 2) retention of the mounting phase, which has a longer “functional memory” for the effects of androgenic steroids.     

Drosophila male courtship behavior is modulated by ecdysteroids

Temperature-dependent induction of ecdysteroid deficiency in the ecdysoneless mutant ecd¹ adult Drosophilamelanogaster results in altered courtship behavior in males. Ecdysteroid deficiency brings about significantly elevated male-male courtship behavior including song production resembling that directed toward females. Supplementation with dietary 20-hydroxyecdysone reduces male-male attraction, but does not change motor activity, courtship patterns or attraction to females. These observations support the hypothesis that reduced levels of ecdysteroids increase the probability that male fruit flies will display courtship behaviors to male stimuli.     

Hormonal correlates of social status and courtship display in the cooperatively lekking lance-tailed manakin

Though cooperative behavior has long been a focus of evolutionary biology, the proximate hormonal mechanisms underlying cooperative interactions remain poorly understood. Lance-tailed manakins (Chiroxiphia lanceolata) are tropical passerines that form long-term male-male partnerships and cooperate in paired male courtship displays. To elucidate patterns of natural hormonal variation in relation to cooperation and reproductive behavior, we examined circulating androgen levels of male lance-tailed manakins in relation to social status, display behavior, and time of year. We found significantly higher circulating androgen levels in alpha-ranked (breeding) males compared to non-alpha adult males in the population. Beta males, which participated in courtship displays but did not copulate, had androgen levels indistinguishable from those of unpaired adult males that never displayed for females, suggesting that an elevated concentration of plasma testosterone in tropical lekking birds may be associated primarily with copulatory behavior or other status-specific traits, and not the performance of courtship display. Androgens decreased throughout the breeding season for males of all status categories. Interestingly, alphas that displayed for females in the observation session prior to sampling had lower androgen levels than alphas that did not display for females. This pattern may result from female discrimination against alpha males at display areas with high levels of social conflict among males, as social disruption is linked to elevated testosterone in many species. However, recent change of a display partner was not related to alpha androgen levels. We discuss alternative explanations and the possible implications of these results, and generate several testable predictions for future investigations.     

Underwater vocalizations and associated behavior in captive ringed seals (<Emphasis Type="Italic">Pusa hispida</Emphasis>)

In pinniped species, especially those that mate in the water, acoustic communication is suggested to play an important role in various aspects of behavior. However, little is known about the behavioral context or function of vocalization, principally because direct observation is difficult in the wild. In the present study, we analyzed the seasonality, sexual differences, and behavioral contexts of the vocalizations of captive ringed seals to explore the function of such communication. The behavior of and underwater sounds made by three ringed seals (an adult male, an adult female, and a subadult female) living in Otaru Aquarium, Japan, were recorded for 19 days between August 2011 and April 2012. Six call types (long snort, knock, yelp, bark, click, and woof) were identified in the recordings. The 12 observed social behaviors could be categorized into three categories (male courtship, aggression, and submission). All call types except clicks were vocalized during social behavior. Vocalizations of all types increased during the breeding season. The long snorts were only produced by the adult male toward an adult female during his courtship behavior. All three individuals emitted knocks, yelps, and bark sounds. Of these three call types, knocks were associated with aggressive behavior or the male’s courtship behavior. In contrast, alternate series of yelps and barks were vocalized by the recipients of aggressive behaviors, suggesting their function as submissive signals. This study could be applied to the monitoring of wild ringed seals with passive acoustic recordings to assess not only their distribution but also their behavior.     

Effect of social condition on behavioral development during early adult phase in <Emphasis Type="Italic">Drosophila prolongata</Emphasis>

Behavioral changes during early development provide useful insights into the internal mechanisms that generate complex behavior expressed by mature individuals. At the same time, social conditions during early adult phase can influence behavior in later stages of development even in holometabolous insects. In this study, age-dependent changes in courtship behavior and the effect of social conditions were examined in a fruit fly, Drosophila prolongata. Younger males showed lower mating activity and simpler courtship behavior. Mating activity reached a maximum level by 5 days after eclosion, whereas expression of complex courtship behavior was not yet fully developed at that time, suggesting that they are controlled by different mechanisms. When two males were maintained in the same vial, not only mating activity but also courtship complexity was reduced, demonstrating for the first time that preceding social experience, not current social conditions, influenced the complexity of male courtship. The effect of social experience was completely erased by 1 day of isolation, however, showing that social experience did not suppress or promote behavioral development itself. Rather, these results suggest that the observed effect of social experience was a plastic response of males that reduced investment in courtship effort by anticipating increased male–male competition.     

Role of the anterior hypothalamus-preoptic area in the regulation of courtship behavior in the male Canadian red-sided garter snake (Thamnophis sirtalis parietalis): intracranial implantation experiments

Testosterone (T) was administered intracranially to intact adult male Canadian red-sided garter snakes (Thamnophis sirtalis parietalis) in the fall and in the summer. Implants in the anterior hypothalamus-preoptic area (AH-POA) as well as other regions of the brain, including the medial and basal hypothalamus, thalamus, medial cortex, and third ventricle, failed to elicit courtship behavior. The spermatogenic stage was more advanced, and the circulating level of androgens was significantly higher, in animals that received implants of T in the AH-POA. These findings suggest the sex steroid-concentrating sites in the AH-POA of the garter snake are involved in feedback regulation of pituitary gonadotropin secretion and not in the control of courtship behavior. Hematocrit was found to be higher in animals that received implants of T, regardless of location, a response that may be related to changes in blood chemistry prior to hibernation. These findings support previous research indicating that in the adult male red-sided garter snake, a species exhibiting a dissociated reproductive tactic, courtship behavior is independent of testicular androgens.