家鹌鹑卵可进行孤雌发育

美国密西西比州立大学家禽科学系的科研人员最近针对鹌鹑的孤雌发育进行了研究。他们主要针对未受精的家鹌鹑卵是否能发育成胚胎，以及产卵的顺序是否会对发育有影响进行了研究。家鹌鹑第二性征羽毛出现在4周龄，此时将雄性与雌性分离以阻止受精。大约6周龄时母鹌鹑被单独饲养，每天收集卵并做标记。     

体外培养体系对牛体外受精胚胎性比的影响

研究了不同体外培养体系对牛体外受精胚胎性比的影响。结果表明，添加血清的2组培养系统中所得雄性囊胚与雌性囊胚的性比虽偏离了1：1，但差异不显著（P〉0．05），而总的体外胚胎的性比则显著偏离了1：1（P〈0．05）。这说明在体外培养系统中雄性胚胎比雌性胚胎发育能力更强，并且血清的存在对于雄性胚胎的发育有明显的促进作用。     

利用大卵培养优质蜂王

通常在养王实践中,选择繁殖力强、能维持大群、生产性能好的蜂群作母群,这是对的。但是在养王过程中,往往选择母群产卵旺盛期移虫养王,其结果是养出的后代处女王的初生重、外部形态和卵巢管数目不是增加而是减小。这是人们忽略了蜂王的产卵速度与卵重的关系、卵的大小对蜂王质量影响所造成的。育王所用的蜂卵的重量对子代蜂王的质量有很大的影响。最重的蜂王是育自较大的蜂卵,蜂王在春天和秋天产卵数相对少时,卵的体积大,在仲夏时节,产卵多,卵的重     

苏丹红Ⅰ对果蝇生殖发育和寿命的影响

为了研究苏丹红Ⅰ对果蝇的影响,试验以不同浓度苏丹红Ⅰ处理培养基饲养果蝇,测定了果蝇子代生殖力、生长发育周期及与寿命相关的3个指标。结果表明:苏丹红Ⅰ能诱发果蝇生殖细胞突变并导致不育,浓度越高对生殖力的影响越显著;而且生殖力一代比一代下降得更加明显,苏丹红Ⅰ浓度越高对后代延长卵期、幼虫期、生长发育周期的效应越显著,对后代降低寿命的效应越显著;而且这种影响也存在性别差异,表现出对雌性的影响大于雄性。     

影响蜂王调节性比的营养因素

在社会性膜翅目昆虫 ,群体后代的性比和生殖个体的比例可通过职虫来调节。职虫能分辩出幼虫的性别。它们为同性幼虫提供优先的照顾或除去雄性幼虫。职虫可通过调整雌性幼虫的食物类型来决定雌性群体。因此 ,它们能够决定在雄性个体和职虫间用于群体的发展和维持的投资分配。除了一些对职虫调节性比的经验观察外 ,在社会性膜翅目很少有对母王调节卵性比的潜在能力的研究。在蚂蚁 ,蚁王调节卵性比的能力种间有差别。但是蚁王能控制所产单倍体和双倍体卵的数量 ,并且职虫在这种限制下工作。因此 ,母王能够决定在何时产雄性生殖个体或非生殖个体…     

人工饲养环境下斑鳖产卵规律的研究

斑鳖目前仅在中国和越南的动物园中有4只存活个体,为了拯救这一物种,中国的苏州动物园和长沙动物园开展了斑鳖联合繁育项目。在2008～2011年对斑鳖的产卵时间、产卵窝数、产卵数量和卵的重量、直径等进行了测量。结果表明,雌性斑鳖在夜间产卵,有护卵行为。每年可产卵2—4窝,首次产卵在5月底或6月中旬,最晚在7月中旬结束。产卵间隔变化较大,最短的为12d,最长的达到36d,平均18．4±8．3d。每窝产卵数45～70枚,平均为60．3±7．5枚,年产卵总数在100～200枚之间,年度之间波动很大,在1～136枚之间。卯的重量在19．0-21．5g之间,平均20．1±0．7g;卵的直径在31．5～34．4mm之间,平均为32．6±0．7mm。产卵次数、窝卵数、卯重和大小都会受到运输或环境变化的影响。以上结果表明,目前提供的环境条件和饲养管理符合斑鳖的繁殖要求,但是管理中要注意减少运输应激和环境的改变。     

原尾蜥虎繁殖生态的探讨

对原尾蜥虎 (Hemidactylusbowringii,Gray)的雌雄成体外形差异、性腺发育、产卵与孵化特性进行了观测。其雄性成体头部大于雌性成体。雌雄性腺发育具有较明显的季节性变化。雄性睾丸 5月为最大值 ,重量 2 2 5mg ,其长径为 7 2 8( 6 8～ 7 5 )mm ,短径为 4 2 9( 4 0～ 4 5 )mm ,8月降为最低值 ,重量 3 74mg,其长径为 4 62 ( 4 5～ 5 0 )mm ,短径为 1 2 2( 1 1～ 1 4)mm ;雌性产卵盛期 5～ 6月 ,一年一次性产卵 2枚 ,卵重 0 2 9( 0 2 4 8～ 0 32 5 )g,卵的长径为 9 5 8( 8 45～ 1 1 4)mm ,短径为 7 91 ( 7 70～ 8 41 )mm。孵化期 42～ 46d。 6月中旬出现当年幼体。     

糖饲料对短头熊蜂工蜂群发育的影响

为探讨不同糖饲料对熊蜂发育的影响,优化短头熊蜂Bombus breviceps的糖饲料组配,本实验用市售3种糖源(白砂糖、葡萄糖和果葡糖浆)组配7组不同的糖水饲喂无王工蜂群,并统计蜂群发育相关性状。结果表明,饲喂不同糖饲料组配的蜂群发育期不同,其中工蜂产卵前期、子代雄蜂的卵期和幼虫拖出数存在差异,子代雄蜂的幼虫期、蛹期、出房时间、幼虫数、幼虫总重、蛹数、蛹总重量和初生重等发育性状指标差异不显著。饲喂白砂糖溶液,工蜂产卵前期和卵期最短,分别为3.00±0.00天和5.20±1.64天;而饲喂葡萄糖溶液时,时间最长,分别为6.50±1.97天和7.83±3.37天;白砂糖和葡萄糖混合液组幼虫拖出数量最多(3.76±2.66头),显著高于其他饲料组。本研究可为熊蜂繁育饲料组配优化提供基础数据。     

蚁群中不存在遗传冲突的工蚁监督

在群居动物中,互相之间抑制繁殖的监督机制在维持个体和种群的平衡中起着重要作用。社会性昆虫如蜜蜂、蚂蚁、黄蜂,工蜂(蚁)监督的对象是工蜂(蚁)所产生的只能孵化出雄性后代的卵,以使种群中的性比维持在一个合适的比例。然而,由于群体效率的说法还没有得到证实,种种迹象表明监督行为是由遗传冲突引起的,我们通过观察Platythyreapunctata(其工蚁能够孤雌产生雌性后代)蚂蚁来了解其中的规律。如果所有工蚁的繁殖均不受控制的话,那将会使整个群体崩溃。因此我们认为极具攻击性的工蚁通过对产卵工蚁的监督把产卵工蚁的数量控制在低水平。此外,…     

诱蝇球对柑橘大实蝇雌、雄成虫诱粘能力研究

通过羽化监测取得大实蝇Bactrocera minax（Enderlein）成虫雌雄性比数据,采用诱蝇球诱集方式,监测弃管园田间成虫数量和性比变化情况,对各时段诱集的雌性成虫进行卵巢解剖分级,发现诱蝇球对雌性成虫的诱集能力略高于雄虫;田间成虫盛期雌性成虫卵巢发育加快,普遍具备产卵能力,田间成虫盛期与产卵为害盛期同步。大实蝇防治实践中,根据成虫发生时间确定诱蝇球的使用时间,不必考虑性别影响。     

Geographic segregation and evidence of density‐dependent changes in sex ratios in an abundant colonial waterbird

Demographic information, such as geographic segregation of sexes and sex ratio data, is needed to develop, model and evaluate conservation and management strategies for wildlife. A variety of physiological, behavioral and environmental factors can influence segregation of sexes and sex ratios, many of which originate with density‐dependent processes. Departure from 50:50 sex ratios of double‐crested cormorants (Phalacrocorax auritus) collected during control efforts in breeding and wintering areas across their eastern range of the USA were evaluated using using a Z‐test as well as Stouffer's weighted Z‐tests. In addition, a specifically‐designed randomization test was used to evaluate density‐dependent effects on primary sex ratios in cormorants from egg collections and colony nest count data over a 21‐year period. Cormorants collected from breeding colonies were strongly male‐biased, whereas cormorants collected from feeding flocks were slightly biased toward females. Cormorants were partly segregated by sex on the wintering grounds, with significantly more males found in areas with intensive channel catfish aquaculture. The null hypothesis that females produced a balanced sex ratio independent of number of nesting cormorants was rejected: more male embryos were produced during rapid population growth, whereas at maximum nesting number more female embryos were produced. Once populations stabilized, the sex ratio was more equal. This examination of sex ratios indicates that different management methods and locations result in sex‐biased culling of cormorants. Sex‐biased culling in cormorants could make population reduction efforts more efficient and reduce overall take. We suggest further research to examine density‐dependent effects on primary sex ratios documented here.     

Existing theories do not explain sex ratio variation at birth in monomorphic roe deer (Capreolus capreolus)

The phenomenon of skewed sex ratios at birth has been reported in many ungulate species. So far, no consistent trend has emerged for roe deer (Capreolus capreolus), because male‐biased, female‐biased and equal sex ratios at birth have all been found. Nevertheless, both the Trivers‐Willard hypothesis and the theory of local resource competition have gained support. Despite the great number of studies carried out regarding the ecology of roe deer, too many aspects remain unclear, and contradictory results have been produced with respect to several crucial elements. Without further research, the discussion on which theory applies will therefore remain inconclusive. We put forward the argument that eventually the theories of Trivers‐Willard and local resource competition can be considered as being not essentially different. After all, both theories explain the observed skewed sex ratios as being due to the effect of the progeny's sex on the mother's body condition and hence her reproductive success in subsequent years. Furthermore, neither theory is likely to prove to be suitable for roe deer, as several assumptions are unlikely to be met. In roe deer, skewed ratios probably only have a temporal character. As a matter of fact, several observations of skewed sex ratios in birds and mammals did not withstand the accumulation of further data, as sex ratios that were initially believed to be biased turned out to be equal in the long term. This is likely to be the case in roe deer as well. We hypothesize that roe deer, as r‐strategists, will produce as many offspring as possible, regardless of sex.     

Nesting ecology of Ferruginous Duck Aythya nyroca in north-eastern Algeria

The status of waterbirds breeding in protected areas in North Africa needs constant monitoring because of a naturally fluctuating environment and permissive attitudes towards illegal activities likely to negatively affect population dynamics of threatened species. We present the results of a study conducted at a protected site, Lake Tonga, north-eastern Algeria, on a breeding population of Ferruginous Duck Aythya nyroca, a Near-Threatened duck subjected to considerable pressure from egg-pilfering and illegal hunting. Two distinct habitats within the lake were used by Ferruginous Duck: an Alder carr (Alnus glutinosa) and floating islets across the lake. The mean clutch size was 9.51±1.84 eggs (N = 51 clutches) with hatching rate of 80.7% for successful clutches. Breeding success was low (37%) with predation (33%) and clutch desertion (17%) accounting for the majority of failed nests. The probabilities of nest failure and nest desertion increased with a delayed onset of egg laying. Predation was not significantly associated with egg laying date and vegetation cover, but late breeders nesting in dense vegetation seemed to suffer less predation. Conspecific brood parasitism was positively associated with nest size, whereas interspecific brood parasitism was marginally associated with water depth. We discuss different hypotheses concerning nest desertion, and argue that illegal hunting and disturbance may best explain why birds desert their nests.     

Effects of social and climatic factors on birth sex ratio in Macaca mulatta in Mount Taihangshan area

Sex allocation theory predicts the optimal investment to male and female offspring. However, a biased sex ratio requires explanations as to why the deviation occurs. Rhesus macaque (Macaca mulatta) is the most widely distributed nonhuman primate species and the Taihangshan macaque (Macaca mulatta tcheliensis) occupies the northern limit of all rhesus macaque natural populations worldwide. We observed one macaque troop (Wangwu‐1 [WW‐1]) inhabiting Taihangshan Macaque National Nature Reserve and recorded all birth events and the sex of newborn macaques from 2004 to 2013. Our aim was to apply the Trivers–Willard hypothesis to this free‐ranging rhesus macaque troop, and to understand the relationship between climatic parameters (precipitation and temperature) and birth sex ratio. We found that the total newborn macaques showed a female‐biased sex ratio at birth in the WW‐1 troop, but there were no significant biased birth sex ratios in all matriarchs and in high‐ranking and middle‐ranking matrilineal units. However, the low‐ranking macaque matrilineal unit was significantly female‐biased. Moreover, we found that the annual precipitation of the previous year was positively associated with the birth sex ratio, and there was an interactive effect of troop size and current winter temperature on the birth sex ratio. The underlying mechanisms for the effects of social and climatic factors on birth sex ratio could be complex, and we discuss several plausible explanations.     

Sperm Supply and Egg fertilization in the Ostrich (Struthio camelus)

We used egg break‐out and spermatozoa trapped in the perivitelline layer of eggs to test the hypothesis that sperm supply and egg fertilization rate are high in the ostrich. Egg fertilization status was determined at break‐out by the appearance of the germinal disc (GD) and then the perivitelline layer overlying the GD region was collected to count sperm (Sperm_OPVL) under fluorescence following staining with 4′,6′‐diamidino‐2‐phenyindole (DAPI). The study was carried out on commercial ostrich farms over two laying seasons. In the first year, 229 eggs from nine randomly chosen ostrich pens comprising pairs, trios (two females, one male) and larger groups were collected for 1 week of every month of laying. Eggs contained 253 ± 18 Sperm_OPVL/mm² of the GD (mean ± SEM; range 0–1330). Egg fertilization rate averaged 89.4 ± 3.4% and varied from 78.6 to 98.2% between pens. Month had no effect on sperm supply or egg fertilization status. Eggs from paired birds (sex ratio 1 : 1) had less sperm in the GD than the eggs from pens with a higher sex ratio. In the second year, 150 eggs from seven pens, each containing only one male and either one, two or three females, were studied for 2 weeks at the beginning (winter), middle (spring) and end (summer) of laying. Eggs contained 364 ± 45 Sperm_OPVL/mm² of the GD (range 0–2880). Season had no effect on sperm supply or egg fertilization. The number of Sperm_OPVL varied between pens, assumed to be due to variation between individual males. The number of Sperm_OPVL increased as the sex ratio increased only when very high‐ranking males were excluded from the analysis. Egg fertilization rate was 94.4 ± 3.1% but varied from 64.0 to 100% between pens. Egg fertilization was not affected by season or sex ratio. Low fertilization rates were observed in two pens and appeared related to the lack of synchrony between timing of laying and sperm production in the first, and lack of mating in the second pen. We conclude that ostrich flocks generally have high rates of egg fertilization and any infertility is associated with lack of sperm supply.     

Influence of hatching order and brood size on growth in jackass penguins

Jackass penguins Spheniscus demersus hatch two different-sized eggs asynchronously: the second-hatched chick, being, on average, 59% of the weight of the first-hatched chick on hatching. We examined the effect of hatching order on growth rates of mass, culmen length and culmen depth by comparing: (i) growth rates of first-and second-hatched chicks, and (ii) chicks from experimentally synchronized broods to chicks from normal asynchronous broods. Only growth rates in mass showed significant variation. Within a brood, B chicks grew more slowly than A chicks. The effect of synchronizing a brood was to lower the growth rate of both chicks to that of a B chick, suggesting that equal-sized siblings feed less efficiently. Chicks hatching from larger A eggs, that had been synchronized for age and size with chiçks from B eggs, did not grow faster, indicating that chicks hatching from A and B eggs do not have intrinsically different growth rates. Single-chick nests result usually from egg infertility. Singletons showed only a non-significant trend towards faster growth in mass than offspring in two-chick broods, even though food availability in one-chick nests should be better than in two-chick nests. Overall, hatching order had more impact on growth rates of mass than did brood size or egg dimensions.     

Egg trait variation in a large hawk‐cuckoo (Hierococcyx sparverioides) host population of Chinese babax (Babax lanceolatus)

Mutual interaction between brood parasites and their hosts is a well‐known model system for studying host–parasite coevolution. Both parties have acted reciprocally, resembling an evolutionary arms race, in which adaptations and counter‐adaptations have evolved as a result of host–parasite dynamics, such as the classical cuckoo–host system. Discrimination among parasite and cuckoo eggs and rejection of foreign eggs is regarded as an important anti‐parasitism strategy. The Chinese babax (Babax lanceolatus) is a large hawk‐cuckoo (Hierococcyx sparverioides) host distributed in southwest China. A previous study shows that the babax is an intermediate egg rejector, and most cuckoo eggs are accepted by the Chinese babax, although a small proportion of hosts reject cuckoo eggs. Interestingly, the large hawk‐cuckoo lays non‐mimetic eggs in contrast to the uniform blue eggs of babaxes. Because egg coloration is a critical cue used by host species in favor of the recognition of parasitic eggs by hosts, we used a spectrometer to quantify egg color variation to understand the differentiation in discrimination ability between the egg rejectors and acceptors. We found that the chroma of intra‐clutch variation of babax eggs was more consistent in egg rejectors than in acceptors. However, no statistical significance was found in inter‐clutch variation between these two types of hosts. Our results suggest that hosts lay eggs with a low level of intra‐clutch variation without the necessity of a high level of inter‐clutch variation simultaneously as predicted by the egg signature hypothesis. This study may further indicate that selection pressures from evolutionarily recent parasites can drive individual‐based differences in an anti‐parasitism strategy.     

影响猪第二性比若干因素的研究

本文分析研究了２３８１窝共３４８２５头二花脸仔猪第二性比与若干因素的关系，发现产仔年份季节，胎次及产仔数等四个因素对仔猪第二性比有明显的影响，调控某些因素可望在一定程度上控制猪的第二性比。     

Reproductive management of captive parrots.

Studies of the behavior of Amazon parrots throughout a reproductive trial indicate that activities such as food gathering, which may occupy large fractions of the activity budget of wild parrots, occupy little time in captivity. This may be one factor contributing to the large percentage of time during which Amazon parrots are generally inactive in typical captive conditions. The extent of inactivity in captive Amazons creates an open time niche wherein enrichment devices might play a role in improving their well being. Studies of the reproductive endocrinology and the behavior of parrots suggest that hand rearing may impair adult fertility and nest box use. Hand rearing may also cause adult Cockatiels to lay eggs on cage floors rather than in nest boxes. However, the use of nest boxes with oversized nest entrances can be very effective in alleviating chronic floor laying in Cockatiels. Another egg-laying problem in Cockatiels, unwanted egg laying, can be prevented by the use of long-acting formulations of the superactive GnRH agonist, leuprolide acetate, which presumably [figure: see text] acts in birds, as in mammals, by down-regulating pituitary GnRH receptors. Manipulations to limit the increases in prolactin normally seen during incubation in poultry can significantly increase egg production. As clutch size in Cockatiels may also be limited by rising prolactin levels, such manipulations may be effective in stimulating egg production in parrots. An alternative approach for increasing flock egg production is to place foster eggs in nests of Cockatiel pairs that are slow to lay. This technique stimulates males to increase their nest-oriented behavior and, subsequently, may stimulate egg laying in some females that might not otherwise have laid eggs. The parental phases of reproduction in Amazon parrots are often a time of heightened aggressiveness towards humans, but low levels of serum testosterone in males during that time suggest that this particular interspecies aggressiveness may not be dependent on elevated testosterone levels. Occasional human handling during the nestling stage may produce a degree of tameness comparable with hand-reared chicks, yet not impair adult reproductive performance. Such handling may also alter the immune status of captive parrots, and possibly reduce the serum corticosterone response to handling. If so, occasional human handling during the nestling stage could improve the adaptation of parrots to captivity.