棕背伯劳两种色型繁殖特征的比较

棕背伯劳（Lanius schach）具羽色多态现象,其中黑色型是否为独立种曾存在着争议。为此,于2008年2—6月在广东海丰地区对两色型（棕色型和黑色型）的繁殖生态进行对比研究,以探讨黑色型的分类地位。结果表明：1) 两色型伯劳窝卵数、卵的度量值及发育上皆无显著差异(P>0.05);2) 两色型雏鸟在15日龄前的体长、翼长及体重等生长曲线均符合Logistic方程,除尾长渐进值参数呈显著差异（P<0.05)外,其他均无显著性差异(P>0.05);3) 据14日龄的雏鸟测量值表明,两色型在身体外部器官各项生长量度均无显著性差异(P>0.05);4) 易卵易雏实验表明,在孵卵和育雏过程中,两种色型棕背伯劳亲鸟之间皆可相互接受对方同一时期的卵和雏鸟,但不接受对方的异期卵;5）易雏后亲子和义子索食、站立、理羽、休息等行为差异不明显。因此认为黑伯劳只是棕背伯劳的一个色型而非独立种。     

Mate switching and copulation behaviour in King Penguins

Extra‐pair paternity (EPP) in monogamous birds may result from either extra‐pair copulations (EPCs) or mate switching. In this study of King Penguins in South Georgia, we observed no EPCs at all, an effect of very efficient mate guarding. Onshore males fast and need not divert attention to foraging or to defending nest or territory, as this species has neither. However, we found that mate switching was common. On average 38% (range: 29%–56%; three years pooled) of the birds established pair bonds with at least one initial partner before switching to the partner they bred with (i.e. the “pair mate”). Of the observed copulations of 44 studied females, 22% were with initial partners and 78% with the pair mate. This and the high proportion of mate switching suggest that roughly 10% of the females could have received sperm from males other than the pair mate. The average copulation frequency was 0.026 h^?1, resulting in an estimated 8.2 copulations per clutch (which consists of one egg). That more copulations than necessary for fertilisation occur suggests that males try to protect paternity by sperm competition, and that this is a result of the potential for EPP due to mate switching in King Penguins. All observed copulations except one took place between days 13 and 5, with the peak 7.5 days prior to egg‐laying. The birds found their pair mates (often not the same as in the previous year) on average about 10 days before egg‐laying, and always established themselves at the outskirts of the colony about 8 days before egg‐laying. Thus, most copulations occurred around the time the birds joined the colony. We suggest that it is adaptive to obtain a breeding spot early, because the colony will grow and pairs joining later will protect the offspring. Additionally, we suggest that early copulation outside the colony is adaptive because of the risk of failing to fertilise the egg when copulating among aggressive neighbours inside the dense colony. Based on these two arguments we suggest a “safe place hypothesis” to explain the early copulation peak in King Penguins.     

Eye structure and foraging in King Penguins Aptenodytes patagonicus

Anterior eye structure and retinal visual fields were determined in King Penguins Aptenodytes patagonicus using keratometry and an ophthalmoscopic reflex technique. The cornea is relatively flat (radius 32.9 mm) and hence of low refractive power (10.2 dioptres in air) and this may be correlated with the amphibious nature of penguin vision. The large size of the eye and of the fully dilated pupil may be correlated with activity at low light levels. In air, the binocular field is long (vertical extent 180̀) and narrow (maximum width 29̀), with the bill placed approximately centrally—a topography found in a range of bird species which employ visual guidance of bill position when foraging. Upon immersion in water, the optical power of the cornea is abolished, with the effect that the monocular fields decrease and binocularity is lost. King Penguins have a pupil type which has not hitherto been recorded in birds. In daylight it contracts to a square-shaped pinhole but dilates to a large circular aperture in darkness. This change alters retinal illumination by 300-fold (2.5 log₁₀ units). When diving, this permits the retina to be pre-adapted to the low ambient light levels that the birds encounter upon reaching mesopelagic depths. These penguins also forage at depths where ambient light levels, even during the day, can fall below the equivalent of terrestrial starlight. Under these conditions, the birds must rely upon the detection of light from the photophores of their prey. In this they are aided by their absolutely large pupil size and broad cyclopean visual field.     

Mate Choice and Colored Beak Spots of King Penguins

The theory of sexual selection explains sexual dimorphisms in ornaments used in mate choice. Mutual mate choice is a form of sexual selection that might explain sexually monomorphic ornamental traits. Under mutual mate choice, both sexes select partners based on the same ornament. We tested the mutual mate choice hypothesis in a mutually ornamented seabird, the king penguin (Aptenodytes patagonicus), through observations of the pair formation process in the field. Penguins that were ready to mate formed displaying pairs at the edge of the colony. Some of these pairs moved into the breeding colony and produced an egg (definitive pairs), while other pairs separated and often switched to another potential partner (temporary pairs). Colored ornaments were quantified using color vision modeling. We predicted that birds would mate assortatively by their elaborate ornamental traits (specifically, colors of beak spots, auricular patches of feathers, and breast patch of feathers). We also predicted that definitive pairs would exhibit more elaborate ornaments than temporary pairs. The mutual mate choice hypothesis was supported by assortative pairing for color of the beak spots, but not for color or size of the auricular patches or for the color of the breast patch. An alternative hypothesis was also consistent with our results, that female choice for a male ornamental trait and superior female condition associated with the same trait produced assortative pairing patterns. More UV‐ and yellow‐colored beak spots for females in definitive than temporary pairs supported the female choice hypothesis over the mutual mate choice hypothesis, but previous experimental results from altered beak spot colors supported the latter. Evidence to date thus supports both the mutual mate choice and female choice hypotheses.     

Post-Fledging Dispersal of King Penguins (Aptenodytes patagonicus) from Two Breeding Sites in the South Atlantic

Most studies concerning the foraging ecology of marine vertebrates are limited to breeding adults, although other life history stages might comprise half the total population. For penguins, little is known about juvenile dispersal, a period when individuals may be susceptible to increased mortality given their naïve foraging behaviour. Therefore, we used satellite telemetry to study king penguin fledglings (n = 18) from two sites in the Southwest Atlantic in December 2007. The two sites differed with respect to climate and proximity to the Antarctic Polar Front (APF), a key oceanographic feature generally thought to be important for king penguin foraging success. Accordingly, birds from both sites foraged predominantly in the vicinity of the APF. Eight king penguins were tracked for periods greater than 120 days; seven of these (three from the Falkland Islands and four from South Georgia) migrated into the Pacific. Only one bird from the Falkland Islands moved into the Indian Ocean, visiting the northern limit of the winter pack-ice. Three others from the Falkland Islands migrated to the eastern coast of Tierra del Fuego before travelling south. Derived tracking parameters describing their migratory behaviour showed no significant differences between sites. Nevertheless, generalized linear habitat modelling revealed that juveniles from the Falkland Islands spent more time in comparatively shallow waters with low sea surface temperature, sea surface height and chlorophyll variability. Birds from South Georgia spent more time in deeper waters with low sea surface temperature and sea surface height, but high concentrations of chlorophyll. Our results indicate that inexperienced king penguins, irrespective of the location of their natal site in relation to the position of the APF, develop their foraging skills progressively over time, including specific adaptations to the environment around their prospective breeding site.     

Inter-Annual Variability of Fledgling Sex Ratio in King Penguins

As the number of breeding pairs depends on the adult sex ratio in a monogamous species with biparental care, investigating sex-ratio variability in natural populations is essential to understand population dynamics. Using 10 years of data (2000–2009) in a seasonally monogamous seabird, the king penguin (Aptenodytes patagonicus), we investigated the annual sex ratio at fledging, and the potential environmental causes for its variation. Over more than 4000 birds, the annual sex ratio at fledging was highly variable (ranging from 44.4% to 58.3% of males), and on average slightly biased towards males (51.6%). Yearly variation in sex-ratio bias was neither related to density within the colony, nor to global or local oceanographic conditions known to affect both the productivity and accessibility of penguin foraging areas. However, rising sea surface temperature coincided with an increase in fledging sex-ratio variability. Fledging sex ratio was also correlated with difference in body condition between male and female fledglings. When more males were produced in a given year, their body condition was higher (and reciprocally), suggesting that parents might adopt a sex-biased allocation strategy depending on yearly environmental conditions and/or that the effect of environmental parameters on chick condition and survival may be sex-dependent. The initial bias in sex ratio observed at the juvenile stage tended to return to 1∶1 equilibrium upon first breeding attempts, as would be expected from Fisher’s classic theory of offspring sex-ratio variation.     

Sex identification in King Penguins Aptenodytes patagonicus through morphological and acoustic cues

In the context of sexual selection, animals have developed a variety of cues conveying information about the sex of an individual to conspecifics. In many colonial seabird species, where females and males are monomorphic and do not show obvious differences in external morphology, acoustic cues are an important signal for individual and sex recognition. Here, we study the vocal and morphological sex dimorphism in the King Penguin Aptenodytes patagonicus, a colonial, monomorphic seabird for which our knowledge about the role of vocalizations and morphology in mate choice is very limited. Data were collected at Possession Island, Crozet Archipelago, in a breeding colony consisting of about 16 000 breeding pairs. Using measurements of six morphological features and analysing acoustic parameters of call recordings of adult individuals, we show that King Penguins can be sexed based on a single morphological measurement of the beak with an accuracy of 79%. We found a sex‐specific syntax in adult King Penguin calls that provided a 100% accurate method to distinguish between the sexes in our study population. To confirm the method at the species level, we analysed calls recorded from King Penguin adults in Kerguelen Island, 1300 km away from our study population and found the same accuracy of the sex‐specific syntax. This sex‐specific syllable arrangement is rare in non‐passerines and is a first step in understanding the mate choice process in this species. Furthermore, it offers a cost‐effective, non‐invasive technique for researchers to sex King Penguins in the field.     

Presence of Breeding Birds Improves Body Condition for a Crocodilian Nest Protector

Ecological associations where one species enhances habitat for another nearby species (facilitations) shape fundamental community dynamics and can promote niche expansion, thereby influencing how and where species persist and coexist. For the many breeding birds facing high nest-predation pressure, enemy-free space can be gained by nesting near more formidable animals for physical protection. While the benefits to protected species seem well documented, very few studies have explored whether and how protector species are affected by nest protection associations. Long-legged wading birds (Pelecaniformes and Ciconiiformes) actively choose nesting sites above resident American alligators (Alligator mississippiensis), apparently to take advantage of the protection from mammalian nest predators that alligator presence offers. Previous research has shown that wading bird nesting colonies could provide substantial food for alligators in the form of dropped chicks. We compared alligator body condition in similar habitat with and without wading bird nesting colonies present. Alligator morphometric body condition indices were significantly higher in colony than in non-colony locations, an effect that was statistically independent of a range of environmental variables. Since colonially nesting birds and crocodilians co-occur in many tropical and subtropical wetlands, our results highlight a potentially widespread keystone process between two ecologically important species-groups. These findings suggest the interaction is highly beneficial for both groups of actors, and illustrate how selective pressures may have acted to form and reinforce a strongly positive ecological interaction.     

大头平胸龟体色、体形随年龄变化的初步观察

通过野外采集和室内饲养发现１、２、３、４、５龄的大头平胸龟体形、体色在不同的年龄段各不相同。一般要在５龄后才完全定型。该文报道了大头平胸龟的颜色、眉纹、后缘盾凹刻、肋盾突起以及股后及肛侧锥状鳞的变化规律。并指出,在标本鉴定中,上述特征的引用,应注意年龄的影响。     

The breeding biology and population dynamics of King Penguins Aptenodytes patagonica on the Crozet Islands

Among King Penguins Aptenodytes patagonica at Possession Island, one of the Crozet Islands, the length of the moult period, pre-laying period, incubating and brooding shifts were highly variable according to the year and to the stage of the breeding season. The moulting period was shorter in late breeders than in early breeders. Only half of the birds which successfully reared a chick bred the following cycle, but late in the season. Almost all these late breeders were unsuccessful. The reasons for the high variability in the breeding pattern observed in this species between years, as well as between colonies and between individuals are discussed. Breeding success was on average 30.6% and survival during the first year at sea could reach 50%. The survival of adult birds has increased during the past 10 years from 90.7% to 95.2% per annum. Despite an almost biennial breeding frequency and a very high rate of chick loss during the winter fast, the King Penguin population of Possession Island has doubled between 1966 and 1985 due to a high survival rate of adult and immature birds. The increase during the last decade in adult survival and in adult and chick condition suggests that the population increase could be the result of an improvement in food availability.     

Comparative fuel metabolism in Gentoo and King Penguins: adaptation to brief versus prolonged fasting

To compare fuel utilization in large birds adapted to brief or prolonged fasting, protein and lipid utilization were quantified in the Gentoo Penguin (Pygoscelis papua) and the King Penguin (Aptenodytes patagonica). The inshore feeder Gentoo Penguin fasts for only a few days in its colony, while King Penguin chicks starve for several months in the subantarctic winter and male King Penguins starve for 5–6 weeks at the beginning of their breeding cycle. After an initial decrease in both daily body mass loss and nitrogen excretion during the first days of food deprivation, these two parameters thereafter stabilized at low values. At that time, protein utilization accounted for 15% of total energy expenditure in Gentoo Penguins and only 6% in King Penguin chicks during winter, the remainder (85% and 94%, respectively) being provided by fat oxidation. Similar percentages in fuel metabolism as seen in chicks during winter were reached in fasting adult King Penguins and spring chicks. However, a seasonal adaptation occurs in fasting chicks because energy expenditure is lower during winter. As previously described in starved mammals, the effectiveness in protein sparing could be related to the initial adiposity of the birds: the larger the fat stores (about 9% and 30% in Gentoo Penguins and winter chicks of King Penguins, respectively), the longer the fast duration and the better the level of protein conservation.     

Genetics,Genomics and Breeding of Late Blight and Early Blight Resistance in Tomato

Late blight (LB), caused by the oomycete Phytophthora infestans, and early blight (EB), caused by the fungi Alternaria solani and A. tomatophila, are two common and destructive foliar diseases of the cultivated tomato (Solanum lycopersicum) and potato (Solanum tuberosum) in the United States and elsewhere in the world. While LB can infect and devastate tomato plants at any developmental stages, EB infection is usually associated with plant physiological maturity and fruit load where older senescing plants exhibit greater susceptibility and a heavy fruit set enhances the disease. At present, cultural practices and heavy use of fungicides are the most common measures for controlling LB and EB. Genetic resources for resistance have been identified for both diseases, largely within the tomato wild species, in particular the red-fruited species S. pimpinellifolium and the green-fruited species S. habrochaites. A few race-specific major resistance genes (e.g., Ph-1, Ph-2 and Ph-3) and several race-nonspecific resistance QTLs have been reported for LB. Ph-3 is a strong resistance gene and has been incorporated into many breeding lines of fresh market and processing tomato. However, new P. infestans isolates have been identified which overcome Ph-3 resistance. Recently, a new resistance gene (Ph-5) has been identified, which confers resistance to several pathogen isolates including those overcoming the previous resistance genes. Advanced breeding lines including Ph-5 alone and in combinations with Ph-2 and Ph-3 are being developed. Genetic controls of EB resistance have been studied and advanced breeding lines and cultivars with improved resistance have been developed through traditional breeding. Additionally, QTLs for EB resistance have been identified, which can be utilized for marker-assisted resistance breeding. Currently, new inbred lines and cultivars of tomato with good levels of EB resistance and competitive yield performance are being developed at the Pennsylvania State University. This review will focus on the current knowledge of both LB and EB with respect to the causal pathogens, host resistances, and genetics and breeding progresses.     

Body Girth as an Alternative to Body Mass for Establishing Condition Indexes in Field Studies: A Validation in the King Penguin

Abstract Body mass and body condition are often tightly linked to animal health and fitness in the wild and thus are key measures for ecophysiologists and behavioral ecologists. In some animals, such as large seabird species, obtaining indexes of structural size is relatively easy, whereas measuring body mass under specific field circumstances may be more of a challenge. Here, we suggest an alternative, easily measurable, and reliable surrogate of body mass in field studies, that is, body girth. Using 234 free-living king penguins (Aptenodytes patagonicus) at various stages of molt and breeding, we measured body girth under the flippers, body mass, and bill and flipper length. We found that body girth was strongly and positively related to body mass in both molting ([Formula: see text]) and breeding ([Formula: see text]) birds, with the mean error around our predictions being 6.4%. Body girth appeared to be a reliable proxy measure of body mass because the relationship did not vary according to year and experimenter, bird sex, or stage within breeding groups. Body girth was, however, a weak proxy of body mass in birds at the end of molt, probably because most of those birds had reached a critical depletion of energy stores. Body condition indexes established from ordinary least squares regressions of either body girth or body mass on structural size were highly correlated ([Formula: see text]), suggesting that body girth was as good as body mass in establishing body condition indexes in king penguins. Body girth may prove a useful proxy to body mass for estimating body condition in field investigations and could likely provide similar information in other penguins and large animals that may be complicated to weigh in the wild.     

梭鱼早期发育阶段体色形成与鳍的分化

采集池塘育苗的39日龄之前的梭鱼(Liza haematocheila)仔、稚、幼鱼,对其早期发育阶段体色的变化以及鳍的发生、发育进行了连续观察。初孵仔鱼体表不具黑色素,仅卵黄囊具黑色素,孵化后2日龄体表黑色素增加,鳍膜无色透明。8日龄仔鱼开始变得不透明,腹侧有黑色线状斑点。在18~19日龄仔鱼转化为稚鱼时,鱼体背部具大量雪花状黑色素颗粒,在透色光下可观察到淡黄色斑点(黄色素)。30日龄幼鱼与成鱼相似,体表具淡白色,背褐腹白。梭鱼仔鱼在早期发育阶段各鳍的发育顺序是:胸鳍→尾鳍→腹鳍→背鳍→臀鳍→第二鳍棘。初孵仔鱼,鳍褶从头部后缘向后绕过尾部,终止于卵黄囊后缘油球外侧。2日龄仔鱼具胸鳍芽,全身由鳍膜包裹,5日龄仔鱼胸鳍和尾鳍鳍膜已具有相当的运动能力,能够起到推动和维持身体平衡的作用。梭鱼鳍在早期发育过程中最明显的变化是尾鳍的生长和鳍节的发育。梭鱼仔鱼在12日龄时出现腹鳍棘芽基,15日龄时第二背鳍棘出现。17日龄,尾椎骨向上弯曲,尾鳍基本发育完成,长鳍条16根,具10节,中间几根棘条末三节二向分叉,短鳍条上下各6~8根;背鳍有鳍条11根,具5节,最外侧鳍棘具刺,基部有支鳍骨。至30日龄,梭鱼幼鱼各鳍发育完全,与成鱼相似。     

Plumage Bacterial Assemblages in a Breeding Wild Passerine: Relationships with Ecological Factors and Body Condition

Microorganisms have been shown to play an important role in shaping the life histories of animals, and it has recently been suggested that feather-degrading bacteria influence the trade-off between parental effort and self-preening behavior in birds. We studied a wild breeding population of great tits (Parus major) to explore habitat-, seasonal-, and sex-related variation in feather-degrading and free-living bacteria inhabiting the birds' yellow ventral feathers and to investigate associations with body condition. The density and species richness of bacterial assemblages was studied using flow cytometry and ribosomal intergenic spacer analysis. The density of studied bacteria declined between the nest-building period and the first brood. The number of bacterial phylotypes per bird was higher in coniferous habitat, while bacterial densities were higher in deciduous habitat. Free-living bacterial density was positively correlated with female mass; conversely, there was a negative correlation between attached bacterial density and female mass during the period of peak reproductive effort. Bacterial species richness was sex dependent, with more diverse bacterial assemblages present on males than females. Thus, this study revealed that bacterial assemblages on the feathers of breeding birds are affected both by life history and ecological factors and are related to body condition.     

The Relationship between Endogenous Androgens and Body Fat Distribution in Early and Late Postmenopausal Women

Objectives

To investigate the relationship between endogenous androgens and body fat distribution in early and late postmenopausal women.

Materials and Methods

We enrolled postmenopausal women consisting of an early group (≤5 years since menopause, n = 105) and a late group (≥10 years since menopause, n = 107). Each group was subdivided into normal weight (BMI <24 kg/m²) group, overweight and obese (BMI ≥24 kg/m²) group. Fasting total testosterone (T), dehydroepiandrosterone-sulfate (DHEA-S) and sex hormone-binding globulin (SHBG) levels were measured. Body fat distribution was evaluated by dual-energy X-ray absorptiometry (DEXA).

Results

Late postmenopausal women had a higher proportion of body fat than early postmenopausal women. The body fat of the overweight and obese women had a greater tendency to accumulate in the abdomen compared with the normal weight women both in early and late postmenopausal groups. The overweight and obese women had a higher free testosterone (FT) than the normal weight women in early postmenopausal women (P<0.05). In late postmenopausal women, the overweight and obese women had higher DHEA-S levels than normal weight women (P<0.05). No direct relationship was observed between the T levels and body fat distribution both in early and late postmenopausal groups (P>0.05).The FT in early postmenopausal women and the DHEA-S levels in late postmenopausal women correlated positively with the trunk/leg fat ratio (T/L) and the proportion of android fat whereas correlated negatively with the proportion of gynoid fat in the partial correlation and multiple linear regression analyses (all P<0.05).

Conclusions

Serum T levels do not correlate directly with body fat distribution, the FT in early postmenopausal women and DHEA-S levels in late postmenopausal women correlate positively with abdominal fat accumulation.     

Effect of Regain of Body Weight on Regional Body Fat Distribution: Comparison Between Pre- and Postmenopausal Obese Women

The aim of our study was to determine if regain of body weight increases visceral fat in obese women and if regain of weight has a different effect upon pre- and postmenopausal women. Twenty obese women (11 pre- and 9 postmenopausal) underwent a very low energy diet (VLED) for 2 weeks to lose weight. They then regained body weight in spite of the recommended hypocaloric diet. No significant modifications in body fat distribution indexes were found by computed tomography between VLED and after regain of weight. No significant changes were found in metabolic variables. No interactions between menopausal status and regain of body weight were observed. In conclusion, regain of weight does not seem to cause an increase in visceral fat; both pre- and postmenopausal women showed the same body fat distribution before weight loss and after regain of weight.     

红斑马鱼体色观察及敲除mitfa基因对其体色发育的影响

斑马鱼(Danio rerio)是一种常见的模式生物,红斑马鱼为小型观赏性鱼类之一.鱼类体色主要是由皮肤或鳞片上的色素细胞的种类和分布决定的.黑色素细胞诱导转录因子(MITF)主要调控动物黑色素细胞发育和分化.本文观察了红斑马鱼成鱼的背鳍、臀鳍、腹鳍、胸鳍色素细胞的组成和分布,跟踪观察了红斑马鱼早期体色发育过程.通过C...