大鸨东方亚种遗传多样性的微卫星分析

为了探索东方亚种数量正在减少的原因和制定科学、有效的保护措施,利用微卫星DNA对大鸨东方亚种(Otistardadybowskii)的遗传多样性进行了研究。应用3个大鸨指名亚种的微卫星位点和13个波斑鸨的微卫星位点扩增了47个个体的基因组DNA,筛选出8个具有多态性的微卫星。其中有3个微卫星的多态性较低,其余5个微卫星的多态性较高。各位点的观察杂合度为0.0435-1.0000,平均杂合度(h)为0.6595;各位点多态信息含量(PIC)为0.0416-0.8520,平均为0.5497;有效等位基因数(E)为1.04-7.46,平均为3.61。4个位点符合HardyWeinberg平衡,4个位点偏离了HardyWeinberg平衡。多方面比较发现,大鸨东方亚种遗传多样性很低,且低于指名亚种,这可能由于其种群较小、历史遗传瓶颈作用、生境破碎化、分布地域紧缩等原因造成的。     

白洋淀流域大鸨越冬栖息地的适宜性评价

基于大鸨越冬期生境选择的相关研究成果,结合专家意见和近年来白洋淀流域大鸨的分布点记录,选择3项一级指标和13项二级指标,用以表征影响大鸨越冬生境选择的关键因子,并通过构建适宜性评价模型,对白洋淀流域大鸨越冬生境的质量进行了评价.结果表明:2005年,白洋淀流域内大鸨越冬适宜栖息地面积11907.25 km2,占流域总面积的34.1%;其中,最适宜生境面积4596.25 km2,仅占流域总面积的13.2%.研究区最适宜生境的空间分布相对集中,主要位于流域东部的白洋淀自然保护区及其周边(I区)和流域西南部的行唐、曲阳2县(II区).I区和II区中最适宜生境面积之和达2803.55 km2,占流域内最适宜生境面积的61.0%.为保护流域内大鸨的越冬生境,须重点针对上述2个区域的特点,分别采取适当措施加以保护.     

Isolation and characterization of microsatellite loci in the great bustard,Otis tarda

With the aim to study population genetics of the endangered great bustard, Otis tarda, dinucleotide microsatellite loci were isolated using an adapted hybrid‐capture enrichment protocol. This work reports the characterization of a set of six polymorphic microsatellite markers within the great bustard (n = 52). Results from cross‐species amplifications in several other members of the family Otididae demonstrate that five primer pairs also successfully amplified homologous loci outside the species Otis tarda.     

Population subdivision in Europe's great bustard inferred from mitochondrial and nuclear DNA sequence variation

A continent-wide survey of sequence variation in mitochondrial (mt) and nuclear (n) DNA of the endangered great bustard (Otis tarda) was conducted to assess the extent of phylogeographic structure in a morphologically monotypic bird. DNA sequence variation in a combined 809 bp segment of the mtDNA genome from 66 individuals from the last six breeding regions showed relatively low levels of intraspecific sequence diversity (n = 0.32%) but significant differences in the regional distribution of 11 haplotypes (phiST = 0.49). Despite their exceptional potential for dispersal, a complete and long-term historical separation between the populations from the Iberian Peninsula (Spain) and mainland Europe (Hungary, Slovakia, Germany, and Russia) was demonstrated. Divergence between populations based on a 3-bp insertion-deletion polymorphism within the intron region of the nuclear CHD-Z gene was geographically concordant with the primary subdivision identified within the mtDNA sequences. Inferred aspects of phylogeography were used to formulate conservation recommendations for this endangered species.     

Male sexual display and attractiveness in the great bustard Otis tarda: the role of body condition

Individual display rates and attractiveness of 17 radio-tagged, free-living great bustard males in north-western Spain were studied in relation to the degree of development of secondary sex traits, body condition, and age. Variance in display rate was significantly explained by body condition and length of moustache feathers, and neck development and display rate significantly accounted for the variance in male attractiveness. Age did not present any clear association with display rate or attractiveness, and it was significantly correlated only with neck development. These results suggest a total viability scenario of female mate choice in which the advertisement of global fitness is based on condition-dependent phenotypic and behavioural traits. Electronic Publication     

Field determination of age in male great bustards (Otis tarda) in spring

During a long-term study of individually marked, free-living male great bustards captured as chicks and radio-tracked through several years in Spain, we studied the development with age of two secondary sex traits, the moustachial feathers and the neck plumage pattern. Juvenile males acquired full adult plumage between their fourth and seventh years. The main changes occurred at the neck, coinciding with the onset of sexual maturity. The grey colour typical of immature males turned to ivory white around the fourth to fifth spring, and a gradual increase was appreciated in adults in the brightness of the white colour of the upper neck and in the contrast between this and a progressively more intense chestnut brown at the neck base. Based on these changes, we proposed four neck plumage patterns that can be used to differentiate male age classes during the mating period. The development of moustachial feathers showed more interindividual variability and was not as useful as the neck plumage to estimate male age.     

Proximate and ultimate causes of dispersal in the Iberian lynx Lynx pardinus

Most studies on the causes of animal dispersal focus on speciesof birds or small mammals, but there are few such studies onsolitary carnivores. A complete picture of the causes of animaldispersal is not possible without considering cases on a representativeset of animals. The Iberian lynx is a medium-size, solitarycarnivore that inhabits metapopulations, where dispersal playsa prominent role. Between 1983 and 1998 we studied the proximateand ultimate causes of dispersal in Iberian lynx in the Doñanametapopulation (southwestern Spain), based on radio-trackingof 49 individuals. Saturation of limited breeding areas in thissmall population leads to high dispersal rates in both sexes.Most lynxes dispersed from their natal area between 12 and 24months of age. Males younger than 1 year old tended to dispersein a higher proportion than females of the same age. However,high dispersal rates for both sexes by the age of 2 years andthe lack of differences in the dispersal distances do not supportinbreeding avoidance as an ultimate cause of dispersal. Dispersalmainly started between January and June (24/29 cases), whenmost social interactions occur, which supports the social subordinationhypothesis. Lynxes left the natal range at an earlier age fromthe local population with higher density, which supports intraspecificcompetition for resources as a cause for dispersal. However,prey seems not to be the limiting resource because dispersalmostly started during the season of increasing prey density,and individual probability of dispersal increases with preydensity in the natal area. Dispersers suffered higher mortalitythan nondispersing lynxes of the same age, due mostly to anthropogeniccauses. About half of the dispersers successfully settled ina territory at distances that differed between areas of origin,but not between sexes. Distances reached, shorter than thosereported for other similar-size solitary felids, are limitedby anthropogenic barriers that prevent connection with closermetapopulations.     

Alarming decline and range reduction of the highly threatened Great Bustard Otis tarda in Morocco

A Great Bustard Otis tarda survey carried out in spring 2015 in Morocco confirmed the decline of this highly endangered population. Bustards were only seen at two of the seven leks occupied ten years ago. The total number of birds counted was 40-44, which represents a 40% decline over the last decade. The sex-ratio was still strongly female-biased (1 male: 3 females), but less than in previous surveys, which suggests that trophy hunting has not been the major mortality cause in recent times. The productivity was 0.29-0.33 juveniles per female, the highest ever recorded in this population, suggesting that breeding success doesn’t represent the main problem for the survival of this population. Based on the recent development of the power line network at some areas, the main threat today is probably collision with power lines. Reducing this mortality cause should be considered a high conservation priority.     

Sex-biased dispersal and natal philopatry in the diamondback terrapin, Malaclemys terrapin

Nesting ecology and population studies indicate that diamondback terrapins (Malaclemys terrapin) exhibit nest site fidelity and high habitat fidelity. However, genetic studies indicate high levels of gene flow. Because dispersal affects the genetics and population dynamics of a species, we used six highly polymorphic microsatellite markers to investigate sex-biased dispersal and natal philopatry of M. terrapin in Barnegat Bay, NJ. We compared results of spatial autocorrelation analysis, assignment methods and Wright's F(ST) estimators to a mark-recapture analysis. Mark-recapture analysis over a 4-year period indicated that most individuals have relatively small home ranges (<2 km), with mature females displaying greater home ranges than males. Goodness of fit analysis of our mark-recapture study indicated that some juvenile males were likely transient individuals moving through our study location. Mean assignment indices and first-generation migrant tests indicated that mature males were more prone to disperse than mature females, but first-generation migrant tests indicated that per capita there are more female than male dispersers. Thus, the relative importance of males and females on gene flow in terrapin populations may change in relation to population sex ratios. Spatial autocorrelation analysis indicated that mature females exhibited natal philopatry to nesting beaches, but first-generation migrant tests indicated that a small number of females failed to nest on natal beaches. Finally, we discuss the important conservation implications of male-biased dispersal and natal philopatry in the diamondback terrapin.     

Philopatry and natal dispersal in a sedentary population of western marsh harrier

Dispersal is a key life-history trait because it influences population dynamics and population genetic structure. From a behavioural perspective, the study of natal dispersal requires some understanding of the mechanisms that affect individual movements, because movements of an animal form a path that is continuous throughout its life. Our aim was to investigate juvenile dispersal strategies in the western marsh harrier Circus aeruginosus , between fledging and first breeding attempt (from 1 to 4 years later, depending on the sex and individual). Using radio tracking, we monitored dispersing juvenile harriers and their home-range size variations within a sedentary population in central western France from 2001 to 2007. Juvenile dispersal strategy was mainly characterized by a very high natal philopatry (i.e. birds that remained within the study area) and short-distance dispersal. All but one bird (out of 39) remained within the study area between their first winter and their first spring, and 96.0% during their first spring. The distance moved at 2 years of age was significantly larger for males than for females (3800± sd 3593 m and 935± sd 481 m for seven males and six females, respectively), in contrast to most bird species studied so far. Home-range size was not sex biased and significantly decreased with age. In addition, non-breeding birds had larger home ranges (1603± sd 2128 ha) than breeders (349± sd 185 ha). Using data obtained from other populations, juvenile marsh harrier dispersal strategies appeared to be determined by migratory status (migratory birds dispersing farther) and demographic parameters (juvenile survival or fecundity).     

Natal dispersal in great bustards: the effect of sex, local population size and spatial isolation

1. We investigated the causes of natal dispersal in four Spanish areas where 35 breeding groups of the polygynous great bustard Otis tarda were monitored intensively. A total of 392 juveniles were radio-tracked between 1991 and 2006 by ground and via aeroplane to avoid potential biases derived from the non-detection of long-distance dispersers. 2. We explored 10 explanatory variables that were related to individual phenotypic features, habitat and conspecific traits in terms of group size and breeding performance, and spatial distribution of available breeding groups. Probability of group change and natal dispersal distances were investigated separately through multifactorial analyses. 3. Natal dispersal occurred in 47.8% of the birds and median natal dispersal distance of dispersers was 18.1 km (range 4.97-178.42 km). Sex largely determined the dispersal probability, with 75.6% of males being dispersers and 80.0% of females being philopatric, in contrast to the general pattern of female-biased dispersal found in most avian species. 4. Both the frequency of natal dispersal and dispersal distances were affected by the spatial distribution of breeding groups. More isolated groups showed a higher proportion of philopatric individuals, the effect being more evident in males than in females. This implies a reduction in gene flow in fragmented populations, as most genetic exchange is achieved through male dispersal. Additionally, dispersers hatched in more isolated groups tended to exhibit longer dispersal distances, which increases the associated energetic costs and mortality risks. 5. The dispersal decision was influenced by the number of conspecifics in the natal group. The individual probability of natal dispersal was related inversely to the size of the natal group, which supports the balanced dispersal model and the conspecific attraction hypothesis. 6. Overall, our results provide a good example of phenotypic plasticity and reinforce the current view that dispersal is an evolutionary complex trait conditioned by the interaction of individual, social and environmental causes that vary between individuals and populations.     

Genetic diversity of the great bustard in Iberia and Morocco: risks from current population fragmentation

We studied the genetic diversity of great bustards (Otis tarda) in Iberia and Morocco, the main stronghold of this globally endangered species. Samples were collected from 327 individuals covering most of the distribution range within the study area. Sequence variation in a 657 bp fragment of the mtDNA control region revealed 20 variable sites defining 22 haplotypes, two of them exclusive to Morocco. Genetic diversity showed marked regional differences (π = 0–0.53, h = 0–0.89). Multidimensional scaling analysis based on F _ST values showed a clear division between Morocco and the Iberian Peninsula, with no evidence of current gene flow between them. Our results suggest that Morocco, where few matrilines have persisted to present, was colonized from Iberia thousands of years ago. Last century reports suggest dispersal through Gibraltar, when the species was more abundant at both sides of the Strait but later population declines and the Strait’s barrier effect have favoured current genetic isolation. Within Iberia, only the most peripheral populations (Navarra, Aragón and Andalusia) differed significantly from the main ones in central Spain. The first two showed extremely low genetic diversity and are probably threatened by inbreeding depression. Diversity was higher in Andalusia, where three exclusive haplotypes were found, suggesting some degree of isolation from other populations. Andalusia and Morocco could be regarded as separate management units which hold a significant proportion of the current genetic diversity and thus deserve urgent conservation measures.     

内蒙古图牧吉大鸨种群动态及时空分布稳定性

大鸨（Otis tarda）是我国I级重点保护野生鸟类,对大鸨重要栖息地种群数量的变化趋势进行研究,将为大鸨及其栖息地的保护提供科学依据。2017年至2020年,对内蒙古图牧吉国家级自然保护区内及周边的大鸨种群数量动态进行了全面调查,共选择33个监测地点,对大鸨的数量、性别和分布地点进行了调查。结果表明,大鸨种群数量从2017年193只增加至2020年253只;大鸨1月的越冬种群数量从2017年67只减少至2019年55只,2020年重新恢复至67只。各月大鸨种群数量呈现较大的变化,数量高峰期分别是5月和10月。12月至次年2月,越冬种群数量50 ~ 70只。雌性大鸨从3月开始监测到,数量高峰值出现在4月和5月,达到50 ~ 70只,不同的年份略有差别;6月之后数量开始下降,至9月开始略有回升,在10月以后,野外基本观察不到雌性个体。在野外易于观察的4月,2017至2020年4年中雌雄比的平均值是1︰2。2017年和2018年,大鸨在马鞍山区域分布较多,数量也较为稳定。然而进入2019年,分布地点减少,这可能与当地人类活动的干扰有关;2020年保护区功能区进行了调整,将2014年调整出保护区范围的马鞍山区域重新划入保护区中,湿地和草地面积均有所增加,大鸨分布地点数量逐渐恢复。针对目前保护区存在的问题,建议采取退耕还草、加强保护空缺管理及禁牧等保护措施对大鸨及其栖息地进行保护。     

Costs and benefits of female-biased natal philopatry in the common goldeneye

Sex-biased natal dispersal in long-lived species may resultin interactions between parents and mature young of the philopatricsex. To investigate the evolutionary basis of natal philopatryin a noncooperative species, the common goldeneye Bucephalaclangula, we studied possible costs and benefits of simultaneousbreeding of females and philopatric daughters. We did not find any fitness consequences of a daughter's breeding on their mother'sbreeding in terms of nest-site selection, body weight, clutchsize, hatching date, or hatching success. Our results, therefore,did not support the assumption of the local resource competitionhypothesis, that the natally philopatric sex should be morecostly to a breeding parent. As possible benefits for daughters returning to their natal area, we tested inheritance of nestsites from mothers and explored whether daughters utilize thepresence of their mother by parasitically sneaking into hermother's nest. Daughters' nest-site selection was not associatedwith the presence of their mothers. A comparison between daughtersand control females revealed that daughters chose their nestsite closer to their natal nest than expected by nest-siteavailability alone. Daughters could not expect to inherit anest site from their mother, and we did not find other indicationsof cooperation between relatives either. The mother's clutchsize did not increase in the year breeding with the daughter, indicating daughters do not parasitize their mother's nest.We suggest that benefits such as decreased nest predation riskassociated with nesting close to the natal nest site may beimportant in the natal philopatric behavior of the species.