The study of familial migratory network: An inquiry whithin the help center A. Chiara (Palermo)

The present paper proposes a synthetic methodology in order to give a more exhaustive picture of the migratory phenomenon by the use of different instructive sources. In particular we suggest a socio-demographic analysis of the procreative behaviour and familiar strategies. For this purpose a socio-sanitarian centre in Palermo, as a place of observation of the migratory realities, offers the possibility to investigate the process under different facets. The use of a non-institutional centre allows a direct contact with the “less visible” migrants which enables the researcher to get more complete information. This survey has adopted the questionnaire as main tool of investigation, in order to recognise the influences of kinship and cultural constraints. Two different but complementary typologies of questionnaires have been adopted: a familial background questionnaire and a gynaecological questionnaire.     

Metapopulation models for seasonally migratory animals

Metapopulation models are widely used to study species that occupy patchily distributed habitat, but are rarely applied to migratory species, because of the difficulty of identifying demographically independent subpopulations. Here, we extend metapopulation theory to describe the directed seasonal movement of migratory populations between two sets of habitat patches, breeding and non-breeding, with potentially different colonization and extinction rates between patch types. By extending the classic metapopulation model, we show that migratory metapopulations will persist if the product of the two colonization rates exceeds the product of extinction rates. Further, we develop a spatially realistic migratory metapopulation model and derive a landscape metric-the migratory metapopulation capacity-that determines persistence. This new extension to metapopulation theory introduces an important tool for the management and conservation of migratory species and may also be applicable to model the dynamics of two host-parasite systems.     

The medial migratory stream

Adult subventricular zone neurogenesis is an important process in most mammals. However, whether it persists in humans is highly debated. Recent work by Sanai and colleagues provides a major step in settling this debate. Using histological approaches, they demonstrated an active subventricular zone with limited neurogenesis in humans as well as discovered a new migratory route.     

Wing dimorphism and the migratory syndrome: Correlated traits for migratory tendency in wing dimorphic insects

The hypothesis that the morphological, physiological, and behavioral traits comprising the migratory syndrome in insects are genetically correlated through pleiotropic effects of genes controlling the titre of a common hormonal determinant is explored. Evidence that juvenile hormone (JH) influences the component traits of the migratory syndrome is presented, and thus JH is assumed to be the underlying, common determinant. However, readers are cautioned that this does not imply that JH is solely responsible for these traits, nor is this necessary for the arguments presented. For wing dimorphic taxa, the “correlated traits hypothesis” predicts covariance within wing morphs between JH titre and the proportion winged. Four simple genetic models for wing-morph determination are considered: single-locus with short-winged (SW) dominant; single-locus with long-winged (LW) dominant; polygenic, fixed threshold, shifting distribution; and polygenic, shifting threshold, fixed distribution. In each case, wing morphology is assumed to be a threshold trait with the liability being JH titre at some critical stage of development. All models predict covariation between %LW and the mean JH titre of at least one of the wing morphs, but the form and direction of the relationship depends critically on the genetic model used. The results suggest that we should expect the traits associated with the migratory syndrome, and hence the trade-offs associated with the evolution of wing dimorphism, to be correlated with proportion winged and, in this sense, to be frequency-dependent.     

Species-specific attraction of migratory banded kokopu juveniles to adult pheromones

Juvenile migratory Galaxias fasciatus juveniles or whitebait were attracted to odours produced by adults. The attraction was dependent on concentration with an upstream movement and attraction to the odour chamber at intermediate level concentrations. At a high concentration the migratory response of whitebait was retarded with the majority of fish not moving upstream but remaining in the lower section of the apparatus. There was no response to odours from adults of other galaxiid species, the inanga G. maculatus or koaro G. brevipinnis at any concentration. These results demonstrate G. fasciatus whitebait have the ability to discriminate species-specific pheromones during their migratory phase, providing evidence of a pheromonal attraction in migratory amphidromous fish which could possibly provide a basis for effective habitat selection.     

Overseas seed dispersal by migratory birds

Long-distance dispersal (LDD) promotes the colonization of isolated and remote habitats, and thus it has been proposed as a mechanism for explaining the distributions of many species. Birds are key LDD vectors for many sessile organisms such as plants, yet LDD beyond local and regional scales has never been directly observed nor quantified. By sampling birds caught while in migratory flight by GPS-tracked wild falcons, we show that migratory birds transport seeds over hundreds of kilometres and mediate dispersal from mainland to oceanic islands. Up to 1.2% of birds that reached a small island of the Canary Archipelago (Alegranza) during their migration from Europe to Sub-Saharan Africa carried seeds in their guts. The billions of birds making seasonal migrations each year may then transport millions of seeds. None of the plant species transported by the birds occurs in Alegranza and most do not occur on nearby Canary Islands, providing a direct example of the importance of environmental filters in hampering successful colonization by immigrant species. The constant propagule pressure generated by these LDD events might, nevertheless, explain the colonization of some islands. Hence, migratory birds can mediate rapid range expansion or shifts of many plant taxa and determine their distribution.     

Apulia (south Italy): From a land of emigration to a land of immigration

For more than a century Italian emigration contributed to rebalancing the labour market in Italy, through the absorption of significant numbers of the Italian workforce abroad and by alleviating unemployment levels, and also represented a source of national economic wealth. In the last two decades the Italian migratory trend has been reversed: there has, in fact, been an intensification of migratory flows towards Italy owing to the return of our compatriots, whose economic goals have been realised, and to the arrival of citizens either from poorer countries whose growth rate is zero or negative, or from developing countries. It is certainly necessary to bear in mind that the foreigners are not all workers: there are spouses, children, family members and other persons present for reasons other than work or family, and there are the children of immigrants born in Italy. The data regarding the wealth produced by the work of the immigrants could be significant, also and above all, in view of demographic shrinkage and the ageing of the Italian population forecast for the next fifty years. In view of this, immigration could become a real source of wealth both in economic terms and in terms of human capital. If we evaluate separately and comparatively the immigrations that take place for the demand for manpower and those due to flight from situations of economic and political hardship, we can see that Apulia, starting from 1990s, has become not only a land of passage towards the rest of Europe, but also an objective for settlement.     

Antennae: the strongest magnetic part of the migratory ant

Pachycondyla marginata (P.m.), a migratory and termitophageous ant, hunting only the termite species Neocapritermes opacus, migrates significantly oriented 13 degrees with respect to the magnetic North-South axis. Results of hysteresis curves at room temperature of four Pachycondyla marginata heads, thorax, pairs of antennae and abdomens, oriented parallel to the magnetic field, indicate that the antennae give the strongest saturation magnetization, suggesting this sensory organ as being also a magnetic sensory organ. The total saturation magnetization in a whole P.m. is composed by 42 +/- 3%, 24 +/- 3%, 19 +/- 3% and 15 +/- 3% of antennae, head, thorax and abdomen contributions, respectively. The abdomen hysteresis curve presents a wasp-waisted loop with Hcr/Hc of 4.75, characteristic of mixed magnetic systems.     

Cryopreservation of sperm in Brazilian migratory fish conservation

Simple, effective protocols for cryopreserving milt of five Brazilian migratory characids ( Brycon orbignyanus , Prochilodus lineatus , Piaractus mesopotamicus , Salminus maxillosus and Leporinus elongatus ) and one Brazilian migratory catfish ( Pseudoplatystoma corruscans ) are described. Milt was frozen and stored in dry shippers immediately after collection, making the procedure practical for use in the field. A diluent of 5% glucose, 10% dimethyl sulphoxide and 10% egg yolk was effective for all of the characid species, and a diluent of 10% methanol and 15% powdered milk was effective for P. corruscans . Milt was thawed in an ambient temperature water bath (28–30° C). Activation of thawed milt was effective with either saline (0·9 or 0·45% NaCl) or bicarbonate (1% NaHCO₃). Fertilization rates with frozen milt varied between 49 and 300% of the control. Application of the technology for increasing genetic diversity in hatchery programmes for enhancement, mitigation or conservation breeding is discussed, as is its application in aquaculture. Inappropriate use of the technology can threaten wild biodiversity and appropriate legislation and education may be required for its responsible use.     

飞蝗型变分子机理研究前沿

飞蝗的型变是重要的科学问题,也是防治害虫的理论基础。近年来,我国昆虫学家围绕飞蝗型变的分子机制方面取得一系列开创性的工作进展,鉴定了多个飞蝗型变的关键基因及其生物学功能,提出了飞蝗型变的分子机制。这些研究成果在PNAS,PLoS Genetics,Genome Biology,Bioinformatics,Insect Molecular Biology,Journal of Insect Physiology,PLoS One等国际著名刊物发表,极大地提高了我国在该领域的研究水平,为今后彻底解决飞蝗型变这一科学难题奠定了基础。     

九段沙湿地鸻形目鸟类迁徙季节环境容纳量

根据对九段沙湿地2005年春、秋季食物资源调查来计算迁徙期鸻形目鸟类的环境容纳量。结果表明,九段沙湿地春季食物总量为4541．20kgAFDW（去灰分干重）,秋季为2279．64kgAFDW,按鸻形目鸟类有效栖息生境计算,春季鸟类可利用食物资源量为3429．03kgAFDW,秋季为1700．92kgAFDW。通过鸟类体型类群分类（根据去脂净重、基础代谢率和体长）和能量消耗模型可以得出,九段沙湿地迁徙季节总食物量理论上可维持的鸻形目鸟类最大数量约为春季350万只,秋季175万只。按有效生境计算,春季约为260万只,秋季约为130万只。考虑到食物取入率的影响,九段沙湿地实际可容纳约13～26万只鸟类。根据地理信息分析可知,高潮位期有效栖息地的缺乏可能是限制鸟类数量达到估计上限的主要原因,建议在不危害保护区生态安全的前提下,开辟一些隐蔽性强的裸地和浅水塘,以提高鸻形目鸟类对九段沙湿地资源的利用率。     

Hybrid songbirds employ intermediate routes in a migratory divide

Migratory divides are contact zones between populations that use different routes to navigate around unsuitable areas on seasonal migration. Hybrids in divides have been predicted to employ intermediate and potentially inferior routes. We provide the first direct test of this hypothesis, using light‐level geolocators to track birds breeding in a hybrid zone between Swainson's thrushes in western Canada. Compared to parental forms, hybrids exhibited increased variability in their migratory routes, with some using intermediate routes that crossed arid and mountainous regions, and some using the same routes as one parental group on fall migration and the other on spring migration. Hybrids also tended to use geographically intermediate wintering sites. Analysis of genetic variation across the hybrid zone suggests moderately strong selection against hybrids. These results indicate that seasonal migratory behaviour might be a source of selection against hybrids, supporting a possible role for migration in speciation.     

对中国飞蝗种下阶元划分和历史演化过程的几点看法

前人把我国飞蝗划分为东亚飞蝗、亚洲飞蝗和西藏飞蝗三个亚种，并推测我国最原始的飞蝗发生地可能是郑州-开封东北至临清-禹南以南的古黄河冲积扇地带。由于飞蝗的形态、生理、生态等性状受气候与生态条件影响，从而在地区间变化很大，而且过去关于我国飞蝗发生动态和演化的分析均忽视了地史中重大气候事件的影响，因此有关结论的可靠性值得质疑并有待深入验证。根据分子群体遗传学的最新研究结果，我们认为：(1)我国飞蝗应被重新划分为青藏种群、海南种群和北方种群3大类群；(2)我国东部地区(辽宁、黄淮平原、陕西和山西)的飞蝗与海南的飞蝗之间的遗传差别已达亚种水平，因此不是东亚飞蝗，而是亚洲飞蝗经过适应性演化在我国华北地区形成的特异地理宗——华北地理宗；(3)华北地理宗的形成应是末次冰期后种群大规模扩张的结果，推测是由蒙新高原的飞蝗沿黄河流域逐步扩散而来；(4)结合历史上飞蝗发生的情况可以推断，在中国，至少在北至北纬46℃的地区，光周期不会成为飞蝗发育的限制性因素，有效积温可能是惟一限制性气候因子。因此，在气候逐渐变暖的趋势下，飞蝗有逐渐向北扩散的可能，东北地区将会逐步具有飞蝗大发生所需要的必要气候条。     

Development of lateralization of the magnetic compass in a migratory bird

The magnetic compass of a migratory bird, the European robin (Erithacus rubecula), was shown to be lateralized in favour of the right eye/left brain hemisphere. However, this seems to be a property of the avian magnetic compass that is not present from the beginning, but develops only as the birds grow older. During first migration in autumn, juvenile robins can orient by their magnetic compass with their right as well as with their left eye. In the following spring, however, the magnetic compass is already lateralized, but this lateralization is still flexible: it could be removed by covering the right eye for 6 h. During the following autumn migration, the lateralization becomes more strongly fixed, with a 6 h occlusion of the right eye no longer having an effect. This change from a bilateral to a lateralized magnetic compass appears to be a maturation process, the first such case known so far in birds. Because both eyes mediate identical information about the geomagnetic field, brain asymmetry for the magnetic compass could increase efficiency by setting the other hemisphere free for other processes.     

Migratory flows in apulia: Preliminary studies on some samples

The aim of this study is to analyse the structural characteristics, educational level, professed religion, composition of the family nucleus in Italy and in the home country, and work conditions in Italy and in the home country, in order to describe the anthropological stress of the sample of immigrants examined. A series of questions was given to Albanian population immigrating to the province of Bari after 1991, Albanian refugees of 1997, Chinese population resident in Bari, and a sample of immigrants in Metaponto, regarding their specific motives for immigration.     

The strength of migratory connectivity for birds en route to breeding through the Gulf of Mexico

The strength of migratory connectivity is a measure of the cohesion of populations among phases of the annual cycle, including breeding, migration, and wintering. Many Nearctic‐Neotropical species have strong migratory connectivity between breeding and wintering phases of the annual cycle. It is less clear if this strength persists during migration when multiple endogenous and exogenous factors may decrease the cohesion of populations among routes or through time along the same routes. We sampled three bird species, American redstart Setophaga ruticilla, ovenbird Seiurus aurocapilla, and wood thrush Hylocichla mustelina, during spring migration through the Gulf of Mexico region to test if breeding populations differentiate spatially among migration routes or temporally along the same migration routes and the extent to which within‐population timing is a function of sex, age, and carry‐over from winter habitat, as measured by stable carbon isotope values in claws (δ¹³C). To make quantitative comparisons of migratory connectivity possible, we developed and used new methodology to estimate the strength of migratory connectivity (MC) from probabilistic origin assignments identified using stable hydrogen isotopes in feathers (δ²H). We found support for spatial differentiation among routes by American redstarts and ovenbirds and temporal differentiation along routes by American redstarts. After controlling for breeding origin, the timing of American redstart migration differed among ages and sexes and ovenbird migration timing was influenced by carry‐over from winter habitat. The strength of migratory connectivity did not differ among the three species, with each showing weak breeding‐to‐spring migration MC relative to prior assessments of breeding‐wintering connectivity. Our work begins to fill an essential gap in methodology and understanding of the extent to which populations remain together during migration, information critical for a full annual cycle perspective on the population dynamics and conservation of migratory animals.     

东亚飞蝗不同来源聚集信息素的电生理活性

采用触角电位测定仪器测定不同来源的东亚飞蝗Locustamigratoriamanilensis聚集信息素的生理活性 ,结合行为生物测定的结果分析表明 :来源于粪便中的聚集信息素的活性较高 ,同时 ,使用较高极性溶剂抽提制备蝗蝻粪便中的信息素和采用中极性的溶剂制备成蝗粪便中的聚集信息素 ,其信息素的活性均较高 ;利用低极性溶剂从东亚飞蝗粪便中制备得到的聚集信息素的活性较低 ;采用层析柱吸附浓缩飞蝗粪便中自然挥发出的气味和飞蝗体表的气味并进行生物测定后表明 ,其EAG活性普遍较低 ;因此 ,来自于飞蝗粪便中的且采用合适的溶剂抽提制备的聚集信息素 ,具有较高的生物学活性。     

天津地区迁徙水鸟群落的季节动态及种间相关性分析

对天津地区迁徙水鸟群落的季节变化及迁徙物种间种群数量变化的相关性进行了研究.以每个调查日为聚类实体,以每日调查记录到的每个物种的数量为变量,采用聚类分析法分别对秋季和春季(1998～1999年)的水鸟群落的时间结构进行了聚类分析,得到以下结论秋季天津地区水鸟群落组成按时间顺序大致可以分为4个阶段,分别为9月20日～10月11日、10月16日～10日25日、11月3日～11月20日及11月26日～12月10日;春季也可分为4个阶段,分别为3月7日～3月10日、3月11日～3月14日、3月15日～3月21日及3月25日～4月21日.秋季各种水鸟迁经天津的时间较为集中,大部分种类在11月中、下旬的20多天内进入天津,而春季水鸟群落则大致可分为3月的雁鸭类高峰期和4月的鸻鹬类高峰期.对10种鸭类和10种鸻鹬类进行种间种群数量随时间变化的相关性分析表明,在45个鸭类配对中,有24对呈负相关,21对则呈正相关;在21种正相关的配对中,12对为显著正相关(P<0.05),其中6对为极显著正相关(P<0.001).在45对鸻鹬类配对中,有20对呈负相关, 25对呈正相关.在25对正相关的配对中,有10对显著正相关,其中2对呈极显著正相关.白秋沙鸭(Mergus albellus)、针尾鸭(Anas acuta)、绿翅鸭(A. Crecca)、黑尾塍鹬(Limosa limosa)与其他多个物种的正相关性显著.     

A unified evolutionary framework for understanding parasite infection and host migratory behaviour

Animal migration impacts organismal health and parasite transmission: migrants are simultaneously exposed to parasites and able to reduce infection for both individuals and populations. However, these dynamics are difficult to study; empirical studies reveal disparate results while existing theory makes assumptions that simplify natural complexity. Here, we systematically review empirical studies of migration and infection across taxa, highlighting key gaps in our understanding. Next, we develop a unified evolutionary framework incorporating different selective pressures of parasite–migration interactions while accounting for ecological complexity that goes beyond previous theory. Our framework generates diverse migration–infection patterns paralleling those seen in empirical systems, including partial and differential migration. Finally, we generate predictions about which mechanisms dominate which empirical systems to guide future studies. Our framework provides an overarching understanding of selective pressures shaping migration patterns in the context of animal health and disease, which is critical for predicting how environmental change may threaten migration.