Commensal ecology, urban landscapes, and their influence on the genetic characteristics of city-dwelling Norway rats (Rattus norvegicus)

Movement of individuals promotes colonization of new areas, gene flow among local populations, and has implications for the spread of infectious agents and the control of pest species. Wild Norway rats ( Rattus norvegicus ) are common in highly urbanized areas but surprisingly little is known of their population structure. We sampled individuals from 11 locations within Baltimore, Maryland, to characterize the genetic structure and extent of gene flow between areas within the city. Clustering methods and a neighbour-joining tree based on pairwise genetic distances supported an east–west division in the inner city, and a third cluster comprised of historically more recent sites. Most individuals (~95%) were assigned to their area of capture, indicating strong site fidelity. Moreover, the axial dispersal distance of rats (62 m) fell within typical alley length. Several rats were assigned to areas 2–11.5 km away, indicating some, albeit infrequent, long-distance movement within the city. Although individual movement appears to be limited (30–150 m), locations up to 1.7 km are comprised of relatives. Moderate F _ST, differentiation between identified clusters, and high allelic diversity indicate that regular gene flow, either via recruitment or migration, has prevented isolation. Therefore, ecology of commensal rodents in urban areas and life-history characteristics of Norway rats likely counteract many expected effects of isolation or founder events. An understanding of levels of connectivity of rat populations inhabiting urban areas provides information about the spatial scale at which populations of rats may spread disease, invade new areas, or be eradicated from an existing area without reinvasion.     

Isolation by environmental distance in mobile marine species: molecular ecology of franciscana dolphins at their southern range

The assessment of population structure is a valuable tool for studying the ecology of endangered species and drafting conservation strategies. As we enhance our understanding about the structuring of natural populations, it becomes important that we also understand the processes behind these patterns. However, there are few rigorous assessments of the influence of environmental factors on genetic patterns in mobile marine species. Given their dispersal capabilities and localized habitat preferences, coastal cetaceans are adequate study species for evaluating environmental effects on marine population structure. The franciscana dolphin, a rare coastal cetacean endemic to the Western South Atlantic, was studied to examine these issues. We analysed genetic data from the mitochondrial DNA and 12 microsatellite markers for 275 franciscana samples utilizing frequency‐based, maximum‐likelihood and Bayesian algorithms to assess population structure and migration patterns. This information was combined with 10 years of remote sensing environmental data (chlorophyll concentration, water turbidity and surface temperature). Our analyses show the occurrence of genetically isolated populations within Argentina, in areas that are environmentally distinct. Combined evidence of genetic and environmental structure suggests that isolation by distance and a process here termed isolation by environmental distance can explain the observed correlations. Our approach elucidated important ecological and conservation aspects of franciscana dolphins, and has the potential to increase our understanding of ecological processes influencing genetic patterns in other marine species.     

Biochemical assessment of evolution and taxonomy of the morphologically poorly diverged geckos, Gekko yakuensis and G. hokouensis (Reptilia: Squamata) in Japan, with special reference to their occasional hybridization

We assessed the validity of two gekkonid species, Gekko yakuensis and G. hokouensis, in southern Japan. We first assigned all 398 specimens into 18 samples merely on the basis of localities. By conducting significance test for deviations of genotype frequencies from Hardy‐Weinberg at 11 allozyme loci, we checked the reproductive unity of constituents in each of those local samples, and where necessary, rearranged them into subsamples on the basis of genetic markers so that we recognized minimum reproductively cohesive units. We then compared allele frequencies among all samples and subsamples examined. Results clearly indicated that all but two can be classified into two groups that can be discriminated from each other by remarkable allele frequency differences at four diagnostic loci, and by large genetic distances even between sympatric subsamples. Observations of morphological features of the samples and subsamples confirmed that the two groups correspond to G. yakuensis and G. hokouensis, supporting validities of these two species. Allele frequency comparisons, however, also revealed that the remaining two samples, both from southern Kyushu, possessed ‘marker alleles' of both G. yakuensis and G. hokouensis at all four diagnostic loci. These samples thus were considered to represent populations that have been derived through hybridization of the two species. Detailed analyses for genetic structures demonstrated that all hybrid genotypes in the two samples are post‐Fi generations with only one individual resulting from the back‐cross with a pure line population of G. yakuensis. This finding negates the possibility that the hybrid populations are maintained by a constant supply of newly produced Fj hybrids, but suggests that the hybrid genotypes constitute stable breeding populations. This implies that the genealogical independence of G. yakuensis and G. hokouensis in several other sympatric areas has been maintained by operations of some isolation mechanisms at a pre‐mating phase. Investigations of the morphological variation in each sample or subsample revealed that although the two species can be externally largely discriminated from each other by slight modifications of the currently used diagnoses, it is difficult to detect their hybrids based solely on the morphological features.     

Further expansion of the genus Cercopagis (Crustacea,Branchiopoda, Onychopoda) in the Baltic Sea,with notes on the taxa present and their ecology

The onychopod cladoceran Cercopagis that recently invaded the Baltic Sea is reported from new zones of the northern Baltic proper. Because of successful survival and an expanding distribution range, the addition of Cercopagis to the Baltic fauna is considered to be permanent. What has previously been cited as Cercopagis pengoi encompasses the morphology of several other species, subspecies and forms. Either a number of morphologically similar species is present, or there is a number of spurious species in Cercopagis. The last hypothesis is favoured. The spatial distribution pattern of Cercopagis, as well as that of total zooplankton, was correlated with depth. Deep (>100 m) and shallow (<10 m) stations had significantly lower abundance than stations of intermediate depth (<100 m). An overview of the distribution of C. pengoi group in fresh and brackish waters suggests a high tolerance to environmental factors, but with differences among taxa. Due to this ecological flexibility, the colonization of the Baltic is not unexpected. Increasing salinity may restrict dispersal of cercopagids to the southern areas of the Baltic and to the North Sea, but inland lakes (e.g. in Sweden) present an ecological profile suitable for colonization.     

Population structure, growth and reproduction of roughhead grenadier on the Flemish Cap and Flemish Pass

Roughhead grenadier Macrourus berglax were collected during the Flemish Cap bottom survey (1991–2001, NAFO division 3M, depth of 200–720 m) and on commercial vessels (1998–2000, NAFO divisions 3L, M and N, depth of 700–1700 m). The abundance of roughhead grenadier, as well as their average size, increased with depth. Age and length composition of the catches showed clear differences between the sexes. The proportion of males in the catch declined in the larger length classes and there were no males in the largest length classes (25 cm). There were differences in the growth trajectories of the two sexes; both sexes grew similarly up to 9 years, but the male growth was slower thereafter. The pre-anal fin length at first maturity ( L _PA50) for roughhead grenadier females was 28·5 cm, whilst the age at 50% maturity was 15–16 years. Individual total fecundity varied between 8522 and 61 844 oocytes. Macrourus berglax had a prolonged life cycle and multi-aged population structure, with differences in growth and mortality between males and females, slow maturation and low fecundity.     

混合生物结皮对土壤养分的影响与群落结构之关联——以黄土丘陵区的生物结皮为例

自然条件下生物结皮是藻、藓及地衣等结皮类型以不同比例组成的混合群落,显著影响土壤养分含量,目前混合生物结皮对土壤养分的影响与其群落结构的关系尚不清楚,限制了混合生物结皮土壤养分的评估。为此,研究通过测定单一组成的藻结皮、藓结皮以及80%藻+20%藓、60%藻+40%藓、40%藻+60%藓和20%藻+80%藓4个不同藻藓比例的混合生物结皮土壤有机碳、全氮、全磷、速效磷、铵态氮和硝态氮含量,研究了混合生物结皮土壤养分与其群落结构之间的关联。结果显示：(1)藓结皮层土壤有机碳、全氮、速效磷、铵态氮和硝态氮含量显著高于藻结皮,分别高出166.4%、77.2%、55.1%、56.2%和42.2%。(2)藻藓混合生物结皮土壤有机碳、全氮、速效磷和铵态氮含量与组成和盖度等结构特征有关,可以通过单一类型生物结皮土壤养分含量与盖度加权预测混合生物结皮土壤养分储量。(3)混合生物结皮土壤有机碳、全氮、速效磷和铵态氮储量实测值(x)与预测值(y)拟合的线性函数分别为y=0.97x、y=0.96x、y=1.18x和y=0.92x。(4)混合生物结皮对全磷和硝态氮含量的影响与群落结构无关。生物结皮对下层0—5 ...     

A second species of Oculogryphus (Coleoptera, Lampyridae), with notes on the phylogenetic affinities of the genus

A second species of the enigmatic lampyrid genus Oculogryphus is described and figured as Oculogryphus bicolorsp. n. from Vietnam. The definition of the genus is slightly modified with consideration of newly detected morphological variation from this species. According to a comprehensive phylogenetic analysis including nearly 80% of documented lampyrid genera, Oculogryphus is the putative sister group to Stenocladius s. str. within the paraphyletic group of Ototretinae-Ototretadrilinae.The classification of Stenocladius is briefly discussed in this context.     

Primates in northern Viet Nam: A review of the ecology and conservation status of extant species,with notes on pleistocene localities

We discuss the distribution of living and fossil primates in northern Viet Nam, integrate new localities into the known ranges, and address the ecological parameters and status of extant primate species. In addition, we interpolate fossil specimens from Pleistocene cave sites into the discussion of current ranges. This approach provides a unique glimpse into the past ranges of extant species in a tropical setting, which is unavailable for most regions of the world. Finally, we review the effects of ecocide and other anthropogenic threats to nonhuman primates in Viet Nam.     

A phylogenetically informed search for an alternative Macrostomum model species,with notes on taxonomy,mating behavior,karyology, and genome size

The free-living flatworm Macrostomum lignano is used as a model in a range of research fields—including aging, bioadhesion, stem cells, and sexual selection—culminating in the establishment of genome assemblies and transgenics. However, the Macrostomum community has run into a roadblock following the discovery of an unusual genome organization in M. lignano, which could now impair the development of additional resources and tools. Briefly, M. lignano has undergone a whole-genome duplication, followed by rediploidization into a 2n = 8 karyotype (distinct from the canonical 2n = 6 karyotype in the genus). Although this karyotype appears visually diploid, it is in fact a hidden tetraploid (with rarer 2n = 9 and 2n = 10 individuals being pentaploid and hexaploid, respectively). Here, we report on a phylogenetically informed search for close relatives of M. lignano, aimed at uncovering alternative Macrostomum models with the canonical karyotype and a simple genome organization. We taxonomically describe three new species: the first, Macrostomum janickei n. sp., is the closest known relative of M. lignano and shares its derived genome organization; the second, Macrostomum mirumnovem n. sp., has an even more unusual genome organization, with a highly variable karyotype based on a 2n = 9 base pattern; and the third, Macrostomum cliftonensis n. sp., does not only show the canonical 2n = 6 karyotype, but also performs well under standard laboratory culture conditions and fulfills many other requirements. M. cliftonensis is a viable candidate for replacing M. lignano as the primary Macrostomum model, being outcrossing and having an estimated haploid genome size of only 231 Mbp.     

, Jost's D,and FST are similarly constrained by allele frequencies: A mathematical,simulation, and empirical study

Statistics and Jost's D have been proposed for replacing F_ST as measures of genetic differentiation. A principal argument in favour of these statistics is the independence of their maximal values with respect to the subpopulation heterozygosity H_S, a property not shared by F_ST. Nevertheless, it has been unclear if these alternative differentiation measures are constrained by other aspects of the allele frequencies. Here, for biallelic markers, we study the mathematical properties of the maximal values of and D, comparing them to those of F_ST. We show that and D exhibit the same peculiar frequency‐dependence phenomena as F_ST, including a maximal value as a function of the frequency of the most frequent allele that lies well below one. Although the functions describing , D, and F_ST in terms of the frequency of the most frequent allele are different, the allele frequencies that maximize them are identical. Moreover, we show using coalescent simulations that when taking into account the specific maximal values of the three statistics, their behaviours become similar across a large range of migration rates. We use our results to explain two empirical patterns: the similar values of the three statistics among North American wolves, and the low D values compared to and F_ST in Atlantic salmon. The results suggest that the three statistics are often predictably similar, so that they can make quite similar contributions to data analysis. When they are not similar, the difference can be understood in relation to features of genetic diversity.     

被子植物地下结实和地上/下两型结实的生态适应意义

地下结实和地上/下两型结实是被子植物两类独特的结实方式, 多发生在陆生和草本植物中, 主要生长在缺少水分或光照、土壤扰动频繁及环境波动较为剧烈的生境中。两种结实方式不仅是植物适应性进化的重要方面, 也是选择性进化的产物。其中, 地下结实对于植物在母株附近适宜微环境中保存后代、在极端环境下保持种子活力、逃避地面动物取食和火灾伤害以及延长果实发育时间等方面, 地上/下两型结实对于减少同胞子代及种群内竞争、维持和扩大种群以及提高物种的适应力和进化可塑性等方面, 都具有重要的生态适应意义, 是植物抵御不利生物与非生物环境的两类重要防御策略。但两种结实方式同时也存在着限制果实与种子扩散、影响基因传递与种群遗传结构、加大种群隔离以及提高繁殖代价等进化限制, 对物种的分布、种群增长、迁移、适合度和生活史进化等具有重要影响。目前, 地下和地上/下两型结实现象分别在大约24科57属和13科34属中进行了报道, 其中在菊科、十字花科、豆科和玄参科等类群中两种结实现象同时存在。从系统发育看, 地下结实在木兰分支、单子叶植物分支及双子叶植物分支中均存在, 而地上/下两型结实仅出现在单子叶植物分支和双子叶植物分支中, 在被子植物基部类群(ANITA类群)中两种结实方式均不存在。该文对植物地下和地上/下两型结实的类型、系统进化、繁殖特性和扩散对策进行了介绍, 并对其生态适应意义进行了总结, 以期为深入研究植物结实的进化策略提供参考。     

Aspects of the spawning of labrid and scarid fishes (Pisces: Labroidei) at Enewetak Atoll,Marshall Islands with notes on other families

Synopsis Spawning of 32 species of Labridae and 13 species of Scaridae was seen at Enewetak Atoll, Marshall Islands. Most spawned on a reef bisecting the main ocean-lagoon passage which had strong tidal currents. Others spawned on lagoon reefs and in Halimeda beds. Polygynous haremic, lek-like and promiscuous mating systems were found which were species specific. Data on reproductive patterns, sexual dichromatism, sexual dimorphism, seasonality and spawning behavior were determined. Many spawned during the day in a time-phase dependent pattern from near sunrise to sunset. Scarid spawning began at slack high water or after when currents were starting to move out of the lagoon. Labrid spawning usually started about 30 min later with some continuing up to 2 h after high tide. With high tide before sunrise, scarid spawning began 30–50 min after sunrise as the current started flowing over the reef. With high tide near sunset, spawning occurred with an incoming current. Most labroids spawned on all phases of the moon. Acanthuridae (6 spp), Caesionidae (1 sp.) and Zanclidae (1 sp.) spawned after high tide at the same time as labroids. Pomacanthidae (5 spp.) spawned only shortly before sunset without reference to tidal currents. Fishes producing pelagic eggs at the lagoon-ocean channel spawned (1) at or slightly after high tide (44spp.), (2) in late afternoon without reference to tide (6 spp.) or (3) after slack low water (1 sp. ). Spawning style can vary within a single species in different environments. Despite the presence of many piscivores, no successful predation on spawning adults was seen. Predation on newly released eggs was uncommon. Labrichthys unilineata and Anampses twistii attempted to defend their eggs for a few sec after release. Attacks by piscivores on spawning adults on tropical reefs occur once per 100–1000 spawnings. Most are wary when preparing to spawn and prespawning behavior is easily interrupted. The risk from piscivores goes down and spawning ascent speed decreases with increasing size of spawners. Egg predation by zooplanktivores is less for pair spawners than group spawners possibly due to less conspicuous gamete clouds and times of spawning. Increasing height of egg release, speed and length of the spawning ascent, and trajectory alteration of ascending adults are believed to make it more difficult for zooplanktivores to locate eggs after release. For labrids, permanent full sexual dichromatism was found among haremic, lek-like and promiscuous mating systems. Species with temporary full dichromatism, permanent and temporary partial dichromatism and monochromatism were haremic. Smaller scarids were believed to have lek-like, and larger species haremic, mating systems. Smaller scarids had male looping behavior and post spawning displays, plus faster spawning ascents and different locations for egg release than larger ones. Eggs of 21 labrids were spherical or nearly spherical, ranging from 0.55–0.80 mm in diameter, and most had one oil globule. Among 7 is scarids, 6 had spindle-shaped eggs ranging from 1.25 ×0.50 mm 2.14× 0.48 mm while one had a nearly spherical egg. One scarid egg lacked an oil globule.     

The social and reproductive behavior of the eyed flounder,Bothus ocellatus,with notes on the spawning ofBothus lunatus andBothus ellipticus

Synopsis Observations of the Caribbean eyed flounder,Bothus ocellatus, were made during two field trips to Bonaire, Netherlands Antilles (January 1990, and December 1990 – January 1991) at depths from 3 to 6 meters. Data were collected by six scuba divers during 54 dives totaling 70 hours. Three mating groups were observed, each consisted of a male and 1 to 6 females. Each female had a distinct subunit within the male's territory. Courtship activity began about one hour before sunset and continued until sunset, when the male retired for the night. Both males and females retired into the sand at locations outside their daytime territory. Every day, males attempted to mate with each female individually within their territory. Spawning began with the male moving under the female who was resting on the sandy bottom. The pair then made a slow upward rise approximately 15 to 75 cm above the substrate, which culminated in a release of a cloud of gametes.Bothus lunatus andBothus ellipticus exhibited similar social organization toB. ocellatus, but differences in the spawning rise were observed. Intraspecific agonistic behavior was observed within males ofB. ocellatus andB. ellipticus.Senior author     

食物、捕食及种间竞争对东方田鼠(Microtus fortis)种群攻击行为的作用

在野外围栏条件下,采用重复的2×2×2析因实验设计,测定食物、捕食和竞争物种黑线姬鼠对东方田鼠攻击行为作用的格局。东方田鼠各处理种群攻击水平与其种群密度的相关甚为复杂,与Chitty多态行为假设的预测不一致。东方田鼠双冲突个体间的攻击水平与其体重的相关不显著,而与冲突个体的体重差异则呈显著的负相关,体重差异越大,冲突个体间的攻击水平越低。雄体攻击水平与其繁殖特征无显著的相关关系,而雌体间攻击水平则受繁殖状态的影响,动情雌体间的攻击水平显著地高于非动情雌体。体重差异和食物对雄体的攻击行为具有极显著的独立作用,捕食和种间竞争对雄体攻击行为的独立作用不显著,而捕食与种间竞争交互作用对雄体攻击行为的效应则达到显著水平。体重差异、食物、捕食和种间竞争对动情雌体的攻击水平均有极显著的独立作用,3类外部因子交互作用的效应达到极显著水平;而3类外部因子交互作用对非动情雌体攻击行为的效应则不显著。结果检验了外部因子食物、捕食、种间竞争对田鼠类动物种群攻击行为具有独立和累加的整合效应的假设。     

Vespidae (Hymenoptera) of Vietnam 3: Synoptic key to Vietnamese species of the polistine genus Ropalidia, with notes on taxonomy and distribution

Nineteen species of the paper wasp genus Ropalidia are recorded from Vietnam, of which three are new records for Vietnam. A key to all of the species, distribution records and taxonomic remarks are given. New synonymies proposed are: Ropalidia bicolorata parvula van der Vecht, 1962, under R. bicolorata van der Vecht, 1962; R. hongkongensis juncta van der Vecht, 1941, under R. hongkongensis (de Saussure, 1854); Icaria jucunda Cameron, 1898, and R. marginata sundaica van der Vecht, 1941, under R. marginata (Lepeletier, 1836); R. rufocollaris atrata van der Vecht, 1941, under R. rufocollaris (Cameron, 1900); and R. stigma rufa van der Vecht, 1941 and R. stigma nigrolineata van der Vecht, 1962, under R. stigma (Smith, 1858).     

Reproduction site preference and performance by sexuparae,and mating behavior of their sexual generation on the primary host plant in a heteroecious aphid,Neothoracaphis yanonis (Homoptera: Aphididae)

We studied reproduction site preference and performance by the sexuparae (autumnal migrants) of Neothoracaphis yanonis and mating behavior of their sexual generation on its primary host plant, Distylium racemosum. The sexuparae preferred younger leaves of D. racemosum for settlement and imbibing leaf sap, and they produced more offspring there than on older leaves. Thus, it is suggested that the sexuparae selected more nutritious younger leaves to increase their own fecundity. The offspring consist of yellowish dark-grey and creamy yellow type nymphs, which develop into small males and large oviparae, respectively. Yellowish dark-grey nymphs were deposited gregariously on the basal part of the abaxial surface of a leaf blade, while creamy yellow nymphs were deposited evenly over the abaxial surface. Such a localized distribution pattern probably resulted from sexuparae's strategy to enhance a possibility for their male offspring to mate with oviparae at the base of leaf blade, over which oviparae crawl to twigs. During mating and sometimes afterwards, the ovipara incidentally carried a male on her back and crawled downward on twig to find an axillary bud for oviposition. This behavior may be advantageous to males, who can guard their mate during this period against other conspecific males. Such mate-guarding behavior seems to be related to the development of dual mate-seeking strategies, in which males try to copulate, first at the basal part of midrib, and second on the axillary bud.     

Morphology of two marine euplotids (Ciliophora: Euplotida), Aspidisca fusca and A. hexeris,with notes on their small subunit rRNA gene sequences

We investigate the living morphology, infraciliature, and small subunit rRNA gene sequences of two poorly known marine euplotids, Aspidisca fusca Kahl, 1928 and A. hexeris Quennerstedt, 1869, isolated from intertidal sewage outfall, northern China and sandy sediments, southern China, respectively. Improved diagnoses and morphometric data are provided for both species. Aspidisca fusca is characterized by having a peristomial spur, seven frontoventral cirri in a “polystyla-arrangement”, and two oval macronuclear nodules. Aspidisca hexeris can be recognized by having an elliptical body shape, a peristomial spur, seven membranelles in the anterior portion of adoral zone and 11–13 in the posterior part, as well as seven frontoventral cirri arranged in two oblique rows. In addition, the presence and degree of projections along the left margin of A. hexeris are highly variable among populations. Phylogenetic analyses based on small subunit rRNA gene sequence data support the validity of both A. hexeris and A. fusca as distinct species, and indicate that A. fusca is most closely related to A. aculeata and A. steini, whereas A. hexeris shows a close relationship with A. magna.     

A study on mono-, bis- and tris-N-functionalized 1,4,7-triazacyclononane with benzimidazolyl groups and their nickel(II) complexes

Three new ligands, 1-(benzimidazolyl-2-methyl)-1,4,7-triazacyclononane L¹, 1,4-bis(benzimidazolyl-2-methyl)-1,4,7-triazacyclonone L², and 1,4,7-tris-(benzimidazolyl-2-methyl)-1,4,7-triazacyclonane L³, were synthesized by a straightforward one-pot method. Their nickel(II) complexes , [NiL²CH₃CN](ClO₄)₂ · 2CH₃OH · H₂O (or [NiL²Cl] · ClO₄) and [Ni(H₋₂L³)] · H₂O were obtained and characterized by electrospray mass spectrum, ¹H NMR, CV and other physical methods. Their crystal structures were determined by X-ray analyses. The crystal structure of the nickel(II) complex of L¹ shows that two Ni(II) atoms are bridged by two Cl⁻ anions. A ferromagnetic exchange coupling and zero-field splitting effect exist in complex 1.