Breeding system, colony and population structure in the weaver ant Oecophylla smaragdina

Weaver ants ( Oecophylla smaragdina ) are dominant ants in open forests from India, Australia, China and Southeast Asia, whose leaf nests are held together with larval silk. The species, together with its sole congener O. longinoda , has been important in research on biological control, communication, territoriality and colony integration. Over most of the range, only one queen has been found per colony, but the occurrence of several queens per nest has been reported for the Australian Northern Territory. The number of males mating with each queen is little known. Here we report on the colony structure of O. smaragdina using published and new microsatellite markers. Worker genotype arrays reflect the occurrence of habitual polygyny (more than one queen per colony) in 18 colonies from Darwin, Northern Australia, with up to five queens inferred per colony. Monogyny (one queen per colony) with occasional polygyny was inferred for 14 colonies from Queensland, Australia, and 20 colonies from Java, Indonesia. Direct genotyping of the sperm carried by 77 Queensland queens and worker genotypic arrays of established colonies yielded similar results, indicating that less than half of the queens mate only once and some mate up to five times. Worker genotype arrays indicated that queens from Java and the Northern Territory also often mate with more than one male, but less often than those from Queensland. A strong isolation-by-distance effect was found for Queensland samples. The variation uncovered means that O. smaragdina is a more versatile study system than previously supposed.     

西双版纳入侵长足捷蚁与土著黄猄蚁的种间竞争

【目的】入侵物种能够通过竞争影响本地物种的种群,从而影响入侵地的生物多样性。长足光捷蚁Anoplolepis gracilipes是全球最具破坏力的入侵蚂蚁之一。本研究旨在明确西双版纳地区入侵长足捷蚁与土著优势种蚂蚁黄猄蚁Oecophylla smaragdina之间的竞争关系。【方法】通过野外调查和室内控制试验相结合的方法,观察和对比分析长足捷蚁和黄猄蚁的体型大小,雾凉季和雨季的巢穴外觅食活动规律,觅食能力(搜寻食物的时间、在觅食时间内召集的最大工蚁数),打斗行为(不同打斗组合的攻击强度和死亡率)以及对饥渴的耐受性(无食物和水分供应时平均存活时间和存活率随时间的变化)。【结果】长足捷蚁工蚁体长(3.66±0.06 mm)显著小于黄猄蚁工蚁(8.27±0.16 mm)。在雾凉季时,长足捷蚁具有比黄猄蚁更长的觅食活动时间;而在雨季时,两种蚂蚁均在下午温度较高时段觅食活动的个体数量减少。苹果、蜂蜜和火腿肠3种食物作为诱饵时,长足捷蚁具有更快搜寻食物的能力,4~8 min便能找寻到食物,而黄猄蚁需要8~21 min才能找寻到食物,此外在寻找到食物后,长足捷蚁也有更快召集同伴的能力。在人工控制试验中,1头长足捷蚁和1头黄猄蚁同时存在时主要以不攻击和低强度攻击为主,而当两种蚂蚁中的任意其中一种的个体数量增加到5头时,攻击强度会显著增加,两种蚂蚁均存在种间协作行为。在饥渴状态下,两种蚂蚁工蚁的平均存活时间差异不显著,但长足捷蚁最长存活120 h,黄猄蚁最长存活96 h。【结论】在西双版纳地区,长足捷蚁相较于土著黄猄蚁具有更强的觅食的能力,雾凉季觅食活动时间更长,暗示长足捷蚁可能具有较强的温度适应能力。有必要加强对这一入侵蚂蚁的研究,并密切关注其种群在该地区的发展。     

黄猄蚁对橡胶盔蚧种群消长的影响

调查西双版纳地区黄猄蚁OecophyllasmaragdinaFabricius对橡胶盔蚧Parasaissetianigra(Nietner)种群数量和寄生蜂的影响。结果表明:黄猄蚁对橡胶盔蚧种群消长及寄生蜂均有影响。"有蚂蚁"枝条上介壳虫种群数量显著高于"无蚂蚁"枝条。"有蚂蚁"枝条介壳虫死亡率和寄生蜂都显著低于"无蚂蚁"枝条。说明黄猄蚁的存在影响了橡胶树介壳虫的种群繁殖率和死亡率。建议在今后综合防治中,充分利用蚂蚁与橡胶树介壳虫关系。通过驱逐橡胶树上的蚂蚁来有效遏制介壳虫的发生。     

Winter range compression of migrants in Central America

Where there is seasonal disparity among opportunities, the season with those in shortest supply is most likely to limit populations. Among migrant birds that travel between different breeding and winter ranges, any of breeding, migratory or winter conditions could exclusively constitute such population-limiting factors. In both the New and Old Worlds, landmass is disproportionately concentrated in temperate latitudes. In the Americas, most passerine bird species that breed in the USA and Canada spend the winter further south, commonly in parts of the tropics where landmass is significantly less. Using a sample of 89 migratory species (eight passerine families) that breed in eastern North America, I considered patterns of geographic breeding range size, winter range size and winter distribution. Winter range size is usually smaller than breeding range size (84 of 89 species), often substantially so (minimum 8%, mean 52%). Wintering latitude explains significant variation in both breeding range size and winter range size, as well as in winter range size relative to breeding range size. In particular, all three measures vary latitudinally in patterns similar to latitudinal variation in landmass. These patterns collectively suggest that the reduction in landmass in the latitudes of Central America and the Caribbean is a limiting factor for migrant bird populations, adding to other research concluding that winter conditions sometimes prevail over breeding conditions in the limitation of populations. Hectare for hectare, habitat destruction in the tropics is likely to have the greater impact on the welfare of passerine populations breeding in North America.     

Winter range compression of migrants in Central America

Where there is seasonal disparity among opportunities, the season with those in shortest supply is most likely to limit populations. Among migrant birds that travel between different breeding and winter ranges, any of breeding, migratory or winter conditions could exclusively constitute such population‐limiting factors. In both the New and Old Worlds, landmass is disproportionately concentrated in temperate latitudes. In the Americas, most passerine bird species that breed in the USA and Canada spend the winter further south, commonly in parts of the tropics where landmass is significantly less. Using a sample of 89 migratory species (eight passerine families) that breed in eastern North America, I considered patterns of geographic breeding range size, winter range size and winter distribution. Winter range size is usually smaller than breeding range size (84 of 89 species), often substantially so (minimum 8%, mean 52%). Wintering latitude explains significant variation in both breeding range size and winter range size, as well as in winter range size relative to breeding range size. In particular, all three measures vary latitudinally in patterns similar to latitudinal variation in landmass. These patterns collectively suggest that the reduction in landmass in the latitudes of Central America and the Caribbean is a limiting factor for migrant bird populations, adding to other research concluding that winter conditions sometimes prevail over breeding conditions in the limitation of populations. Hectare for hectare, habitat destruction in the tropics is likely to have the greater impact on the welfare of passerine populations breeding in North America.     

Molecular phylogeny of the Greek legless skink Ophiomorus punctatissimus (Squamata: Scincidae): the impact of the mid-Aegean trench in its phylogeography

Sequence data derived from three mitochondrial markers (cytochrome b, 16S rRNA and 12S rRNA genes) were used to infer the evolutionary history of several insular and mainland populations of the Greek legless skink (Ophiomorus punctatissimus), covering most of its distributional range. All phylogenetic analyses produced topologically identical trees that revealed a well-resolved phylogeny. These trees support two O. punctatissimus clades, which are geographically separated (west and east of the mid-Aegean trench). The assumption of a clock-like evolution could not be rejected, and thus a local clock was calibrated for the O. punctatissimus lineages. The non-overlapping geographic distributions of the major clades suggest a spatial and temporal sequence of diversification that coincides with paleogeographic separations during the geological history of the Aegean region. It seems that O. punctatissimus is an old eastern Mediterranean species that has been differentiating in this region at least from middle Miocene. It is possible that the ancestral form of O. punctatissimus invaded the Aegean region from Anatolia before the complete formation of the mid-Aegean trench, when the Aegean was still a uniform landmass, while other vicariant events have led to its present distribution.     

Differences in worker caste behaviour of Oecophylla smaragdina (Hymenoptera: Formicidae) in response to larvae of Anthene emolus (Lepidoptera: Lycaenidae)

The larvae of Anthene emolus (Lycaenidae) cannot survive in the wild without their associated ant Oecophylla smaragdina (Formicidae) . The ants groom the lycaenid larvae for secretions and, in turn, protect them from parasitoids and predators. Both major and minor worker ants tend larvae, although, in the present study, the frequencies of tending by different castes proved to be significantly different. Ants also tended late instars significantly more than young larvae. O. smaragdina ants of the same colony were observed fighting when A. emolus larvae were present. Aggression was exhibited by the major workers against the minor workers that tried to tend secreting larvae. Major ants precluded the minors from the most nutritious secretions, leaving minors to tend the less productive, early instars. On a few occasions, aggression was unchecked and major workers killed the larvae they were tending (presumably accidentally). When larvae were experimentally reared with only one caste of ant, the resulting butterflies showed no differences in dry weight. Mortality was high when larvae were reared with only minor ants or in the absence of ants.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 391–395.     

四个奥利亚罗非鱼群体的微卫星分析

应用筛选到的19对微卫星引物,对四个不同来源的奥利亚罗非鱼（Oreochromis aureus）群体（奥利亚罗非鱼83系、奥利亚罗非鱼02系、奥利亚罗非鱼05系和红色奥利亚罗非鱼）的基因组DNA进行PCR扩增,分析其群体遗传结构和亲缘关系。根据几个群体在19个位点上的PCR扩增图谱,统计计算各群体的遗传多样性指数。四个群体的平均观测遗传杂合度值在0．154—0．391间;平均预期杂合度在0．181—0．428间;平均多态信息含量值在0．1513—0．3882间,说明它们的遗传多样性水平较低。遗传偏离指数D的评估结果显示这4个群体有多个位点存在不同程度的Hardy—Weinberg遗传平衡偏离。运用MicroChecker软件进行零等位基因预测,结果显示除红色奥利亚罗非鱼群体外,其他3个群体中均可能存在零等位基因位点。各群体零等位基因的位点数分别为：83系1个,02系3个,05系7个,红奥群体为0。零等位基因位点的存在可能是导致位点发生Hardy—Weinberg遗传平衡偏离的原因之一。4个群体中,05系群体与83系群体间的遗传相似性系数最高（0．9422）,遗传距离最小（0．0596）,说明两者亲缘关系最近;83系群体与红奥群体的遗传相似性系数最低（0．6977）,遗传距离最大（0．3599）,可推断两者亲缘关系最远。根据群体间的遗传距离采用UPGMA法进行聚类,结果表明：83系首先与05系聚类为一支,然后与02系群体聚类,最后与红奥群体聚类。聚类结果说明红奥群体与其他三个群体亲缘关系最远;83系群体与05系群体亲缘关系最近,与02系群体次之。     

Locomotion and adhesion: dynamic control of adhesive surface contact in ants

Tarsal adhesive pads of insects are highly dynamic organs that play an important role in locomotion. Many insects combine fast running performance with strong resistance to detachment forces. This capacity requires an effective control of attachment forces at the tarsus and pretarsus. Here we investigate mechanisms of attachment control in Asian weaver ants (Oecophylla smaragdina) by measuring the dynamics of the adhesive contact area and the claws during locomotion. O. smaragdina ants walking upside down on a smooth substrate used only a fraction (approx. 14%) of their maximum possible contact area. When these ants were loaded with 30 mg weights (corresponding to approx. 6 times their own body weight), however, they employed much larger (but still submaximal; approx. 60%) contact areas. The increase of contact area was accompanied by a stronger flexion of the claws, which demonstrates the participation of the claw flexor muscle in the control of adhesive contact. However, only part of the contact area dynamics could be explained by the action of the claw flexor. During the stance phase, adhesive contact area changed while the claws remained motionless. Even when corrected for the effects of claw flexion, adhesive contact areas differed by a factor of 2.1 between loaded and unloaded ants. Our findings give evidence that running ants control their adhesive contact area by a combination of active movements of the claw flexor muscle and passive reactions of the mechanical system.     

Homogeneity of common cosmopolitan inversion frequencies in Southeast AsianDrosophila melanogaster

East AsianDrosophila melanogaster are known for great variation in morphological and physiological characters among populations, variation that is believed to be maintained by genetic drift. To understand the genetic properties of AsianD. melanogaster populations, we initiated a population genetic study of chromosome inversion polymorphisms in hitherto unanalysed population samples from Southeast (SE) Asia. We generally found a high frequency of each of the four common cosmopolitan inversions in comparison to populations from Africa, Asia, and Australia. In contrast to the great phenotypic variation among Asian populations, however, we could not detect differences in inversion frequencies among populations. Furthermore, we observed neither correlations of inversion frequencies with population latitude and longitude, nor evidence for linkage disequilibrium between different inversion loci. We propose two explanations for the observed genetic homogeneity among these SE AsianD. melanogaster populations: (i) the observed pattern simply reflects the retention of ancestral polymorphisms originating from a panmictic population that was once present on a large single landmass (Sundaland), and/or is a consequence of high recent gene flow between populations; and (ii) it is caused by selective forces (e.g. balancing selection).     

黄猄蚁对柚子花期害虫的影响

于2008年3月柚子花期,将柚园划分为两个区域,一个区域引迁黄蚁,另一个区域不做处理作为对照。在2个区域分别选取20个枝条共40枝,对柚子花期主要害虫(柑桔花蕾蛆、蓟马)及健叶率进行调查。结果表明:对照区柑桔花蕾蛆和蓟马的虫口密度及虫花率都显著高于处理区,而且虫口数量一直保持在较高的水平;有黄蚁存在的情况下,柚子树花蕾蛆的有虫花率减少了70%～80%,蓟马有虫花率减少了近60%,健叶率增加了30%左右。建议在今后害虫综合防治中,充分认识到黄蚁对害虫的防治作用,通过保护和引迁黄蚁来有效防治害虫。     

Mutation accumulation affects male virility in Drosophila selected for later reproduction

An intensive study of longevity, female fecundity, and male reproductive behavior in Drosophila melanogaster was undertaken in order to establish whether late-life fitness characters in short-lived populations might be affected by the increase in deleterious alleles due to random genetic drift. We also sought to determine whether selection for late-life fertility could eliminate alleles that produce a decline in later fitness components in short-lived populations, as predicted by the mutation accumulation hypothesis for the evolution of aging. These experiments employed long-lived (O) populations, short-lived (B) populations, and hybrids made from crosses of independent lines from within the O and B populations. No detectable longevity differences were seen between hybrid B males and females and purebred B males and females. Reproduction in aged B purebred females was significantly less than in hybrid females at 3 wk of age only. A full diallel cross of the five replicate B lines showed a steady increase in hybrid male reproductive performance after the first week of adult life, relative to the parental lines. A full diallel cross of the five replicate O lines revealed no significant increase in hybrid O age-specific male reproductive success compared with the purebred O lines when assayed over the first 5 wk of adult life. The results on male reproductive behavior are consistent with the idea that relaxed age-specific selection in the B populations has been accompanied by an increase in deleterious, recessive traits that exhibit age-specific expression. Consequently, we conclude that a mutation accumulation process has been at least partly responsible for the age-specific decline in male B virility relative to that of the O populations.     

PHENOLOGY OF THREE ANT SPECIES IN THE SOLOMON ISLANDS

i
Seasonal variation in the composition of colonies is described, with particular reference to the incidence of sexual castes. The ant species are Oecophylla smaragdina F., Iridomyrmex cordatus Fr. Smith and Anoplolepis longipes Jerdon.     

Modern State of Populations of Endemic <Emphasis Type="Italic">Oxytropis</Emphasis> Species from Baikal Siberia and Their Phylogenetic Relationships Based on Chloroplast DNA Markers

The genetic diversity and population structure of the endemic species of Baikal Siberia Oxytropis triphylla, O. bargusinensis, and O. interposita were studied for the first time on the basis of the nucleotide polymorphism of intergenic spacers psbA–trnH, trnL–trnF, and trnS–trnG of chloroplast DNA. All populations of these species were characterized by a high haplotype (0.762–0.924) and relatively low nucleotide (0.0011–0.0022) diversity. Analysis of the distribution of variability in O. triphylla and O. bargusinensis showed that there was no significant genetic differentiation between populations of each species; the gene flow was 4.43 and 8.91, respectively. The high level of genetic diversity in the studied populations indicates a relatively stable state of these populations. A study of the phylogenetic relationships of closely related species confirms the concept of the origin of O. bargusinensis and O. tompudae as a result of intersectional hybridization of the species of the sections Orobia and Verticillares.     

Bee population returns and cherry yields in an orchard pollinated with Osmia lignaria (Hymenoptera: Megachilidae)

During 1998-2003, we used populations of the solitary bee Osmia lignaria Say to pollinate a commercial sweet cherry orchard in northern Utah. Bee densities released each year ranged from 1290 to 1857 females/ha, with approximately twice as many males. Female progeny produced each year were greater than parental populations released, except in 2003, when nesting was poor due to bird predation. Despite poor weather during bloom, and in contrast to most other local producers, the study orchard produced harvestable crops in 1999 (2,964 kg/ha) and 2001 (3,154 kg/ha). In 1998 and 2000, record yields were obtained (10,625 and 12,096 kg/ha, respectively). Including only those years with harvestable crops, average production was 2.2 times higher in 1998-2003 (when O. lignaria populations were used) compared with 1992-1997 (when 10 Apis mellifera hives were used). This is the first study reporting multiyear cherry yields in an orchard pollinated with O. lignaria in North America.     

The Genetic Structure of Oreochromis spp. (Tilapia) Populations in Malaysia as Revealed by Microsatellite DNA Analysis

The genetic make-up of five populations of Oreochromis spp. was examined by microsatellite analysis. Eleven polymorphic microsatellite loci showed significant departures from the Hardy-Weinberg equilibrium. The mean heterozygosity ranged from 0.6280 to 0.7040 for each population. The genetic distance values showed a clear separation between O. niloticus and O. mossambicus. The differentiation of the O. niloticus populations was then tested with various genetic measures, which are based on both the Infinite Allele and the Stepwise Mutation models. All these measures grouped the populations similarly.     

Chloroplast genome sequence confirms distinctness of Australian and Asian wild rice

Cultivated rice (Oryza sativa) is an AA genome Oryza species that was most likely domesticated from wild populations of O. rufipogon in Asia. O. rufipogon and O. meridionalis are the only AA genome species found within Australia and occur as widespread populations across northern Australia. The chloroplast genome sequence of O. rufipogon from Asia and Australia and O. meridionalis and O. australiensis (an Australian member of the genus very distant from O. sativa) was obtained by massively parallel sequencing and compared with the chloroplast genome sequence of domesticated O. sativa. Oryza australiensis differed in more than 850 sites single nucleotide polymorphism or indel from each of the other samples. The other wild rice species had only around 100 differences relative to cultivated rice. The chloroplast genomes of Australian O. rufipogon and O. meridionalis were closely related with only 32 differences. The Asian O. rufipogon chloroplast genome (with only 68 differences) was closer to O. sativa than the Australian taxa (both with more than 100 differences). The chloroplast sequences emphasize the genetic distinctness of the Australian populations and their potential as a source of novel rice germplasm. The Australian O. rufipogon may be a perennial form of O. meridionalis.     

Biochemical Polymorphisms and Genetic Relationships in Rodents of the Genera Oryzomys and Oligoryzomys (Sigmodontinae) from Brazil

An electrophoretic analysis of 12 allozyme systems (14 loci, 40 alleles) was performed in the rodent genera Oryzomys and Oligoryzomys, in order to determine the levels of genetic variability within and among populations and species. One hundred and fifty-five individuals from 16 populations of Oryzomys russatus, Or. angouya, Oligoryzomys flavescens, and O1. nigripes species were trapped in nine Brazilian localities. Genetic divergence among populations, as well as the interpopulational gene diversity, was higher in Oryzomys than in Oligoryzomys. The dendrogram of the phenetic relationships among the 16 populations of these four species displays three clusters: the first one joins the O1. flavescens populations with those of O1. nigripes; the second groups the populations of Or. russatus, and the last assembles the populations of Or. angouya. The genetic parameters analyzed reveal that the species belonging to the genus Oryzomys are genetically more structured than those of Oligoryzomys, the latter presenting lower levels of intrademe genetic differentiation (G(ST)')     

Inferring the population structure and demography of Drosophila ananassae from multilocus data

Inferring the origin, population structure, and demographic history of a species is a major objective of population genetics. Although many organisms have been analyzed, the genetic structures of subdivided populations are not well understood. Here we analyze Drosophila ananassae, a highly substructured, cosmopolitan, and human-commensal species distributed in the tropical, subtropical, and mildly temperate regions of the world. We adopt a multilocus approach (with 10 neutral loci) using 16 population samples covering almost the entire species range (Asia, Australia, and America). Analyzed with our recently developed Bayesian method, 5 populations in Southeast Asia are found to be central, while the other 11 are peripheral. These 5 central populations were sampled from localities that belonged to a single landmass ("Sundaland") during the late Pleistocene ( approximately 18,000 years ago), when sea level was approximately 120 m below the present level. The inferred migration routes of D. ananassae out of Sundaland seem to parallel those of humans in this region. Strong evidence for a population size expansion is seen particularly in the ancestral populations.