Genetic structuring in Andean landlocked populations of Galaxias maculatus: effects of biogeographic history

Aim To test whether the genetic diversity of diadromous and landlocked populations of the small puyen Galaxias maculatus (known as jollytail in Australia and inanga in New Zealand) follow the same structuring patterns observed for migratory and non‐migratory species of the genus Galaxias. This work also aimed to test whether the genetic structuring of a group of populations could be predicted from differences in the geomorphologic history of the region they inhabit. Location Eight landlocked populations were sampled from cold‐temperate lakes in north‐western Patagonia. The study area could be split latitudinally into two sectors that differed in their geomorphology, each of them hosting four populations. The southern sector shows evidence of a higher degree of glacial coverage, and the lakes are probably remnants of a big proglacial palaeolake. Lakes in the northern sector, on the other hand, suggest no common origin. Results Significant genetic structuring was found among the studied populations (Θ = 0.188), being the highest value reported to date for the species. Significant correlation was found between genetic diversity and lake area and perimeter. Diversity also showed a slight latitudinal variation suggesting the presence of genetically distinct groups of populations. The comparison of populations from the two geographical sectors showed that those from the north had a higher diversity, more private alleles and strong structuring, while those from the south were less diverse and much more homogeneous. Main conclusions Non‐migratory populations of G. maculatus show much higher values of genetic structuring than those reported for diadromous populations. This follows the pattern seen when comparing migratory and non‐migratory species of Galaxias. This agrees with population genetics theory which predicts that restricted gene flow would result in greater among‐population divergence. Also, differences between northern and southern populations agreed with what was predicted by the geomorphologic history of the study area. During the Last Glacial Maximum ice cover in that region may have reduced the habitat of G. maculatus to a refuge with an impoverished gene pool. When the ice receded, leaving a great proglacial lake, that former population expanded and became fragmented after water levels descended. This resulted in present day lakes harbouring homogeneous populations with reduced diversity. The northern sector, in contrast, was less affected by glaciers, resulting in more geomorphologically stable lakes holding genetically diverse populations.     

Acute toxicity of kaolin and essential oils from Mentha pulegium and Zingiber officinale against different stages of Callosobruchus maculatus under laboratory conditions

Naturally derived compounds such as essential oils and natural mineral are relatively cheap, non-toxic to food grains and environmentally friendly and would be suitable alternatives for currently used chemical insecticides if they have high insecticidal effectiveness. In the present study, acute toxicity of kaolin and essential oils from Mentha pulegium and Zingiber officinale were assessed on different stages of Callosobruchus maculatus at 28?±?2?°C, 65?±?5% R. H and dark condition. The calculated LC₅₀ values on the egg, larvae and adult stages of C. maculatus were 1.15, 2.33 and 2.18?μl/ml air for Z. officinale and 0.07, 0.11 and 0.09?μl/ml air for M. pulegium, respectively. The result showed that M. pulegium was more effective essential oil against different stages of C. maculatus compared with the Z. officinale, and also the egg and adult stages of C. maculatus were more susceptible against essential oils compared with larval stage. The LC₅₀ values of kaolin were 0.71 and 0.18?mg/cm² on egg and adult of C. maculatus, respectively. The combination of tested essential oils with kaolin increased mortality of C. maculatus adults compared with their application alone. It was found that tested essential oils and kaolin had high potential in controlling different stages of C. maculatus.     

A comparison of nuclear and cytoplasmic genetic effects on sperm competitiveness and female remating in a seed beetle

It is widely assumed that male sperm competitiveness evolves adaptively. However, recent studies have found a cytoplasmic genetic component to phenotypic variation in some sperm traits presumed important in sperm competition. As cytoplasmic genes are maternally transmitted, they cannot respond to selection on sperm and this constraint may affect the scope in which sperm competitiveness can evolve adaptively. We examined nuclear and cytoplasmic genetic contributions to sperm competitiveness, using populations of Callosobruchus maculatus carrying orthogonal combinations of nuclear and cytoplasmic lineages. Our design also enabled us to examine genetic contributions to female remating. We found that sperm competitiveness and remating are primarily encoded by nuclear genes. In particular, a male's sperm competitiveness phenotype was contingent on an interaction between the competing male genotypes. Furthermore, cytoplasmic effects were detected on remating but not sperm competitiveness, suggesting that cytoplasmic genes do not generally play a profound evolutionary role in sperm competition.     

Response of cowpea bruchid,Callosobruchus maculatus (Fab.) (Coleoptera: Chrysomelidae) to cheese wood,Alstonia boonei De Wild stem bark oil extracted with different solvents

Cheese wood, Alstonia boonei De Wild stem bark was extracted with five different solvents namely: methanol, ethanol, acetone, petroleum ether and n-hexane. The extracts were tested for insecticidal activity on cowpea bruchid, Callosobruchus maculatus (Fab.). Adult mortality and adult emergence of the insects were investigated. Oviposition deterrences using dual-choice and multiple-choice tests were also investigated as well as percentage damage and weight loss at temperature of 28?±?2?°C and 75?±?5% relative humidity. Results showed that at the rate of 2% extract per 20?g of cowpea seeds, methanol, petroleum ether and n-hexane extracts caused 100% mortality of adult cowpea bruchid after four?days of post treatment. When the bruchid had choice of oviposition substrate, they laid significantly (p?<?0.05) fewer eggs on cowpea seeds treated with extracts compared to untreated seeds. There was no adult emergence in seeds treated with methanol, ethanol, petroleum ether and n-hexane extracts and 100% reduction in F₁ progeny was recorded compared with untreated that had 81.86% adults emergence and 0% reduction in F₁ progeny. The results obtained from this study revealed that methanol, ethanol, acetone, petroleum ether and n-hexane extracts of A. boonei stem bark were effective in controlling C. maculatus and could serve as an alternative to synthetic insecticides for the protection of stored cowpeas against bruchids.     

斑蜓蜥分布新纪录和补充描述

2007年8月至2009年7月,在云开山脉广东黑石顶自然保护区和广西六万山脉罗阳山采集到3只斑蜓蜥Sphenomorphus maculatus(Blyth,1853)标本,为广东省和广西壮族自治区爬行动物的新纪录.斑蜒蜥的现代核心分布区为中南半岛,在云开山脉和六万山脉的分布是斑蜓蜥自其核心分布区沿十万大山向六万山及云开山脉扩散的结果.检视所采集的斑蜓蜥标本,发现其存在一定程度变异:每侧颞鳞4或5个,环体中段鳞最少为36行;顶鳞和前颊鳞存在分裂为二和愈合的现象.     

中国多斑按蚊类群小记（双翅目：蚊科）

多斑按蚊Anopheles maculatus(Theobald)(s.l.)广布于我国北纬34°以南地区,过去都视作单一蚊种。根据近年的研究,它实际是包含若干亲缘种的种团。为此,我们检视了本单位收藏的标名为多斑按蚊的标本,发现有本种团的以下5种,多斑按蚊(s.s.)伪威氏按蚊pseudowillmori、塞沃按蚊sawadwonaporni、达罗毗按蚊dravidicus和威氏按蚊willmori,后两种为我国的新记录。 本文附有上述5种雌蚊的检索表。     

长江口中国花鲈食性分析

中国花鲈(Lateolabrax maculatus)是长江口重要的经济鱼类之一。根据2010年7月至10月在长江口崇明东滩团结沙和东旺沙水域采集到的胃含物样品,对中国花鲈的摄食习性进行了研究。结果表明,从中国花鲈胃含物中共鉴定出6类27种饵料生物,其多样性指数H’值为2.484,均匀度指数J’为0.7535,优势指数D为0.1262。采用百分比相对重要性指数(IRI%)和综合指标优势指数(Ip)分析的结果较一致,鱼类是长江口中国花鲈夏季主要食物,其百分比相对重要性指数(IRI%)和综合指标优势指数(Ip)分别为82.63%和94.48,鮻(Liza haematocheila)为优势饵料生物(IRI%=41.89,Ip=53.20)。团结沙和东旺沙中国花鲈食性差异较大,主成分分析(PCA)表明鲚属(Coilia spp.)、舌虾虎鱼(Glossogobius giuris)、脊尾白虾(Exopalaemoncarinicauda)和雷伊著名团水虱(Gnorimosphaeroma rayi)是造成这种差异的主要饵料生物种类。     

Lipid and fatty acid composition during embryo and larval development of puye Galaxias maculatus Jenyns, 1842, obtained from estuarine, freshwater and cultured populations

Galaxias maculatus eggs and larvae obtained from broodfish captured either in an estuarine or a freshwater environment, as well as from cultured broodstock were analysed to compare their lipid and fatty acid profiles. Results showed a lower lipid content in embryos and larvae from estuarine populations than those from fresh water, denoting the influence of environmental conditions. The n-3:n-6 ratio was higher in eggs from estuarine and cultured populations, being in the range of marine fishes, whereas for eggs from freshwater fish was lower and typical of freshwater fishes. The polyunsaturated fatty acids (PUFA), particularly docosahexaenoic acid (22:6n-3) and eicosapentaenoic acid (20:5n-3), were higher in eggs and larvae of broodstock coming from culture or estuarine environments than in those from fresh water. Moreover, these fatty acids markedly increased after hatching in larvae coming from estuarine populations, suggesting the effect of the environment on fatty acid profiles to physiologically prepare the larvae to adapt to higher salinity conditions. Linoleic acid (18:2n-6) content was higher in fresh water fish and its reduction during embryo and larval development was accompanied by a significant increase of arachidonic acid (20:4n-6), which was not observed in embryos or larvae from broodstock fish from estuary or aquaculture origin. Both environment and diet of broodstock fish affected lipid and fatty acid composition of G. maculatus embryo and larvae as well as their changes during development.     

Ten novel microsatellite loci characterized for a remarkably widespread fish: Galaxias maculatus (Galaxiidae)

Ten polymorphic microsatellite markers (five tetra‐, one compound tetra‐, one octa‐ and three dinucleotides) were isolated and characterized for Galaxias maculatus, a fish species widely distributed in the Southern Hemisphere. Markers were tested in 89 individual samples from a single location and the number of alleles ranged between 2 and 28. Observed and expected heterozygosities ranged from 0.103 to 0.910 and 0.098 to 0.935 respectively. No evidence was detected for either linkage disequilibrium (P‐values > 0.05 for each locus pair) or deviations from HWE (P‐values > 0.05 for every loci).