Estimates of Genetic Relatedness Among Males in a Polygynous Wasp

Cyclical oligogyny is considered to be the mechanism that is most likely to be responsible for stabilizing cooperation in polygynous, epiponine wasps, in which single-queen colonies produce new queens and multiple-queen colonies produce males. In contrast with the number of studies on relatedness among adult females, we know little about relatedness among males in polygynous epiponine wasps. We estimated worker and male relatedness in the Brazilian epiponine wasp Polybia paulista Ihering and found that colonies of P. paulista produced males when they contained multiple queens. Although average relatedness within males did not differ significantly from 0.5, the number of alleles observed suggests that there were more than one queen to produce males in each colony. Our data would be helpful to elucidate dynamics of the male production in a colony of epiponine wasps.     

Intra-Population Genetic Variation in the Temporal Pattern of Egg Maturation in a Parasitoid Wasp

Parasitoid wasps are taxonomically and biologically extremely diverse. A conceptual framework has recently been developed for understanding life-history evolution and diversification in these animals, and it has confirmed that each of two linked life-history traits – the mode of larval development and the temporal pattern of egg maturation – acts as an organiser of life-history. The framework has been predicated on the assumption that there exists sufficient genetic variation in the latter trait to allow it to be shaped by natural selection. Focusing on the parasitoid wasp Trichogramma brassicae, our aim was to test the validity of that assumption, using established quantitative genetic methods. We demonstrate the existence of a statistically significant degree of intra-population polygenic variation in the temporal pattern of egg production within the wasp population we studied. Furthermore, our results, together with published data on clinal variation in the egg maturation pattern of another species, suggest that intra-specific evolutionary shifts in the temporal pattern of egg maturation of parasitoid wasps can result from a change in allocation to egg production either before, or very shortly after adult emergence, without there being an accompanying change in lifetime fecundity. As well as opening new avenues of research into the reproductive strategies, behaviour, community organisation and biological control potential of parasitoid wasps, this discovery also has implications for studies of life-history evolution and diversification in insects generally.     

单性生殖动物的进化

传统的观念认为,单性动物由于失去了重组机会,必然难以适应变化的环境,终将绝灭。但是已被发现的近50种单性脊椎动物不仅没有因失去基因的重组和交换而绝灭,反而表现出强大的生命力。其有害突变积累和较长的生物演化历程之间的矛盾和在缺乏遗传重组情况下的进化机制是特别引人关注的重大生物学问题。简要论述了单性动物独特的基因组结构、存在历史及其进化途径（突变、三倍化、异精雌核发育生殖方式和异精效应及生殖方式多样化）。     

Genetic Segregation Analysis of Early-Onset Recurrent Unipolar Depression

Major depression is a relatively common psychiatric disorder that can be quite debilitating. Family, twin, and adoption studies indicate that unipolar depression has both genetic and environmental components. Early age at onset and recurrent episodes in the proband each increase the familiarity of the illness. To investigate the potential genetic underpinnings of the disease, we have performed a complex segregation analysis on 832 individuals from 50 multigenerational families ascertained through a proband with early-onset recurrent unipolar major depression. The analysis was conducted by use of regressive models, to test a variety of hypotheses to explain the familial aggregation of recurrent unipolar depression. Analyses were conducted under two alternative definitions of affection status for the relatives of probands: (1) "narrow," in which relatives were assumed to be affected only if they were diagnosed with recurrent unipolar depression; and (2) "broad," in which relatives were assumed to be affected if diagnosed with any major affective illness. Under the narrow-definition assumption, the model that best explains these family data is a transmitted (although non-Mendelian) recessive major effect with significant residual parental effects on affection status. Under the broad-definition assumption, the best-fitting model is a Mendelian codominant major locus with significant residual parental and spousal effects.     

Segregation Analysis on Genetic System of Quantitative Traits in Plants

Based on the traditional polygene inheritance model of quantitative traits, the author suggests the major gene and polygene mixed inheritance model. The model was considered as a general one, while the pure major gene and pure polygene inheritance model was a specific case of the general model. Based on the proposed theory, the author established the segregation analysis procedure to study the genetic system of quantitative traits of plants. At present, this procedure can be used to evaluate the genetic effect of individual major genes (up to two to three major genes), the collective genetic effect of polygene, and their heritability value. This paper introduces how to establish the procedure, its main achievements, and its applications. An example is given to illustrate the steps, methods, and effectiveness of the procedure. Translated from Hereditas, 2005, 27(1) (in Chinese)     

植物数量性状遗传体系的分离分析方法研究

在传统的数量性状多基因遗传模型基础上提出主基因-多基因遗传模型具普遍性,纯主基因或纯多基因遗传模型只是其特例。由此初步建立了植物数量性状遗传体系分离分析方法。目前该方法可以检验2～3个主基因的个别遗传效应、多基因整体的遗传效应和两者的遗传率。本文介绍这种分离分析方法的研究经过、主要进展及应用效果,并以实例说明其分析步骤、方法和效果。     

Segregation Analysis on Genetic System of Quantitative Traits in Plants

Based on the traditional polygene inheritance model of quantitative traits,the author suggests the major gene and polygene mixed inheritance model.The model was considered as a general one,while the pure major gene and pure polygene inheritance model was a specific case of the general model.Based on the proposed theory,the author established the segregation analysis procedure to study the genetic system of quantitative traits of plants.At present,this procedure can be used to evaluate the genetic effect of individual major genes (up to two to three major genes),the collective genetic effect of polygene,and their heritability value.This paper introduces how to establish the procedure,its main achievements,and its applications.An example is given to illustrate the steps,methods,and effectiveness of the procedure.     

Unisexual rock lizard might be outcompeting its bisexual progenitors in the Caucasus

We compared the distributions, abundances and ecological requirements of parthenogenetic lizard Darevskia ‘dahli’ and its bisexual progenitors, D. portschinskii and D. mixta, in Georgia. We developed a regression model relating the species abundances with the distribution of climates. Darevskia portschinskii lives in warmer and drier climates than D. mixta; D. ‘dahli’ has the intermediate requirements. Temperature is more important than humidity for D. portschinskii, humidity is more important for D. mixta and both temperature and humidity are important for D. ‘dahli’. Suitable habitats of all three species overlap broadly; however, the observed ranges partly overlap only for D. ‘dahli’ and D. portschinskii. The observed abundance of each species, related to its predicted abundance, is lower at the sites with potential competitors. Darevskia ‘dahli’ occupies a higher proportion of the suitable habitats and has higher abundances than the progenitor species. Competition with D. ‘dahli’ is an important factor determining current distribution pattern of D. portschinskii and D. mixta. The parthenogen is a stronger competitor than the bisexual breeders and potential advantages of the bisexual reproduction remain unrealized in the given temporal and spatial scale. To explain domination of bisexually breeding lizards on the global scale, considering climate changes in geological timescale is necessary. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 447–460.     

The Genetic Analysis of Distributive Segregation in Drosophila Melanogaster. II. Further Genetic Analysis of the Nod Locus

In Drosophila melanogster females the segregation of nonexchange chromosomes is ensured by the distributive segregation system. The mutation noda specifically impairs distributive disjunction and induces nonexchange chromosomes to undergo nondisjunction, as well as both meiotic and mitotic chromosome loss. We report here the isolation of seven recessive X-linked mutations that are allelic to noda. As homozygotes, all of these mutations exhibit a phenotype that is similar to that exhibited by noda homozygotes. We have also used these mutations to demonstrate that nod mutations induce nonexchange chromosomes to nondisjoin at meiosis II. Our data demonstrate that the effects of noda on meiotic chromosome behavior are a general property of mutations at the nod locus. Several of these mutations exhibit identical phenotypes as homozygotes and as heterozygotes with a deficiency for the nod locus; these likely correspond to complete loss-of-function or null alleles. None of these mutations causes lethality, decreases the frequency of exchange, or impairs the disjunction of exchange chromosomes in females. Thus, either the nod locus defines a function that is specific to distributive segregation or exchange can fully compensate for the absence of the nod+ function.     

Protein Polymorphisms, Segregation in Genetic Crosses and Genetic Distances among Fishes of the Genus Xiphophorus (Poeciliidae)

The products of 49 protein-coding loci were examined by starch gel electrophoresis for populational variation in six species of Xiphophorus fishes and/or segregation in intra- and interspecific backcross and intercross hybrids. Electrophoretic variation was observed for 29 of the 35 locus products in a survey of 42 population samples. The highest frequency of polymorphic loci observed in noninbred populations was 0.143. After ten or more generations of inbreeding, all loci studied were monomorphic. Inbred strains generally exhibited the commonest electrophoretic alleles of the population from which they were derived. An assessment of genetic distances among Xiphophorus populations reflected classical systematic relationships and suggested incipient subspeciation between X. maculatus from different drainages as well as several species groups. Thirty-three loci were analyzed with respect to segregation in hybrids. The goodness of fit of segregations to Mendelian expectations at all loci analyzed (except loci in linkage group I) is interpreted as evidence for high genetic compatibility of the genomes of Xiphophorus species. It is anticipated that these data will result in a rapid expansion of the assignment of protein-coding loci to linkage groups in these lower vertebrate species.