Natural genetic variation in male reproductive genes contributes to nontransitivity of sperm competitive ability in Drosophila melanogaster

Female Drosophila melanogaster frequently mate with multiple males, and the success of a given male depends not only on his genotype but also on the genotype of his competitor. Here, we assess how natural genetic variation affects male–male interactions for traits influencing pre‐ and postcopulatory sexual selection. Males from a set of 66 chromosome substitution lines were competed against each other in a ‘round‐robin’ design, and paternity was scored using bulk genotyping. We observed significant effects of the genotype of the first male to mate, the second male to mate and an interaction between the males for measures of male mating rate and sperm utilization. We also identified specific combinations of males who show nontransitive patterns of reproductive success and engage in ‘rock‐paper‐scissors’ games. We then tested for associations between 245 polymorphisms in 32 candidate male reproductive genes and male reproductive success. We identified eight polymorphisms in six reproductive genes that associate with male reproductive success independent of the competitor (experimentwise P < 0.05). We also identified four SNPs in four different genes where the relative reproductive success of the alternative alleles changes depending on the competing males' genetic background (experimentwise P < 0.05); two of these associations include premature stop codons. This may be the first study that identifies the genes contributing to nontransitivity among males and further highlights that ‘rock‐paper‐scissors’ games could be an important evolutionary force maintaining genetic variation in natural populations.     

Population genomic footprints of selection and associations with climate in natural populations of Arabidopsis halleri from the Alps

Natural genetic variation is essential for the adaptation of organisms to their local environment and to changing environmental conditions. Here, we examine genomewide patterns of nucleotide variation in natural populations of the outcrossing herb Arabidopsis halleri and associations with climatic variation among populations in the Alps. Using a pooled population sequencing (Pool‐Seq) approach, we discovered more than two million SNPs in five natural populations and identified highly differentiated genomic regions and SNPs using F_ST‐based analyses. We tested only the most strongly differentiated SNPs for associations with a nonredundant set of environmental factors using partial Mantel tests to identify topo‐climatic factors that may underlie the observed footprints of selection. Possible functions of genes showing signatures of selection were identified by Gene Ontology analysis. We found 175 genes to be highly associated with one or more of the five tested topo‐climatic factors. Of these, 23.4% had unknown functions. Genetic variation in four candidate genes was strongly associated with site water balance and solar radiation, and functional annotations were congruent with these environmental factors. Our results provide a genomewide perspective on the distribution of adaptive genetic variation in natural plant populations from a highly diverse and heterogeneous alpine environment.     

The impact of paternity on male–infant association in a primate with low paternity certainty

In multimale groups where females mate promiscuously, male–infant associations have rarely been studied. However, recent studies have shown that males selectively support their offspring during agonistic conflicts with other juveniles and that father's presence accelerates offspring maturation. Furthermore, it was shown that males invest in unrelated infants to enhance future mating success with the infant's mother. Hence, infant care might provide fitness gain for males. Here, we investigate male–infant associations in rhesus macaques (Macaca mulatta), a primate with low paternity certainty as females mate with multiple partners and males ensure paternity less efficiently through mate‐guarding. We combined behavioural data with genetic paternity analyses of one cohort of the semi‐free‐ranging population of Cayo Santiago (Puerto Rico) and recorded affiliative and aggressive interactions between focal subjects and adult males from birth to sexual maturation (0–4 years) of focal subjects. Our results revealed that 9.6% of all interactions of focal subjects involved an adult male and 94% of all male–infant interactions were affiliative, indicating the rareness of male–infant aggression. Second and most interestingly, sires were more likely to affiliate with their offspring than nonsires with unrelated infants. This preference was independent of mother's proximity and emphasized during early infancy. Male–infant affiliation rose with infant age and was pronounced between adult males and male rather than female focal subjects. Overall, our results suggest that male–infant affiliation is also an important component in structuring primate societies and affiliation directed towards own offspring presumably represent low‐cost paternal care.     

Nuclear division in the red algae Chondria nidifica and Chondria tenuissima

Cytological investigations are reported for two Chondria species, the Pacific species Chondria nidifica Harvey and Chondria tenuissima (Goodenough et Woodward) C. A. Agardh from the shore of the Marmara Sea in Istanbul. Nuclear division during mitosis and meiosis has been followed in somatic cells and in tetrasporangial mother cells respectively of diploid tetrasporic plants. The spherical interphase nucleus stains densely, showing many chromatin granules. Mitotic nuclei in the apical groove show a large number of chromosomes at metaphase; the chromosome number has been estimated at diakinesis to be 40 in both C. nidifica and C. tenuissima. The meiotic nuclei of tetraspore mother cells in prophase contain several relatively large nucleolar-derivatives in both species. The nucleolar derivatives disappear completely before the chromosomes begin to differentiate. In meiotic prophase the tetraspore mother cell enlarges from its original diameter. The period of the second meiotic anaphase seems to be extremely short in comparison with other nuclear phases. When the chromosomes reach the poles, they spread and subsequently form a relatively compact mass at telophase. The spindle has not been observed in C. tenuissima. Photographs are presented of nucleoli and nucleolar-derivatives in mitotic and meiotic divisions.     

高寒退化草地狼毒种群株丛间格局控制机理

在黑河上游祁连山北坡高寒退化草地,应用Ripley's K函数检测种间格局控制关系的技术方法,按狼毒个体分枝数设置Ⅰ级株丛(1-10枝)、Ⅱ级株丛(11-20枝)、Ⅲ级株丛(21-30枝)、Ⅳ级株丛(31-40枝)、V级株丛(40以上)5个株丛,研究了各株丛之间的格局控制关系和空间关联性.结果表明:Ⅲ和Ⅳ级狼毒株丛对其他狼毒株丛有一定的格局控制作用,尤其是Ⅳ级狼毒株丛对其他狼毒株丛格局控制的程度和尺度最大;Ⅳ级狼毒株丛在20cm尺度内和Ⅰ、Ⅱ以及Ⅴ级狼毒株丛表现出正关联,Ⅲ级狼毒株丛在0-10cm尺度上和Ⅰ级狼毒株丛表现为正关联.狼毒种群中两个形体大小越相近的株丛之间存在格局控制关系的可能性相对较小,尤其是在种群内处于劣势地位或受其他株丛格局控制的株丛之间存在格局控制关系的可能性更小,Ⅳ级狼毒株丛表现出较强的格局控制作用,同时对其他狼毒个体有保护作用,在种群内具有重要作用和地位.     

北京西山地区大山雀与其它鸟类种群种间联结分析

引入2*2列联表联结指数法,用固定样带法月连续全天定位调查数据,以森林鸟类广布种山雀科大山雀(Parus major)为目标种,研究了北京西山地区该种与留鸟、夏候鸟、冬候鸟、旅鸟的种间联结关系,结合前人关于营巢行为、取食行为、生态位等方面成果分析了产生联结的原因,首次确立了鸟类群落种间联结的研究方法。结果表明： （1）用固定样带法月连续全天定位调查,引入2*2列联表以日尺度的定性数据检验与测定联结度,与月尺度的联结频率结合起来,分析鸟类群落的种间联结是可行的;鸟类群落的种间联结具有时间与空间尺度的双重属性,鸟类群落的种间联结度不仅是鸟类群落时空结构与格局的表征,同时,反映了鸟类群落的动态性,而且,鸟类群落的种间联结对栖息的植物群落具有依赖性与关联性。 （2）日尺度上,选择χ2统计量、PCC与PC指数相结合进行种间联结检验、测度,能充分反映鸟类群落的种间联结特征,但由于鸟类的居留、繁殖、迁移等季节动态性特征,种间联结度存有不确定性。 （3）月尺度上,鸟类总体种间联结8月份为显著负联结,其余各月为显著正联结;根据PCC联结度的月联结频率,可将鸟类划分为正联结组、正负联结均较弱组、负联结组;大山雀与留鸟、夏候鸟、冬候鸟、旅鸟等不同居留型的联结关系,随着种数的减少,显著联结种对、联结度、联结复杂程度呈递减趋势。大山雀与留鸟的联结：与鸦科鸟类呈明显正联结,与同科鸟类呈正负均等的弱联结并趋于负联结,与体型较大的雉、啄木鸟、乌鸦等鸟类呈负联结。大山雀与夏候鸟的联结：与杜鹃科四声杜鹃呈正联结,与同科的黄腹山雀、鹟科的白眉姬正负联结均较弱,与莺科的黄腰柳莺、鸫科的北红尾鸲等呈负联结。大山雀与冬候鸟的联结：与岩鹨科棕眉山岩鹨的正负联结均较弱,与鸫科的斑鸫、鹀科多种鸟类呈明显的负联结。大山雀与旅鸟的联结：与莺科鸟类由正负联结均较弱到明显的负联结。     

基于盐分梯度的荒漠植物多样性与群落、种间联接响应

土壤盐分是影响干旱区荒漠植物群落动态的决定因素之一。基于样方调查和不同土壤盐分梯度下植物多样性指数及群落与种间关联的计算结果,分析干旱区荒漠群落植物多样性、群落联接性和种间关联对土壤盐分梯度的响应动态。结果表明,在土壤盐含量为0.03%-0.55% (S1)、0.61%-1.24% (S2)和1.41%-1.79% (S3)的盐分梯度上,(1)随土壤盐含量升高,群落生活型结构改变,草本比例减少,乔木比例增加;(2)植物多样性指数随土壤盐分增加而下降,低盐分梯度下,二者极显著正相关(P<0.01),中盐梯度下二者间呈部分显著负相关(P<0.05),高盐梯度下则转为以正相关为主(P>0.05);(3)群落联接性随土壤盐分梯度转变,在0.61%-1.24%的中度盐含量时正联接性最强(VR=1.89),高盐度含量下群落转为不显著的负联接,稳定性降低;(4)沿盐分升高梯度,种间的负相关种对数增加,正相关种对数减少,种间关联(相关)强度提高,正负相关种对比(PNR)与多样性指数呈显著正相关(P<0.05)。综上可知,干旱区荒漠植物多样性在土壤盐含量达到1.41%-1.79%水平时总体显著降低;土壤盐分水平显著影响植物群落和种间联接性,种间互利性随盐分梯度增加下降,物种趋于独立分布,并最终导致荒漠植物多样性降低。     

Interaction of Tea Catechins with Lipid Bilayers Investigated by a Quartz-Crystal Microbalance Analysis

The quartz-crystal microbalance (QCM) technique was applied to investigate the interaction of tea catechins with lipid bilayers. The association constants obtained from the frequency changes of QCM revealed that (?)epicatechin gallate and (?)epigallocatechin gallate interacted with 1,2-dimyristoyl-sn-glycero-3-phosphocholine ca. 1000 times more strongly than (?)epicatechin and (?)epigallocatechin. The results exhibited good correlation with the strength of biological activity.     

Structure of a mosaic hybrid zone between the field crickets Gryllus firmus and G. pennsylvanicus

Hybrid zones provide insight into the nature of species boundaries and the evolution of barriers to gene exchange. Characterizing multiple regions within hybrid zones is essential for understanding both their history and current dynamics. Here, we describe a previously uncharacterized region of a well‐studied hybrid zone between two species of field crickets, Gryllus pennsylvanicus and G. firmus. We use a combination of mitochondrial DNA sequencing, morphological data, and modeling of environmental variables to identify the ecological factors structuring the hybrid zone and define patterns of hybridization and introgression. We find an association between species distribution and natural habitat; Gryllus pennsylvanicus occupies natural habitat along forest edges and natural clearings, whereas G. firmus occupies more disturbed areas in agricultural and suburban environments. Hybridization and introgression occur across patch boundaries; there is evidence of substantial admixture both in morphological characters and mtDNA, over a broad geographic area. Nonetheless, the distribution of morphological types is bimodal. Given that F₁ hybrids are viable and fertile in the lab, this suggests that strong pre‐zygotic barriers are operating in this portion of the hybrid zone.