Females' choice of "good genotypes" as mates is promoted by an insect mating system

Can animal mating systems result in the choice of mates carrying genotypes that are otherwise favored by natural selection? This question is addressed by studying, in natural populations of Colias butterflies, how the phosphoglucose isomerase (PGI) enzyme genotype of males mating Colias females varies with degree of female mate discrimination. Certain PGI genotypes (as predicted from their biochemical properties) have been found previously to have an advantage in diverse fitness-related properties: flight capacity, survivorship, and overall mating success. It is shown here that males of these same genotypes have even greater advantage in remating older, more discriminating females than they do in mating previously unmated, less discriminating females. Assortative mating is not found and thus cannot explain this effect. The mating system of these insects does, at least in this case, result in active female choice of generally favorable male genotypes as mates.     

Correlated Evolution of Female Mating Preferences and Male Color Patterns in the Guppy Poecilia reticulata

Sexual selection may explain why secondary sexual traits of males are so strongly developed in some species that they seem maladaptive. Female mate choice appears to favor the evolution of conspicuous color patterns in male guppies (Poecilia reticulata) from Trinidad, but color patterns vary strikingly among populations. According to most theory, correlated evolution of female mating preferences and preferred male traits within populations could promote this kind of divergence between populations. But mating preferences could also constrain the evolution of male traits. In some guppy populations, females discriminate among males based on variation in the extent of orange pigment in male color patterns, and populations differ significantly in the degree offemale preferences for orange area. In a comparison ofseven populations, the degree offemale preference based on orange is correlated with the population average orange area. Thus male traits and female preferences appear to be evolving in parallel.     

Negative frequency-dependent selection of sexually antagonistic alleles in Myodes glareolus

Sexually antagonistic genetic variation, where optimal values of traits are sex-dependent, is known to slow the loss of genetic variance associated with directional selection on fitness-related traits. However, sexual antagonism alone is not sufficient to maintain variation indefinitely. Selection of rare forms within the sexes can help to conserve genotypic diversity. We combined theoretical models and a field experiment with Myodes glareolus to show that negative frequency-dependent selection on male dominance maintains variation in sexually antagonistic alleles. In our experiment, high-dominance male bank voles were found to have low-fecundity sisters, and vice versa. These results show that investigations of sexually antagonistic traits should take into account the effects of social interactions on the interplay between ecology and evolution, and that investigations of genetic variation should not be conducted solely under laboratory conditions.     

Genetic consequences of mate choice: a quantitative genetic method for testing sexual selection theory

To investigate whether female mate choice could be directed at male genetic quality, male chemical signals and progeny fitness were studied in the red flour beetle (Tribolium castaneum). Differences among males in the attractiveness of their pheromone to females were statistically significant. Developmental time of progeny was significantly heritable, indicating that some males have "good genes" for this trait. There was no statistically significant correlation between progeny fitness and male attractiveness. These results do not support the hypothesis that in this species the evolution of female preferences for male pheromone is adaptive.     

鹅伴性羽色性状的遗传分析

【目的】 豁眼鹅是我国著名的白鹅品种,其1日龄雏鹅往往呈现黄色或淡黄色。然而,笔者在进行豁眼鹅纯系继代选育过程中,发现自由交配群体的后代中有20%雏鹅个体绒羽呈现浅褐色,且公母比例差别明显（公母比例接近1﹕3）,推测豁眼鹅群体白羽性状存在伴性遗传可能。以雏鹅期浅褐色公鹅和黄色母鹅为亲本,利用杂交试验,检验雏鹅绒羽表型的情况是否符合孟德尔遗传规律,从而揭示鹅羽色性状的遗传方式。为此开展鹅的羽色性状遗传规律及机制研究,以期对鹅新品种或品系的培育以及鹅羽色自别雌雄配套系生产提供指导。【方法】 选用40只豁眼鹅公鹅和200只豁眼鹅母鹅为亲本,组建随机交配群产生豁眼鹅纯系G₁代,观察G₁代中1日龄雏鹅中黄色绒羽和浅褐色绒羽表型的表现和分离比例;4只浅褐色豁眼鹅公鹅和20只黄色豁眼鹅母鹅为亲本,杂交产生F₁代,观察其1日龄雏鹅中黄色绒羽和浅褐色绒羽表型的表现和分离比例。【结果】 ①在豁眼鹅随机交配G₁代中,浅褐色绒羽表型个体的比例为19.5%。其中,公母雏之间浅褐色个体占比差别比较大,公雏中浅褐色的比例在10%左右,而母雏有30%左右的个体呈现浅褐色。根据Hardy-Weinberg定律,绒羽颜色性状等位基因频率计算如下,母雏中浅褐色个体的比例就是豁眼鹅群体中绒羽浅褐色等位基因的频率,本试验中29.8%的母雏个体是呈现浅褐色,所以该等位基因的频率约为0.3。同时,公雏中浅褐色个体比例的开方也能计算出豁眼鹅群体中浅褐色等位基因的频率,本例中,10%的公雏是浅褐色,所以该等位基因的频率约为0.3左右,同母雏计算所得基因频率比较接近。相应的,绒羽黄色等位基因频率则为0.7左右。②杂交F₁中,黄羽81只,占50%;浅褐色79只,占50%。且黄羽全为公雏,浅褐色羽全是母雏。结果表明,浅褐色性状呈伴性遗传;已研究证实,银色羽（S*S）和不完全白化（S*AL）是位于Z染色体上的一对等位基因控制,不完全白化基因AL对银色羽基因S为隐性。因此,根据杂交试验结果,可以初步判断浅褐色和黄色是由一个基因座的复等位基因所决定的结果,且浅褐色对于黄色性状呈隐性遗传。【结论】 本试验通过羽色性状选配杂交和随机交配试验,分析了豁眼鹅1日龄雏鹅绒羽颜色表型的分离情况,结果表明：（1）浅褐色绒羽性状相对黄色绒羽性状为隐性遗传;（2）豁眼鹅雏鹅绒羽浅褐色/黄色性状呈伴性遗传;（3）豁眼鹅雏鹅绒羽颜色性状主要为Z染色体银色羽基因座控制,控制该基因座的等位基因存在变异位点与相应表型关联。     

Adaptive plasticity in female mate choice dampens sexual selection on male ornaments in the lark bunting

Theory on the evolution of ornamental male traits by sexual selection assumes consistency in selection over time. Temporal variation in female choice could dampen sexual selection, but scant information exists on the degree to which individual female preferences are flexible. Here we show that in lark buntings sexual selection on male traits varied dramatically across years and, in some cases, exhibited reversals in the direction of selection for a single trait. We show that these shifts are probably because of flexibility in mate choice by individual females and that they parallel shifts in the male traits that predict female reproductive success in a given year. Plasticity in choice and concomitant reversals in mating patterns across time may weaken the strength of sexual selection and could maintain genetic variation underlying multiple sexual ornaments.     

Sexual difference theory: mormon crickets show role reversal in mate choice

Male Mormon crickets produce a large spermatophore that the female eats. Spermatophore proteins are important to female reproduction, and females compete for access to singing males. Males reject most receptive females as mates, and those accepted are more fecund than rejected individuals. This role reversal in courtship is in contrast to the behavior of the sexes in katydid species in which the males produce small spermatophores.     

Inbreeding promotes female promiscuity

The widespread phenomenon of polyandry (mating by females with multiple males) is an evolutionary puzzle, because females can sustain costs from promiscuity, whereas full fertility can be provided by a single male. Using the red flour beetle, Tribolium castaneum, we identify major fitness benefits of polyandry to females under inbreeding, when the risks of fertilization by incompatible male haplotypes are especially high. Fifteen generations after inbred populations had passed through genetic bottlenecks, we recorded increased levels of female promiscuity compared with noninbred controls, most likely due to selection from prospective fitness gains through polyandry. These data illustrate how this common mating pattern can evolve if population genetic bottlenecks increase the risks of fitness depression due to fertilization by sperm carrying genetically incompatible haplotypes.     

Function, developmental genetics, and fitness consequences of a sexually antagonistic trait

Sexual conflict is thought to be a potent force driving the evolution of sexually dimorphic traits. In the water strider Rheumatobates rileyi, we show that elaborated traits on male antennae function to grasp resistant females during premating struggles. Using RNA interference, we uncovered novel roles of the gene distal-less (dll) in generating these male-specific traits. Furthermore, graded reduction of the grasping traits resulted in a graded reduction of mating success in males, thus demonstrating both selection for elaboration of the traits and the role of dll in their evolution. By establishing developmental genetic tools in model systems where sexual selection and conflict are understood, we can begin to reveal how selection can exploit ancient developmental genes to enable the evolution of sexually dimorphic traits.     

Male Esterase 6 Catalyzes the Synthesis of a Sex Pheromone in Drosophila melanogaster Females

Esterase 6, a component of the seminal fluid of Drosophila melanogaster males, hydrolyzes cis-vaccenyl acetate, a lipid made only by males, to cis-vaccenyl alcohol. This reaction occurs in the female reproductive tract and is virtually complete within 6 hours after copulation. Both the alcohol and the acetate decrease the number of matings among pairs of virgin flies in which the female is treated topically with these substances. Although females tested 10 minutes after copulation elicit less courtship than virgin females, females tested 6 hours after copulation stimulate even less courtship if they received active esterase 6 in the seminal fluid of their respective mates. Either the alcohol or a derivative appears to be an antiaphrodisiac that decreases courtship elicited by inseminated females and thus reduces the probability of further mating. Thus the activity of the pheromone depends on a final reaction which occurs in the female, using both substrate and enzyme provided by the male.     

Facultative mate choice drives adaptive hybridization

Mating with another species (hybridization) is often maladaptive. Consequently, females typically avoid heterospecifics as mates. Contrary to these expectations, female spadefoot toads were more likely to choose heterospecific males when exposed to environmental conditions that favor hybridization. Indeed, those females with phenotypic characteristics for which hybridization is most favorable were most likely to switch from choosing conspecifics to heterospecifics. Moreover, environmentally dependent mate choice has evolved only in populations and species that risk engaging in, and can potentially benefit from, hybridization. Thus, when the benefits of mate choice vary, females may radically alter their mate selection in response to their own phenotype and their environment, even to the point of choosing males of other species.     

Infantile experience with suckling odors determines adult sexual behavior in male rats

Because infant rats learn about odors that elicit suckling, and because certain chemosensory cues that help elicit mating behavior in adults are similar to those that elicit suckling, an experiment was undertaken to assess the influence of suckling-associated odors experienced during infancy on adult sexual behavior. Rat pups lived with and suckled dams whose nipple and vaginal odors were altered with citral, a lemon scent. The rats were weaned and never exposed again, until testing, to citral or females. At about 100 days of age, the males were paired in mating tests with a normal sexually receptive female or with a sexually receptive female that had been treated perivaginally with citral immediately before testing. The males ejaculated readily when paired with citral-treated females but were slow to achieve ejaculation when paired with normal females. These findings implicate an infantile experience as a determinant of adult sexual behavior in a mammal.     

基于F_2群体的豁眼鹅豁眼性状遗传分析

【目的】豁眼鹅产蛋性能优良,是中国宝贵的地方家禽资源。作为豁眼鹅的品种标志,豁眼性状的遗传规律有待揭示。文章通过构建鹅豁眼性状F_2资源群,结合表型分析,验证决定豁眼性状基因为隐性遗传的假设,从而了解豁眼性状的遗传机制,为豁眼鹅遗传资源利用提供理论依据。【方法】选用20只豁眼公鹅和100只豁眼母鹅为亲本,组建随机交配群产生豁眼鹅纯系F_1代,观察F_1代中眼睑的表现和分离比例;资源群采用远交群体F_2设计,选用豁眼鹅(3只♂,15只♀)和四川白鹅(3只♂,15只♀)为亲本建立资源群,正反交交配产生F_1代,F_1代在避开近交的前提下互交产生F_2代,观察资源群F_1和F_2代中眼睑的表现和分离比例。【结果】豁眼鹅纯系随机交配下一代的豁眼表型比例为89%(n=444),11%(n=444)的个体为正常眼睑表型,其中,豁眼与正常表型公鹅的实际比值为7﹕1(n=238),与理论值差异不显著(χ~2=2.09χ~2_(0.05)(1)=3.84),母鹅的实际比值为10﹕1(n=206),与理论值差异不显著(χ~2=0.06χ~2_(0.05)(1)=3.84),表明决定豁眼性状的基因为隐性遗传的假设为正确的;同时,提示豁眼性状可能由两个基因座决定的,其中一个基因座影响眼睑形成,另一个起修饰作用的基因座影响豁眼表型的外显率。②豁眼鹅与四川白鹅的反交F_1代群体中公鹅和母鹅全部为正常眼睑,表明豁眼性状相对正常眼睑为隐性遗传。③正交F_1代中公鹅100%(n=71)为正常眼睑,母鹅中83%(n=76)的个体表现豁眼,17%(n=76)的个体表现正常,其中,豁眼母鹅与正常表型母鹅的实际比值为5﹕1(n=76),与理论值差异不显著(χ~2=3.51χ~2_(0.05)(1)=3.84),表明豁眼性状呈伴性遗传。④正交F_2群体中豁眼公、母鹅与正常眼睑实际比值分别为5﹕8(n=102)和2﹕3(n=94),与理论比值差异不显著(χ~2=0.36,0.02χ~2_(0.05)(1)=3.84);同时,反交F_2群体中豁眼公、母鹅与正常眼睑的实际比值分别为0﹕1(n=61)和5﹕7(n=60),与相应的理论比值差异不显著(χ~2=0.02χ~2_(0.05)(1)=3.84),正反交F_2群体中公母鹅的豁眼表型分离情况进一步证实了豁眼性状呈伴性隐性遗传的遗传规律。【结论】豁眼性状相对正常眼睑为隐性遗传,且呈伴性遗传;豁眼性状的形成主要受两个基因座的影响,一个起主要作用的基因座位于Z染色体上,另一个修饰作用的基因座位于常染色体上。     

Extreme reversed sexual dichromatism in a bird without sex role reversal

Brilliant plumage is typical of male birds, reflecting differential enhancement of male traits when females are the limiting sex. Brighter females are thought to evolve exclusively in response to sex role reversal. The striking reversed plumage dichromatism of Eclectus roratus parrots does not fit this pattern. We quantify plumage color in this species and show that very different selection pressures are acting on males and females. Male plumage reflects a compromise between the conflicting requirements for camouflage from predators while foraging and conspicuousness during display. Females are liberated from the need for camouflage but compete for rare nest hollows.     

Competition Among Courting Male Moths: Male-to-Male Inhibitory Pheromone

The behavioral function of a pheromone released by males of the army-worm moth Pseudaletia unipuncta was investigated both in laboratory wind-tunnel experiments and in experiments with moth-baited traps in the field. Such male moth scents have been thought to act at close range as sexual stimulants for females of the same species. However, the only obvious effect of the P. unipuncta male pheromone was upon other males, decreasing their tendency to approach sexually receptive, pheromone-releasing females and to exhibit copulatory behavior when near those females. The adaptive significance of the male pheromone may be related to the increased reproductive efficiency that results if multiple males are prevented from competing for a single female.     

瓯江彩鲤形态特征的两性异形和雌性个体生育力

研究了瓯江彩鲤(Cyprinus carpio var.color)体重和形态特征等19个参数的两性异形及雌性个体生育力.结果表明:除特定体长1龄雌性个体的体高和体重显著小于雄性个体外,其它17个性状不存在显著的雌雄两性异型.在2龄鱼中,雌性个体的头长、头宽、头高、眼后头长、眼间距、尾鳍长、体重和躯干重显著大于雄性个体,而体高却显著小于雄性个体,其它性状也不存在显著的雌雄两性异型;对这9个差异显著的形态特征变量进行主成分分析发现,第一和第二主成分共解释67.6%的变异,体高、体重和躯干重在第一主成分有较高的正负载系数(解释42.9%变异),头宽和眼间距在第二主成分有较高的正负载系数(解释24.7%变异).以年龄、性别为固定效应的两因素方差分析(Two-way ANOVA)显示,1龄鱼第一主成分的分值显著小于2龄鱼,雌性第二主成分的分值显著大于雄性,其它主成分的年龄、性别间无显著差异,两因素交互作片{对第一、第二主成分的分值亦无显著影响.雌性个体的生育力结果表明,瓯江彩鲤的怀卵数量与体长和体重回归关系显著.偏相关分析表明,雌性怀卵数量与体重呈显著的正相关(P<0.004),而与体长的相关不显著(P=0.502).生育力选择是瓯江彩鲤个体大小和局部特征两性异形的主要原因之一.     

鹅豁眼性状H基因座候选基因FREM1的验证分析

【目的】鹅豁眼性状呈隐性伴性遗传,其遗传基础有待揭示。基因FRAS-related extracellular matrix 1(FREM1)编码区的一些隐性突变导致了人类及模型小鼠上眼睑部分或完全缺失。本试验以鹅豁眼性状资源群为主要材料,通过对鹅基因FREM1的克隆、表达及基因多态性分析,验证FREM1是影响鹅上眼睑性状候选基因的假设,为深入研究眼睑性状的分子遗传机制奠定基础。【方法】采集鹅豁眼性状F2资源群中成年纯种豁眼鹅母鹅(3只)、四川白鹅(6只,雌雄各半)、♂豁眼×♀四川白鹅F1代公鹅(3只)的眼睑和肾组织,提取其总RNA,以鹅FREM1(XM_013193557)全长转录序列为参考设计引物,利用反转录RT-PCR克隆鹅FREM1基因,对其进行生物信息学分析,进而,采用实时荧光定量PCR法研究鹅眼睑和肾组织FREM1基因的表达特性。采集成年纯种豁眼鹅公鹅、四川白鹅公鹅和♂豁眼×♀四川白鹅正反交F1代公鹅各30只的血液,提取全血DNA,以鹅FREM1(Anser cygnoides domesticus breed Zhedong scaffold203_32,NCBI)序列设计引物,利用直接测序法检测FREM1基因变异位点在不同鹅群体中的分布情况。【结果】(1)经测序和拼接,获得鹅FREM1基因c DNA序列7 305bp,该序列包含一个完整的CDS(Coding Sequences)区,编码2 184个氨基酸。与四川白鹅和浙东白鹅相比,在豁眼鹅FREM1基因CDS序列上发现第4 515bp:TC是错义突变,导致第1 505aa:ValAla变化,位于FREM1蛋白的CSPG重复结构域中第10个CSPG上。利用在线工具SIFT预测该氨基酸替换对蛋白功能的影响较小。通过I-MutantΔΔG和MUPro程序分析,p.1505VA位点氨基酸替换大幅度降低了FREM1蛋白的稳定性。(2)FREM1基因在四川白鹅公、母鹅的眼睑和肾脏2个组织中均有表达,但肾脏表达水平远远高于眼睑,更为重要的是,公鹅FREM1基因的组织表达水平正好接近母鹅的2倍。ZHW(正常眼睑)和ZhW(上眼睑部分缺失)基因型鹅FREM1基因相对表达量无差异(P0.05),虽然ZHZh(正常眼睑)基因型鹅的FREM1基因相对表达量是ZHW和ZhW基因型鹅的2倍多,但这可能是性别不同导致的差异。(3)豁眼鹅群体中基因型HH、Hh和hh的频率分别是0、0和1.0,等位基因H和h的频率分别是0和1.0,杂合度为0;四川白鹅群体中基因型HH、Hh和hh的频率分别是1.0、0和0,等位基因H和h的频率分别是1.0和0,杂合度为0;F1代群体中基因型HH、Hh和hh的频率分别是0、1.0和0,等位基因H和h的频率分别是0.5和0.5,杂合度为1.0。【结论】基因FREM1是决定鹅上眼睑性状的H基因座,该基因编码区1个纯合型错义突变导致了FREM1蛋白第10个CSPG结构域的变化,从而影响了FREM1蛋白的稳定性,基因FREM1的c.4514TC突变可作为鹅豁眼性状重要的分子标记。     

Transmission of a female sex pheromone thwarted by males in the spider Linyphia litigiosa (Linyphiidae)

When a male Sierra dome spider (Linyphia litigiosa) encounters a virgin female that has been sexually mature for 7 to 10 days, he rapidly packs the silk of her web into a tight mass. This behavior hinders evaporation of a male-attractant chemical that such highly receptive females apply to their webs. The male thereby reduces the likelihood that his mating partner will attract rival males.     

Female responses to ancestral advertisement calls in tungara frogs

Phylogenetic techniques were used to estimate and reconstruct advertisement calls at ancestral nodes. These calls were used to investigate the degree of preference of female túngara frogs (Physalaemus pustulosus) for both extant and ancestral calls. Females did not discriminate between calls of males of their own species and calls at their most recent ancestral node. They also recognized calls of three extant species and at four ancestral nodes as the signals of appropriate mates. Both shared ancestral history, and call convergence might differentially influence call preferences.     

矮牵牛闭花瓣型性状转育效果评价

以两对隐性等位基因控制的闭花瓣型矮牵牛为母本,正常开放纯合型的矮牵牛为轮回父本,采用杂交、回交、测交验证和自交方法,保留闭花瓣型基因的同时获得不同颜色的闭花瓣型矮牵牛,并对不同回交世代数的植株进行植物学性状调查,确定最佳的回交代数.试验结果表明,在每一代回交后代中,注重同型株的选择,颜色、大小越接近轮回亲本,回交的效果越好,回交3代可以基本满足目标经济性状的要求.