鸟类羽色多态现象：概念及其进化机制假说

多态现象对了解物种的遗传、变异和进化有着重要意义,鸟类羽色多态现象的进化机制,是多态现象研究中非常重要的内容。鸟类羽色多态现象的进化机制假说主要有：分化选择假说、异类选择假说和非随机性交配假说等。本文对鸟类羽色多态现象的概念和以上进化机制假说进行了综述,并针对鸟类羽色多态现象进化机制研究中存在争议的问题及研究的不足提出了自己的看法。     

鸟类羽色多态现象:概念及其进化制假说

多态现象对了解物种的遗传、变异和进化有着重要意义,鸟类羽色多态现象的进化机制,是多态现象研究中非常重要的内容.鸟类羽色多态现象的进化机制假说主要有分化选择假说、异类选择假说和非随机性交配假说等.本文对鸟类羽色多态现象的概念和以上进化机制假说进行了综述,并针对鸟类羽色多态现象进化机制研究中存在争议的问题及研究的不足提出了自己的看法.     

实蝇类昆虫生殖行为的研究进展

实蝇是全世界重要的农业害虫,其生殖行为规律对其防治方法的研究具有重要指导意义。本文在文献调研的基础上,对实蝇类昆虫求偶、交配和产卵等行为的最新研究进展进行综述。实蝇类昆虫具有非资源型交配系统,性内、性间选择共同驱动实蝇的性特征进化;同时,实蝇生殖行为受到性信息素、翅信号、物理、化学以及环境等因素的影响。此外,雌虫在交配后会为理想产卵位置发生竞争,而产卵标记信息素起着调节作用。实蝇类昆虫的诸多生殖行为研究结果已成功应用于田间防治,取得了较好的效果。     

异色瓢虫不同光环境下的交配行为

光照条件是影响昆虫生长发育及生理行为变化的重要环境因子之一。以重要的捕食性天敌异色瓢虫为研究对象,借助动物行为自动观察系统对其在不同光照强度、光周期和光波长下的交配行为及繁殖力进行了分析研究。结果显示:(1)异色瓢虫的各交配行为和繁殖能力在有光和黑暗处理间具有显著差异;(2)异色瓢虫的求偶行为不受光照强度变化的影响,而交配持续时间及交配间隔时间在高光照强度下均显著短于低光照强度。尽管异色瓢虫的累积产卵量在不同光照强度间未见显著性差异,但是其幼虫孵化率随光照强度的增强显著降低;(3)异色瓢虫在光照时间较长的条件下表现出较高的交配求偶欲望,交配持续时间及交配间隔时间随光照时间的延长而缩短,其累积产卵量和幼虫孵化率均随光照时间的延长而显著增加;(4)不同环境颜色对异色瓢虫的求偶行为没有显著影响,但是其交配持续时间及交配间隔时间随照射光波长的增加而显著降低,雌虫的累积产卵量和幼虫孵化率均在黄色(575 nm)和绿色(510 nm)条件下最高,且显著大于其它处理。结果表明异色瓢虫的交配受光照条件影响极为显著,为进一步深入研究异色瓢虫环境适应性及提升其在生物防治中大规模饲养中的扩繁效率提供了重要的理论依据。     

合作行为的进化

达尔文在<物种起源>中阐释了生物体的竞争进化.但是合作行为和利他行为的发现却给了自然选择学说致命一击.20世纪60年代开始,进化生物学家开始重视对合作行为的研究.一方面,这些行为的本质至关重要,而且与基因学的观点相悖.另一方面,对合作行为和利他行为,尤其是实验室控制条件下行为的研究非常困难.阐述了合作行为进化发展的方式.同时综述了合作行为模式的框架,简要解释了这些模式的进化机制,以期为进一步理解合作行为的进化及其模式奠定基础.     

二种食蚜瓢虫Cheilomenes sexmaculata和Coccinella transversalis的生殖行为

在实验室中对二种食蚜瓢虫,Cheilomenes sexmaculata(Cs)和Coccinella transversalis(Ct)的生殖行为进行了研究。观察发现Cs和Ct交配前期分别为5.00±0.50和11.70±0.43天,而产卵前期则分别是5.51±0.7和12.67±0.49天。两种雄蛾的求偶行为表现出五个阶段,即靠近、观察、检查、伪装及交配尝试。性不成熟的、近期交配过且正在产卵的两种雌蛾会拒绝雄蛾的进一步行为。化学的和视觉的行为似乎在配偶识别中扮演一个角色。Cs交配相对地平静,而Ct的腹部摇动和敲击是特征。与Ct交配时间(37.90±1.99分钟)相比,Cs相对地延长的交配期间(133.43±8.87分钟),可能与缺少腹部来回摇动和敲击这些活跃的过程有关。经历了一天的多次交配后,Ct的交配的活跃程序减少了。两种未交配过的瓢虫在交配过程中比使那些已交配过成虫显得精力更充沛。两种瓢虫的生殖表现在多次交配中得以改善。     

大蜡螟的性选择行为

【目的】针对大蜡螟Galleria mellonella L.的性选择行为进行系统观察分析,为大蜡螟性信息素全组分的结构鉴定及利用信息素行为调控技术防控该虫提供依据。【方法】分别对不同体重、不同日龄和不同交配经历的大蜡螟成虫进行标记,在红光灯下观察并记录大蜡螟雌雄虫的性选择行为。【结果】在（26±0.5）℃、相对湿度60%、全黑暗条件下,无论雌虫还是雄虫,均倾向于选择与之体重相接近的异性个体进行交配。雌雄成虫均偏向于选择3日龄的异性个体进行交配;雌虫对不同日龄雄虫的选择率大小顺序为3日龄> 5日龄> 1日龄,而雄虫对不同日龄雌虫的选择率大小顺序为3日龄>1日龄> 5日龄。交配经历影响大蜡螟的性选择行为,雌虫优先选择已交配的雄虫进行交配,选择率为74.6%;雄虫也优先选择已交配的雌虫进行交配,选择率为79.4%。【结论】雌雄虫体重、日龄和交配经历能不同程度的影响大蜡螟的性选择行为,这为进一步研究雌雄交配信号奠定基础。     

异色瓢虫对蚜虫性外激素的行为反应研究

蚜虫性外激素假荆芥内酯(Z,E-Nepetalactone,NEP)能够吸引多种捕食性和寄生性天敌昆虫,它专一性强,生物活性突出,对非靶标生物安全。异色瓢虫Harmonia axyridis(Pallas)作为一种重要的捕食性天敌,被广泛应用于农业生产中。为明确异色瓢虫对蚜虫性外激素的行为反应,本研究在室内用"Y"型嗅觉仪测定了异色瓢虫成虫对不同剂量NEP的嗅觉行为反应;并在田间,每7 d释放100μL浓度为1 mg/m L的NEP,测定了NEP对异色瓢虫种群数量变动的影响。室内嗅觉测定试验结果表明异色瓢虫雌虫对10μL剂量NEP有显著的选择性,而雄虫对1μL剂量NEP有显著的选择性;田间试验发现,释放NEP的处理区异色瓢虫数量显著高于对照区。本研究为蚜虫性外激素在害虫绿色防控中的应用提供了依据。     

草地贪夜蛾的择偶与生殖力研究

【目的】探究草地贪夜蛾Spodoptera frugiperda主要择偶策略及其与生殖力的关系,并基于性选择理论探讨其择偶策略的进化意义和机制。【方法】将经过标记的不同日龄、不同体重及不同交配经历的草地贪夜蛾雌雄成虫进行配对,然后对配偶选择进行观察并对交配成功的雌雄成虫形态特征(体长、触角长度、翅长、胸部及腹部长度和宽度)及生殖力(单雌产卵量、卵孵化率和孵化出的幼虫数)进行比较分析。【结果】草地贪夜蛾雌雄成虫均偏好与年轻、体重较重及未交配过的成虫进行交配。雌成虫选择年轻(3日龄)雄成虫进行交配的概率(65.45%)显著高于选择年老(7日龄)雄成虫进行交配的概率(34.55%),雄成虫选择3日龄雌成虫进行交配的概率(82.35%)显著高于选择7日龄雌成虫进行交配的概率(17.65%)。雌成虫选择体重较大雄成虫进行交配的概率(74.58%)显著高于选择体重较轻雄成虫进行交配的概率(25.42%),雄成虫选择体重较重雌成虫进行交配的概率(66.67%)显著高于选择体重较轻雌成虫进行交配的概率(33.33%)。雌成虫选择无交配经历雄成虫进行交配的概率(64.91%)显著高于选择有交配经历雄成虫...     

载脂蛋白基因家族的密码子空间分析——核苷酸替换的非随机进化选择

ＤＮＡ分子进化中,对核苷酸替换的选择可呈选择中性或选择倾向性。为研究载脂蛋白基因进化过程中对核苷酸变化的选择方式,本文建立了基因的密码子空间分析方法。密码子空间是由密码子３个位置上核苷酸出现机率所组成的矩阵。对该空间中核苷酸分布的非随机性度量可以反映进化过程中核苷酸替换的选择方式。应用该法,我们发现载脂蛋白基因密码子空间第一及第三位的核苷酸分布呈高度非随机性。进一步研究表明：这种核苷酸的非随机分布可能与腺苷酸、胸苷酸对密码子位置的非中性选择有关。此外,还研究了同义密码子的选择使用与分支种系发生的关系。结果显示：载脂蛋白分子演化中存在着同义密码子使用的分子进化钟。这些研究提示密码子空间中核苷酸替换的非随机选择可能是载脂蛋白基因进化的一种特征。     

Benefits of polyandry: Molecular evidence from field‐caught dung beetles

When females mate with multiple males, they set the stage for postcopulatory sexual selection via sperm competition and/or cryptic female choice. Surprisingly little is known about the rates of multiple mating by females in the wild, despite the importance of this information in understanding the potential for postcopulatory sexual selection to drive the evolution of reproductive behaviour, morphology and physiology. Dung beetles in the genus Onthophagus have become a laboratory model for studying pre‐ and postcopulatory sexual selection, yet we still lack information about the reproductive behaviour of female dung beetles in natural populations. Here, we develop microsatellite markers for Onthophagus taurus and use them to genotype the offspring of wild‐caught females and to estimate natural rates of multiple mating and patterns of sperm utilization. We found that O. taurus females are highly polyandrous: 88% of females produced clutches sired by at least two males, and 5% produced clutches with as many as five sires. Several females (23%) produced clutches with significant paternity skew, indicating the potential for strong postcopulatory sexual selection in natural populations. There were also strong positive correlations between the number of offspring produced and both number of fathers and paternity skew, which suggests that females benefit from mating polyandrously by inciting postcopulatory mechanisms that bias paternity towards males that can sire more viable offspring. This study evaluates the fitness consequences of polyandry for an insect in the wild and provides strong evidence that female dung beetles benefit from multiple mating under natural conditions.     

A phylogenetic analysis of the evolution of sexual dimorphism and mating systems in water striders (Hemiptera: Gerridae)

Conflicts over mating decisions characterize the sexual behaviour of many insects, in particular when males encounter females that already carry enough sperm to fertilize their eggs, since a mating often will inflict greater costs than benefits upon females. Therefore, coevolutionary models predict adaptation and counter-adaptation by the sexes in a battle to control the outcome of sexual encounters. A phylogenetic analysis was performed on patterns of sexual dimorphism and mating systems within water striders (Hemiptera, Gerridae). Phylogenetic effects or 'constraints' have significantly shaped patterns of sexual dimorphism in female/ male size ratios, legs and genitalia of males, and the structure of the female abdomen. Males of ancestral gerrids were probably slightly smaller than conspecific females, had powerful fore legs adapted to grasp the female's thorax during mating, and had clasping genitalic structures suited to grasp or pinch the female posteriorly. Most gerrids have a female/male size ratio between 1.05 and 1.14, but more pronounced sexual size ratios (above 1.25) have independently evolved several times in the family, usually in association with extended post-copulatory mate guarding. The comparative, phylogenetic analysis suggests coevolution of female anticlasper and male clasping devices for the clade comprising the subfamilies Cylindrostethinae, Ptilomerinae, and Halobatinae while female anticlasper devices have evolved in the absence of male clasping genitalia in the Gerrinae. The ancestral and most common mating system in gerrids is 'scramble competition polygyny' from which has evolved 'resource defence polygyny' at least four times independently of each other. The phylogenetic effects on patterns of mating behaviour are much less obvious, as exemplified by the large amount of interspecific variation in some genera.     

Female multiple mating in wild and laboratory populations of the two-spot ladybird, Adalia bipunctata

Female mating rate is an important variable for understanding the role of females in the evolution of mating systems. Polyandry influences patterns of sexual selection and has implications for sexual conflict over mating, as well as for wider issues such as patterns of gene flow and levels of genetic diversity. Despite this, remarkably few studies of insects have provided detailed estimates of polyandry in the wild. Here we combine behavioural and molecular genetic data to assess female mating frequency in wild populations of the two-spot ladybird, Adalia bipunctata (Coleoptera: Coccinellidae). We also explore patterns of sperm use in a controlled laboratory environment to examine how sperm from multiple males is used over time by females, to link mating with fertilization. We confirm that females are highly polyandrous in the wild, both in terms of population mating rates (approximately 20% of the population found in copula at any given time) and the number of males siring offspring in a single clutch (three to four males, on average). These patterns are consistent across two study populations. Patterns of sperm use in the laboratory show that the number of mates does not exceed the number of fathers, suggesting that females have little postcopulatory influence on paternity. Instead, longer copulations result in higher paternity for males, probably due to the transfer of larger numbers of sperm in multiple spermatophores. Our results emphasize the importance of combining field and laboratory data to explore mating rates in the wild.     

Sub-lethal effects of deltamethrin residues on the within-crop behaviour and distribution ofCoccinella septempunctata

The behaviour and distribution of adultCoccinella septempunctata L. (Coleoptera: Coccinellidae) were recorded in two plots of winter wheat infested with the cereal aphidsSitobion avenae (F.) andMetopolophium dirhodum (Walk.) (Homoptera: Aphididae). One plot was sprayed with the pyrethroid insecticide deltamethrin at a rate of 6.25 g a.i./ha and the other was left unsprayed. Single ladybird beetles were released sequentially on the ground at the centre of the sprayed and unsprayed plots and their behaviour and position in the crop canopy were recorded at 30 second intervals for a total of 15 min per beetle. Assessments, with fresh beetles, continued for four days after spray application with a total of eighty ladybird beetles observed. The 15 min period was selected to avoid lethal effects and no ladybird beetles were killed or knocked down as a result of exposure to deltamethrin residues during this period. Significant differences were found between the overall behaviour patterns ofC. septempunctata in the untreated and deltamethrin treated plots up to three days after the spray application. Ladybird beetles exposed to deltamethrin residues were observed to walk and groom significantly more frequently and to rest significantly less frequently than those in the unsprayed plot. Significant differences were also found between the observed distribution of ladybird beetles in the sprayed and unsprayed crop canopies, with higher numbers of observations towards the bottom of the crop canopy and on the ground in the deltamethrin treated plot than in the untreated plot during the first two days after deltamethrin application. Upon the foliage itself, ladybird beetles were observed significantly more frequently on the abaxial leaf surface in the deltamethrin treated crop compared with the untreated crop. The results are discussed in terms of possible evidence for the repellency of deltamethrin toC. septempunctata and also the implications for integrated pest management of changes in predator behaviour and crop distribution resulting from sub-lethal uptake of insecticides.     

Sexual selection and condition dependence of courtship display in three species of horned dung beetles

Sexual selection has traditionally been divided into competitionover mates and mate choice. Currently, models of sexual selectionpredict that sexual traits are expressed in proportion to thecondition of their bearer. In horned beetles, male contestcompetition is well established, but studies on female preferencesare scarce. Here I present data on male mating success and condition dependence of courtship rate in three species of horn-dimorphicdung beetles, Onthophagus taurus, Onthophagus binodis, andOnthophagus australis. I found that in the absence of malecontest competition, mating success of O. taurus and O. australiswas unrelated to their horn length and body size, whereas inO. binodis horn size had a negative effect but body size hada positive effect on male mating success. Overall, in O. binodismajor morph males had greater mating success than minor morphmales. In all three species male mating success was affectedby courtship rate, and the courtship rate was condition dependent such that when males were manipulated to be in poor conditionthey had lower courtship rates than males that were manipulatedto be in good condition. My findings provide new insight intothe mating systems of horned dung beetles and support an importantassumption in indicator models of sexual selection.     

Pairing Patterns in Japanese Beetles (Popillia japonica Newman): Effects of Sex Ratio and Time of Day

Size-related patterns between unpaired and paired individuals and between males and females of a given pair give clues about both a species' sexual behavior and the environmental factors affecting its sexual behavior. We studied the mating patterns of Japanese beetles (Popillia japonica) in east–central Illinois. The frequency of male–female pairs varied significantly among days and within a day, with pairs being significantly more common in the morning and the evening. The sex ratio on the food plants was significantly male biased, but although the sex ratio fluctuated among days and among time periods, the variation in the frequency of mating pairs was not explained by variation in the sex ratio. We found no assortative pairing with respect to size, but sizes of paired and unpaired individuals did differ. Paired females were larger than unpaired females at all time periods. In contrast, paired males were larger at 0700 and smaller at 1000, and little difference existed at other times of the day. The size of males and females, sex ratio, and pairing frequency also differed among days. Much of this variation in size and pairing frequency was related to a seasonal effect: later in the summer, beetles of both sexes were smaller and pairs were less common. Interestingly, pairs were also less frequent on days with higher average temperatures. This between-day variation in pairing, in combination with the within-day pairing differences, suggests that the temperature may alter the cost, and hence likelihood, of pairing in this species.     

Relative abundance and the species-specific reinforcement of male mating preference in the Chrysochus (Coleoptera: Chrysomelidae) hybrid zone

Most studies of reinforcement have focused on the evolution of either female choice or male mating cues, following the long-held view in sexual selection theory that mating mistakes are typically more costly for females than for males. However, factors such as conspecific sperm precedence can buffer females against the cost of mating mistakes, suggesting that in some hybrid zones mating mistakes may be more costly for males than for females. Thus, the historical bias in reinforcement research may underestimate its frequency. In this study, we present evidence that reinforcement has driven the evolution of male choice in a hybrid zone between the highly promiscuous leaf beetles Chrysochus cobaltinus and C. auratus, the hybrids of which have extremely low fitness. In addition, there is evidence for male choice in these beetles and that male mating mistakes may be costly, due to reduced opportunities to mate with conspecific females. The present study combines laboratory and field methods to quantify the strength of sexual isolation, test the hypothesis of reproductive character displacement, and assess the link between relative abundance and the strength of selection against hybridization. We document that, while sexual isolation is weak, it is sufficient to produce positive assortative mating. In addition, reproductive character displacement was only detected in the relatively rare species. The strong postzygotic barriers in this system are sufficient to generate the bimodality that characterizes this hybrid zone, but the weak sexual isolation is not, calling into question whether strong prezygotic isolation is necessary for the maintenance of bimodality. Growing evidence that the cost of mating mistakes is sufficient to shape the evolution of male mate choice suggests that the reinforcement of male mate choice may prove to be a widespread occurrence.     

Sexual dimorphism and sexual conflict in the diving beetle Agabus uliginosus (L.) (Coleoptera: Dytiscidae)

Sexual conflict can drive intersexual arms races, with female resistance and male persistence traits coevolving antagonistically. Such arms races are well documented in some diving beetles, although the extent of sexual conflict in this family remains unclear. The European dytiscid Agabus uliginosus has a strikingly dimorphic female; individuals from most regions are smooth and male‐like, whereas those from some populations have a strongly roughened dorsum, a trait that has attracted the name dispar. We demonstrate that rough and smooth females differ consistently in the development of dorsal surface microreticulation, and that these females are associated with males that differ in the development of their persistence traits. These findings extend the occurrence of pre‐insemination sexual conflict and associated intrasexual dimorphism in Dytiscidae, and suggest that such mating systems are relatively widespread in these beetles.     

Mating asymmetry and the direction of evolution in the Hawaiian cricket genus Laupala

Based on studies from native Hawaiian Drosophila, a model was proposed to explain sexual isolation and mating asymmetry, from which one could potentially infer the 'direction of evolution'. We examined sexual isolation between allopatric cricket species of the genus Laupala, another endemic Hawaiian insect with an elaborate mating system, to begin to explore the nature of sexual isolation and mating asymmetry in closely related Hawaiian organisms. We studied sexual isolation and mating asymmetry in two contrasts. First, an inter-island comparison, including L. makaio from the older island of Maui and L. paranigra from the younger island of Hawaii, and second, an intra-island (Hawaii) comparison, including L. nigra from the older volcano of Mauna Kea and L. paranigra with a primary distribution on the younger volcanoes of Mauna Loa and Kilauea. We used a 'no-choice' experimental design, pairing individual males and females in homospecific or heterospecific combinations. Several behavioural aspects of courtship (proportion of male singing, latency to male singing, production of spermatophores and courtship initiation speed) were quantified as well as the success or failure of matings. We demonstrate asymmetry in sexual isolation between reciprocal combinations of L. makaio and L. paranigra. This result is examined in light of the differences in courtship behaviour manifest in the experiments with these two species. We did not find evidence of asymmetry in sexual isolation between L. nigra and L. paranigra, although differences in courtship initiation speed were evident between reciprocal combinations of these two species. In addition to the geological argument that species on older islands and older volcanoes give rise to species on younger islands and younger volcanoes, we discuss phylogenetic evidence consistent with these biogeographic hypotheses of relationships among the focal taxa. The patterns of asymmetrical sexual isolation and mating asymmetry are consistent with those found in the native Hawaiian Drosophila.