Histological study of the spermatheca in three thelytokous parthenogenetic ant species,Pristomyrmex punctatus,Pyramica membranifera and Monomorium triviale (Hymenoptera: Formicidae)

Gotoh, A., Billen, J., Tsuji, K., Sasaki, T. and Ito, F. 2011. Histological study of the spermatheca in three thelytokous parthenogenetic ant species, Pristomyrmex punctatus, Pyramica membranifera and Monomorium triviale (Hymenoptera: Formicidae). —Acta Zoologica (Stockholm) 00 :1–8. The evolution of obligate parthenogenesis may induce the degeneration of female mating ability and subsequently affect the morphology of the female reproductive organs related to mating and/or sperm storage. Here, we investigated the size and structure of the sperm storage organ, the spermatheca, in three thelytokous parthenogenetic myrmicine ant species, Pristomyrmex punctatus, Pyramica membranifera and Monomorium triviale, and compared it with that of their related sexually reproducing species. So far, mated individuals have never been found in these three species, which appears to be in line with their parthenogenetic status. Although the spermatheca appears to be useless in these species, we could not find any evidence on the degeneration in size and morphology of their spermathecae. The spermathecal reservoir still has the columnar hilar epithelium, which is one of the major features for a functional spermatheca in ants.     

Reproductive biology of the viviparous scorpion,Liocheles australasiae (Fabricius) (Arachnida,Scorpiones, Scorpionidae). I. Absence of males in two natural populations

Summary

Sex of the viviparous scorpion, Liocheles australasiae, collected in two localities in Asia at various seasons during the years 1977 to 1983, was examined on the basis of morphology of gonads and germ cells. A total of 569 specimens consisted of 408 pregnant and 7 interpregnant adult females, 126 immature or nymphal females, and 28 young nymphs in which the sex was not distinguishable. Distinct males were never collected in either locality at any season. No spermatozoa were found in any region of the female reproductive systems. Judging from these results, males do not occur in these populations, and it is presumed that these populations reproduce by thelytokous parthenogenesis.     

孤雌产雌生殖品系松毛虫赤眼蜂产卵强度对Wolbachia诱导的其生殖表型的影响

[目的]松毛虫赤眼蜂Trichogramma dendrolimi是一种用于鳞翅目害虫生物防治的重要卵期寄生蜂.本研究旨在明确孤雌产雌生殖品系松毛虫赤眼蜂的产卵强度对其体内Wolbachia滴度及Wolbachia诱导的孤雌产雌生殖表型的影响.[方法]在室内调查了3个处理组松毛虫赤眼蜂雌蜂不同产卵强度(每日仅1 h供寄...     

Asexual queen succession in the higher termite Embiratermes neotenicus

Asexual queen succession (AQS), in which workers, soldiers and dispersing reproductives are produced sexually while numerous non-dispersing queens arise through thelytokous parthenogenesis, has recently been described in three species of lower termites of the genus Reticulitermes. Here, we show that AQS is not an oddity restricted to a single genus of lower termites, but a more widespread strategy occurring also in the most advanced termite group, the higher termites (Termitidae). We analysed the genetic structure in 10 colonies of the Neotropical higher termite Embiratermes neotenicus (Syntermitinae) using five newly developed polymorphic microsatellite loci. The colonies contained one primary king accompanied either by a single primary queen or by up to almost 200 neotenic queens. While the workers, the soldiers and most future dispersing reproductives were produced sexually, the non-dispersing neotenic queens originated through thelytokous parthenogenesis of the founding primary queen. Surprisingly, the mode of thelytoky observed in E. neotenicus is most probably automixis with central fusion, contrasting with the automixis with terminal fusion documented in Reticulitermes. The occurrence of AQS based on different mechanisms of ploidy restoration raises the hypothesis of an independent evolutionary origin of this unique reproductive strategy in individual lineages of lower and higher termites.     

Brood stimulation controls the phasic reproductive cycle of the parthenogenetic ant Cerapachys biroi

Several groups of ants display a reproductive cycle in which two phases of adult activity alternate in synchrony with the brood instars. The brood stimulation hypothesis (Schneirla, 1957) was developed for ecitonine army ants to explain the proximate control of such biphasic cycles. According to it, onsets of cyclic activities are triggered by social stimulations arising from the developing brood, rather than by innate pace-makers inbuilt in adult ants. While it seemed to provide an acceptable explanation, this hypothesis failed to be experimentally demonstrated, in spite of numerous field observations. We used colonies of thelytokous populations of the phasic ant Cerapachys biroi as a model in order to test the brood stimulation theory. Brood removal and substitution experiments allowed us to confirm, first, that the periodicity of the cycle is not controlled by an endogenous rhythm in adults. Moreover, we could also characterise the influence of each brood instar on the activity of adult ants. Although we confirmed the existence of a brood stimulation involved in the control of the cycle, experiments revealed that it was not performed accordingly to Schneirla’s hypothesis. In effect, our study suggests a primacy of larval influence: the foraging phase was triggered and sustained by larvae- induced excitement rather than by stimulation from the newly-emerged callows. Received 21 March 2005; revised 1 June 2005; accepted 6 june 2005.     

Density and variability of dinucleotide microsatellites in the parthenogenetic polyploid snail Melanoides tuberculata

Characterization of microsatellites in the parthenogenetic polyploid snail Melanoides tuberculata revealed an unusual high density of dinucleotide repeats. Multiple banding patterns were obtained at these loci, and interpreted as a consequence of polyploidy. Microsatellite variability was low within, but high between, shell morphotypes. Genotypes were wholly transmitted from mothers to offspring. These results suggest that reproduction is strictly apomictic, and that shell morphotypes are genetic clones.     

中国鸟类的种内巢寄生:基于超常窝卵数的证据

鸟类种内巢寄生(Intraspecific nest parasitism,INP)是近年来行为生态学和进化生物学理论遇到的新问题。自1980年以来,国外学者就开始搜集总结具有INP的鸟种,迄今的列表已达236种。然而,由于语言的障碍,中国鸟类学者所发现的例子未能归入列表中。本文以超常窝卵数为标准,查阅所发表的中文鸟类学文献,发现18种发生于中国的鸟类具有INF,其中14种未被国际学者收录。随着研究的深入,预计将在更多种类、特别是雉类中发现：INP现象;建议在进行INP综合评价研究时,应当以种或种群INP发生的几率,而不是它的有或无,作为分析的标准[动物学报49(6)：851～853,2003]。     

Wolbachia感染对拟澳洲赤眼蜂寿命、生殖力和嗅觉反应的影响

研究了通过共享同一寄主卵,短管赤眼蜂Trichogramma pretiosum体内共生的Wolbachia被水平传递到拟澳洲赤眼蜂T. confusum体内后,Wolbachia对新宿主拟澳洲赤眼蜂的影响。结果表明： Wolbachia的侵染能使拟澳洲赤眼蜂进行不完全的产雌孤雌生殖,增加拟澳洲赤眼蜂子代雌性比例,但却导致了雌蜂寿命缩短和繁殖力降低的生理损失。Wolbachia感染的当代处女蜂及其建立的种群连续5代(F₁～F₅),其子代雌蜂百分率分别为79.17%、76.60%、68.66%、72.58%、68.15%和64.06%,基本上呈现出逐代降低的趋势,并越来越接近对照的63.85%。处女蜂及F₁～F₅代雌蜂的平均寿命分别为4.33、5.50、5.60、6.68、7.32和7.50天,而未感染交配雌蜂寿命为7.59 天;处女蜂及F₁～F₅代雌蜂平均产卵量分别为11.33、70.00、86.41、93.90、102.92和124.38粒/雌,除F₅代外,均显著低于未感染交配雌蜂的产卵量134.81粒/雌。用四臂嗅觉仪测定了Wolbachia新宿主拟澳洲赤眼蜂对寄主小菜蛾的嗅觉反应,结果表明Wolbachia的侵染具轻微干扰拟澳洲赤眼蜂嗅觉反应的负面影响。未感染Wolbachia的拟澳洲赤眼蜂及Wolbachia供体短管赤眼蜂对寄主小菜蛾具较强的嗅觉反应,其雌蜂在小菜蛾腹部鳞片正己烷提取液和小菜蛾卵表正己烷提取液处理区内滞留时间显著或极显著长于对照区。而感染Wolbachia的拟澳洲赤眼蜂F₂代和F₃代雌蜂,尽管在小菜蛾腹部鳞片正己烷提取液处理区内滞留时间比对照区长,但没有达到显著水平;其F₂代雌蜂在小菜蛾卵表正己烷提取液处理区内滞留时间与对照区相比,也没有达到显著水平。随Wolbachia在拟澳洲赤眼蜂种群中垂直感染代数的增加,拟澳洲赤眼蜂对寄主小菜蛾的嗅觉反应恢复正常,在Wolbachia感染后的 F₄～F₆代,雌蜂在两种提取液处理区内的滞留时间均显著或极显著长于对照区。     

Asymmetry, reproductive success and parasitism of Pomatoschistus microps in a French lagoon

There was an allometry between length of nesting male Pomatoschistus microps and the size of the nest. There was also a positive relationship between parasite load and pectoral fin asymmetry. There was no marked relationship between the number of eggs in the nest and parasitism or level of asymmetry. These results are discussed in terms of energy allocation and fish reproductive success.     

Shell size and shape in Madeiran land snails: do niches remain unfilled?

The distribution of shell heights and diameters in the mainly endemic Madeiran land snail fauna shows the bimodal pattern of high- and low-spired shells found in many other faunas. Field and laboratory studies show that shell shape is associated with the angle of substrate on which the snails crawl; as elsewhere, tall spired species use vertical surfaces or burrow in soft material. Flattened species predominate on horizontal surfaces, while globular species are less specific in their preferences. Detailed comparisons with the fauna of N.W. Europe show that the proportion of high-spired species in the Madeiran fauna is low, and large high-spired species associated with vertical surfaces are very few in number despite an apparent abundance of suitable habitats. Amongst low-spired species, one family, the Helicidae, dominates the Madeiran fauna. While the overall distribution of size in these species is much as in Europe, Madeiran helicids extend into smaller size classes than do those in Europe, and they appear to fill a gap in the scatter created by the absence of other families.
Non-endemic species, other than those strictly associated with man-made environments, are generally small in size. In the upper scatter, their size distribution parallels that of endemics, but in the lower scatter they constitute the whole of the smallest size classes.
The role of interspecific competition in determining these distributions is discussed. The range of helicid sizes is compatible with a relaxation of competition or predator pressure relative to other areas, but in the upper scatter there appear to be gaps in the range of size and shape expected despite a long period in which the fauna could evolve. This could indicate the existence of adaptive troughs blocking, or delaying, radiation over the full spectrum of size and shape.