Sexual Generation Research Articles

A new species of oak gall wasp (Hymenoptera: Cynipidae, Cynipini) from Turkey.

A new species of the genus Andricus Hartig, 1840 (Cynipidae: Cynipini) is described from Burdur province in Turkey: Andricus arslani Azmaz Katlm sp. n. sexual generation. The new species induce galls on Quercus cerris L. belonging to section Cerris. SEM images, photos of the host galls, and data on the diagnosis, distribution, and biology of the new species are provided.

Food and Social Politics in Early Modern Ireland: Representing the Peasant in The Parliament of Clan Tomas

Recent historiography has demonstrated the immense material and metaphorical importance of food to representing social distinction in medieval and early modern Europe. To date there has been no effort to explore the Irish experience in this context. This article approaches the “meaning” of food in sixteenth and seventeenth-century Ireland through a focused gastro-political analysis of Irish literary and material satire. It will examine representations of low-born food consumption in relation to broader early modern discourse around dietary classification, manners and food consumption. It will also explore the basis of Irish social food stereotypes by locating them in contemporary nutritional theories, philosophical and “scientific” ideas and by comparing imagined Irish foodways with a broad range of comparative European visual, literary and material examples. The “meaning” of food will be considered thematically, exploring dietary codification; the physical and moral embodiment of peasant foods; and the relationship between food association and sexual generation. This approach will demonstrate the highly sophisticated conceptual integration of European ideas and symbols in Irish culture, whilst developing a new tool for understanding the metaphorical intricacy of this period in Irish history. The article will move food, for the first time, into the arena of early modern Irish history, opening a window for future comparative studies of Irish and European food cultures.

Why do plants need agrobacterial genes?

Agrobacterium mediated transformation in nature is the cause of the development of diseases: crown galls and hairy roots. These neoplasms are transgenic tissues on a non-transgenic plant. However, in nature, full-fledged GMOs arise, containing agrobacterial transgenes in every cell and transmitting them in a series of sexual generations. These plants are called naturally transgenic plants or natural GMOs. Over the past 3 years, the list of natural GMO species has been significantly expanded. Due to this, it became possible to make certain generalizations and more substantively discuss the possible evolutionary role of this phenomenon. The presented mini-review is devoted to the generalization of data on the possible functions of genes of agrobacterial origin in plant genomes.

On computing relative effective population size estimates and parameters from an equilibrium cycle of hermaphrodite frequency fluctuation due to mixed reproductive modes in filamentous fungi

Many filamentous ascomycete fungi reproduce primarily asexually, with only occasional sexual generations. This can lead to a departure from the 1:1 mating type ratio that is expected in obligate sexual populations. The relaxed selection on sexual traits also can lead to a decrease in the frequency of female fertile strains in field populations, while male fertility does not similarly decrease since male gametes also can serve as asexual spores. Both changes ultimately impact the strength of genetic drift in populations. The frequency of female sterility likely increases with the time since the last generation of sexual reproduction, such that it can be used to estimate the relative frequency of sexual reproduction. Here I provide additional details relevant to Leslie and Klein’s (1996) model of mixed sexual reproduction and vegetative propagation as related to the frequency of female sterility. This includes new or modified equations that allow for simpler calculations of i) two estimates of relative Ne, ii) the expected range of hermaphrodite frequencies during the cycles of mixed reproduction, and iii) the relative frequency of sex. These equations also are included in spreadsheet templates into which researchers can directly enter frequencies computed from their population data to estimate these parameters for their own populations. These resources will make the results of Leslie and Klein (1996) more accessible and should increase the use of this model in evaluating the frequency of sexual reproduction of filamentous fungi.

Paradoxes of Plant Epigenetics

Plants have a unique ability to adapt ontogenesis to changing environmental conditions and the influence of stress factors. This ability is based on the existence of two specific features of epigenetic regulation in plants, which seem to be mutually exclusive at first glance. On the one hand, plants are capable of partial epigenetic reprogramming of the genome, which can lead to adaptation of physiology and metabolism to changed environmental conditions as well as to changes in ontogenesis programs. On the other hand, plants can show amazing stability of epigenetic modifications and the ability to transmit them to vegetative and sexual generations. The combination of these inextricably linked epigenetic features not only ensures survival in the conditions of a sessile lifestyle but also underlies a surprisingly wide morphological diversity of plants, which can lead to the appearance of morphs within one population and the existence of interpopulation morphological differences. The review discusses the molecular genetic mechanisms that cause a paradoxical combination of the stability and lability properties of epigenetic modifications and underlie the polyvariance of ontogenesis. We also consider the existing approaches for studying the role of epigenetic regulation in the manifestation of polyvariance of ontogenesis and discuss their limitations and prospects.

Leaf Galls with the Same Morphology Induced on the Same Plant Species by Two Species of Latuspina (Hymenoptera: Cynipidae), with a Description of a New Species

A new species in the genus Latuspina (Hymenoptera: Cynipidae) that induces galls on the leaves of Quercus variabilis Blume (Fagaceae) in China is described here as Latuspina jinzhaiensis Abe, Ide, Su, and Zhu, new species. The sexual generation gall of the new species is indistinguishable from that produced by L. abemakiphila Ide and Abe, which is induced on leaves of the same oak species in Japan. However, these two cynipid species can be distinguished based on the morphological characteristics of the propodeum of adult wasps. Moreover, differences in the partial sequence of the mitochondrial cytochrome c oxidase subunit I (COI) gene (18–19 of 658 bp) supports the morphological distinction between these two species. Although congeneric gall-inducing cynipids, as well as other gall-inducing insects such as gall midges, can typically be distinguished based solely on gall characteristics (e.g., shape and position on the plant) and host plant species, these two Latuspina species are an exception. Since the asexual generations of both species are currently unknown, finding asexual generation galls and adults in the future is considered necessary.

Two new oak gall wasp species (Hymenoptera: Cynipidae, Cynipini) from Quercus pontica (Fagaceae) in Turkey.

Two new species of oak gall wasp, Andricus mammadovi Azmaz Katlm sp. n. sexual generation and Cynips fatihi Azmaz Katlm sp. n. asexual generation (Cynipidae: Cynipini) are described from the eastern Black Sea region in Turkey. These species induce galls on Quercus pontica K.Koch representing the first record of cynipids associated with the natural Q. pontica population in Turkey. SEM images, photos of the host galls, and data on the diagnosis, distribution, and biology of both new species are provided.

Massive colonization of protein-coding exons by selfish genetic elements in Paramecium germline genomes.

Ciliates are unicellular eukaryotes with both a germline genome and a somatic genome in the same cytoplasm. The somatic macronucleus (MAC), responsible for gene expression, is not sexually transmitted but develops from a copy of the germline micronucleus (MIC) at each sexual generation. In the MIC genome of Paramecium tetraurelia, genes are interrupted by tens of thousands of unique intervening sequences called internal eliminated sequences (IESs), which have to be precisely excised during the development of the new MAC to restore functional genes. To understand the evolutionary origin of this peculiar genomic architecture, we sequenced the MIC genomes of 9 Paramecium species (from approximately 100 Mb in Paramecium aurelia species to >1.5 Gb in Paramecium caudatum). We detected several waves of IES gains, both in ancestral and in more recent lineages. While the vast majority of IESs are single copy in present-day genomes, we identified several families of mobile IESs, including nonautonomous elements acquired via horizontal transfer, which generated tens to thousands of new copies. These observations provide the first direct evidence that transposable elements can account for the massive proliferation of IESs in Paramecium. The comparison of IESs of different evolutionary ages indicates that, over time, IESs shorten and diverge rapidly in sequence while they acquire features that allow them to be more efficiently excised. We nevertheless identified rare cases of IESs that are under strong purifying selection across the aurelia clade. The cases examined contain or overlap cellular genes that are inactivated by excision during development, suggesting conserved regulatory mechanisms. Similar to the evolution of introns in eukaryotes, the evolution of Paramecium IESs highlights the major role played by selfish genetic elements in shaping the complexity of genome architecture and gene expression.

Progress in the characterization of insulin-like peptides in aphids: Immunohistochemical mapping of ILP4

Aphids were the first animals described as photoperiodic due to their seasonal switch from viviparous parthenogenesis to sexual reproduction (cyclical parthenogenesis) caused by the shortening of the photoperiod in autumn. This switch produces a single sexual generation of oviparous females and males that mate and lay diapausing cold-resistant eggs that can overcome the unfavourable environmental conditions typical of winter in temperate regions. Previous studies have hinted at a possible implication of two insulin-like peptides (ILP1 and ILP4) in the aphid seasonal response, changing their expression levels between different photoperiodic conditions. Moreover, in situ localization of their transcripts in particular neurosecretory cells (NSCs) in the aphid brain supported the idea that these neuropeptides could correspond to the formerly called virginoparin, an uncharacterized factor originally proposed to be transported directly to the aphid embryos to promote their development as parthenogenetic individuals. To further investigate the fate of these ILPs, we raised a specific antiserum against one of them (ILP4) and mapped this neuropeptide by immunohistochemistry (IHC) in Acyrthosiphon pisum and Megoura viciae aphids. Coincident with in situ localization, our results show that ILP4 is synthesized in two groups (one in each brain hemisphere) of four neurosecretory cells in the pars intercerebralis (NSC group I) and then it is transported outside the brain to the corpora cardiaca. From there, three nerves (two laterals and one medial) transport it to the abdomen. Although no precise site of release has been found, the terminations of these nerves near the germaria would be compatible with the proposal of a direct connection between group I of NSCs and the reproductive system by localized release. In addition, we detected some collateral arborizations originating from the eight NSCs going to the pars lateralis, where clock neurons and some photoreceptors have been previously localized, suggesting a possible communication between the circadian and photoperiodic systems.

The epiallelic potential of transposable elements and its evolutionary significance in plants.

DNA provides the fundamental framework for heritability, yet heritable trait variation need not be completely ‘hard-wired’ into the DNA sequence. In plants, the epigenetic machinery that controls transposable element (TE) activity, and which includes DNA methylation, underpins most known cases of inherited trait variants that are independent of DNA sequence changes. Here, we review our current knowledge of the extent, mechanisms and potential adaptive contribution of epiallelic variation at TE-containing alleles in this group of species. For the purpose of this review, we focus mainly on DNA methylation, as it provides an easily quantifiable readout of such variation. The picture that emerges is complex. On the one hand, pronounced differences in DNA methylation at TE sequences can either occur spontaneously or be induced experimentally en masse across the genome through genetic means. Many of these epivariants are stably inherited over multiple sexual generations, thus leading to transgenerational epigenetic inheritance. Functional consequences can be significant, yet they are typically of limited magnitude and although the same epivariants can be found in nature, the factors involved in their generation in this setting remain to be determined. On the other hand, moderate DNA methylation variation at TE-containing alleles can be reproducibly induced by the environment, again usually with mild effects, and most of this variation tends to be lost across generations. Based on these considerations, we argue that TE-containing alleles, rather than their inherited epiallelic variants, are the main targets of natural selection. Thus, we propose that the adaptive contribution of TE-associated epivariation, whether stable or not, lies predominantly in its capacity to modulate TE mobilization in response to the environment, hence providing hard-wired opportunities for the flexible exploration of the phenotypic space.This article is part of the theme issue ‘How does epigenetics influence the course of evolution?’

The Heterogonic Life Cycles of Oak Gall Wasps Need to Be Closed: A Lesson From Two Species ofDryophanta(Hymenoptera: Cynipidae: Cynipini)

AbstractIn heterogonic gall wasps, the gall structure, phenology, and adult morphology differ between the asexual and sexual generations, even within the same species. Dryophanta japonica Ashmead and Dryophanta mitsukurii Ashmead were described in 1904, but their heterogonic life cycles were uncertain. To match their asexual and sexual generations, we compared the type specimens of both species with specimens of gall wasps reared to demonstrate heterogonic life cycles. This revealed that these two species are the respective asexual and sexual generations of a single heterogonic species. Based on the morphological characteristics, we transferred D. japonica to Cerroneuroterus Melika and Pujade-Villar as Cerroneuroterus japonicus (Ashmead, 1904) comb. nov. and treated the sexual generation as a junior synonym: Dryophanta mitsukuriiAshmead, 1904syn. nov. Moreover, we examined the type specimens of other species previously suggested to be synonymous with D. mitsukurii. This showed that Neuroterus vonkuenburgiDettmer, 1934syn. nov. (and N. vonkuenburgi wakayamensisMonzen, 1954syn. nov.) is the asexual generation of C. japonicus and that Neuroterus bonihenriciDettmer, 1934syn. nov. is the sexual generation. Judging from the original descriptions, Andricus asakawaeShinji, 1943syn. nov., Andricus kanagawaeShinji, 1943syn. nov., Andricus asakawaeShinji, 1944syn. nov., Andricus kanagawaeShinji, 1944syn. nov., and Neoneuroterus kashiyamaiMonzen, 1954syn. nov. were also regarded as the sexual generation of C. japonicus. Finally, we discussed how matching asexual and sexual generations in heterogonic gall wasps not only avoids taxonomic confusion but also contributes to progress in gall wasp biology.

One hundred and sixty years of taxonomic confusion resolved:Belonocnema(Hymenoptera: Cynipidae: Cynipini) gall wasps associated with live oaks in the USA

AbstractGall wasps (Hymenoptera: Cynipidae) in the genus Belonocnema induce galls on live oaks (Quercus series Virentes), forming multilocular root galls in the sexual generation and unilocular leaf galls in the asexual generation. Using morphological characters, host records, museum specimens, flight propensity and phylogenetic analysis of published cytochrome c oxidase subunit I (COI) and nuclear SNP data, we resolve the long-standing taxonomic confusion within Belonocnema and recognize three distinct species that are distributed throughout the southern and south-eastern USA: B. fossoria (rev. stat.), B. kinseyi (rev. stat.) and B. treatae, while B. quercusvirens is treated as species inquirenda. The presence of mitonuclear discordance results in the failure of a mitochondrial DNA barcode region to distinguish between B. fossoria and B. treatae, while recognizing B. kinseyi, despite the three species being clearly separated based on morphology and phylogenetic analysis of SNP data. We provide re-descriptions and an updated dichotomous key for both asexual and sexual generations of these widespread species. Finally, as Belonocnema has emerged as a model organism for ecological and evolutionary studies, we clarify the species examined in published studies to date.

Two new species of oak gall wasps from Turkey (Hymenoptera: Cynipidae, Cynipini).

Two new species of oak gall wasps, Cynips izzetbaysali sp. nov. and Callirhytis afion sp. nov. (Hymenoptera: Cynipidae: Cynipini) are described from Turkey. The new Cynips species is known only from asexual females and induces detachable leaf galls on Quercus infectoria. The sexual generation of the new Callirhytis species is known to induce acorn galls on Quercus cerris. Data on the diagnosis, distribution, and biology of the two new species are given.

Reproduction site preference and performance by sexuparae, and mating behavior of their sexual generation on the primary host plant in a heteroecious aphid, Neothoracaphis yanonis (Homoptera: Aphididae)

AbstractWe studied reproduction site preference and performance by the sexuparae (autumnal migrants) of Neothoracaphis yanonis and mating behavior of their sexual generation on its primary host plant, Distylium racemosum. The sexuparae preferred younger leaves of D. racemosum for settlement and imbibing leaf sap, and they produced more offspring there than on older leaves. Thus, it is suggested that the sexuparae selected more nutritious younger leaves to increase their own fecundity. The offspring consist of yellowish dark‐grey and creamy yellow type nymphs, which develop into small males and large oviparae, respectively. Yellowish dark‐grey nymphs were deposited gregariously on the basal part of the abaxial surface of a leaf blade, while creamy yellow nymphs were deposited evenly over the abaxial surface. Such a localized distribution pattern probably resulted from sexuparae's strategy to enhance a possibility for their male offspring to mate with oviparae at the base of leaf blade, over which oviparae crawl to twigs. During mating and sometimes afterwards, the ovipara incidentally carried a male on her back and crawled downward on twig to find an axillary bud for oviposition. This behavior may be advantageous to males, who can guard their mate during this period against other conspecific males. Such mate‐guarding behavior seems to be related to the development of dual mate‐seeking strategies, in which males try to copulate, first at the basal part of midrib, and second on the axillary bud.

Description of three new species of oak gallwasps of the genus Amphibolips Reinhard from Mexico (Hymenoptera, Cynipidae).

Three new species of oak gall wasps of the genus Amphibolips Reinhard, 1865 (Hymenoptera: Cynipidae: Cynipini) are described from Mexico: Amphibolips magnigalla Nieves-Aldrey & Castillejos-Lemus, Amphibolips kinseyi Nieves-Aldrey & Castillejos-Lemus and Amphibolips nigrialatus Nieves-Aldrey & Castillejos-Lemus. The specimens of the first two species were representative of sexual generations and come from the State of Oaxaca, while only a female, collected in the State of Veracruz, is described for A. nigrialatus. The new species induces galls on Quercus zempoaltepecana and Q. sapotifolia (Fagaceae, section Lobatae, red oaks). Descriptions of the diagnostic morphological characteristics of the three species and a key for their identification are provided. The taxonomic relationships of the new species with other species of Amphibolips are discussed; the three new species are closely allied amongst themselves and are related to A. dampfi Kinsey, 1937. With the three newly-described species, the number of Amphibolips in Mexico is increased to 23.

A new species of Cerroneuroterus Melika Pujade-Villar from the Eastern Palaearctic (Hymenoptera, Cynipidae, Cynipini).

A new gall wasp species, Cerroneuroterus yukawamasudai Pujade-Villar Melika sp. nov., is described from China. The asexual generation induces leaf lenticular galls, and the sexual generation induces catkin galls on Q. acutissima and Q. variabilis. Sexual females and males are not described yet. Data on the diagnosis, distribution, and biology of the new species are provided, including a key to sexual and asexual females of all described Cerroneuroterus species. Previous misidentifications of host galls recorded in Japan are commented on. Molecular analyses were performed to assess the validity of the genus Cerroneuroterus and the affiliation of the new species.

Contributions to Disholcaspis Dalla Torre And Kieffer (Hymenoptera: Cynipidae: Cynipini).

The sexual generations for D. mamillana and D. prehensa are described based on a combination of molecular and host plant data. A new species, Disholcaspis erugomamma Cooke-McEwen n. sp., is described from Texas. The locations for the various type specimens and image data for a majority of the species in the genus are presented with discussion about the overall morphology of the genus. Lastly, a large image-based dataset was established for this group to aid in an eventual revision of the genus.

Structure of the reproductive system of the sexual generation of the endemic Arctic species Acyrthosiphon svalbardicum and its temperate counterpart Acyrthosiphon pisum (Hemiptera, Aphididae).

The Arctic aphids live briefly and must breed quickly to survive. Shortened life cycle, with only two generations: the stem mother and sexuales-oviparous females and males is an adaptation for optimal use of the short breeding period, which lasts from late July to the end of August. Using Acyrthosiphon svalbardicum, an endemic High Arctic aphid species, we describe the structure of the reproductive system of sexual morphs and compare with its temperate counterparts, in particular the model organism the pea aphid Acyrthosiphon pisum. Generally, the histological composition and ultrastructure of reproductive system of sexuales of A. svalbardicum is broadly similar to the reproductive systems described already in other species of aphids. The unique characters include in both oviparous females and males an enormous layer of the fat body, adhering to the structures of the internal reproductive system. The greatly enlarged accessory glands of males accumulate a heterogenous secretion composed of irregularly organized bunches of spicule-like structures of high electron density embedded in fine and coarse granular material. This material, unknown among temperate counterparts of A. svalbardicum, during mating is transported from the accessory glands of the male to its ejaculatory duct, where it is mixed with the ejaculate, and then is transferred to the spermatheca of the oviparous female.

Description of the sexual generation of Dryocosmus destefanii (Hymenoptera: Cynipidae: Cynipini) and disclosure of its life cycle.

The sexual generation of Dryocosmus destefanii Cerasa Melika, 2018 that emerges from galls on Q. suber L. in Italy is described for the first time, establishing its heterogonic life cycle. We provide observations on its distribution, illustration of adults and galls and information on its biology as supported by morphological and molecular data. An illustrated identification key to Western Palaearctic Dryocosmus species is also given.

Micromorphology of the model species pea aphid Acyrthosiphon pisum (Hemiptera, Aphididae) with special emphasis on the sensilla structure

The pea aphid complex [Acyrthosiphon pisum (Harris 1776)] (Hemiptera, Aphididae), listed among the 14 aphid species of the greatest economic importance, is a globally distributed key pest of pulse crops. Since the pea aphid is a well-studied model organism, an enormous amount of literature has been published about this species. However, comprehensive morphological analyses using scanning electron microscopy (SEM), focused on all body parts of adult viviparous and sexual generations of A. pisum, are lacking. Thus, we present the first detailed morphological description of all body parts of adult wingless and winged viviparous females (parthenogenetic generation) as well as oviparous females, winged and wingless males (sexual generation), representing the most common A. pisum pea biotype. In particular, the sensilla of the body surface, antennae, mouthparts, legs and male genitalia are mapped by the high-resolution scanning electron microscope. The morphological diversity of sensilla is discussed in the context of their function and the biology of aphids.