Latest Articles from Comparative Cytogenetics Latest 19 Articles from Comparative Cytogenetics https://compcytogen.pensoft.net/ Fri, 29 Mar 2024 11:46:56 +0200 Pensoft FeedCreator https://compcytogen.pensoft.net/i/logo.jpg Latest Articles from Comparative Cytogenetics https://compcytogen.pensoft.net/ Assessment of quadrivalent characteristics influencing chromosome segregation by analyzing human preimplantation embryos from reciprocal translocation carriers https://compcytogen.pensoft.net/article/115070/ Comparative Cytogenetics 18: 1-13

DOI: 10.3897/compcytogen.18.115070

Authors: Ziravard N. Tonyan, Irina L. Puppo, Alsu F. Saifitdinova, Tatyana V. Vavilova, Andrey S. Glotov

Abstract: Patterns of meiotic chromosome segregation were analyzed in cleavage stage and blastocyst stage human embryos from couples with autosomal reciprocal translocations (ART). The influence of quadrivalent asymmetry degree, the presence of terminal breakpoints, and the involvement of acrocentric chromosomes in the rearrangement were analyzed to evaluate their contribution to the formation of non-viable embryos with significant chromosomal imbalance due to pathological segregation patterns and to assess the selection of human embryos by the blastocyst stage. A selection of viable embryos resulting from alternate and adjacent-1 segregation and a significant reduction in the detection frequency of the 3 : 1 segregation pattern were observed in human embryos at the blastocyst stage. The presence of terminal breakpoints increased the frequency of 3 : 1 segregation and was also associated with better survival of human embryos resulting from adjacent-1 mode, reflecting the process of natural selection of viable embryos to the blastocyst stage. The demonstrated patterns of chromosome segregation and inheritance of a balanced karyotype in humans will contribute to optimizing the prediction of the outcomes of in vitro fertilization programs and assessing the risks of the formation of unbalanced embryos for ART carriers.

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Research Article Mon, 22 Jan 2024 17:28:21 +0200
Karyotype and reproductive traits of the unique symbiotic mealybug Orbuspedum machinator G.-Z. (Homoptera, Coccinea) https://compcytogen.pensoft.net/article/116550/ Comparative Cytogenetics 17: 283-286

DOI: 10.3897/compcytogen.17.116550

Authors: Ilya A. Gavrilov-Zimin

Abstract: The karyotype and reproductive features of Orbuspedum machinator Gavrilov-Zimin, 2017 (Pseudococcidae) were studied for the first time. Diploid chromosome number is 18 in females. Reproduction is probably bisexual, as indicated by the presence of characteristic Lecanoid heterochromatinization of the paternal set of chromosomes in embryonic cells of about 50% of the embryos studied. The female reproductive system has a pair of lateral oviducts merged into enlarged common oviduct; the spermatheca and accessory glands are connected to the common oviduct in its proximal part. Complete ovoviviparity occurs in ontogenesis.

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Short Communication Mon, 18 Dec 2023 15:54:01 +0200
Ancient reproductive modes and criteria of multicellularity https://compcytogen.pensoft.net/article/109671/ Comparative Cytogenetics 17: 195-238

DOI: 10.3897/compcytogen.17.109671

Authors: Ilya A. Gavrilov-Zimin

Abstract: It is demonstrated that the initial method of fertilization in animals (Metazoa), embryophyte plants (Embryophyta), most groups of multicellular oogamous algae, oogamous and pseudoogamous multicellular fungi was internal fertilization (in the broad meaning) in/on the body of a maternal organism. Accordingly, during the bisexual process, the initial method of formation of a daughter multicellular organism in animals was viviparity, and in embryophyte plants and most groups of oogamous multicellular algae – the germination of a zygote in/on the body of maternal organism. The reproductive criteria of multicellularity are proposed and discussed. In this regard, the multicellularity is considered to subdivide terminologically into three variants: 1) protonemal, the most simple, characteristic of multicellular prokaryotes, most groups of multicellular algae and gametophytes of some higher plants; 2) siphonoseptal, found among multicellular fungi, some groups of green and yellow-green algae; 3) embryogenic, most complicated, known in all animals (Metazoa), all sporophytes and some gametophytes of higher plants (Embryophyta), charophyte green algae Charophyceae s.s., oogamous species of green and brown algae, some genera of red algae. In addition to the well-known division of reproduction methods into sexual and asexual, it is proposed to divide the reproduction of multicellular organisms into monocytic (the emergence of a new organism from one cell sexually or asexually) and polycytic (fragmentation, longitudinal / transverse division or budding based on many cells of the body of the mother organism), since these two ways have different evolutionary and ontogenetic origins.

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Review Article Fri, 20 Oct 2023 11:52:00 +0300
Comparative analysis of chromosome numbers and sex chromosome systems in Paraneoptera (Insecta) https://compcytogen.pensoft.net/article/71866/ Comparative Cytogenetics 15(3): 279-327

DOI: 10.3897/CompCytogen.v15.i3.71866

Authors: Valentina G. Kuznetsova, Ilya A. Gavrilov-Zimin, Snejana M. Grozeva, Natalia V. Golub

Abstract: This article is part (the 4th article) of the themed issue (a monograph) “Aberrant cytogenetic and reproductive patterns in the evolution of Paraneoptera”. The purpose of this article is to consider chromosome structure and evolution, chromosome numbers and sex chromosome systems, which all together constitute the chromosomal basis of reproduction and are essential for reproductive success. We are based on our own observations and literature data available for all major lineages of Paraneoptera including Zoraptera (angel insects), Copeognatha (=Psocoptera; bark lice), Parasita (=Phthiraptera s. str; true lice), Thysanoptera (thrips), Homoptera (scale insects, aphids, jumping plant-lice, whiteflies, and true hoppers), Heteroptera (true bugs), and Coleorrhyncha (moss bugs). Terminology, nomenclature, classification, and the study methods are given in the first paper of the issue (Gavrilov-Zimin et al. 2021).

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Review Article Mon, 27 Sep 2021 10:18:45 +0300
Aberrant ontogeneses and life cycles in Paraneoptera https://compcytogen.pensoft.net/article/70362/ Comparative Cytogenetics 15(3): 253-277

DOI: 10.3897/compcytogen.v15.i3.70362

Authors: Ilya A. Gavrilov-Zimin

Abstract: The paper is a third part of the themed issue “Aberrant cytogenetic and reproductive patterns in the evolution of Paraneoptera”, prepared by a Russian-Bulgarian research team on the basis of long-term collaborative studies. This chapter reviews different peculiar aberrations in the ontogenesis of Paraneoptera, such as the appearance of the quiescent apodal and/or arostrate instars, exuviatrial, pupillarial and pseudopupillarial development, cyclic parthenogenesis, etc. The material and methods, terminology and the nomenclature of the used taxonomic names are listed in the first chapter of the issue (Gavrilov-Zimin et al. 2021).

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Review Article Wed, 25 Aug 2021 15:09:54 +0300
Egg retention, viviparity and ovoviviparity in Paraneoptera https://compcytogen.pensoft.net/article/70216/ Comparative Cytogenetics 15(3): 239-252

DOI: 10.3897/CompCytogen.v15.i3.70216

Authors: Ilya A. Gavrilov-Zimin

Abstract: This article is a second part of the themed issue “Aberrant cytogenetic and reproductive patterns in the evolution of Paraneoptera insects”, prepared by the Russian-Bulgarian research team. Here, analysis of aberrations related to the egg development is provided based on literature data and the author’s own investigations. Evolutionary aspects of ovoviviparity/viviparity are also briefly discussed. Material and methods, terminology and nomenclature of taxonomic names are listed in the first paper of the issue (Gavrilov-Zimin et al. 2021).

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Review Article Tue, 3 Aug 2021 12:10:57 +0300
Introduction to the study of chromosomal and reproductive patterns in Paraneoptera https://compcytogen.pensoft.net/article/69718/ Comparative Cytogenetics 15(3): 217-238

DOI: 10.3897/compcytogen.v15.i3.69718

Authors: Ilya A. Gavrilov-Zimin, Snejana M. Grozeva, Dmitrii A. Gapon, Andrei S. Kurochkin, Katia G. Trencheva, Valentina G. Kuznetsova

Abstract: This paper opens the themed issue (a monograph) “Aberrant cytogenetic and reproductive patterns in the evolution of Paraneoptera”, prepared by a Russian-Bulgarian research team on the basis of long-term collaborative studies. In this first part of the issue, we provide the basic introductory information, describe the material involved and the methods applied, and give terminology and nomenclature of used taxonomic names.

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Research Article Mon, 19 Jul 2021 16:09:06 +0300
Homologous series by Nikolai Vavilov in the phylogeny of Homoptera https://compcytogen.pensoft.net/article/60894/ Comparative Cytogenetics 14(4): 589-596

DOI: 10.3897/CompCytogen.v14.i4.60894

Authors: Ilya A. Gavrilov-Zimin

Abstract: The paper briefly discusses the most impressive examples of the Nikolai Vavilov’s “Law of homologous series” in the evolution of one of the largest animal groups, homopterous insects, which comprise about 65,000 recent species in the world fauna. Different taxonomic and phylogenetic characters (morpho-anatomical, cytogenetic, reproductive and others) are considered at the taxonomic ranks of the order, suborder, superfamily and family.

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Short Communication Thu, 17 Dec 2020 21:57:26 +0200
Chromosomal and reproductive features of some Oriental and Australasian scale insects (Homoptera, Coccinea) https://compcytogen.pensoft.net/article/53367/ Comparative Cytogenetics 14(3): 339-352

DOI: 10.3897/CompCytogen.v14i3.53367

Authors: Ilya A. Gavrilov-Zimin

Abstract: Fourteen species of scale insects from the families Margarodidae s.l., Pseudococcidae, Eriococcidae, and Coccidae were investigated for the first time in respect to karyotypes, genetic systems, modes of reproduction and general anatomy of the female reproductive system. One of the studied species, Steatococcus samaraius Morrison, 1927, showed hermaphroditic reproduction of the female-like specimens, the other species demonstrated bisexual reproduction with a peculiar “Lecanoid” heterochromatinization of the paternal set of chromosomes in male embryos or thelytocous parthenogenesis. Antonina parazonata Williams, 2004 and Saccharolecanium krugeri (Zehntner, 1897) are recorded here for the first time from Thailand, Antonina vietnamensis Williams, 2004 and Geococcus satellitum Williams, 2004 – for the first time from Laos.

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Research Article Mon, 20 Jul 2020 14:39:37 +0300
Cytogenetic markers as a tool for characterization of hybrids of Astyanax Baird & Girard, 1854 and Hyphessobrycon Eigenmann, 1907 https://compcytogen.pensoft.net/article/49513/ Comparative Cytogenetics 14(2): 231-242

DOI: 10.3897/CompCytogen.v14i2.49513

Authors: Caio Augusto Gomes Goes, Sandro Natal Daniel, Lucas Henrique Piva, George Shigueki Yasui, Roberto Ferreira Artoni, Diogo Teruo Hashimoto, Fausto Foresti, Fábio Porto-Foresti

Abstract: Astyanax Baird et Girard, 1854, is one of the largest genera in the family Characidae and comprises 177 valid species. This genus has been the focus of cytogenetic studies primarily owing to the presence of B chromosomes and high karyotypic diversity among different populations. The intense genetic variability in Astyanax is one of the factors responsible for the occurrence of species complexes, which are groups (1) with certain difficulties in establishing common genetic pools or (2) belonging to different cryptic species. To evaluate cytogenetic marker inheritance and the possibility of the identification of these hybrids, this study aimed to describe cytogenetic hybrids from three strains of species of the genera Astyanax and Hyphessobrycon Eigenmann, 1908. A. lacustris Lütken, 1875, A. schubarti Britski, 1964, A. fasciatus Cuvier, 1819, and H. anisitsi Eigenmann, 1907 were used to generate three hybrid lineages. The diploid number, heterochromatin sites, and ribosomal genes (18S and 5S rDNA) of the parental strains and the hybrids were analyzed. The results indicated that the three hybrid lineages had cytogenetic markers of both parents, presenting Mendelian inheritance. However, differences in distribution of heterochromatic blocks were observed between the hybrids and the parent strains. Our results allowed the identification of the hybrid strains based on the cytogenetic markers applied, reinforcing the efficiency of cytogenetic markers as tools for identification and indicating that such events may increase the karyotypic diversity in the genera Astyanax and Hyphessobrycon.

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Research Article Wed, 27 May 2020 11:24:10 +0300
New data on karyotype, spermatogenesis and ovarian trophocyte ploidy in three aquatic bug species of the families Naucoridae, Notonectidae, and Belostomatidae (Nepomorpha, Heteroptera) https://compcytogen.pensoft.net/article/48709/ Comparative Cytogenetics 14(1): 139-156

DOI: 10.3897/CompCytogen.v14i1.48709

Authors: Desislava Stoianova, Nikolay Simov, Manh Quang Vu, Duc Minh Nguyen, Snejana Grozeva

Abstract: We report the karyotype, some aspects of spermatogenesis, and ovarian trophocytes ploidy in three aquatic bug species: Ilyocoris cimicoides (Linnaeus, 1758), Notonecta glauca Linnaeus, 1758, and Diplonychus rusticus Fabricius, 1871 from previously unexplored regions – South Europe (Bulgaria) and Southeast Asia (Vietnam). Our results add considerable support for the published karyotype data for these species. In I. cimicoides, we observed achiasmate male meiosis – the first report of achiasmy for the family Naucoridae. More comprehensive cytogenetic studies in other species of the Naucoridae are required to elucidate the role of achiasmy as a character in the systematics of the family. Our observations on the association between phases of spermatogenesis and developmental stages in I. cimicoides and N. glauca differ from the previously published data. In these species, we assume that the spermatogenesis phases are not strongly associated with certain developmental stages. For further cytogenetic studies (on the Balkan Peninsula), we recommend July as the most appropriate month for collection of I. cimicoides and N. glauca. In the ovaries of both species, we studied the level of ploidy in metaphase and interphase trophocytes. In I. cimicoides, diploid and tetraploid metaphase trophocytes were found. Heteropycnotic elements, observed in interphase trophocytes of this species, represented the X chromosomes. It allowed us to determine the trophocytes ploidy at interphase (2n was repeated up to 16 times). The situation with N. glauca was different. The metaphase trophocytes were diploid and we were not able to determine the ploidy of interphase trophocytes since such conspicuous heteropycnotic elements were not found. The scarce data available suggest a tendency for a low level of trophocyte ploidy in the basal infraorders (Nepomorpha and Gerromorpha) and for a high level in the more advanced Pentatomomorpha. Data about this character in species from other infraorders are needed to confirm that tendency.

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Research Article Thu, 5 Mar 2020 17:12:41 +0200
Triploidy in Chinese parthenogenetic Helophorus orientalis Motschulsky, 1860, further data on parthenogenetic H. brevipalpis Bedel, 1881 and a brief discussion of parthenogenesis in Hydrophiloidea (Coleoptera) https://compcytogen.pensoft.net/article/47656/ Comparative Cytogenetics 14(1): 1-10

DOI: 10.3897/CompCytogen.v14i1.47656

Authors: Robert B. Angus, Fenglong Jia

Abstract: The chromosomes of triploid parthenogenetic Helophorus orientalis Motschulsky, 1860 are described from material from two localities in Heilongjiang, China. 3n = 33. All the chromosomes have clear centromeric C-bands, and in the longest chromosome one replicate appears to be consistently longer than the other two. The chromosomes of additional triploid parthenogenetic H. brevipalpis Bedel, 1881, from Spain and Italy, are described. In one Italian population one of the autosomes is represented by only two replicates and another appears more evenly metacentric than in material from Spain and the other Italian locality. Parthenogenetic and bisexual specimens of H. orientalis are illustrated, along with Pleistocene fossil material. Parthenogenetic H. brevipalpis is also illustrated. Parthenogenesis in Hydrophiloidea is discussed. It appears to be rare and, in all cases has been detected by chromosomal analysis of populations in which males are unexpectedly scarce. Parthenogenesis is suspected in Helophorus aquila Angus et al., 2014, from northern Qinghai (China), which should be verified in further studies.

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Research Article Mon, 13 Jan 2020 13:09:37 +0200
First illustration of chromosomes and genetic system of Lecanodiaspidinae (Homoptera, Coccinea, Asterolecaniidae s.l.) https://compcytogen.pensoft.net/article/29648/ Comparative Cytogenetics 12(3): 439-443

DOI: 10.3897/CompCytogen.v12i3.29648

Authors: Ilya A. Gavrilov-Zimin

Abstract: The karyotype of Psoraleococcus multipori (Morrison, 1921) was studied for the first time, based on material from Indonesia (Sulawesi). The diploid chromosome number was found to be 18 in both males and females, but some cells contained also additional small chromosomal elements, probably B chromosomes. About 50 % of the studied embryos demonstrated paternal genome heterochromatinization of one haploid set of chromosomes (PGH) suggesting presence of a Lecanoid genetic system. The embryos with PGH are known to be always the male embryos in scale insects and so, bisexual reproduction may be presumed for P. multipori. The information provided represents the first probative cytogenetic data for the subfamily Lecanodiaspidinae Targioni Tozzetti, 1896 as a whole. A detailed morphological figure and photos of female and male embryonic cells are given. Additionally, it was discovered that the females of P. multipori exhibit complete ovoviviparity.

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Short Communication Thu, 4 Oct 2018 17:44:35 +0300
23rd International Colloquium on Animal Cytogenetics and Genomics (23 ICACG) June 9–12, 2018, Saint-Petersburg, Russia https://compcytogen.pensoft.net/article/27748/ Comparative Cytogenetics 12(3): 299-360

DOI: 10.3897/CompCytogen.v12i3.27748

Authors: Svetlana Galkina, Maria Vishnevskaya

Abstract: In memory of Ingemar Gustavsson 23rd International Colloquium on Animal Cytogenetics and Genomics (23 ICACG) took place in June 9–12, 2018 in Saint-Petersburg, Russia. Organized biennially, the Colloquium runs from 1970. From its very start this meeting is associated with the name of Ingemar Gustavsson to whom we dedicated the Colloquium 2018. The long and productive career of Ingemar Gustavsson had focused on chromosomes and their fundamental role in animal physiology, fertility, health and production in the context of agriculture and veterinary medicine. His meticulous analysis of breeding data performed back in 1964–69 resulted in the unequivocal identification of an association between heterozygosity for the 1/29 translocation in Swedish cattle and reduction in the fertility of the breed. Eventually, the argument in favor of selective elimination of bulls carrying the translocation from the breeding programs prevailed and the field of modern veterinary cytogenetics was established. Participants from fourteen different countries attended the 23 ICACG in Russia, the country having long lasting traditions in cytogenetics and the Scientific schools of N.K. Koltzov, S.S. Chetverikov and A.S. Serebrovsky, geneticists who made important conceptual contributions to studies of chromosomes and genes, population genetics and evolutionary theory as early as in the beginning of the XX-th century. All the abstracts received were subdivided between plenary and seven scientific sessions covering the issues in evolutionary and comparative cytogenetics, cytogenetics and genomes of domestic animals, meiosis studies, particular chromosome analyses, clinical cytogenetics, karyotypes and genomes of vertebrate and invertebrate animals, chromatin studies. In the abstract text below each presentation is marked with a capital letter: „L” stands for lectures, „O” for oral presentations and „P” for poster presentations. We gratefully acknowledge the support from the Saint-Petersburg Association of Scientists and Scholars (SPbSU), Veterinary Genetics Center ZOOGEN, Russian Foundation for Basic Research (RFBR), VEUK, Helicon, Axioma BIO, BioVitrum, Sartorius, DIA-M companies. The current collected abstracts comprise written contributions of the presentations during the 23 ICACG and were edited by Svetlana Galkina and Maria Vishnevskaya. The next Colloquium – 24 ICACG – will be held at the University of Kent in Canterbury (UK) in 2020. Please, cite abstracts as follows: Gall JG (2018) Giant chromosomes and deep sequences: what the amphibian egg tells us about transcription. In: Galkina SA, Vishnevskaya MS, Mikhailova EI (Eds) 23rd Inernational Colloquium on Animal Cytogenetics and Genomics (23rdICACG), June 9–12, 2018, St Petersburg, Russia. Comparative Cytogenetics 12(3): p–p. https://doi.org/10.3897/CompCytogen.v12i3.27748

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Forum Paper Thu, 16 Aug 2018 15:53:12 +0300
Mysterious meiotic behavior of autopolyploid and allopolyploid maize https://compcytogen.pensoft.net/article/24907/ Comparative Cytogenetics 12(2): 247-265

DOI: 10.3897/CompCytogen.v12i2.24907

Authors: Muhammad Zafar Iqbal, Mingjun Cheng, Yanli Zhao, Xiaodong Wen, Ping Zhang, Lei Zhang, Asif Ali, Tingzhao Rong, Qi Lin Tang

Abstract: This study was aimed to investigate the stability of chromosomes during meiosis in autopolyploid and allopolyploid maize, as well as to determine an association of chromosomes between maize (Zea mays ssp. mays Linnaeus, 1753) and Z. perennis (Hitchcock, 1922) Reeves & Mangelsdor, 1942, by producing a series of autopolyploid and allopolyploid maize hybrids. The intra-genomic and inter-genomic meiotic pairings in these polyploids were quantified and compared using dual-color genomic in-situ hybridization. The results demonstrated higher level of chromosome stability in allopolyploid maize during meiosis as compared to autopolyploid maize. In addition, the meiotic behavior of Z. perennis was relatively more stable as compared to the allopolyploid maize. Moreover, ten chromosomes of "A” subgenome in maize were homologous to twenty chromosomes of Z. perennis genome with a higher pairing frequency and little evolutionary differentiation. At the same time, little evolutionary differentiation has been shown by chromosomes of "A” subgenome in maize, while chromosomes of "B” subgenome, had a lower pairing frequency and higher evolutionary differentiation. Furthermore, 5IM + 5IIPP + 5IIIMPP and 5IIMM + 5IIPP + 5IVMMPP were observed in allotriploids and allotetraploids respectively, whereas homoeologous chromosomes were found between the "A” and "B” genome of maize and Z. perennis.

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Research Article Fri, 20 Jul 2018 22:47:35 +0300
Variation in chromosome number and breeding systems: implications for diversification in Pachycereus pringlei (Cactaceae) https://compcytogen.pensoft.net/article/21554/ Comparative Cytogenetics 12(1): 61-82

DOI: 10.3897/compcytogen.v12i1.21554

Authors: Carina Gutiérrez-Flores, José L. León-de la Luz, Francisco J. García-De León, J. Hugo Cota-Sánchez

Abstract: Polyploidy, the possession of more than two sets of chromosomes, is a major biological process affecting plant evolution and diversification. In the Cactaceae, genome doubling has also been associated with reproductive isolation, changes in breeding systems, colonization ability, and speciation. Pachycereus pringlei (S. Watson, 1885) Britton & Rose, 1909, is a columnar cactus that has long drawn the attention of ecologists, geneticists, and systematists due to its wide distribution range and remarkable assortment of breeding systems in the Mexican Sonoran Desert and the Baja California Peninsula (BCP). However, several important evolutionary questions, such as the distribution of chromosome numbers and whether the diploid condition is dominant over a potential polyploid condition driving the evolution and diversity in floral morphology and breeding systems in this cactus, are still unclear. In this study, we determined chromosome numbers in 11 localities encompassing virtually the entire geographic range of distribution of P. pringlei. Our data revealed the first diploid (2n = 22) count in this species restricted to the hermaphroditic populations of Catalana (ICA) and Cerralvo (ICE) Islands, whereas the tetraploid (2n = 44) condition is consistently distributed throughout the BCP and mainland Sonora populations distinguished by a non-hermaphroditic breeding system. These results validate a wider distribution of polyploid relative to diploid individuals and a shift in breeding systems coupled with polyploidisation. Considering that the diploid base number and hermaphroditism are the proposed ancestral conditions in Cactaceae, we suggest that ICE and ICA populations represent the relicts of a southern diploid ancestor from which both polyploidy and unisexuality evolved in mainland BCP, facilitating the northward expansion of this species. This cytogeographic distribution in conjunction with differences in floral attributes suggests the distinction of the diploid populations as a new taxonomic entity. We suggest that chromosome doubling in conjunction with allopatric distribution, differences in neutral genetic variation, floral traits, and breeding systems has driven the reproductive isolation, evolution, and diversification of this columnar cactus.

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Research Article Tue, 13 Feb 2018 10:55:16 +0200
Characteristics of parthenogenesis in Cacopsylla ledi (Flor, 1861) (Hemiptera, Sternorryncha, Psylloidea): cytological and molecular approaches https://compcytogen.pensoft.net/article/21362/ Comparative Cytogenetics 11(4): 807-817

DOI: 10.3897/CompCytogen.v11i4.21362

Authors: Seppo Nokkala, Valentina G. Kuznetsova, Christina Nokkala

Abstract: Characteristics of parthenogenesis in Cacopsylla ledi (Flor, 1861) were analyzed using cytological and molecular approaches. In all three populations studied from Finland, i.e. Turku, Kustavi and Siikajoki, males were present at a low frequency but were absent from a population from Vorkuta, Russia. In a follow-up study conducted in the Turku population during 2010–2016, the initial frequency of males was ca. 10 % and showed no intraseasonal variation, but then dramatically decreased down to approximately 1–2 % level in seasons 2015–2016. Male meiosis was chiasmate with some traces of chromosomal fragmentation and subsequent fusions. In most females, metaphase in mature eggs included 39 univalent chromosomes which indicated apomictic triploidy. Only a small fraction of females was diploid with 13 chiasmate bivalents. The frequency of diploid females approximately equaled that of males. COI barcode analyses showed that triploid females (N = 57) and diploids (7 females and 5 males) displayed different haplotypes, demonstrating that triploid females reproduced via obligate parthenogenesis. The rarity of diploids, along with the lack of males’ preference towards diploid females, suggested that most likely diploids were produced by rare triploid females which shared the same haplotype with the diploids (not found in the present analysis). Minimum haplotype diversity was detected in the Turku population, but it was much higher in Vorkuta with some indication for the mixed origin of the population. We suggest that functional diploids produced in a parthenogenetic population can give rise either to a new parthenogenetic lineage or even to a new bisexual species.

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Research Article Fri, 24 Nov 2017 17:16:16 +0200
General trends of chromosomal evolution in Aphidococca (Insecta, Homoptera, Aphidinea + Coccinea) https://compcytogen.pensoft.net/article/4930/ Comparative Cytogenetics 9(3): 335-422

DOI: 10.3897/CompCytogen.v9i3.4930

Authors: Ilya Gavrilov-Zimin, Andrey Stekolshchikov, D.C. Gautam

Abstract: Parallel trends of chromosomal evolution in Aphidococca are discussed, based on the catalogue of chromosomal numbers and genetic systems of scale insects by Gavrilov (2007) and the new catalogue for aphids provided in the present paper. To date chromosome numbers have been reported for 482 species of scale insects and for 1039 species of aphids, thus respectively comprising about 6% and 24% of the total number of species. Such characters as low modal numbers of chromosomes, heterochromatinization of part of chromosomes, production of only two sperm instead of four from each primary spermatocyte, physiological sex determination, "larval" meiosis, wide distribution of parthenogenesis and chromosomal races are considered as a result of homologous parallel changes of the initial genotype of Aphidococca ancestors. From a cytogenetic point of view, these characters separate Aphidococca from all other groups of Paraneoptera insects and in this sense can be considered as additional taxonomic characters. In contrast to available paleontological data the authors doubt that Coccinea with their very diverse (and partly primitive) genetic systems may have originated later then Aphidinea with their very specialised and unified genetic system.

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Review Article Thu, 9 Jul 2015 13:28:59 +0300
Meiosis in rare males in parthenogenetic Cacopsylla myrtilli (Wagner, 1947) (Hemiptera, Psyllidae) populations from northern Europe https://compcytogen.pensoft.net/article/1794/ Comparative Cytogenetics 7(3): 241-251

DOI: 10.3897/compcytogen.v7i3.6126

Authors: Christina Nokkala, Seppo Nokkala, Valentina Kuznetsova

Abstract: For studying meiosis in males, large samples of Cacopsylla myrtilli (Wagner, 1947) (Hemiptera, Psyllidae) were collected in Norway, Sweden, Finland and northwest Russia. In addition to all-female populations, males were present in 10 out of 47 populations; still, all populations were highly female-biased, the proportion of males varying from 0.1% to 9.1%. These males are thus rare or so-called spanandric males. Males in northern Norway, Finland and northwest Russia showed normal chiasmate meiosis, while complete absence of chiasmata due to asynapsis was found in males collected in Norway and northern Sweden. In asynaptic meiosis, all univalent chromosomes divided during the first meiotic division resulting in incomplete second meiotic division and formation of diploid sperms. Hence, males in these populations are nonfunctional and do not contribute to the genetic constitution of the population, but appear in every generation as reversals from apomictic parthenogenesis and the mode of parthenogenesis is of obligatory type.

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Research Article Mon, 30 Sep 2013 00:00:00 +0300