scholarly journals APOMICTIC PARTHENOGENESIS IN A HERMAPHRODITIC TERRESTRIAL SLUG,DEROCERAS LAEVE(MÜLLER)

1981 ◽  
Vol 160 (1) ◽  
pp. 123-135 ◽  
Author(s):  
NANCY L. NICKLAS ◽  
RICHARD J. HOFFMANN
Keyword(s):  
Apomictic Parthenogenesis

scholarly journals Apomictic parthenogenesis in a parasitoid waspMeteorus pulchricornis, uncommon in the haplodiploid order Hymenoptera

2014 ◽  
Vol 104 (3) ◽  
pp. 307-313 ◽  
Author(s):  
Y. Tsutsui ◽  
K. Maeto ◽  
K. Hamaguchi ◽  
Y. Isaki ◽  
Y. Takami ◽  
...  
Keyword(s):  
Parasitoid Wasp ◽  
Parasitoid Wasps ◽  
Genetic Studies ◽  
Insect Order ◽  
Egg Maturation ◽  
Polar Bodies ◽  
Lepidopteran Larvae ◽  
Apomictic Parthenogenesis ◽  
Meteorus Pulchricornis ◽  
New Type

AbstractAlthough apomixis is the most common form of parthenogenesis in diplodiploid arthropods, it is uncommon in the haplodiploid insect order Hymenoptera. We found a new type of spontaneous apomixis in the Hymenoptera, completely lacking meiosis and the expulsion of polar bodies in egg maturation division, on the thelytokous strain of a parasitoid waspMeteorus pulchricornis(Wesmael) (Braconidae, Euphorinae) on pest lepidopteran larvaeSpodoptera litura(Fabricius) (Noctuidae). The absence of the meiotic process was consistent with a non-segregation pattern in the offspring of heterozygous females, and no positive evidence was obtained for the induction of thelytoky by any bacterial symbionts. We discuss the conditions that enable the occurrence of such rare cases of apomictic thelytoky in the Hymenoptera, suggesting the significance of fixed heterosis caused by hybridization or polyploidization, symbiosis with bacterial agents, and occasional sex. Our finding will encourage further genetic studies on parasitoid wasps to use asexual lines more wisely for biological control.

scholarly journals POLYMORPHISM IN A CYCLIC PARTHENOGENETIC SPECIES: SIMOCEPHALUS SERRULATUS

Genetics ◽  
1976 ◽  
Vol 84 (3) ◽  
pp. 631-637
Author(s):  
M Yao Smith ◽  
Alex Fraser
Keyword(s):  
Seasonal Changes ◽  
Natural Populations ◽  
Genetic Homogeneity ◽  
Laboratory Population ◽  
Gametic Disequilibrium ◽  
Polymorphic Loci ◽  
Parthenogenetic Species ◽  
Apomictic Parthenogenesis ◽  
Isozyme Loci ◽  
Electrophoretic Techniques

ABSTRACT A survey of sixteen isozyme loci using electrophoretic techniques was conducted for three isolated natural populations and one laboratory population of the cyclic parthenogenetic species, Simocephalus serrulatus. The proportion of polymorphic loci (33%-60%) and the average number of heterozygous loci per individual (6%-23%) in the three natural populations were found to be comparable to those found in most sexually reproducing organisms. Detailed analyses were made for one of these populations using five polymorphic loci. The results indicated that (1) seasonal changes in genotypic frequencies took place, (2) apomictic parthenogenesis does not lead to genetic homogeneity, and (3) marked gametic disequilibrium at these five loci was present in the population, indicating that selection acted on coadapted groups of genes.

scholarly journals The evolution of meiotic sex and its alternatives

2016 ◽  
Vol 283 (1838) ◽  
pp. 20161221 ◽  
Author(s):  
Ghader Mirzaghaderi ◽  
Elvira Hörandl
Keyword(s):  
Dna Damage ◽  
Oxidative Dna Damage ◽  
Strand Break ◽  
Life Cycles ◽  
Recombinational Repair ◽  
Homologous Recombinational Repair ◽  
Apomictic Parthenogenesis ◽  
Shared Component ◽  
Normal Meiosis ◽  
Break Formation

Meiosis is an ancestral, highly conserved process in eukaryotic life cycles, and for all eukaryotes the shared component of sexual reproduction. The benefits and functions of meiosis, however, are still under discussion, especially considering the costs of meiotic sex. To get a novel view on this old problem, we filter out the most conserved elements of meiosis itself by reviewing the various modifications and alterations of modes of reproduction. Our rationale is that the indispensable steps of meiosis for viability of offspring would be maintained by strong selection, while dispensable steps would be variable. We review evolutionary origin and processes in normal meiosis, restitutional meiosis, polyploidization and the alterations of meiosis in forms of uniparental reproduction (apomixis, apomictic parthenogenesis, automixis, selfing) with a focus on plants and animals. This overview suggests that homologue pairing, double-strand break formation and homologous recombinational repair at prophase I are the least dispensable elements, and they are more likely optimized for repair of oxidative DNA damage rather than for recombination. Segregation, ploidy reduction and also a biparental genome contribution can be skipped for many generations. The evidence supports the theory that the primary function of meiosis is DNA restoration rather than recombination.

scholarly journals Apomictic Parthenogenesis and the Pattern of the Environment

1979 ◽  
Vol 19 (3) ◽  
pp. 739-751 ◽  
Author(s):  
KARI VEPSÄLÄINEN ◽  
OLLI JÄRVINEN
Keyword(s):  
Apomictic Parthenogenesis

Fine Structure of Spermatogenesis in the Snail Tarebia Granifera (Melaniidae)

1977 ◽  
Vol 35 ◽  
pp. 620-621
Author(s):  
Ronald W. Scates ◽  
Robert V. Blystone
Keyword(s):  
Electron Microscopy ◽  
Sodium Phosphate ◽  
Osmium Tetroxide ◽  
Reproductive Tract ◽  
San Antonio ◽  
Snail Population ◽  
Sodium Phosphate Buffer ◽  
Apomictic Parthenogenesis ◽  
Comprehensive Study ◽  
Tarebia Granifera

Jacob (1), citing chromosomal studies, emphasized the extreme rarity, or possible non-existence of viable males in observed Indian populations of Melanoides tuberculatus, of the same family as Tarebia granifera. The snail population, almost totally female in chromosomal count, were presumed to reproduce parthenogenetically; no sexual reproduction was in evidence (no sperm were ever reported observed). Similar findings were reported by Pace (2) in his comprehensive study of populations of T. granifera on the island of Taiwan. Pace, correlating his own findings with those of Jacob, suggested that T. granifera reproduce by apomictic parthenogenesis.A population of T. granifera is found in Brackenridge Park, San Antonio, Texas. The reproductive tract of randomly selected snails was prepared for electron microscopy. The tissue was fixed in 3% glutaraldehyde in 0.1 M sodium phosphate buffer, postfixed in buffered 1% Osmium tetroxide, dehydrated, and embedded in Spurr embedding media.

Automictic and Apomictic Parthenogenesis in Psocids (Insecta: Psocoptera)

2006 ◽  
Vol 54 (1) ◽  
pp. 19-22 ◽  
Author(s):  
Seppo Nokkala ◽  
Natalia V. Golub
Keyword(s):  
Apomictic Parthenogenesis

ON THE USELESSNESS OF MEN — COMPARISON OF SEXUAL AND ASEXUAL REPRODUCTION

2000 ◽  
Vol 11 (07) ◽  
pp. 1305-1312 ◽  
Author(s):  
D. STAUFFER ◽  
J. S. SÁ MARTINS ◽  
S. MOSS DE OLIVEIRA
Keyword(s):  
Asexual Reproduction ◽  
Single Species ◽  
Aging Model ◽  
External Influences ◽  
Sexual And Asexual Reproduction ◽  
Apomictic Parthenogenesis ◽  
Males And Females ◽  
Number Of Births ◽  
Better Than

A comparison of sexual with asexual reproduction in the Penna aging model for a single species shows the separation into males and females at a disadvantage due to the halved number of births. Also meiotic and apomictic parthenogenesis and hermaphroditism seem better than sex, even when the individuals follow the suggestion of Jan et al. to engage in sex only when their lifes are endangered by a large number of harmful mutations. In our comparison, we looked only for intrinsic effects, not for external influences like parasites or environmental catastrophes.

Reproduction in the daughter sporocyst of Cercaria bucephalopsis haimeana (Lacaze-Duthiers, 1854) (Bucephalidae) and Cercaria dichotoma Lebour, 1911 (non Müller) (Gymnophallidae)

Parasitology ◽  
1967 ◽  
Vol 57 (4) ◽  
pp. 607-625 ◽  
Author(s):  
B. L. James ◽  
E. A. Bowers
Keyword(s):  
Cell Cycle ◽  
Life Cycle ◽  
Germ Cell ◽  
Daughter Sporocyst ◽  
Apomictic Parthenogenesis ◽  
Mother Sporocyst

The germ-cell cycle and method of reproduction in the daughter sporocysts of the bucephalid Cercaria bucephalopsis haimeana (Lacaze-Duthiers, 1854) and the gymnophallid Cercaria dichotoma Lebour, 1911 (non Müller) from the edible cockle, Cardium edule L., have been investigated by the examination of stained sections. A review is given of the principal interpretative theories which attempt to explain the nature of the reproduction and the homology of the germinal sacs of the Digenea. It is suggested that the life-cycle includes a cyclic alternation of homologous generations. Of these, the miracidium/mother-sporocyst and the daughter germinal-sac generations usually reproduce by apomictic parthenogenesis but polyembryony may also occur secondarily in some species.We are very grateful to Dr Gwendolen Rees and Professor E. W. Knight-Jones for considerable help with the manuscript.

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