Chromosomal similarities and differences among three sibling species of the Acalles echinatus group (Coleoptera, Curculionidae, Cryptorhynchinae)

Zootaxa ◽  
2009 ◽  
Vol 1985 (1) ◽  
pp. 63-68 ◽  
Author(s):  
DOROTA LACHOWSKA ◽  
MARIA ROŻEK ◽  
MILADA HOLECOVÀ
Keyword(s):  
Chromosome Number ◽  
Sibling Species ◽  
Karyotype Evolution ◽  
Relative Length ◽  
Silver Impregnation ◽  
Modal Formula ◽  
Meiotic Chromosomes ◽  
Group A ◽  
Determination System ◽  
Sex Determination System

In order to clarify the taxonomic position of three sibling species of weevils from the Acalles echinatus group, A. echinatus, A. fallax and A. petryszaki, cytogenetic relationships are investigated by studying the mitotic and meiotic chromosomes, including the localisation of heterochromatin by C-banding, as well as the localisation of NORs by silver impregnation. These sources of data are congruent and strongly support that the examined species are closely related. All examined species are characterised by a karyotype of the same chromosome number and sex determination system but with different morphology of chromosomes. All the analysed features, such as the centromeric index, relative length, Cbands and NORs, show that the structure of the karyotype of A. echinatus is more similar to that of A. petryszaki, whereas the karyotype of A. fallax is divergent. The higher chromosome number (2n = 30) in relation to the modal formula in Curculionidae (2n = 22) suggests that karyotype evolution in these species could have occurred by centric fissions of metacentric elements leading to acrocentry.

Karyotype of the South African katydid Hetrodes pupus (Linnaeus, 1758) (Orthoptera, Tettigoniidae) with special reference to relationships within the Hetrodinae subfamily

Zootaxa ◽  
2009 ◽  
Vol 2137 (1) ◽  
pp. 43-50 ◽  
Author(s):  
ELŻBIETA WARCHAŁOWSKA-ŚLIWA ◽  
ALEXANDER G. BUGROV
Keyword(s):  
Comparative Analysis ◽  
Sex Determination ◽  
Special Reference ◽  
South African ◽  
X Chromosome ◽  
Chromosome Evolution ◽  
Cytogenetic Study ◽  
Meiotic Chromosomes ◽  
Determination System ◽  
Sex Determination System

The taxonomic position of Hetrodes pupus (Tettigoniidae, Hetrodinae) was clarified by a cytogenetic study of mitotic and meiotic chromosomes, including the localization of heterochromatin by C-banding. The karyotype of this species consists of 26 acrocentric autosomes and an acrocentric X chromosome, the largest element of the karyotype (2n male=27, FN=27; sex determination system is X0 male/XX female). A cytogenetic comparative analysis of the Hetrodinae and other katydids revealed (1) the similarity of the karyotypic features of Hetrodinae and Microtettigoninae, indicating monophyly; (2) that the morphology of the Hetrodinae karyotype is the result of parallel chromosome evolution via a decrease in the number of chromosome arms (FN).

SEX AND SUPERNUMERARY CHROMOSOMES IN THE DIOECIOUS GRASS SOHNSIA FILIFOLIA

1972 ◽  
Vol 14 (1) ◽  
pp. 175-180 ◽  
Author(s):  
D. N. Singh
Keyword(s):  
Sex Determination ◽  
Y Chromosome ◽  
Supernumerary Chromosome ◽  
The Other ◽  
Male Plant ◽  
Diploid Male ◽  
Male And Female ◽  
Supernumerary Chromosomes ◽  
Determination System ◽  
Sex Determination System

A dioecious grass Sohnsia filifolia (Fourn.) Airy Shaw (Syn. Calamochloa filifolia Fourn.) from Mexico has been found to have 2n = 20 chromosomes in both male and female plants. The staminate plants have one chromosome much longer than the other chromosomes of the complement. One pistillate plant was found to have 30 chromosomes, among which the largest chromosome is quite similar to the largest component of the diploid male plant. The longest chromosome has been designated as the Y chromosome. An XY-mechanism of the Drosophilia type has been suggested for the sex determination system in this species. One small supernumerary chromosome was observed in the microsporocytes of some male plants, but was absent in roots.

The Genome Size of Some Species of Hyalomma Ticks from Turkish Thrace 

2018 ◽  
Vol 23 (11) ◽  
pp. 2122 ◽  
Author(s):  
Nadim Yılmazer
Keyword(s):  
Genome Size ◽  
X Chromosome ◽  
Tick Species ◽  
Animal Health ◽  
Chromosome Size ◽  
Diploid Genome ◽  
Flow Cytometric ◽  
Determination System ◽  
Sex Determination System ◽  
First Time

Hyalomma scupense, H. excavatum and H. marginatum are globally important tick species, as well as in Turkey, both in terms of human and animal health. The genome sizes of these tick species were determined in this study for the first time. From flow cytometric measurements, diploid genome sizes of female and male H. scupense were found to be 2.13 pg and 1.75 pg, respectively, while H. excavatum were 2.21 pg and 1.94 pg, and H. marginatum were 2.48 pg and 1.98 pg, respectively. Differences in diploid genome size indicate X chromosome size of females and males in these ticks because they have an XX:XO sex determination system. Thus, it was estimated that the X chromosome of H. scupense, H. excavatum, and H. marginatum may be composed of as much as 0.38 pg, 0.27 pg, and 0.50 pg of DNA, respectively. These findings indicate suitability of these three species for genome sequencing due to the relatively small size of their genomes compared with other tick species.

scholarly journals Restricted X chromosome introgression and support for Haldane's rule in hybridizing damselflies

2021 ◽  
Author(s):  
Janne Swaegers ◽  
Rosa Ana Sanchez-Guillen ◽  
Pallavi Chauhan ◽  
Maren Wellenreuther ◽  
Bengt Hansson
Keyword(s):  
X Chromosome ◽  
Sex Chromosomes ◽  
Hybrid Zones ◽  
Haldane’S Rule ◽  
Haldane's Rule ◽  
Genome Wide ◽  
Determination System ◽  
Heterogametic Sex ◽  
Sex Determination System ◽  
Genomic Introgression

Contemporary hybrid zones act as natural laboratories for the investigation of species boundaries and allow to shed light on the little understood roles of sex chromosomes in species divergence. Sex chromosomes are considered to function as a hotspot of genetic divergence between species; indicated by less genomic introgression compared to autosomes during hybridisation. Moreover, they are thought to contribute to Haldane's rule which states that hybrids of the heterogametic sex are more likely to be inviable or sterile. To test these hypotheses, we used contemporary hybrid zones of Ischnura elegans, a damselfly species that has been expanding its range into the northern and western regions of Spain, leading to chronic hybridization with its sister species Ischnura graellsii. We analysed genome-wide SNPs in the Spanish I. elegans and I. graellsii hybrid zone and found (i) that the X chromosome shows less genomic introgression compared to autosomes and (ii) that males are underrepresented among admixed individuals as predicted by Haldane's rule. This is the first study in Odonata that suggests a role of the X chromosome in reproductive isolation. Moreover, our data adds to the few studies on species with X0 sex determination system and contradicts the hypothesis that the absence of a Y chromosome causes exceptions to Haldane's rule.

scholarly journals A 180 Myr-old female-specific genome region in sturgeon reveals the oldest known vertebrate sex determining system with undifferentiated sex chromosomes

2021 ◽  
Vol 376 (1832) ◽  
pp. 20200089
Author(s):  
Heiner Kuhl ◽  
Yann Guiguen ◽  
Christin Höhne ◽  
Eva Kreuz ◽  
Kang Du ◽  
...  
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Specific Sequence ◽  
Genome Region ◽  
Acipenser Ruthenus ◽  
Determination System ◽  
Sex Determination System ◽  
Female Specific ◽  
Polyploidization Event

Several hypotheses explain the prevalence of undifferentiated sex chromosomes in poikilothermic vertebrates. Turnovers change the master sex determination gene, the sex chromosome or the sex determination system (e.g. XY to WZ). Jumping master genes stay main triggers but translocate to other chromosomes. Occasional recombination (e.g. in sex-reversed females) prevents sex chromosome degeneration. Recent research has uncovered conserved heteromorphic or even homomorphic sex chromosomes in several clades of non-avian and non-mammalian vertebrates. Sex determination in sturgeons (Acipenseridae) has been a long-standing basic biological question, linked to economical demands by the caviar-producing aquaculture. Here, we report the discovery of a sex-specific sequence from sterlet ( Acipenser ruthenus ). Using chromosome-scale assemblies and pool-sequencing, we first identified an approximately 16 kb female-specific region. We developed a PCR-genotyping test, yielding female-specific products in six species, spanning the entire phylogeny with the most divergent extant lineages ( A. sturio, A. oxyrinchus versus A. ruthenus, Huso huso ), stemming from an ancient tetraploidization. Similar results were obtained in two octoploid species ( A. gueldenstaedtii, A. baerii ). Conservation of a female-specific sequence for a long period, representing 180 Myr of sturgeon evolution, and across at least one polyploidization event, raises many interesting biological questions. We discuss a conserved undifferentiated sex chromosome system with a ZZ/ZW-mode of sex determination and potential alternatives. This article is part of the theme issue ‘Challenging the paradigm in sex chromosome evolution: empirical and theoretical insights with a focus on vertebrates (Part I)’.

Invasive Asian Carps in North America

2011 ◽  
Keyword(s):  
Death Rate ◽  
Normal Population ◽  
Fish Population ◽  
Exotic Fish ◽  
Y Chromosomes ◽  
Eradication Strategy ◽  
Determination System ◽  
Normal Fish ◽  
Asian Carps ◽  
Sex Determination System

<em>Abstract</em>.—The directed extinction of an exotic fish population is proposed using a genetic approach to drastically reduce the ratio of females to males within the population. In the proposed strategy, sex-reversed female fish containing two Y chromosomes (Fyy) are introduced into a normal fish population. The frequencies of each of the four expected genotypes of fish in the simulated population (Fxx, Fyy, Mxy, and Myy) were modeled with a set of coupled ordinary differential equations. The equations take into account birth rate, death rate, and a fixed carrying capacity of the system. Using computer-generated simulations, it was determined that the continuous introduction of a relatively small proportion of Fyy females to the normal population leads to extinction of the exotic fish over time. The proposed eradication strategy is relevant to fish species with an XY sex-determination system that tolerate a YY genotype. Published literature suggests that Asian carps are likely to fulfill these criteria. However, technical barriers associated with sex reversal in Asian carps presently exist and must be overcome before implementation of a YY eradication strategy for Asian carps can be considered in practice. An idealized theoretical model for the eradication of Asian carps is thus presented.

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