Chromosomal evidence for sibling species of the malaria vector Anopheles cruzii

Genome ◽  
2000 ◽  
Vol 43 (1) ◽  
pp. 143-151 ◽  
Author(s):  
Corália CL Ramírez ◽  
Eliana MB Dessen
Keyword(s):  
Gene Flow ◽  
X Chromosome ◽  
Sibling Species ◽  
Polytene Chromosomes ◽  
Chromosome X ◽  
Standard Pattern ◽  
Banding Patterns ◽  
Chromosomal Form ◽  
Limited Gene Flow ◽  
Anopheles Cruzii

An analysis of the ovarian polytene chromosomes of Anopheles cruzii from three localities in Southeast Brazil revealed the existence of two genetic entities within this morphologically uniform taxon. These cryptic species differed in the banding patterns of the X chromosome and 3L arm. A pattern of bands that cannot be explained by the fixation of any of the known inversions in chromosome X was revealed and named chromosomal form B to distinguish it from the standard pattern of this X chromosome, form A. Each chromosomal form is characterized by a different set of inversions. The lack of heterozygotes (A/B) for these X chromosome forms in populations where both forms coexist is evidence of absence or limited gene flow between the two groups. Key words: Anopheles cruzii, inversion polymorphism, sibling species.

Cytological differences and chromosomal rearrangements in four members of the Anopheles dirus complex (Diptera: Culicidae)

Genome ◽  
1988 ◽  
Vol 30 (3) ◽  
pp. 372-379 ◽  
Author(s):  
V. Baimai ◽  
A. Poopittayasataporn ◽  
U. Kijchalao
Keyword(s):  
X Chromosome ◽  
Chromosomal Rearrangements ◽  
Polytene Chromosomes ◽  
Natural Populations ◽  
Low Frequency ◽  
Anopheles Dirus ◽  
Chromosome Inversion ◽  
Banding Patterns ◽  
Complex Species ◽  
Band Size

A reference photomap of the larval salivary gland, polytene chromosomes of the Anopheles dims complex (species A) is presented. Samples of species A, B, C, and D from natural populations in Thailand were compared to this standard map using the larval progeny of wild-caught females. All species show differences in their chromosome banding patterns involving band size, number, and shape, particularly at the free ends of the X, 2R, and 2L. These differences provide useful diagnostic characters for separating members of the species complex. However, overall banding patterns are conservative in the group: species A, B, and C are virtually homosequential. Species D is highly polymorphic for a single paracentric inversion in each of the four autosomal arms and has a fixed inversion on the X chromosome. This same X chromosome inversion occurs at low frequency in species A.Key words: Anopheles dirus, larval polytene chromosome, inversion polymorphisms.

A standard cytogenetic map for Anopheles sundaicus (Diptera: Culicidae) and evidence for chromosomal differentiation in populations from Thailand and Indonesia

Genome ◽  
1996 ◽  
Vol 39 (1) ◽  
pp. 165-173 ◽  
Author(s):  
S. Sukowati ◽  
V. Baimai
Keyword(s):  
Karyotype Analysis ◽  
Polytene Chromosomes ◽  
Centromeric Heterochromatin ◽  
Chromosome X ◽  
Cytogenetic Map ◽  
Banding Patterns ◽  
Chromosome Y ◽  
Central Java ◽  
Chromosomal Differentiation ◽  
North Sumatra

A standard photographic map of polytene chromosomes of Anopheles sundaicus was constructed from ovarian nurse cells and is described herein. Polytene chromosomes of wild specimens collected from 9 different geographical areas in Thailand and Indonesia have been analyzed. Specimens from these populations appear to share banding patterns with standard gene arrangements, except for some specimens from Purworejo, in Central Java, and South Tapanuli and Asahan, both of North Sumatra, which exhibited distinct banding patterns at the tip of chromosome X (Xb) compared with the standard sequence (Xa). Moreover, some specimens collected from Asahan, North Sumatra, consistently showed distinct loosely diffuse bands in zone 19 of chromosome arm 2R (2Rb) compared with the standard banding patterns (2Ra). The existence of the 2Rb pattern correlates perfectly with the presence of an extra block of centromeric heterochromatin in autosome 2 as revealed by mitotic karyotype analysis (2n = 6). These cytological differences have led to the recognition of 3 distinct forms, viz., A, B, and C, within the taxon An. sundaicus. In addition, forms A and C show a normal size for chromosome Y, (Y1), while form B has a relatively larger type of chromosome Y, (Y2). Form A is widely distributed in Thailand and Indonesia, while form B has been found in North Sumatra and Central Java. Form C, however, has been found only in Asahan, North Sumatra. Key words : Anopheles sundaicus, polytene chromosome map, mitotic karyotype, chromosomal differentiation.

Relationships within the melanogaster species subgroup of the genus Drosophila ( Sophophora ) - II. Phylogenetic relationships between six species based upon polytene chromosome banding sequences

1976 ◽  
Vol 193 (1112) ◽  
pp. 275-294 ◽  
Keyword(s):  
Sample Size ◽  
Sibling Species ◽  
Endemic Species ◽  
Phylogenetic Relationships ◽  
Chromosome Banding ◽  
Polytene Chromosomes ◽  
Evolutionary Relationships ◽  
Banding Patterns ◽  
Two Populations ◽  
Paracentric Inversions

The melanogaster species subgroup of Drosophila comprises six sibling species. The interrelationship between these species has been studied by analysis of the banding patterns of their polytene chromosomes. The species fall into two groups: (1) melanogaster, simulans and mauritiana and (2) erecta, teissieri and yakuba . The former group are chromosomally closely related, indeed simulans and mauritiana are homosequential. The latter group (all African endemic species) are less closely related although they all share eight autosomal inversions of the standard (i. e. melanogaster ) sequence. From this shared sequence the chromosomes of the three African endemic species have diverged considerably by many paracentric inversions. Both D. teissieri and D. yakuba are polymorphic; we describe nine and four inversion sequences in them respectively. D. erecta is monomorphic although our sample size is very small (only two populations). We discuss both the origin of interspecific inversions, especially the problem of inversion breakpoint coincidence, and the light this study throws upon evolutionary relationships within this group of species.

X-linked CNV and skewed X-chromosome inactivation

2020 ◽  
pp. 19-21
Author(s):  
Е.А. Фонова ◽  
Е.Н. Толмачева ◽  
А.А. Кашеварова ◽  
М.Е. Лопаткина ◽  
К.А. Павлова ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Intellectual Disability ◽  
X Chromosome ◽  
Copy Number ◽  
Copy Number Variations ◽  
X Chromosome Inactivation ◽  
Chromosome Inactivation ◽  
Chromosome X ◽  
Skewed X Chromosome Inactivation

Смещение инактивации Х-хромосомы может быть следствием и маркером нарушения клеточной пролиферации при вариациях числа копий ДНК на Х-хромосоме. Х-сцепленные CNV выявляются как у женщин с невынашиванием беременности и смещением инактивации Х-хромосомы (с частотой 33,3%), так и у пациентов с умственной отсталостью и смещением инактивацией у их матерей (с частотой 40%). A skewed X-chromosome inactivation can be a consequence and a marker of impaired cell proliferation in the presence of copy number variations (CNV) on the X chromosome. X-linked CNVs are detected in women with miscarriages and a skewed X-chromosome inactivation (with a frequency of 33.3%), as well as in patients with intellectual disability and skewed X-chromosome inactivation in their mothers (with a frequency of 40%).

Differentiation and Interrelations of Two Representatives of Laudakia stellio Complex (Reptilia: Agamidae) in Israel

2011 ◽  
Vol 4 (2) ◽  
pp. 102-114 ◽  
Author(s):  
Evgenyi N. Panov ◽  
Larissa Yu. Zykova
Keyword(s):  
Population Structure ◽  
Gene Flow ◽  
Habitat Preference ◽  
Additional Data ◽  
Near East ◽  
Field Studies ◽  
Subspecies Level ◽  
Limited Gene Flow ◽  
Study Sites ◽  
And Behavior

Field studies were conducted in Central Negev within the breeding range of Laudakia stellio brachydactyla and in NE Israel (Qyriat Shemona) in the range of an unnamed form (tentatively “Near-East Rock Agama”), during March – May 1996. Additional data have been collected in Jerusalem at a distance of ca. 110 km from the first and about 170 km from the second study sites. A total of 63 individuals were caught and examined. The animals were marked and their subsequent movements were followed. Social and signal behavior of both forms were described and compared. Lizards from Negev and Qyriat Shemona differ from each other sharply in external morphology, habitat preference, population structure, and behavior. The differences obviously exceed the subspecies level. At the same time, the lizards from Jerusalem tend to be intermediate morphologically between those from both above-named localities, which permits admitting the existence of a limited gene flow between lizard populations of Negev and northern Israel. The lizards from NE Israel apparently do not belong to the nominate subspecies of L. stellio and should be regarded as one more subspecies within the species.

Population fragmentation causes inadequate gene flow and increases extinction risk

2017 ◽  
Author(s):  
Richard Frankham ◽  
Jonathan D. Ballou ◽  
Katherine Ralls ◽  
Mark D. B. Eldridge ◽  
Michele R. Dudash ◽  
...  
Keyword(s):  
Gene Flow ◽  
Extinction Risk ◽  
Random Mating ◽  
Large Population ◽  
Isolated Population ◽  
Population Fragmentation ◽  
Single Population ◽  
Total Size ◽  
Limited Gene Flow

Most species now have fragmented distributions, often with adverse genetic consequences. The genetic impacts of population fragmentation depend critically upon gene flow among fragments and their effective sizes. Fragmentation with cessation of gene flow is highly harmful in the long term, leading to greater inbreeding, increased loss of genetic diversity, decreased likelihood of evolutionary adaptation and elevated extinction risk, when compared to a single population of the same total size. The consequences of fragmentation with limited gene flow typically lie between those for a large population with random mating and isolated population fragments with no gene flow.

scholarly journals Molecular Characterization of hobo-Mediated Inversions in Drosophila melanogaster

Genetics ◽  
1996 ◽  
Vol 144 (2) ◽  
pp. 647-656
Author(s):  
William B Eggleston ◽  
Nac R Rim ◽  
Johng K Lim
Keyword(s):  
X Chromosome ◽  
Polymerase Chain Reaction Amplification ◽  
Polytene Chromosomes ◽  
Chromosomal Inversions ◽  
Hobo Element ◽  
Reaction Amplification ◽  
Notch Locus ◽  
Polymerase Chain

Abstract The structure of chromosomal inversions mediated by hobo transposable elements in the Uc-1 X chromosome was investigated using cytogenetic and molecular methods. Uc-1 contains a phenotypically silent hobo element inserted in an intron of the Notch locus. Cytological screening identified six independent Notch mutations resulting from chromosomal inversions with one breakpoint at cytological position 3C7, the location of Notch. In situ hybridization to salivary gland polytene chromosomes determined that both ends of each inversion contained hobo and Notch sequences. Southern blot analyses showed that both breakpoints in each inversion had hobo-Notch junction fragments indistinguishable in structure from those present in the Uc-1 X chromosome prior to the rearrangements. Polymerase chain reaction amplification of the 12 hobo-Notch junction fragments in the six inversions, followed by DNA sequence analysis, determined that each was identical to one of the two hobo-Notch junctions present in Uc-1. These results are consistent with a model in which hobo-mediated inversions result from homologous pairing and recombination between a pair of hobo elements in reverse orientation.

High gene flow through pollen partially compensates spatial limited gene flow by seeds for a Neotropical tree in forest conservation and restoration areas

2021 ◽  
Author(s):  
Patricia Sanae Sujii ◽  
Evandro Vagner Tambarussi ◽  
Carolina Grando ◽  
Ellida de Aguiar Silvestre ◽  
João Paulo Gomes Viana ◽  
...  
Keyword(s):  
Gene Flow ◽  
Forest Conservation ◽  
Neotropical Tree ◽  
High Gene Flow ◽  
High Gene ◽  
Limited Gene Flow ◽  
Flow Through

scholarly journals Detectable chromosome X mosaicism in males is rarely tolerated in peripheral leukocytes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Weiyin Zhou ◽  
Shu-Hong Lin ◽  
Sairah M. Khan ◽  
Meredith Yeager ◽  
Stephen J. Chanock ◽  
...  
Keyword(s):  
X Chromosome ◽  
Gene Dosage ◽  
Large Population ◽  
Population Based ◽  
Chromosome X ◽  
Genotyping Array ◽  
Chromosome Mosaicism ◽  
Age Related ◽  
Leukocyte Function ◽  
Peripheral Leukocytes

AbstractAge-related male Y and female X chromosome mosaicism is commonly observed in large population-based studies. To investigate the frequency of male X chromosome mosaicism, we scanned for deviations in chromosome X genotyping array intensity data in a population-based survey of 196,219 UK Biobank men. We detected 12 (0.006%) men with mosaic chromosome X gains ≥ 2 Mb and found no evidence for mosaic chromosome X loss, a level of detection substantially lower than for autosomes or other sex chromosomes. The rarity of chromosome X mosaicism in males relative to females reflects the importance of chromosome X gene dosage for leukocyte function.

Chromosome polymorphism in natural populations of Anopheles quadrimaculatus Say species A and B

Genome ◽  
1988 ◽  
Vol 30 (2) ◽  
pp. 138-146 ◽  
Author(s):  
P. E. Kaiser ◽  
J. A. Seawright ◽  
B. K. Birky
Keyword(s):  
X Chromosome ◽  
Southeastern United States ◽  
Polytene Chromosomes ◽  
Natural Populations ◽  
Chromosome 3 ◽  
Chromosome Polymorphism ◽  
Chromosome 2 ◽  
Anopheles Quadrimaculatus ◽  
The Right ◽  
Maculipennis Complex

Ovarian polytene chromosomes from eight populations of Anopheles quadrimaculatus in the southeastern United States were observed for chromosomal polymorphisms. Two sibling species, species A and B, each with intraspecific inversions, were distinguished. Species A correlates with the previously published standard maps for salivary gland and ovarian nurse-cell polytene chromosomes. Species A was found at all eight collection sites, and five of these populations also contained species B. Three inversions on the right arm of chromosome 3 were observed in species A. Species B contained a fixed inversion on the X chromosome, one fixed and one floating inversion on the left arm of chromosome 2, and one fixed and one floating inversion on the right arm of chromosome 3. The fixed inversion on the X chromosome makes this the best diagnostic chromosome for distinguishing species A and B. An unusual dimorphism in the left arm of chromosome 3, found in both species A and B, contained two inversions. The heterokaryotypes, as well as two distinct homokaryotypes, were seen in all of the field populations. Intraspecific clinal variations in the frequencies of the species A inversions were noted. The Florida populations were practically devoid of inversions, the Georgia and Alabama populations contained some inversions, and the Arkansas population was mostly homozygous for two of the inversions. The phylogenetic relationships of species A and B to the Maculipennis complex (Nearctic) are discussed.Key words: Anopheles, inversion, populations, chromosome polymorphism, phylogenetics.

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