scholarly journals Cytogenetic differentiation between Palearctic and Nearctic populations of Chironomus plumosus L. (Diptera, Chironomidae)

Genome ◽  
1999 ◽  
Vol 42 (5) ◽  
pp. 797-815 ◽  
Author(s):  
Malcolm G Butler ◽  
Iya I Kiknadze ◽  
Veronica V Golygina ◽  
Jon Martin ◽  
Albina G Istomina ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
High Frequency ◽  
Natural Populations ◽  
Inversion Polymorphism ◽  
Chironomus Plumosus ◽  
Chromosomal Banding ◽  
Great Divergence ◽  
Holarctic Species

Macrogeographic patterns of polytene chromosomal banding sequences were studied in natural populations of the Holarctic species Chironomus plumosus. Of the 31 inversion sequences now known, 16 are endemic to the Palearctic, 7 are endemic to the Nearctic, and 8 are Holarctic sequences common to both zoogeographic zones. Differences in the sets of inversion sequences found on each continent, plus differing frequencies of Holarctic sequences, result in great overall divergence of karyotypes on the two continents. The karyotype of Nearctic C. plumosus differs from that of Palearctic populations primarily by the presence of a homozygous Nearctic sequence in arm A (n'plu A9), along with fixation (h'plu C2, h'plu E2, and h'plu F1), or high frequency (h'plu D2), of Holarctic sequences which are present but less frequent in the Palearctic. Although long continental isolation has led to great divergence of karyotypes on opposite sides of the Atlantic Ocean, all populations of C. plumosus show sufficient cytogenetic similarity to constitute a single Holarctic species.Key words: karyotype, inversion polymorphism, cytogenetic distances, Chironomus.

scholarly journals New Cytogenetic Photomap and Molecular Diagnostics for the Cryptic Species of the Malaria Mosquitoes Anopheles messeae and Anopheles daciae from Eurasia

Insects ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 835
Author(s):  
Gleb N. Artemov ◽  
Valentina S. Fedorova ◽  
Dmitriy A. Karagodin ◽  
Ilya I. Brusentsov ◽  
Elina M. Baricheva ◽  
...  
Keyword(s):  
Cryptic Species ◽  
Natural Populations ◽  
Inversion Polymorphism ◽  
Its2 Region ◽  
Cytogenetic Map ◽  
Nucleotide Substitutions ◽  
Chromosomal Inversions ◽  
Single Location ◽  
Anopheles Daciae ◽  
Malaria Mosquitoes

The Eurasian malaria vector Anopheles messeae is a widely spread and genetically diverse species. Five widespread polymorphic chromosomal inversions were found in natural populations of this mosquito. A cryptic species, Anopheles daciae, was differentiated from An. messeae by the presence of several nucleotide substitutions in the Internal Transcribed Spacer 2 (ITS2) region of ribosomal DNA. However, because of the absence of a high-quality reference cytogenetic map, the inversion polymorphisms in An. daciae and An. messeae remain poorly understood. Moreover, a recently determined heterogeneity in ITS2 in An. daciae questioned the accuracy of the previously used Restriction Fragment Length Polymorphism (RFLP) assay for species diagnostics. In this study, a standard-universal cytogenetic map was constructed based on orcein stained images of chromosomes from salivary glands for population studies of the chromosomal inversions that can be used for both An. messeae and An. daciae. In addition, a new ITS2-RFLP approach for species diagnostics was developed. Both methods were applied to characterize inversion polymorphism in populations of An. messeae and An. daciae from a single location in Western Siberia in Russia. The analysis demonstrates that cryptic species are remarkably different in their frequencies of chromosomal inversion variants. Our study supports previous observations that An. messeae has higher inversion polymorphism in all autosomes than the cryptic species An. daciae.

scholarly journals Intercontinental karyotype–environment parallelism supports a role for a chromosomal inversion in local adaptation in a seaweed fly

2018 ◽  
Vol 285 (1881) ◽  
pp. 20180519 ◽  
Author(s):  
Claire Mérot ◽  
Emma L. Berdan ◽  
Charles Babin ◽  
Eric Normandeau ◽  
Maren Wellenreuther ◽  
...  
Keyword(s):  
North America ◽  
Local Adaptation ◽  
Environmental Gradients ◽  
Balancing Selection ◽  
Chromosomal Rearrangements ◽  
Natural Populations ◽  
Inversion Polymorphism ◽  
Life History Strategies ◽  
Heterogeneous Environments ◽  
Adult Size

Large chromosomal rearrangements are thought to facilitate adaptation to heterogeneous environments by limiting genomic recombination. Indeed, inversions have been implicated in adaptation along environmental clines and in ecotype specialization. Here, we combine classical ecological studies and population genetics to investigate an inversion polymorphism previously documented in Europe among natural populations of the seaweed fly Coelopa frigida along a latitudinal cline in North America. We test if the inversion is present in North America and polymorphic, assess which environmental conditions modulate the inversion karyotype frequencies, and document the relationship between inversion karyotype and adult size. We sampled nearly 2000 flies from 20 populations along several environmental gradients to quantify associations of inversion frequencies to heterogeneous environmental variables. Genotyping and phenotyping showed a widespread and conserved inversion polymorphism between Europe and America. Variation in inversion frequency was significantly associated with environmental factors, with parallel patterns between continents, indicating that the inversion may play a role in local adaptation. The three karyotypes of the inversion are differently favoured across micro-habitats and represent life-history strategies likely to be maintained by the collective action of several mechanisms of balancing selection. Our study adds to the mounting evidence that inversions are facilitators of adaptation and enhance within-species diversity.

scholarly journals Different Mechanisms of Resistance toBacillus thuringiensis Toxins in the Indianmeal Moth

2001 ◽  
Vol 67 (3) ◽  
pp. 1085-1089 ◽  
Author(s):  
Salvador Herrero ◽  
Brenda Oppert ◽  
Juan Ferré
Keyword(s):  
Binding Affinity ◽  
Binding Sites ◽  
High Frequency ◽  
Natural Populations ◽  
Slight Reduction ◽  
Mechanisms Of Resistance ◽  
Drastic Reduction ◽  
Toxin Binding ◽  
Toxicological Studies ◽  
Toxicological Data

ABSTRACT Susceptibility to protoxin and toxin forms of Cry1Ab and the binding of 125I-labeled Cry1Ab and Cry1Ac has been examined in three Plodia interpunctella colonies, one susceptible (688s) and two resistant (198r and Dplr) to Bacillus thuringiensis. Toxicological studies showed that the 198r colony was 11-fold more resistant to Cry1Ab protoxin than to Cry1Ab activated toxin, whereas the Dplr colony was 4-fold more resistant to protoxin versus toxin. Binding results with 125I-labeled toxins indicated the occurrence of two different binding sites for Cry1Ab in the susceptible insects, one of them shared with Cry1Ac. Cry1Ab binding was found to be altered in insects from both resistant colonies, though in different ways. Compared with the susceptible colony, insects from the Dplr colony showed a drastic reduction in binding affinity (60-fold higher Kd ), although they had similar concentrations of binding sites. Insects from the 198r colony showed a slight reduction in both binding affinity and binding site concentration (five-fold-higherKd and ca. three-fold-lowerRt compared with the 688s colony). No major difference in Cry1Ac binding was found among the three colonies. The fact that the 198r colony also has a protease-mediated mechanism of resistance (B. Oppert, R. Hammel, J. E. Throne, and K. J. Kramer, J. Biol. Chem. 272:23473–23476, 1997) is in agreement with our toxicological data in which this colony has a different susceptibility to the protoxin and toxin forms of Cry1Ab. It is noteworthy that the three colonies used in this work derived originally from ca. 100 insects, which reflects the high variability and high frequency of B. thuringiensisresistance genes occurring in natural populations.

Sign in / Sign up

Export Citation Format

Share Document