The genetics of Drosophila subobscura populations XIII. A study of lethal allelism

Genetica ◽  
1980 ◽  
Vol 54 (2) ◽  
pp. 197-207 ◽  
Author(s):  
M. Loukas ◽  
C. B. Krimbas ◽  
J. Sourdis
Keyword(s):  
Drosophila Subobscura ◽  
Lethal Allelism

scholarly journals Colonization of the Americas by Drosophila subobscura: lethal-gene allelism and association with chromosomal arrangements.

Genetics ◽  
1995 ◽  
Vol 140 (4) ◽  
pp. 1297-1305
Author(s):  
F Mestres ◽  
L Serra ◽  
F J Ayala
Keyword(s):  
Drosophila Subobscura ◽  
Rapid Expansion ◽  
Lethal Gene ◽  
Latitudinal Cline ◽  
Recessive Lethal ◽  
Central California ◽  
High Incidence ◽  
Palearctic Species ◽  
Lethal Allelism ◽  
Lethal Genes

Abstract Drosophila subobscura is a Palearctic species that has recently colonized the Americas. It was first found in 1978 in Puerto Montt, Chile, and in 1982 in Port Townsend, WA. The colonization and rapid expansion of the species in western South and North America provides distinctive opportunities for investigating the process of evolution in action. The inversion polymorphism in the O chromosome from populations of central California and northern Washington, separated by 1300 km, corresponds to a previously observed latitudinal cline, also observed in Europe. Recessive lethal genes are not randomly distributed among the chromosomal arrangements. The incidence of lethal allelism is high, yielding unrealistically low estimates of the effective size of these populations (on the order of 1000 individuals). The high incidence of lethal allelism is likely to be a consequence of the low number of the American colonizers (on the order of 10-100 individuals), but the persistence of the allelism over several years suggests that some lethal-carrying chromosomes may be heterotic owing to shared associations between lethal and other genes.

scholarly journals A grand experiment in evolution: the Drosophila subobscura colonization of the Americas

Genome ◽  
1989 ◽  
Vol 31 (1) ◽  
pp. 246-255 ◽  
Author(s):  
Francisco J. Ayala ◽  
Luis Serra ◽  
Antonio Prevosti
Keyword(s):  
Mitochondrial Dna ◽  
Sierra Nevada ◽  
Strong Evidence ◽  
Polytene Chromosomes ◽  
Western Mediterranean ◽  
Drosophila Subobscura ◽  
Lethal Gene ◽  
Allozyme Polymorphism ◽  
Old World ◽  
Lethal Allelism

Drosophila subobscura is a Palearctic species that has been extensively studied by population and evolutionary geneticists for nearly half a century. In 1978, it appeared in Puerto Montt, Chile; within a few years it extended over much of Chile and into Argentina and became the most common drosophilid in many places. In 1982, it appeared in the American northwest; shortly thereafter it was found extensively distributed from southern British Columbia, through Washington and Oregon, into southern California, west of Sierra Nevada. In North America also it has become a common drosophilid in many places. The source of the colonizers has been sought with four lines of research: sequence arrangement of the polytene chromosomes, allozyme polymorphisms, mitochondrial DNA restriction patterns, and frequency of lethal alleles. The origin of the colonizers remains uncertain, although all evidence indicates that both the North American and the South American colonizers derive from the same Palearctic population. The overall configuration of the chromosomal and allozyme frequencies suggests a western Mediterranean origin, which is consistent with the mtDNA data. The presence of a particular chromosome arrangement, O5, suggests a northern European origin. Lethal allelism has opened up the possibility of discovering the precise origin of the colonizers: all O5 chromosomes in the Americas carry a particular recessive lethal gene. There is strong evidence that the number of founders was not very small and not very large, perhaps between 10 individuals and several score. The chromosomal polymorphisms of D. subobscura exhibit well-defined latitudinal clines in the Old World. In the few years since the colonization, clines in every chromosome have evolved in the Americas that have identical latitudinal polarity with those in the Old World. This would seem strong evidence that the polymorphisms and the clines are adaptive.Key words: chromosomal polymorphism, mitochondrial DNA evolution, allozyme polymorphism, lethal allelism, adaptation, geographic clines.

scholarly journals Inbreeding and thermal adaptation in Drosophila subobscura

Genome ◽  
2014 ◽  
Vol 57 (9) ◽  
pp. 481-488 ◽  
Author(s):  
Goran Zivanovic ◽  
Conxita Arenas ◽  
Francesc Mestres
Keyword(s):  
Inbred Line ◽  
Thermal Adaptation ◽  
Inbred Lines ◽  
Light Period ◽  
Drosophila Subobscura ◽  
Adaptive Potential ◽  
Line Number ◽  
Evolutionary Forces ◽  
Laboratory Conditions ◽  
Significant Line

Using a well-adapted Drosophila subobscura population (Avala, Serbia), a drastic experiment of inbreeding was carried out to assess whether the expected level of homozygosity could be reached or if other evolutionary forces affected the process. In general, no significant changes of inversion (or arrangement) frequencies were detected after 12 brother–sister mating generations. Furthermore, no significant differences were obtained between observed and expected (under the inbreeding model) karyotypic frequencies. Thus, these results seemed to indicate that the main evolutionary factor in the experiment was inbreeding. However, in the G12 generation, complete chromosomal fixation was reached only in two out of the eight final inbred lines. In these lines, the chromosomal compositions were difficult to interpret, but they could be likely a consequence of adaptation to particular laboratory conditions (constant 18 °C, food, light period, etc.). Finally, in a second experiment, the inbred lines presented higher fertility at 18 °C than at 13 °C. Also, there was a significant line effect on fertility: inbred line number 6 (A1, J1, U1+2; U1+2+6, E8, and O3+4+7) presented the highest values, which maybe the result of an adaptation to laboratory conditions. Thus, the results obtained in our experiments reflect the adaptive potential of D. subobscura inversions.

scholarly journals Vanishing Chromosomal Inversion Clines in Drosophila subobscura from Chile: Is Behavioral Thermoregulation to Blame?

2013 ◽  
Vol 182 (2) ◽  
pp. 249-259 ◽  
Author(s):  
Luis E. Castañeda ◽  
Joan Balanyà ◽  
Enrico L. Rezende ◽  
Mauro Santos
Keyword(s):  
Chromosomal Inversion ◽  
Drosophila Subobscura ◽  
Behavioral Thermoregulation

scholarly journals Gene flow and gene flux shape evolutionary patterns of variation in Drosophila subobscura

Heredity ◽  
2013 ◽  
Vol 110 (6) ◽  
pp. 520-529 ◽  
Author(s):  
C Pegueroles ◽  
C F Aquadro ◽  
F Mestres ◽  
M Pascual
Keyword(s):  
Gene Flow ◽  
Drosophila Subobscura ◽  
Evolutionary Patterns

Encapsulation ability: Are all Drosophila species equally armed? An investigation in the obscura group

2009 ◽  
Vol 87 (7) ◽  
pp. 635-641 ◽  
Author(s):  
S. Havard ◽  
P. Eslin ◽  
G. Prévost ◽  
G. Doury
Keyword(s):  
Drosophila Melanogaster ◽  
Related Species ◽  
Unusual Case ◽  
Foreign Bodies ◽  
Drosophila Subobscura ◽  
Drosophila Species ◽  
Drosophila Persimilis ◽  
Obscura Group ◽  
Encapsulation Ability

Unable to form cellular capsules around large foreign bodies, the species Drosophila subobscura Collin in Gordon, 1936 was previously shown devoid of lamellocytes, the capsule-forming hemocytes in Drosophila melanogaster Meigen, 1830. This unusual case of deficiency in encapsulation ability was remarkable enough to motivate further investigations in phylogenetically related species of the obscura group. Like D. subobscura, the species Drosophila azteca Sturtevant and Dobzhansky, 1936, Drosophila bifasciata Pomini, 1940, Drosophila guanche Monclus, 1976, Drosophila miranda Dobzhansky, 1935, Drosophila persimilis Dobzhansky and Epling, 1944, and Drosophila pseudoobcura Frovola and Astaurov, 1929 were found to be unable to encapsulate large foreign bodies and also to lack lamellocytes. Surprisingly, Drosophila affinis Sturtevant, 1916, Drosophila tolteca Patterson and Mainland, 1944, and Drosophila obscura Fallen, 1823 were capable of mounting cellular capsules, although their encapsulation abilities remained weak. These three species were free of lamellocytes but possessed small pools of never before described “atypical hemocytes” present in the hemolymph when capsules were formed.

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