RESUMO
In this study, chromosomal inversion polymorphism data for a natural population of Drosophila subobscura from a swampy region near the town of Apatin (Serbia) were compared with data for the same population collected approximately 15 years earlier. The pattern of chromosomal inversion polymorphism changed over time. There were significant increases in the frequency of characteristic southern latitude ("warm" adapted) chromosomal arrangements and significant decreases in the frequency of characteristic northern latitude ("cold" adapted) chromosomal arrangements in the O and U chromosomes. The chromosomal arrangements O(3+4) and O(3+4) (+) (22) (derived from the O(3+4) arrangement) showed significant increases in 2008 and 2009 with regard to the 1994 sample. There was also a significant increase (â¼50%) in the U(1) (+) (2) arrangement, while U(1+8) (+) (2) (a typical southern arrangement) was detected for the first time. Since the Apatin swampy population of D. subobscura has existed for a long time in a stable habitat with high humidity that has not been changed by man our results indicate that natural selection has produced chromosomal changes in response to the increase in temperature that has occurred in the Balkan Peninsula of central southeastern European.
RESUMO
In this study, chromosomal inversion polymorphism data for a natural population of Drosophila subobscura from a swampy region near the town of Apatin (Serbia) were compared with data for the same population collected approximately 15 years earlier. The pattern of chromosomal inversion polymorphism changed over time. There were significant increases in the frequency of characteristic southern latitude ("warm" adapted) chromosomal arrangements and significant decreases in the frequency of characteristic northern latitude ("cold" adapted) chromosomal arrangements in the O and U chromosomes. The chromosomal arrangements O3+4 and O3+4+22 (derived from the O3+4 arrangement) showed significant increases in 2008 and 2009 with regard to the 1994 sample. There was also a significant increase (~50 percent) in the U1+2 arrangement, while U1+8+2 (a typical southern arrangement) was detected for the first time. Since the Apatin swampy population of D. subobscura has existed for a long time in a stable habitat with high humidity that has not been changed by man our results indicate that natural selection has produced chromosomal changes in response to the increase in temperature that has occurred in the Balkan Peninsula of central southeastern European.
Assuntos
Animais , Drosophila/genética , Aquecimento Global , Polimorfismo Genético , Genética Populacional , Cariotipagem , SérviaRESUMO
Knowledge of the frequency, distribution, and fate of lethal genes in chromosomal inversions helps to illuminate the evolution of recently founded populations. We analyze the relationship between lethal genes and inversions in two colonizing populations of D. subobscura in Chile. In the ancestral Palearctic populations of this species, lethal genes seem distributed at random on chromosomes. But in colonizing American populations, some lethal genes are associated with specific chromosomal arrangements. Some of these associated lethals were detected only during the first stages of the colonization (O( 3+4+2 )), and never thereafter, whereas others have persisted (O( 3+4+7 ) and O(5)). However, most lethal genes in American populations have been observed only once: they have arisen by novel mutation and soon disappear. Finally, recombination between different inversions has been observed in America. However, the persistence of lethal genes associated with the heterotic inversions O( 3+4+7 ) and O(5) could indicate that recombination inside these inversions is rare.
Assuntos
Cromossomos/genética , Drosophila/genética , Evolução Molecular , Genes Letais , Alelos , Animais , Chile , Inversão Cromossômica , Genética PopulacionalRESUMO
The O5 chromosomal inversion has been a cornerstone for understanding different aspects of the American colonization by Drosophila subobscura. To obtain more information of this evolutionary event it is important to know the pattern of bands of this inversion in detail. Comparing this pattern with that of D. melanogaster it is possible to predict which genes are located inside or close to the O5 inversion and use them as genetic markers. In this study, the complete band pattern of the O5 inversion is presented. Furthermore, the most important genes located inside it have been predicted. Finally, a constriction located close to the proximal breakage point of the O5 inversion has been observed many times and its possible genetic significance is discussed
Assuntos
Animais , Inversão Cromossômica , Drosophila , Genes Letais , Marcadores Genéticos , Polimorfismo Genético , Técnicas Citológicas , Características de ResidênciaRESUMO
A plasticidade fenotípica de alguns caracteres quantitativos foi estudada em duas populaçöes colonizadoras de Drosophila subobscura (Davis e Eureka, Califórnia). Analisaram-se tanto o efeito da temperatura como o da criaçäo em laboratório. A criaçäo em laboratório durante quatro geraçöes a 18ºC aumentou significativamente o comprimento da asa e da tíbia. Este incremento foi semelhante ao obtido quando as moscas foram cultivadas a 13ºC durante duas geraçöes. O ambiente de temperatura baixa pode ser considerado mais estressante para as fêmeas, pois elas apresentaram um aumento na variância fenotípica. As duas populaçöes analisadas apresentaram uma grande plasticidade fenotípica, apesar do "gargalo" genético produzido durante o processo colonizador. Nossos estudos mostram que a manutençäo das moscas no laboratório por um período de tempo relativamente curto é capaz de mudar significativamente alguns caracteres quantitativos, sendo fundamental analisar as moscas imediatamente após capturá-las, para se obterem estimativas confiáveis na análise de tais caracteres nas populaçöes naturais.