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Chromosomal analysis of D. melanogaster long-term selected lines
A Domínguez1, J Albornoz, E Santiago
1Departamento de Biología Funcional, Universidad de Oviedo, Spain.
The Journal of Heredity
|January 1, 1993
Summary
Genetic crosses in Drosophila melanogaster revealed hidden genetic variability for bristle number. Rare recombination events likely generated this variation during long-term selection, explaining extreme phenotypes despite low genetic diversity.
Area of Science:
- Evolutionary genetics
- Developmental biology
- Quantitative genetics
Background:
- Drosophila melanogaster is a model organism for genetic studies.
- Long-term selection experiments are crucial for understanding genetic variation.
- Bristle number in Drosophila is a well-studied quantitative trait.
Purpose of the Study:
- To investigate the genetic basis of extreme bristle number phenotypes in Drosophila melanogaster.
- To explore the role of hidden genetic variability and interactions in response to selection.
- To determine the origin of genetic variation during prolonged selection.
Main Methods:
- Chromosomal substitutions and crosses were performed among five selected lines of Drosophila melanogaster.
- Lines were selected for increased dorsocentral bristle number, resulting in varying phenotypes.
- Genetic analysis focused on major chromosomes and gene interactions.
Main Results:
- Two lines (Ac-27S, Ac-27P) showed moderate bristle numbers (around 16), while three lines (S-27S, S-27P, N-21) exhibited extreme phenotypes (35-40 bristles).
- Recessive and synergistic gene interactions revealed hidden genetic variability.
- Lines with extreme phenotypes shared additional increasing alleles, suggesting common origins for this variation.
Conclusions:
- Hidden genetic variability, released by selection through recessivity and synergistic interactions, can explain responses in traits with low apparent variability.
- Extreme phenotypes in selected Drosophila lines suggest de novo variation arose during selection.
- Low genetic variability among extreme lines supports a low-probability, nonrandom mechanism like rare recombination events as the source of variation.