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Inversion polymorphisms and natural selection in Trimerotropis pallidipennis (Orthoptera)
1Depto Cs. Biológicas, FCEN, UBA, Ciudad Universitaria, Buenos Aires, Argentina. colombop@bg.fcen.uba.ar
Hereditas
|December 4, 2003
Summary
In grasshoppers, pericentric inversions influence adult male longevity and reveal natural selection in wild populations. This study on Trimerotropis pallidipennis demonstrates karyotype-specific survival differences.
Area of Science:
- Evolutionary genetics
- Population genetics
- Insect biology
Background:
- Inversion polymorphisms are common in grasshoppers but less studied than in Drosophila.
- Trimerotropis pallidipennis exhibits polymorphism for 6 pericentric inversions across 4 chromosome pairs.
Purpose of the Study:
- To detect differential adult male longevity among karyotypes in Trimerotropis pallidipennis.
- To identify phenotypic targets of longevity selection related to inversions.
- To investigate natural selection acting on inversion polymorphisms in a wild population.
Main Methods:
- Sampling 354 males from a natural population at the beginning and end of their adult lifespan.
- Analyzing karyotype frequencies across different age classes to detect selection.
- Examining morphometric characters to link inversions with longevity selection.
Main Results:
- Significant differences in inversion frequencies between young and aged male samples indicate natural selection.
- Gametic phase disequilibrium was observed in aged males but not in young males.
- Inversions are implicated in natural selection, with evidence supporting an adaptive model for inversion frequency patterns.
Conclusions:
- Pericentric inversions in Trimerotropis pallidipennis are subject to natural selection affecting adult male longevity.
- The study provides evidence for karyotype-specific survival and phenotypic associations with inversions.
- Findings support an adaptive role for inversion polymorphisms in grasshopper populations across varying environments.
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