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La selección darwiniana en un locus egoísta.
Kentaro K Shimizu1, Jennifer M Cork, Ana L Caicedo
1Department of Genetics, North Carolina State University, Box 7614, Raleigh, NC 27695, USA.
Science (New York, N.Y.)
|December 18, 2004
Resumen
La evolución de la autopolinización en Arabidopsis thaliana fue impulsada por pseudogenes en los loci de autoincompatibilidad, lo que llevó a una reducción de la variación genética. Este reciente evento adaptativo puede estar relacionado con la planta.
Área de la Ciencia:
- Biología evolutiva Biología evolutiva.
- Genética vegetal Genética vegetal
- Evolución molecular de la evolución molecular.
Sus antecedentes:
- La auto-polinización es una transición evolutiva común en las plantas con flores.
- En Arabidopsis thaliana, los pseudogenes en los loci del receptor de autocompatibilidad (SCR) y del receptor de autoincompatibilidad (SRK) están implicados en la evolución de la autofertilización.
- Se observa una reducción de la variación de nucleótidos en alelos pseudogénicos de SCR debido a la selección direccional positiva.
Objetivo del estudio:
- Para investigar los mecanismos evolutivos que impulsan la transición a la auto-polinización en la Arabidopsis thaliana.
- Determinar el papel de los pseudogenes en los loci SCR y SRK en la evolución de la autofertilización.
- Explorar el momento y las posibles asociaciones ecológicas de este evento adaptativo.
Principales métodos:
- Análisis de alelos de pseudógenos en los loci de autoincompatibilidad de SCR y SRK.
- Identificación de la selección direccional positiva que actúa sobre los alelos del seudógeno SCR.
- Simulaciones coalescentes para inferir el momento del evento adaptativo y su asociación con la expansión posterior al Pleistoceno.
Principales resultados:
- La selección direccional positiva ha llevado a la fijación evolutiva de alelos pseudogénicos de SCR.
- Esta fijación ha resultado en una variación sustancialmente reducida de nucleótidos en estos lugares.
- Las simulaciones de coalescencia sugieren que el evento adaptativo es reciente y potencialmente vinculado a la expansión post-Pleistoceno de Arabidopsis thaliana.
Conclusiones:
- La evolución de la auto-polinización en Arabidopsis thaliana está asociada con la fijación de alelos pseudogénicos en los loci SCR y SRK.
- Esta transición, impulsada por la selección positiva, ha reducido significativamente la diversidad genética.
- Las innovaciones morfológicas auxiliares relacionadas con la auto-polinización pueden evolucionar rápidamente después de la pérdida de la auto-incompatibilidad.
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