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Agrociencia
versão On-line ISSN 2521-9766versão impressa ISSN 1405-3195
Agrociencia vol.41 no.1 Texcoco Jan./Fev. 2007
Applied mathematics-statistics-computer sicence
Estimating QTL biometrics parameters in F 2 populations: a new approach
1Fitotecnia. Universidad Autónoma Chapingo. 56230. Chapingo, Estado de México (jsahagun@correo.chapingo.mx).
The standard procedures for constructing maps of Quantitative Trait Loci (QTL) are based on the estimation by maximum likelihood or minimum squares of the QTL biometrics parameters and generally require numerical methods and special software, given that they do not produce explicit estimators. The objective of the present study was to derive explicit estimators of the biometrics parameters of a QTL in an F2 population. The derivation was based on three linear combinations of random variables with mixed normal distribution and a molecular marker. For each linear combination, its mean and variance were determined, with which estimators were derived of the additive effect and dominance effect of the QTL, as well as the frequency of recombination between the QTL and the marker. The explicit estimators obtained here were asyntotically consistent and unbiased, and do not require special software for their evaluation.
Key words: Quantitative traits; mixed distributions; recombination frequency; molecular markers; likelihood profile
Los procedimientos estándar para construir mapas de loci de caracteres cuantitativos (QTL o QuantitativeTrait Loci, por sus siglas en inglés) se basan en la estimación por máxima verosimilitud o mínimos cuadrados de los parámetros biométricos del QTL y generalmente requieren métodos numéricos y software especial, ya que no producen estimadores explícitos. El objetivo del presente trabajo fue derivar estimadores explícitos de los parámetros biométricos de un QTL en una población F2. La derivación se basó en tres combinaciones lineales de variables aleatorias con distribución normal mezclada y un marcador molecular. Para cada combinación lineal se determinaron su media y varianza y, con éstas, se derivaron estimadores del efecto aditivo y del efecto de dominancia del QTL, además de la frecuencia de recombinación entre éste y el marcador. Los estimadores explícitos aquí obtenidos fueron asintóticamente consistentes e insesgados y no requieren software especial para su evaluación.
Palabras clave: Caracteres cuantitativos; distribuciones mezcladas; frecuencia de recombinación; marcadores moleculares; perfil de verosimilitud
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Received: May 2005; Accepted: November 2006
Este es un artículo publicado en acceso abierto bajo una licencia Creative Commons
