Lecture 23 - Quantitative Genetics the study of the genetic...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Quantitative Genetics – the study of the genetic basis of continuously varying traits. Bract Color in Indian Paintbrush
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Frequency Histograms - a statistical distribution that shows the number of individuals vs. a measure. Distribution Function – a continuous curve that is an idealized representation of the actual distribution.
Background image of page 2
Statistical Measures sued to describe Quantitative traits: 1) Measures of Central Tendency a) Mean = average = x b) Mode = most frequently observed class 1) Measures of Dispersion a) Variance = average squared deviation of the observations from their mean = s2 b) Standard Deviation = Square root of the Variation = s
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
How do you know there is a genetic basis for the variation? The Mean of the F 3 progeny more closely resembles that of the sampled parental types than the overall mean – responds to selection P F 1 F 2 F 3 Clearly not a 1:2:1 ratio Increased Variance relative to F 1 Petal Length in Nicotiana longiflora Mean of the two parental lines Possible Incomplete Dominance?
Background image of page 4
Phenotypic Distributions For Specific Genotypes For a Population
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Convert a Quantitative trait into a Mendelian trait: Controlled environment What makes a Quantitative trait a QT is that the phenotypic variance between genotypes is smaller than the phenotypic variance between individuals of the same genotype.
Background image of page 6
Effect of Gene Numbers Wilhelm Johannsen 1857-1927 Coined terms Gene, genotype, and phenotype Generated 19 inbred lines of beans from same pop. with seed weight varying from 0.35 to 0.64g. Each line had a distinct and heritable weight. If seed weight is controlled by single allele pair Aa In breeding would produce: AA and aa; only two genotypes. 19 generations of self crossing
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/15/2009 for the course BIOL 3301 taught by Professor Gunaratne during the Fall '05 term at University of Houston.

Page1 / 23

Lecture 23 - Quantitative Genetics the study of the genetic...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online