Chapter 24 - Quantitative Genetics and Multifactorial Traits

Chapter 24 - Quantitative Genetics and Multifactorial...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 24 Quantitative Genetics and Multifactorial Traits There are different types of phenotypic variation - discontinuous variation traits with small number of discrete phenotypes o genotype will produce single identifiable phenotype - continuous variation continuous range of phenotypes that cannot be easily classified into distinct categories o human height, weight, milk or meat production in cattle, crop yield, seed protein content o quantitative inheritance where continuous variation across a range of phenotypes is measured and described in quantitative terms sometimes referred to as polygenic many genes - complex and multifactorial describes traits where a range of phenotypes results from gene action and environmental influences not all polygenic traits show continuous variation - when continuous trait is examined in a population, individual measurements form a graduation of phenotypes with no clear categories - meristic traits those in which the phenotypes are recorded by counting whole numbers - threshold traits polygenic (frequently environmental factors affect phenotypes, so also multifactorial) o distinguished from continuous and meristic traits by having a small number of discrete phenotypic classes quantitative traits can be explained in Mendelian terms - multiple-factor/multiple-gene hypothesis many genes, each individually behaving in a Mendelian fashion, contribute to the phenotype in a cumulative or quantitative way o grain color in wheat used by Nilsson Ehle to test concept that cumulative effects of alleles at multiple loci produce range of phenotypes seen in quantitative traits it appears that two genes, each with two alleles, control the
Background image of page 1

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

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/17/2008 for the course BIOL 2500 taught by Professor Finger during the Fall '07 term at Rensselaer Polytechnic Institute.

Page1 / 3

Chapter 24 - Quantitative Genetics and Multifactorial...

This preview shows document pages 1 - 2. Sign up to view the full document.

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