1. IHNERITANCE OF QUANTITATIVE FEATURES
Výukový materiál GE
Tvůrce: Mgr. Šárka Vopěnková
Tvůrce anglické verze: ThMgr. Ing. Jiří Foller
Projekt: S anglickým jazykem do dalších předmětů
Registrační číslo: CZ.1.07/1.1.36/
Tento projekt je spolufinancován ESF a SR ČR
2014

2. QUANTITATIVE FEATURES
genotypically conditioned by a larger amount of genes with a small effect – polygenes, which influence each other with their effect and which form a polygenic system
the most of multicellular organisms
phenotypical evidence of particular alleles add to each other in polygenic additive system
the effect of alleles multiplicate in polygenic multiplicative system

3. QUANTITATIVE FEATURES
by a big amount of active genes is formed a big amount of quantitatively different genotypes
by a monogenous feature are formed 3 genotypes (AA, Aa, aa)
if each gene is represented by two alleles, by the number of genes k is the number of various genotypes given by expression 3k
if a feature is influenced by three genes, 27 various genotypes are formed

4. QUANTITATIVE FEATURES
by 5 participating genes 243 genotypes are formed
so quantitative features show a continual variability – Gaussian curve
because the effect of each polygene is very small, it is difficult to distinguish the influence of polygenes from the influence of external environment!!!

5. QUANTITATIVE FEATURES
the share of external factors, non hereditary variability by the formation of phenotype of quantitative features can be figured out
the mass of inheritance and non-hereditary variability = heritability
is given by the relation between hereditary and total phenotypical part of the feature variability

6. QUANTITATIVE FEATURES
the index of heritability is so called coefficient of inheritance = h2
h2 = Vg/Vp
h2 is the quotient of genetically conditioned variability in total phenotypical variability of a particular feature

7. HERITABILITY
values of coefficient of inheritance are from 0 (total variability of the feature is caused by factors of the environment) to 1 (total variability of the feature is caused by genetic factors)
values of h2 lower than 0,2 are regarded as low heritability
values 0,2 – 0,5 as medium heritability
values over 0,5 as high heritability
the higher heritability, the higher similarity between parents and the posterity is to be expected and on the contrary!!!!!!

8. QUANTITATIVE FEATURES
they usually have low heredity
marks of their genes are easily influenceable by factors of the environment
some influences of the external environment strengthen the mark significantly, some of them inhibit it
non hereditary variability, changing the phenotype of quantitative features, is called modification

9. QUANTITATIVE FEATURES
Laplace-Gauss curve of normal values distribution of
a quantitative feature in the population (the curve is bell-shaped)
b) Variation curves of two features with various but in both cases normal distribution of the variation in the population

10. QUANTITATIVE FEATURES
Model analysis of normal values distribution curve of a polygenic (quantitative) feature in the population (the empty circle marks a neutral allele – not influencing the height; each black circle marks a 1 cm taller stature

11. WORKSHEET
In the second generation of the posterity after interbreed crossing hens of type Bantam and Plymouth following values were marked by a random sample of ten adults:
1030 g, 1210 g, 1560 g, 1390 g, 1160 g, 870 g, 910 g, 1220 g a 1410 g.
What is average body weight, which can be theoretically expected in this collection of hybrids?
What range of values of body weight of adult individuals may occur in this collection under specific conditions?

12. SOURCES
CHALUPOVÁ-KARLOVSKÁ, Vlastimila. Obecná biologie: středoškolská učebnice : evoluce, biologie buňky, genetika : s 558 řešenými testovými otázkami. 2., opr. vyd. Olomouc: Nakladatelství Olomouc, 2010, 206 s. ISBN