2014 FACTORS INFLUENCING GENE FUND OF POPULATION 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

 mutation:  standing change of gene fund  formation of new alleles  change of a dominant allele on recessive or on the contrary  frequency very low  important by evolution  standing source of hereditary variability  it enables implementation of selection in the population FACTORS INFLUENCING GENE FUND OF POPULATION

 selection - natural:  some phenotypes of features are for their bearer from the point of view of reproduction  advantageous => individuals have more descendants  disadvantageous  negative selection – eliminates individuals with disadvantageous mutant alleles  positive selection – it prefers individuals with better adaptable genotype FACTORS INFLUENCING GENE FUND OF POPULATION

 consequence of selection:  is a change of alleles in population  however, frequency rises with an advantageous feature  frequency of alleles decreases with an disadvantageous feature  it depends on:  selection intensity  type of alleles FACTORS INFLUENCING GENE FUND OF POPULATION

 if the selection is aimed against disadvantageous dominant allele => allele can disappear  if the selection is aimed against disadvantageous recessive allele => the frequency of the allele decreases in the population slowly, it never disappears  selection influences only against recessive homozygots FACTORS INFLUENCING GENE FUND OF POPULATION

 migration:  similar effect like mutation  enrichment of gene fund by new alleles or on the contrary also its impoverishment  immigration of individuals from original population  emigration of individuals from original population FACTORS INFLUENCING GENE FUND OF POPULATION

 genetic shift (drift):  coincidental shift of genetic balance  it is used in small alogamic populations  HW law not in force  some alleles can be eliminated from gene fund quite randomly only as a result of insufficient amount of descendants  the choice of alleles is very small, not representative FACTORS INFLUENCING GENE FUND OF POPULATION

 random irregularities appear  they have a considerable importance in a small population  allele frequency still changes between generations  changes cannot be predicted  some alleles are not handed over to the next generation and disappear, the others predominate FACTORS INFLUENCING GENE FUND OF POPULATION

 loss of alleles causes an increased number of homozygots  => it leads to increasing of probability of relational crossbreed - inbreeding FACTORS INFLUENCING GENE FUND OF POPULATION

 Example 1:  In a large panmictic population there were detected 16% of individuals with recessive form of a qualitative feature (it is a complete recessivity). What is in this population:  The frequency of both alleles of the gene?  Frequency of dominant homozygotes?  Frequency of heterozygotes ? WORKSHEET

 Example 2.  Blood cells about 84% of the population of our country have character (agglutinogen) Rh. Blood group of these people is symbolized Rh +. Remaining 16% of our population do not have this character, so they have character Rh-. By the assumption that the Rh factor is a monogenic autosomal, dominantly hereditable, Rh + people are therefore either dominant homozygotes or heterozygotes.  What is the frequency of Rh allele and particular genotypes of Rh group in our population? WORKSHEET

 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 SOURCES