2014 GENETICS OF POPULATIONS 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
population: a group of individuals of the same species, living on a specific area individuals can loosely crossbreed among each other and they arise out of the same ancestor they have got common gene fund (complex of alleles, which are kept genetically) GENETICS REGULARITIES OF POPULATIONS
CAN YOU RECOGNIZE POPULATIONS ?
1) autogamic population individuals reproduce by autogamy (self- fertilization) each individual produces both male and female gametes the new individual is formed by the fusion of gametes originating from one individual KINDS OF POPULATIONS
homozygotic individual (homozygotic dominant homozygotic recessive) can produce only homozygotic descendants in autogamic population appear permanent decrease of heterozygotes increasing share of homozygotes GENETICS REGULARITIES OF POPULATIONS
2) alogamic population the individual arises by the fusion of 2 gametes coming from different individuals a special case is - panmictic population large population which has a non-limited possibility of reciprocal crossbreed GENETICS REGULARITIES OF POPULATIONS
panmixia = by no means limited possibility of reciprocal crossbreed of any individual with any other member of the population every male gamete has identical probability to meet any female gamete GENETICS REGULARITIES OF POPULATIONS
in virtue of Hardy-Weinberg´s law can be figured out genotypical composition of panmictic population HARDY-WEINBERG LAW
the law is in force by these conditions (assumptions): no mutations occur (at least not at the observed gene) no selection occurs no migration occurs population must be panmictic and very numerous
valid for panmictic populations frequency of dominant allele at a specific gene in the gene fund of population frequency of the recessive allele platí: p + q = 1 ( 100%) ( 100%) probability of encountering two dominant alleles (arising a dominant homozygot) probability of encountering two recessive alleles probability of arising a heterozygot so total genotypic composition of population stands good p x p = p 2 q x q = q 2 (p x q)+(q x p) = 2pq p 2 + 2pq + q 2 = 1 p q HARDY-WEINBERG LAW
autogametic and panmictic population: completely different way of reproduction different population– genetic relations in the nature those extreme types rare 100 % self-pollinating plant species does not exist GENETICS REGULARITIES OF POPULATIONS
ABO SYSTEM Frequency of allele IB for basic blood group B (in %) in European populations. Its frequency makes a gradient decreasing from the east to the west. The highest Is in Middle Asia and lowest in northeast Spain. It is still remarkable consequence Og migration waves – historical invasions of Mongolian Tartars in Europe after the breakdown of Roman. Invaders left there the allele IB in their descendants.
GENETICS REGULARITIES OF POPULATIONS Decrease of laetal recessive allele frequency during the rotation of Panmictic population which is nowadays formed only by heterozygots. Even if Arising recessive homozygots cannot survive, the allele will never disappear because it is still kept in heterozygots (selection pressure does not counteract)
GENETICS REGULARITIES OF POPULATIONS
Hardy - Weinberg balance for 2 alleles Task 1: In the population (9800 individuals total) there occurs a hypothetical genetically determined feature. The dominant form of this feature is conditioned by the dominant allele A, the recessive form of the feature is conditioned by a recessive allele. Dominant phenotype occurred by 4998 individuals. Determine the gene frequency of dominant and recessive alleles (the population is in HW balance).
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