State and explain any three factors affecting allele frequency in populations.
$(i)$ Gene migration or gene flow : It involves either emigration or immigration. When migration of a section of population to another place and population occurs, gene frequencies change in the original as well as in the new population. New genes/alleles are added to the new population and these are lost from the old population. There would be a gene flow if this gene migration happens multiple times.
$(ii)$ Genetic drift : If the same change occurs by chance, it is called genetic drift. Sometimes the change in allele frequency is so different in the new sample of population that they become a different species. The original drifted population becomes founders and the effect is called founder effect.
$(iii)$ Mutation : These are sudden, large, spontaneous and inheritable changes in the genetic material. Microbial experiments show that pre-existing advantageous mutations when selected will result in observation of new phenotypes. Over few generations, this would result in speciation. Natural selection is a process in which heritable variations enabling better survival are enabled to reproduce and leave greater number of progeny. Mutations induces new genes and alleles in the gene pool.
Natural selection in which more individuals acquire peripheral character value at both the ends of the distribution curve is
In a population of $1000$ individuals $360$ belong to genotype $AA, 480$ to Aa and the remaining $160$ to $aa$. Based on this data, the frequency of allele $A$ in the population is
In Hardy-Weinberg principle expression of allele frequency is represented by
Which is basis of evolution
According to the Neo-Darwinian theory, which of the following is responsible for the origin of new species