Natural Selection and Evolution

This lecture covers the concept of natural selection and evolution according to Darwin, explaining how new alleles arise through mutations and sexual reproduction. It also explores how natural selection influences variations within populations, using examples such as the frequency of the LDH-B allele in fish populations. The lecture further discusses the maintenance of genetic variation through diploidy and the phenomenon of heterozygote advantage. It delves into the case of sickle cell anemia as an example of selection advantage in heterozygotes. Additionally, it examines how selection based on allele frequency can lead to evolutionary changes, illustrated by examples like the evolution of the flu virus strains. The lecture concludes by highlighting the limitations of evolution in producing 'perfect' organisms due to historical constraints and trade-offs in adaptations.