Final answer:
Single nucleotide polymorphism (SNP) analysis is a genetic test that can identify loci undergoing evolution by detecting nucleotide substitutions associated with trait variation. Deviations in allele frequencies from the Hardy-Weinberg equilibrium in populations and molecular phylogenetics also provide insights into evolutionary changes over time.
Step-by-step explanation:
The genetic test that can prove whether evolution is occurring at a given locus is the analysis of single nucleotide polymorphisms (SNPs). SNP analysis is effective in identifying loci and individual nucleotide substitutions associated with differences in traits between individuals. This method does not require prior pedigree information or trait heritability data, making it suitable for studying genetic diversity in threatened species. In addition, the presence of specific gene mutations, such as those in the BRCA1 and BRCA2 genes, can be definitively tested. Furthermore, population genetics approaches, such as studying allele frequencies and their deviations from the Hardy-Weinberg equilibrium, can indicate evolutionary changes in a population.
Molecular phylogenetics also provides evidence of speciation and extinction throughout Earth's history by revealing the evolution of gene sequences. The comparison of these sequences helps in understanding the evolutionary relationships and changes over time.
Manifestations of evolution at the genetic level can be demonstrated through various methods, including SNP analysis, allele frequency shifts in population genetics, and molecular phylogenetics, all deepening our understanding of evolutionary processes.