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Alleles in a population are continuously changing for better adaptations.Natural selection acts on the heritable modification of alleles.The defective alleles do not get selected by nature as they can decrease the survival rate of the population.

Natural selection causes evolution in a population by acting on the fitness-increasing alleles. The organisms鈥� reproductive success determines its fitness.

Alleles are the variable units of the genomic information of the organism. The arrangement of alleles decides the traits or characters of the individual.

Thus, alleles work at the genetic level of the organism.

Therefore, the given stamen is false.

Loci are the portions of the chromosomes that represent the genes.

Thus, it is the physical location of the gene.

Therefore, the given statement is false.

The group of similar organisms is referred to as species. These organisms are capable of interbreeding. It is the taxonomic naming given to similar individuals. Natural selection occurs at an individual level.

Thus, species are able to survive and reproduce when evolution begins in an individual.

Therefore, the given statement is false.

A change in the gene frequencies of an individual leads to natural selection in a population. When changes in the allele frequency help the individual reproduce successfully, such changes get transferred to the offspring and are widespread in the population.

Thus, changes caused in an individual selected by nature will gradually become apparent at the population level.

Therefore, the given statement is true.