Final answer:
Chargaff's rules are used in species identification by examining the ratios of adenine to thymine and guanine to cytosine in DNA, which vary among species and provide unique patterns for identification.
Step-by-step explanation:
Chargaff's rules can be utilized for species identification by examining nucleotide base ratios. These rules state that in a DNA molecule, the number of adenine (A) bases is approximately equal to the number of thymine (T) bases, and the number of guanine (G) bases is approximately equal to the number of cytosine (C) bases. While the overall proportions of purines (A+G) and pyrimidines (T+C) are consistent, the ratio of A+T to G+C can vary among different species, providing a distinctive pattern that can be used for identification. This biological principle supports DNA sequencing techniques such as dideoxy chain termination and sequence alignment to identify regions of similarity between cell types or species for further comparison.