Final answer:
Matching multiple STRs is essential in determining relatedness because single STRs might be similar across unrelated individuals due to random matches. Computer programs and databases analyze these STRs along with other molecular data, improving the accuracy of DNA fingerprinting and evolutionary studies.
Step-by-step explanation:
It is important to match more than one Short Tandem Repeat (STR) to determine relatedness because individual STRs can be quite similar across unrelated individuals. Matching multiple STRs significantly increases the reliability of the assessment. For instance, considering that a fruit fly shares about 60% of its DNA with humans, relying on a single STR could lead to inaccurate conclusions about relatedness due to random similarities in the DNA sequences. To confirm DNA relationships accurately, scientists utilize computer analysis programs which can consider a wider array of STRs, as well as other molecular and morphologic data, to construct a phylogenetic tree that more accurately reflects the evolutionary distances and relationships.
This process of comparison is crucial for applications such as DNA fingerprinting, where the goal is to determine if two DNA samples come from the same or related individuals. Sophisticated databases and computational tools, such as GenBank and sequence alignment programs, aid in analyzing the extent of genetic similarity. By matching multiple STRs, scientists are able to provide a more nuanced and precise picture of genetic kinship and the evolutionary history of organisms.