Final answer:
The best way to determine if a species reproduces sexually using only DNA samples is to look for genetic recombination. This can be detected by analyzing the DNA samples for variations, such as genetic markers or different alleles of specific genes.
Step-by-step explanation:
The best way to determine if a species reproduces sexually using only DNA samples is to look for genetic recombination. Sexual reproduction involves the exchange of genetic material between two individuals, resulting in offspring with unique combinations of genes. This can be detected by analyzing the DNA samples for variations, such as genetic markers or different alleles of specific genes. If the DNA samples show evidence of genetic recombination, it suggests that the species reproduces sexually.
For example, scientists can examine the DNA samples for the presence of genes that control traits like eye color or blood type. If different variations of these genes are found in the samples, it indicates that the species reproduces sexually, as these variations are the result of genetic recombination between individuals.
It is important to note that the absence of genetic recombination does not necessarily mean a species reproduces asexually, as there may be other factors at play. However, the presence of genetic recombination strongly suggests sexual reproduction.