Final answer:
There isn't a universal percentage threshold to determine species similarity, but above 70% is typically considered to indicate the same species. Phylogenetically, species that are more closely related share greater genetic similarities. In genetic mapping, individuals of a species are genetically similar, not identical, and the predicted frequency of recombinant offspring in test crosses normally does not exceed 50%.
Step-by-step explanation:
When analyzing the genetic similarity to determine whether organisms belong to the same species, there isn't a universal percentage cut-off. However, for the sake of the questions provided, if the species in question share a high degree of genetic similarity, specifically above 70%, they are typically considered to be the same species. This is not a definitive rule but rather a general guideline as species delineation can be complex and involve other factors such as reproductive isolation, morphological differences, and ecological niches.
Regarding phylogenetic relationships and genetic similarities, it's reasonable to predict that species D and E would likely share more genetic similarities with each other than with species A or B based on their closer evolutionary relationship depicted in a phylogenetic tree. With test crosses, the predicted frequency of recombinant offspring typically cannot exceed 50%, due to the nature of chromosomal crossover during meiosis. Hence, a predicted frequency of recombinant offspring of 60% is not expected under normal circumstances.
As for the question related to genetic maps within a given species, individuals are usually genetically similar rather than identical due to variations that can occur through mutations and sexual reproduction resulting in genetic diversity.