D loop is the hypervariable region in mtDNA, which means DNA sequencing in D loop is not conserved. However, this hypervariability is the reason that D loop sequence has been used as a molecular marker to distinguish individuals of the same specie.
Not sure what you mean. there's no reason the markeers should work in turtles but not in deer. However, if you wonder whether you can use the same primers to amplify the region: try to align the primers with the mt genome of the deer (or any species closely related to your target species) and make adjustments where necessary.
It depends on the basic problem you are addressing. D-loop is the most variable region of mtDNA. Generally it is employed to address inter-individual or inter-population genetic divergence.
Dear Simson...Yes the study specie is a endangered specie and not much genetic work has been done on the study specie.Due the limited time of my course i am using the primers of a reptile in deer.I will use the conserved primers