based ▁class ifications ▁were ▁consistent ▁with ▁evolution ary ▁relationships , ▁the ▁ph y log en etic ▁relationships ▁within ▁the ▁genus ▁Ny ct ice bus ▁have ▁been ▁investig ated ▁using ▁DNA ▁sequences ▁derived ▁from ▁the ▁mit och ond rial ▁markers ▁D ▁loop ▁and ▁cy to chrome ▁b . ▁Although ▁most ▁of ▁the ▁recognized ▁line ages ▁of ▁Ny ct ice bus ▁( including ▁N .   py g ma eus , ▁N . ▁men ag ensis ▁and ▁N .   jav an icus ) ▁were ▁shown ▁to ▁be ▁gen et ically ▁distinct — the ▁analysis ▁suggested ▁that ▁DNA ▁sequences ▁from ▁some ▁individuals ▁of ▁N .   cou c ang ▁and ▁N .   b eng al ensis ▁apparently ▁share ▁a ▁closer ▁evolution ary ▁relationship ▁with ▁each ▁other ▁than ▁with ▁members ▁of ▁their ▁own ▁species . ▁The ▁authors ▁suggest ▁that ▁this ▁result ▁may ▁be ▁explained ▁by ▁intro gress ive ▁hy brid ization , ▁as ▁the ▁tested ▁individuals ▁of ▁these ▁two ▁tax a ▁origin ated ▁from ▁a ▁region ▁of ▁sym pat ry ▁in ▁southern ▁Th ailand ; ▁the ▁precise ▁origin ▁of ▁one ▁of ▁the ▁N .   cou c ang ▁individuals ▁was ▁not ▁known . ▁This ▁hypothesis ▁was ▁cor ro bor ated ▁by ▁a ▁ 2 0 0 7 ▁study ▁that ▁compared ▁the ▁variations ▁in ▁mit och ond rial ▁DNA ▁sequences ▁between ▁N .   b eng al ensis ▁and ▁N .   cou c ang , ▁and ▁suggested ▁that ▁there ▁has ▁been ▁gene ▁flow ▁between ▁the ▁two ▁species . ▁ ▁An atom y ▁and ▁phys i