ers ▁have ▁long ▁deb ated ▁the ▁conditions ▁under ▁which ▁sym pat ry ▁truly ▁applies , ▁especially ▁with ▁respect ▁to ▁par as it ism . ▁Because ▁par as it ic ▁organ isms ▁often ▁inhab it ▁multiple ▁hosts ▁during ▁a ▁life ▁cycle , ▁evolution ary ▁bi ologist ▁Ernst ▁May r ▁stated ▁that ▁internal ▁par as ites ▁existing ▁within ▁different ▁hosts ▁demonstrate ▁al lop at ry , ▁not ▁sym pat ry . ▁Today , ▁however , ▁many ▁bi olog ists ▁consider ▁par as ites ▁and ▁their ▁hosts ▁to ▁be ▁sym pat ric ▁( see ▁examples ▁below ). ▁Con vers ely , ▁zo ologist ▁Michael ▁J . ▁D . ▁White ▁considered ▁two ▁populations ▁sym pat ric ▁if ▁gen etic ▁inter bre eding ▁was ▁vi able ▁within ▁the ▁habitat ▁overlap . ▁This ▁may ▁be ▁further ▁specified ▁as ▁sym pat ry ▁occurr ing ▁within ▁one ▁de me ; ▁that ▁is , ▁re product ive ▁individuals ▁must ▁be ▁able ▁to ▁locate ▁one ▁another ▁in ▁the ▁same ▁population ▁in ▁order ▁to ▁be ▁sym pat ric . ▁ ▁O thers ▁question ▁the ▁ability ▁of ▁sym pat ry ▁to ▁result ▁in ▁complete ▁spe ci ation : ▁until ▁recently , ▁many ▁research ers ▁considered ▁it ▁none x istent , ▁doub ting ▁that ▁selection ▁alone ▁could ▁create ▁dispar ate , ▁but ▁not ▁ge ograph ically ▁separated , ▁species . ▁In ▁ 2 0 0 3 , ▁bi ologist ▁Kar en ▁Mc Co y ▁suggested ▁that ▁sym pat ry ▁can ▁act ▁as ▁a ▁mode ▁of ▁spe ci ation ▁only ▁when ▁" the ▁probability ▁of ▁m ating