ically ▁very ▁close ▁and ▁have ▁shared ▁vast ▁port ions ▁of ▁their ▁ranges ▁for ▁mill enn ia . ▁Such ▁ad mi xture ▁in ▁the ▁wild ▁have ▁been ▁detected ▁in ▁many ▁populations ▁scattered ▁throughout ▁Europe ▁and ▁North ▁America , ▁usually ▁occurr ing ▁in ▁areas ▁where ▁w olf ▁populations ▁have ▁decl ined ▁from ▁human ▁impact s ▁and ▁per sec utions . ▁At ▁the ▁same ▁time , ▁w olf d ogs ▁are ▁also ▁often ▁b red ▁in ▁capt ivity ▁for ▁various ▁purposes . ▁Ad mi xture ▁of ▁dogs ▁and ▁two ▁other ▁North ▁American ▁w olf ▁species ▁have ▁also ▁occurred ▁histor ically ▁in ▁the ▁wild , ▁although ▁it ▁is ▁often ▁difficult ▁for ▁bi olog ists ▁to ▁disc rim inate ▁the ▁dog ▁gen es ▁in ▁the ▁eastern ▁tim ber ▁and ▁red ▁wol ves ▁from ▁the ▁gray ▁w olf ▁gen es ▁also ▁present ▁in ▁these ▁w olf ▁species ▁due ▁to ▁their ▁historical ▁over laps ▁with ▁North ▁American ▁gray ▁wol ves ▁as ▁well ▁as ▁with ▁co y otes , ▁both ▁of ▁which ▁have ▁intro gress ed ▁into ▁the ▁eastern ▁tim ber ▁and ▁red ▁w olf ▁gene ▁po ols . ▁At ▁the ▁same ▁time , ▁because ▁many ▁isolated ▁populations ▁of ▁the ▁three ▁w olf ▁species ▁in ▁North ▁America ▁have ▁also ▁mixed ▁with ▁co y otes ▁in ▁the ▁wild , ▁it ▁has ▁been ▁spec ulated ▁by ▁some ▁bi olog ists ▁that ▁some ▁of ▁the ▁co yw olf ▁hy br ids ▁in ▁the ▁n ort he astern ▁third ▁of ▁the ▁continent ▁may ▁also ▁have ▁both ▁co yd ogs ▁and ▁w olf d ogs ▁in