ous ▁populations ▁world wide . ▁The ▁Amer ind ian ▁populations ▁show ▁a ▁lower ▁gen etic ▁divers ity ▁than ▁populations ▁from ▁other ▁contin ental ▁regions . ▁Ob ser ved ▁is ▁both ▁a ▁decre asing ▁gen etic ▁divers ity ▁as ▁ge ographic ▁distance ▁from ▁the ▁Ber ing ▁Stra it ▁occurs ▁and ▁a ▁decre asing ▁gen etic ▁similarity ▁to ▁Si ber ian ▁populations ▁from ▁Al aska ▁( gen etic ▁entry ▁point ). ▁Also ▁observed ▁is ▁evidence ▁of ▁a ▁higher ▁level ▁of ▁divers ity ▁and ▁lower ▁level ▁of ▁population ▁structure ▁in ▁western ▁South ▁America ▁compared ▁to ▁eastern ▁South ▁America . ▁A ▁relative ▁lack ▁of ▁different iation ▁between ▁Mes o amer ican ▁and ▁And e an ▁populations ▁is ▁a ▁scenario ▁that ▁implies ▁coast al ▁routes ▁were ▁easier ▁than ▁in land ▁routes ▁for ▁migr ating ▁pe op les ▁( P ale o - Ind ians ) ▁to ▁traverse . ▁The ▁overall ▁pattern ▁that ▁is ▁emer ging ▁suggests ▁that ▁the ▁Amer icas ▁were ▁recently ▁colon ized ▁by ▁a ▁small ▁number ▁of ▁individuals ▁( effect ive ▁size ▁of ▁about ▁ 7 0 – 2 5 0 ), ▁and ▁then ▁they ▁grew ▁by ▁a ▁factor ▁of ▁ 1 0 ▁over ▁ 8 0 0 – 1 , 0 0 0 ▁years . ▁The ▁data ▁also ▁show ▁that ▁there ▁have ▁been ▁gen etic ▁ex changes ▁between ▁Asia , ▁the ▁Ar ctic ▁and ▁Green land ▁since ▁the ▁initial ▁pe op ling ▁of ▁the ▁Amer icas . ▁A ▁new ▁study ▁in ▁early ▁ 2 0 1 8 ▁suggests ▁that ▁the ▁effective ▁population ▁size ▁of ▁the