▁for ▁some ▁of ▁the ▁basic ▁model ' s ▁o vers ights , ▁such ▁as ▁multiple ▁tra its ▁or ▁assumptions ▁about ▁how ▁the ▁lo ci ▁affect ▁the ▁tra its . ▁They ▁also ▁propose ▁the ▁idea ▁that ▁ple iot ropy ▁increases ▁the ▁phen ot yp ic ▁variation ▁of ▁both ▁tra its ▁since ▁a ▁single ▁mut ation ▁on ▁a ▁gene ▁would ▁have ▁twice ▁the ▁effect . ▁ ▁E volution ▁ ▁P lei ot ropy ▁can ▁have ▁an ▁effect ▁on ▁the ▁evolution ary ▁rate ▁of ▁gen es ▁and ▁alle le ▁frequencies . ▁Trad itionally , ▁models ▁of ▁ple iot ropy ▁have ▁predicted ▁that ▁evolution ary ▁rate ▁of ▁gen es ▁is ▁related ▁neg atively ▁with ▁ple iot ropy as ▁the ▁number ▁of ▁tra its ▁of ▁an ▁organ ism ▁increases , ▁the ▁evolution ary ▁rates ▁of ▁gen es ▁in ▁the ▁organ ism ' s ▁population ▁decrease . ▁However , ▁this ▁relationship ▁has ▁not ▁been ▁clearly ▁found ▁in ▁empir ical ▁studies . ▁ ▁In ▁m ating , ▁for ▁many ▁animals ▁the ▁signals ▁and ▁re cept ors ▁of ▁sexual ▁communication ▁may ▁have ▁evol ved ▁simultaneously ▁as ▁the ▁expression ▁of ▁a ▁single ▁gene , ▁instead ▁of ▁the ▁result ▁of ▁selection ▁on ▁two ▁independent ▁gen es , ▁one ▁that ▁affect s ▁the ▁signal ing ▁trait ▁and ▁one ▁that ▁affect s ▁the ▁re ceptor ▁trait . ▁In ▁such ▁a ▁case , ▁ple iot ropy ▁would ▁facil itate ▁m ating ▁and ▁surv ival . ▁However , ▁ple iot ropy ▁can ▁act ▁neg atively ▁as ▁well . ▁A ▁study ▁on ▁seed ▁be et les ▁found ▁that