. ▁This , ▁in ▁turn , ▁effects ▁how ▁long ▁re product ive ▁cycles ▁will ▁be ▁in ▁both ▁males ▁and ▁females . ▁If ▁the ▁males ▁were ▁to ▁invest ▁more ▁time ▁in ▁the ▁care ▁of ▁their ▁off spring , ▁they ▁would ▁be ▁sp ending ▁less ▁time ▁m ating . ▁This ▁push es ▁the ▁population ▁towards ▁a ▁female ▁bi ased ▁OS R ▁and ▁vice ▁vers a . ▁Whether ▁or ▁not ▁it ▁is ▁the ▁males ▁or ▁females ▁invest ing ▁more ▁care ▁in ▁their ▁off spring , ▁if ▁they ▁were ▁to ▁lose ▁their ▁off spring ▁for ▁whatever ▁reason , ▁this ▁would ▁then ▁change ▁the ▁OS R ▁to ▁be ▁less ▁bi ased ▁because ▁the ▁once ▁occupied ▁sex ▁becomes ▁available ▁to ▁mate ▁again . ▁ ▁As ▁a for ement ioned , ▁another ▁major ▁factor ▁that ▁influ ences ▁OS R ▁is ▁potential ▁rate ▁of ▁reprodu ction ▁( PR R ). ▁Any ▁sexual ▁differences ▁in ▁the ▁PR R ▁will ▁also ▁change ▁the ▁OS R , ▁so ▁it ▁is ▁important ▁to ▁look ▁at ▁factors ▁that ▁change ▁PR R ▁as ▁well . ▁These ▁include ▁constraints ▁to ▁environmental ▁factors ▁such ▁as ▁food ▁or ▁nest ing ▁sites . ▁For ▁example , ▁if ▁males ▁are ▁required ▁to ▁provide ▁a ▁nut ri ent ▁high ▁gift ▁before ▁m ating ▁( most ▁likely ▁food ) ▁then ▁when ▁nut ri ents ▁available ▁is ▁high , ▁the ▁OS R ▁will ▁be ▁male ▁bi ased ▁because ▁there ▁is ▁plenty ▁of ▁nut ri ents ▁available ▁to ▁provide ▁g ifts . ▁However , ▁if ▁nut ri ents ▁is ▁low , ▁less ▁males ▁will ▁be ▁ready