▁organ ism ' s ▁s perm ▁( after ▁cop ulation ) ▁and ▁fert il ize ▁its ▁own ▁eggs ▁from ▁that ▁store ▁after ▁a ▁period ▁of ▁time , ▁essentially ▁making ▁it ▁appear ▁as ▁though ▁fert il ization ▁occurred ▁without ▁s perm ▁( i . e . ▁par then ogen esis ). ▁ ▁F ec und ity ▁is ▁important ▁and ▁well ▁studied ▁in ▁the ▁field ▁of ▁population ▁e col ogy , ▁though ▁it ▁is ▁studied ▁from ▁a ▁neutral ▁perspective . ▁F ec und ity ▁can ▁increase ▁or ▁decrease ▁in ▁a ▁population ▁according ▁to ▁current ▁conditions ▁and ▁certain ▁social ▁factors . ▁For ▁instance , ▁in ▁times ▁of ▁hard ship ▁for ▁a ▁population , ▁such ▁as ▁a ▁lack ▁of ▁food ▁or ▁high ▁temper atures , ▁ju ven ile ▁and ▁eventually ▁adult ▁f ec und ity ▁has ▁been ▁shown ▁to ▁decrease ▁( i . e . ▁due ▁to ▁a ▁lack ▁of ▁resources ▁the ▁ju ven ile ▁individuals ▁are ▁unable ▁to ▁reproduce , ▁eventually ▁the ▁adult s ▁will ▁run ▁out ▁of ▁resources ▁and ▁reprodu ction ▁will ▁ce ase ). ▁Additionally , ▁social ▁tr ends ▁and ▁soci etal ▁norm s ▁may ▁influence ▁f ec und ity , ▁though ▁this ▁influence ▁tends ▁to ▁be ▁temporary . ▁Indeed , ▁it ▁is ▁considered ▁impossible ▁to ▁ce ase ▁reprodu ction ▁based ▁on ▁social ▁factors , ▁and ▁f ec und ity ▁tends ▁to ▁rise ▁after ▁a ▁brief ▁decl ine . ▁▁ ▁F ec und ity ▁has ▁also ▁been ▁shown ▁to ▁increase ▁in ▁ung ul ates ▁with ▁relation ▁to ▁war mer ▁weather . ▁ ▁In ▁sexual