Rayuwa ta fara ne a duniya kimanin shekaru biliyan 3.7 da suka gabata, a wata majiyar, kimanin shekaru biliyan 4.1 da suka gabata. Ci gaba ya ci gaba har zuwa yau. Ta kowane zato, rayuwa zata ci gaba a nan gaba, ta dace da muhalli, kuma kasancewar mutum ko rashi ba zai iya katse shi ba.
Masana kimiyya a Ostiraliya sun gano alamun rayuwa a doron ƙasa, kuma suna da shekaru biliyan 3.5. Abubuwan da suka gano ya tabbatar da cewa rayuwa ta samu ne a cikin ruwa mai kyau, kuma ba a cikin maɓuɓɓugar gishiri ba. Masana kimiyya sun ja hankali kan wadannan hujjojin kuma suna neman tabbatar da su a wasu nahiyoyin.
Babban nau'in rayuwa
Babban mahalli na rayuwa sun hada da:
- ruwa;
- ƙasa-iska;
- ƙasa;
- kwayoyin halitta (parasites and symbionts).
Kowane yanayi yana da halaye irin nasa kuma ya ƙunshi ƙwayoyin halitta daban-daban waɗanda suke rayuwa, haifuwa da haɓaka.
Yanayin ƙasa-iska
Wannan yanayin yana wakiltar dukkan bambancin shuke-shuke da rayuwar dabbobi a Duniya. Ci gaban rayuwar organican adam akan ƙasa ya ba da damar ƙasa ta fito. Developmentarin ci gaba na tsire-tsire, gandun daji, steppes, tundra da dabbobi daban-daban, daidaitawa da wuraren zama daban, ya tafi. Sakamakon cigaban cigaban halittu, rayuwa ta bazu zuwa dukkanin saman bawon duniya - hydrosphere, lithosphere, yanayi. Duk rayayyun halittu sun bunkasa kuma sun dace da karuwar canjin yanayin zafi da mazauna daban-daban. Wakilai masu dumi da jini na dabbobi dabbobi, tsuntsaye iri iri da kwari sun bayyana. A cikin yanayin iska, tsire-tsire sun dace da yanayin girma daban-daban. Wasu kamar haske, wurare masu dumi, wasu suna girma cikin inuwa da danshi, wasu kuma suna rayuwa cikin ƙarancin yanayin zafi. Bambancin wannan yanayin yana wakiltar da bambancin rayuwa a ciki.
Yanayin ruwa
A cikin layi daya tare da ci gaban yanayin-ƙasa, ci gaban duniyar ruwa ya ci gaba.
Yanayin ruwa yana wakiltar dukkanin jikin ruwan da ke wanzu a duniyarmu, tun daga teku da tekuna zuwa tafkuna da rafuka. Kashi 95% na doron duniya ruwa ne.
Daban-daban manya-manyan mazaunan ruwa suna canzawa kuma sun dace a ƙarƙashin taguwar juyin halitta, sun dace da muhallin kuma sun ɗauki sifar da ta fi ƙaruwar rayuwar jama'a. Girman ya ragu, an rarraba yankunan rarraba nau'ikan zaman tare. Bambancin rayuwa a cikin ruwa abin birgewa ne da daɗi. Yanayin zafin cikin yanayin ruwa ba ya fuskantar irin canje-canje masu kaifi kamar a cikin yanayin iska-ƙasa har ma a cikin ruwan da ke cikin sanyi ba ya sauka ƙasa da +4 digiri Celsius. Ba wai kawai kifi da dabbobi ke rayuwa a cikin ruwa ba, har ma ruwan yana cike da algae iri-iri. Kawai a cikin zurfin da basa nan, inda dare madawwami yake mulki, akwai cigaban halittu daban daban.
Mazaunin ƙasa
Layin da ke saman ƙasa na ƙasa ne. Haɗuwa da ƙasa iri daban-daban tare da duwatsu, ragowar ƙwayoyin halittu masu rai, suna haifar da ƙasa mai ni'ima. Babu haske a cikin wannan yanayin, suna zaune a ciki, ko kuma dai suna girma: tsaba da tsire-tsire masu tsire-tsire, tushen bishiyoyi, shrubs, ciyawa. Hakanan ya ƙunshi ƙananan algae. Isasa tana dauke da ƙwayoyin cuta, dabbobi da fungi. Waɗannan sune manyan mazaunanta.
Kwayar halitta a matsayin mazaunin zama
Babu wani mutum, dabba ko nau'ikan tsire-tsire a Duniya wanda babu wata kwayar halitta ko kwayar halitta da ta zauna a ciki. Sanannen dodder yana cikin ƙwayoyin cuta masu parasites. Daga ƙananan ƙwayoyin spores suna tsiro da kwayar halitta wacce ke rayuwa ta hanyar shan ƙarfafan abinci mai gina jiki na shuke-shuke.
Parasites (daga Girkanci - "freeloader") wata kwayar halitta ce da take rayuwa daga maharanta. Yawancin kwayoyin halitta suna kula da jikin mutane da dabbobi. An rarraba su zuwa na wucin-gadi, wadanda ke rayuwa a kan mahalarta na wani zagayen, da kuma na dindindin, wadanda ke lalatad da zagawar jikin mai gida ta hanyar sake zagayowar. Wannan yakan haifar da mutuwar mai masaukin baki. Duk rayayyun abubuwa masu saukin kamuwa ne da cuta, farawa daga kwayoyin cuta, kuma shuke-shuke da dabbobi mafi girma sun kammala wannan jeren. Hakanan ƙwayoyin cuta cuta ce mai cutarwa.
Zuwa ga kwayoyin za'a iya kara musu yanayi (rayuwa tare).
Alamar shuke-shuke da dabbobi ba ta zaluntar mai ita, amma tana aiki a matsayin abokiyar rayuwa. Dangantakar cututtuka na ba da izinin wasu nau'ikan tsire-tsire da dabbobi su rayu. Symbiosis shine rata tsakanin haɗuwa da haɗakar ƙwayoyin cuta.
