Misali na zaɓi mai dorewa da zaɓi na tuki. Misalan aikin aikin gyaran kafa

A misali na tabbatar da dorewar selection - shi ne zabin halitta ', hade da mutane da ciwon babban deflection halaye idan aka kwatanta da wani talakawan kudi.

Yanayi na zaɓi

Kowane ƙarni na kawar da mutanen da suka bambanta da mafi kyau na matsakaicin matsakaici ta wasu halaye. Misali na zaɓi mai dorewa cikin yanayin rayuwa yana da alaka da adana jihar. Domin cikakkiyar rayuwa, wakilanta suna ƙoƙarin zaɓar matsakaicin yanayi don dacewa don wasu yanayi.

Bambanci a yanayi

Misali na gyaran zabin yanayi a yanayi shi ne iyakar gudunmawa ga samar da sabon tsararraki daga mutane mafi girma. Amma masana kimiyya sunyi kokarin tabbatarwa ta hanyar yin la'akari da yawan al'ummomin dabbobi masu rarrafe da tsuntsaye, wanda a hakika halin da ake ciki ya bambanta. Idan akwai babban adadin kajin a cikin gida daya, to amma yana da wuya a ciyar da su, saboda haka suna da yawa kuma sun fi raunana fiye da wadanda suke girma a matsakaicin adadi. Saboda haka, masu bincike sunyi nasara wajen tabbatar da misalin misalin aikin gyaran kafa, tabbatar da daidaito ga rayuwa a cikin tsuntsaye da matsakaicin matsakaicin haihuwa.

Zaɓin zabi na matsakaicin dabi'u

Lokacin da aka gwada tsuntsaye tare da lambobi daban-daban, sai ya nuna cewa akwai alamu da yawa waɗanda suke nuna alamun misalin irin wannan zaɓi. Kwayoyin dabbobi masu haihuwa, da nauyin nauyin nau'i, da nauyin jikin jiki, yawanci sun mutu a cikin makonni 1-2 na rayuwa. Amma ga ƙananan yara tare da matsakaicin matsakaici, sun yi haƙuri a farkon makonni na wanzuwarsu, suka bunkasa, sun mutu a cikin mafi yawa.

Yi la'akari da wani misali na zaɓi mai dorewa da ya shafi tsuntsaye. A lokacin gwajin an yanke shawarar nazarin girman fuka-fuki a cikin tsuntsayen da suka mutu bayan hadari mai tsanani, ya bayyana cewa mafi yawansu suna da gajere ko, a akasin haka, fuka-fuki da yawa. Wannan misali na zaɓi na karfafawa yana nuna mafi yawan rayuka na mutane tare da halaye masu matsakaici.

Dalili don bayyanar kananan kayan ado

Idan muka yi la'akari da wannan misali na aikin gyaran yanayi, za mu yi kokarin gano ainihin dalilai na karamin lafiyar ɗayan mutane zuwa yanayin wanzuwar wanzuwar. Me yasa, tare da taimakon zabin yanayi, yana da wuya a share wasu mutane daga zubar da sababbin siffofin? Dalilin ba shine kawai ba, yayin da aka haife sabon zuriya, maye gurbi daban-daban ya faru, amma kuma saboda jinsin halittar heterozygous sukan sabawa mutane. A lokacin hayewa, suna rarrabawa cikin zuriya, da kuma sababbin tsararrun homozygous sun tashi, wanda ya dace da rage yawan yanayin rayuwa. Wannan sabon abu ana kiranta polymorphism daidai.

Misalan polymorphism

Misalan misalai na tsarin karfafawa na zabin yanayi (polymorphism) sunadarin sickle cell anemia. Wannan cututtukan jini mai tsanani ya kasance a cikin mutane homozygous na hemoglobin tare da kwayoyin mutun (HbS), wanda ke haifar da mutuwa a matashi. Yawancin yawancin bil'adama suna da raguwar wannan mutumin, yana da alaƙa da wasu maye gurbin. Amma masana kimiyya sun yi kokarin kafa dangantaka tsakanin kasancewa a cikin jikin mutum na jinsi da kuma kasancewar malaria a yankin. Sakamakon binciken ya nuna cewa HtS-type heterozygotes suna da tsayayya da cutar irin su malaria fiye da haɓaka da maida daidai.

Hanyar canzawa

Misalan gyare-gyare da zaɓi na tuki yana da wasu nau'i na samfuran alamu na canji a cikin adadin mutane. A karo na farko wannan masanin kimiyya mai ban mamaki II Shmalhausen ya lura da irin wannan yanayin da ya dace. Ya ci gaba da tabbatar da cewa har ma a yanayin zaman lafiya, zabin yanayi bai tsaya ba na minti daya, juyin halitta ya ci gaba. Ko da tare da wannan phenotype, yawancin ya ci gaba da farfadowa. Misalin aikin da aka tsara ta hanyar karfafawa wanda ya dauke shi ya tabbatar da canjin canji a cikin kwayoyin halitta. Saboda zaɓin saɓo, tsarin kirkiro ya halicce shi, tare da taimakon wanda zai yiwu ya haifar da samfurori mafi kyau daga wasu nau'i-nau'i.

Dalilin da ya dace na zabin yanayi

Yana iya kare tsarin kirkiro daga mummunan tasiri na tsarin mutation. Misali na aikin da aka zaɓa na zabin yanayi shine wanzuwar irin wannan jinsin kamar ginkgo, hatteria. Wannan shi ne zaɓi na dindindin wanda ya kare wa'adinmu "burbushin halittu" wanda ke rayuwa a cikin yanayin muhalli mai kyau:

1. Hatteria, wanda yana da siffofin dabbobi masu rarrafe waɗanda suka wanzu a zamanin Mesozoic.
2. Coelacanth ne zuriyar Crossopterygii, saba daga cikin Paleozoic zamanin.
3. Amfanin Arewacin Amirka, wanda shine dabba mai laushi wanda ya kasance daga lokacin Cretaceous.
4. Gymnosperms shuka iri ginkgo, kama da itace siffofin, bitattu a Jurassic lokaci na Mesozoic zamanin.

Akwai irin wannan nau'i na yanayin zabin yanayi har zuwa lokacin da akwai yanayin da aka kafa wani sifa ko dukiya.

Hanyoyin ilimin halayyar ilimin halitta a kan canji

Wadannan yanayi ba dole ba ne a canza tsawon lokaci. Dangane da sauyawa canje-canje a yanayin yanayi, gyare-gyaren yana faruwa tare da taimakon taimakawa ɗayansu na ɗorawa da wasu mutane. Akwai canje-canje a cikin hawan haɓaka, don haka yaran da suka bayyana aukuwa a lokacin lokacin da akwai wadataccen kayan abinci don kare rai. Idan an haifa haifuwa a baya ko daga bisani fiye da kwanakin da ake sa ran, an kawar da su ta hanyar zaɓin tsagewa. Ta yaya tsire-tsire da dabbobi "san" game da farkon hunturu? Tsarancin zafin jiki sau da yawa yana da yaudara. Bugu da ƙari, iyakokin lokacin rani da hunturu suna motsawa kowace shekara. Dabbobi da suke gaggauta amsa sakonni zasu iya zama ba tare da 'ya'ya ba. Saboda haka, tsuntsaye da tsuntsaye masu yawa suna shiryarwa ta tsawon lokacin hasken rana. Wannan sigina ne ga yawancin nau'in dabba da ke taimakawa wajen kaddamar da ayyuka masu muhimmi: molting, hijirar, haifuwa. II Shmalhausen ya yi nasara wajen tabbatar da haɗin tsakanin daidaituwa ta duniya da daidaitawa.

Bambancin bambanci daga al'ada

Zaɓin gyare-gyaren gaba ɗaya yana shafe kowane ɓangare daga ka'idar da aka kafa, yana inganta ƙaddamar da tsarin kwayoyin halitta wanda ke tabbatar da cikakkiyar ci gaba da kuma samar da samfurori masu mahimmanci bisa tushen jinsin daban-daban. Sakamakon zai zama cikakkiyar aiki da kwayoyin koda da sauyawa cikin yanayin waje.

Koyaswar A. Wallace da Charles Darwin

An kirkiro ka'idar zabin yanayi a matsayin babban mahimman karfi wanda ke jagorantar juyin halitta kuma ya tsara siffofinsa. Zabin zabin yanayi shine la'akari da tsarin da mutane kawai suke rayuwa da kuma 'ya'ya suna da dabi'un halayen da ke da amfani ga yanayi na musamman. Idan aka tantance zabin yanayi daga ra'ayi na jinsin, za'a iya tabbatar da cewa yana da mahimmanci ga zaɓi na maye gurbi mai kyau da haɗuwa da kwayoyin halitta. Zasu iya nuna kansu ta hanyar haifuwa da jima'i, kuma yayin da yawancin suke girma, ana inganta su ta hanyar cudanya haɗuwa da haɓaka.

Wadannan kwayoyin da ke da nau'ikan kwayoyin halitta ba su iya tsira a wasu yanayi, sun lalace. Zabin yanayi na iya "aiki" akan haifuwa daga kwayoyin halitta, idan mutane da raunana ba su da shirye-shiryen zuriya masu tsattsauran ra'ayi ko kuma basu bari 'ya'yansu ba. A wannan yanayin, ba wai kawai zaɓin zaɓi da ɓarna wasu nau'o'in halaye na kwayar halitta ba, amma kwayoyin da ke ɗaukar alamun wannan alamun sun ƙare.

A kan siffofin zabin yanayi

A wannan lokacin, al'ada ne don zaɓar siffofin da aka tsara na wannan zaɓi, waɗannan ne waɗanda ake kira su cikin litattafai na ilmin halitta a makarantu.

1. Tsaida yanayi na zaɓi.
2. Zaɓin zaɓi.
3. Yankewa zaɓi.

Zaɓin motsi yana da mahimmancin canza yanayin dabi'a, wanda wani ɓangaren da ya zama juyawa ya bayyana. Alal misali, masana'antu melaninogenez halayyar malam ikonsa ya asu, nasaba da duhun saboda masana'antu toka Birch kututturan. Tun da yake an gano kwari a kan tushen "sabon" bishiyoyi, tsuntsaye sun hallaka su da sauri. Mafarin malamai masu duhu sun tsira, sun ba da zuriya, sabili da haka hankali duhu sun zama mabubbuga domin wannan yawan.

Dangane da matsawa na matsakaicin matsakaicin halin da ake ciki, an bayyana mahimmancin dabbobin sanyi da na thermophilic da tsire-tsire. Sakamakon jagorancin ya haifar da daidaitawar kwayoyin cuta, fungi, wasu cututtuka na cututtuka na mutane, dabbobi zuwa magungunan kashe qwari da magunguna. Zaɓin motsawa zai iya bayanin abin da ya faru na rage ido a cikin mazaunan kogi da ƙaura, da kuma asarar wasu tsuntsaye na fuka-fuki. Tare da irin wannan zaɓi, babu alamar halayen da ke faruwa, wanda sakamakon haka ne wasu mutane ke maye gurbin su, ba tare da haifar da kullun da kuma siffofin miƙa mulki ba.

Zaɓin tadawa ya ba da dama don samun nau'i-nau'i masu yawa, tare da dukkanin siffofin matsakaici sun mutu. Dangane da zaɓin zane-zane, an kafa siffofin biyu ko fiye da yawa, wanda zai haifar da polymorphism. Shi ne gwagwarmayar zama ne mai muhimmanci factor, wanda shi ne babban tsarin ba da wani zabin yanayi. Gasar, jaddadawa, amensalism ana daukar su ne manyan nau'o'i uku na gwagwarmayar rayuwa.