Hasashen tsira na glacial

Dangane da ra'ayin mafaka na arewacin (ko ra'ayin rayuwa na glacial), alokacin zamanin sanyi na ƙarshe da nau'in dabbobi (misali.Norway spruce da Norwegian lemmings) sun cigaba acikin microrefugia ba tareda ƙanƙara ba a arewacin Alps a Turai. Sauran ra'ayi na rashin juriya da ƙaura na tsire-tsire da dabbobi daga mafaka na kudancin Turai (ma'anar mafaka ta kudu) wani lokacin ana kiranta ra'ayin tabula rasa.

Dutsen Nunatak a gabashin gabar Greenland a yankin Amassalik . An gani daga tsawo 15,000ft. Yuli 1996, na Michael Haferkamp

Acikin tsire-tsire da dabbobi da suka gabata sun cigaba da kasancewa ta hanyar dogon lokaci na canjin yanayi ciki har da lokuta da yawa na glacial da interglacial. Akwai muhawara mai tsawo game da abin da ya faru da jinsunan da ke zaune a yankuna masu tsawo alokacin zamanin ƙanƙara na Pleistocene. Ana yawan la'akari da manyan al'amuran biyu. Labarin farko ya bada shawarar cikakkiyar lalacewar jinsuna acikin yankunan glaciated tareda abubuwan da suka faru acikin mafaka a kudu da kuma ƙaura mai yawa na bayan glacial zuwa wuraren da ba su da komai (tabula rasa hypothesis). Labari na biyu yana bada shawarar rayuwa ta dogon lokaci acikin yankuna masu dusar ƙanƙara (tsinkayar rayuwa ta ƙanƙara), ko dai acikin micro-refugia mai tsabta na arewacin arewa a gefen kankara, ko kuma a kan tsaunuka da ba a rufe su da kankara acikin ƙanƙara ba (tsinkaya mai tsabta).

Ga nau'o'in boreal da sanyi-tolerant ra'ayi na rayuwa ne mai gaskiya, koda yake mai rikitarwa, kuma ƙaruwar jikin bayanan ilmin halitta na kwayoyin halitta suna tallafawa shiga nau'in shuka da dabbobi. Yawancin binciken da akayi kwanan nan sun nuna cewa yankuna da yawa na arewa (sama da latitudes >45 °N) sun goyi bayan ƙananan ƙwayoyin bishiyoyi da ƙananan bishiyoyi alokacin ƙarshen ƙanƙara ko farkon Holocene [misali. Arewacin Amurka, Eurasia, Alps, Scandinavia].

A cikin 'yan shekarun nan da yawa binciken sun haɗu da layin shaidu da suka fito daga manyan horo guda uku don ƙaddamar da wanzuwar mafaka da suka gabata: bayanan burbushin halittu, samfuran rarraba jinsuna da binciken kwayoyin / phylogeographic. Ta wannan hanyar, ya kamata ya yiwu a bayyana hanyoyin ƙaura masu rikitarwa da jinsuna da yawan jama'a ke ciki da waje da mafaka ta hanyar lokaci da sarari.

Har ila yau, an yi bincike don ba da shawarar cewa wasu nau'ikan bishiyoyi masu jure sanyi sun sami damar tsira daga yanayin zafi saboda godiya ga kasancewar kwari mai dogaro da sunan G. intermedia.

Duba kuma

• Mafi Girma na Gishiri na Ƙarshe
• Refugium (haɗin jama'a)
• Gidan mafaka na kankara