{"id":642,"date":"2017-04-11T09:05:51","date_gmt":"2017-04-11T09:05:51","guid":{"rendered":"http:\/\/uni.hi.is\/apalsson\/?p=642"},"modified":"2017-04-11T09:07:00","modified_gmt":"2017-04-11T09:07:00","slug":"icelandic-voru-lodfilar-erfdafraedilega-urkynjadir-og-var-utdaudi-theirra-ohjakvaemilegur","status":"publish","type":"post","link":"https:\/\/uni.hi.is\/apalsson\/IS\/2017\/04\/11\/icelandic-voru-lodfilar-erfdafraedilega-urkynjadir-og-var-utdaudi-theirra-ohjakvaemilegur\/","title":{"rendered":"Voru lo\u00f0f\u00edlar erf\u00f0afr\u00e6\u00f0ilega \u00farkynja\u00f0ir og var \u00fatdau\u00f0i \u00feeirra \u00f3hj\u00e1kv\u00e6milegur?"},"content":{"rendered":"

Lo\u00f0f\u00edlar<\/a> (Mammuthus primigenius<\/em>) eru eitt fr\u00e6gasta d\u00e6mi\u00f0 um \u00fatdau\u00f0a tegund<\/a>. \u00deeir eru skyldir afr\u00edkuf\u00edlnum<\/a> (Loxodonta africana africana<\/em>) og \u00e1ttu tegundirnar sameiginlegan forf\u00f6\u00f0ur fyrir um 6,2\u201317,4 millj\u00f3n \u00e1rum*<\/sup>. V\u00edsindamenn hafa n\u00e1\u00f0 heillegu erf\u00f0aefni<\/a> \u00far lo\u00f0f\u00edlshr\u00e6jum sem var\u00f0veist hafa \u00ed s\u00edfreranum. Me\u00f0 n\u00fat\u00edmat\u00e6kni er h\u00e6gt a\u00f0 ra\u00f0greina erf\u00f0aefni\u00f0 og sko\u00f0a erf\u00f0afr\u00e6\u00f0i og s\u00f6gu tegundarinnar. Ni\u00f0urst\u00f6\u00f0ur benda til \u00feess a\u00f0 lo\u00f0f\u00edlar \u00e1 Wrangel-eyju (\u00fear sem s\u00ed\u00f0ustu lo\u00f0f\u00edlarnir lif\u00f0u) hafi veri\u00f0 erf\u00f0afr\u00e6\u00f0ilega \u00farkynja\u00f0ir og a\u00f0 ef til vill voru \u00feeirra einu m\u00f6gulegu \u00f6rl\u00f6g \u00fatdau\u00f0i.<\/p>\n

\n

Erf\u00f0amengi lo\u00f0f\u00edla<\/strong><\/p>\n

Hver er skyldleiki, fj\u00f6lbreytileiki og \u00fer\u00f3unarfr\u00e6\u00f0i lo\u00f0f\u00edla? Mikilv\u00e6gt skref til a\u00f0 svara \u00feessum spurningum var stigi\u00f0 af Love Dalen vi\u00f0 N\u00e1tt\u00faruminjasafni\u00f0 \u00ed Stokkh\u00f3lmi og samstarfsm\u00f6nnum hans sem birtu grein \u00ed Current Biology \u00e1ri\u00f0 2015 um ra\u00f0greiningu \u00e1 erf\u00f0amengi tveggja lo\u00f0f\u00edla. Annar f\u00edllinn var fr\u00e1 S\u00edber\u00edu og um 45.000 \u00e1ra gamall \u2013 \u00feegar hann lif\u00f0i var stofninn st\u00f3r og \u00fatbrei\u00f0slan mikil. Hinn lo\u00f0f\u00edllinn er um 4.300 \u00e1ra og tilheyr\u00f0i sm\u00e1um og einangru\u00f0um stofni \u00e1 Wrangel-eyju nor\u00f0an S\u00edber\u00edu r\u00e9tt vestan Beringssunds<\/a>. Eyjan er l\u00edtil, flatarm\u00e1l hennar er a\u00f0eins um 7.600 km2<\/sup>. Stofninn var um 500-1.000 d\u00fdr og t\u00f3r\u00f0i \u00e1 eyjunni \u00ed um 6.000 \u00e1r. Wrangel-eyjar var s\u00ed\u00f0asta v\u00edgi lo\u00f0f\u00edlanna en tali\u00f0 er a\u00f0 stofninn hafi d\u00e1i\u00f0 \u00fat fyrir um 3.700-4.000 \u00e1rum. Ranns\u00f3knir hafa s\u00fdnt a\u00f0 lo\u00f0f\u00edlarnir \u00e1 Wrangel-eyju voru um fj\u00f3r\u00f0ungi minni en meginlandsf\u00edlarnir, en d\u00e6mi eru um enn sm\u00e1vaxnari lo\u00f0f\u00edla \u00e1 Kr\u00edt og eyjum undan str\u00f6nd Kaliforn\u00edu**. \u00deeir d\u00f3u \u00fe\u00f3 \u00fat mun fyrr.<\/p>\n

Ein merkilegasta ni\u00f0ursta\u00f0a greinar Dalen og f\u00e9laga er s\u00fa a\u00f0 lo\u00f0f\u00edllinn \u00e1 Wrangel-eyju haf\u00f0i minni arfblendni en lo\u00f0f\u00edllinn af meginlandinu. Arfblendni er m\u00e6likvar\u00f0i \u00e1 \u00fea\u00f0 hlutfall gena<\/a> \u00ed erf\u00f0amengi einstaklings sem eru \u00e1 arfblendnu e\u00f0a arfhreinu formi. Ef einstaklingur f\u00e6r sama eintak af geni fr\u00e1 b\u00e1\u00f0um foreldrum er vi\u00f0komandi arfhreinn um \u00fea\u00f0 gen. \u00cd flestum tegundum er arfblendni h\u00e1, margar \u00fatg\u00e1fur eru til af hverju geni, og einstaklingar arfblendnir um flest e\u00f0a \u00f6ll s\u00edn gen. \u00dea\u00f0 gefur tegundum \u00fer\u00f3unarfr\u00e6\u00f0ilegt bolmagn til a\u00f0 svara \u00e1skorunum framt\u00ed\u00f0ar. L\u00e1g arfblendni (\u00fea\u00f0 er l\u00edtill erf\u00f0abreytileiki) er \u00f3\u00e6skileg. Ef einhver er arfhreinn um m\u00f6rg gen er l\u00edklegt a\u00f0 vi\u00f0komandi s\u00e9 arfhreinn um eina e\u00f0a fleiri ska\u00f0lega sams\u00e6tu<\/a>. \u00deannig birtast genagallar. Innr\u00e6ktun lei\u00f0ir til minni arfblendni einstaklinga og eykur l\u00edkurnar \u00e1 \u00fev\u00ed a\u00f0 afkv\u00e6mi f\u00e6\u00f0ist sem \u00fej\u00e1ist af genag\u00f6llum.<\/p>\n

Samspil n\u00e1tt\u00farulegs vals og stofnst\u00e6r\u00f0ar<\/strong><\/p>\n

Stofnerf\u00f0afr\u00e6\u00f0i fjallar um krafta sem hafa \u00e1hrif \u00e1 erf\u00f0abreytileika innan h\u00f3pa og tegunda. Veigamestu kraftarnir eru st\u00f6kkbreytingar<\/a>, hending (genafl\u00f6kt), stofnst\u00e6r\u00f0, stofnbygging og n\u00e1tt\u00farulegt val.<\/p>\n

St\u00f6kkbreytingar lei\u00f0a til n\u00fds breytileika. \u00de\u00e6r geta veri\u00f0 breytingar \u00e1 st\u00f6kum b\u00f6sum, en einnig innskot e\u00f0a \u00farfellingar af lengri strengjum, til d\u00e6mis vegna svonefndra hoppandi gena (svokalla\u00f0ra st\u00f6kkla***) . Ekki eru allar st\u00f6kkbreytingar eins, sumar eru g\u00f3\u00f0ar (f\u00f3\u00f0ur fyrir a\u00f0l\u00f6gun), margar eru hlutlausar (hafa engin \u00e1hrif \u00e1 h\u00e6fni), en st\u00f3r hluti er ska\u00f0legur - skemma gen og l\u00edffr\u00e6\u00f0ileg kerfi (til d\u00e6mis virkni hjartans, lyktarskyn, eiginleika h\u00fa\u00f0ar og felds og svo framvegis).<\/p>\n

Hending hefur \u00e1hrif \u00e1 stofna \u00fev\u00ed myndun kynfruma og p\u00f6run einstaklinga er t\u00f6luver\u00f0ri tilviljun h\u00e1\u00f0. Hending er eins og teningakast, stundum koma upp fimm sexur - stundum engin. \u00c1hrif hendingar eru mest ef stofnar eru litlir. \u00de\u00e1 getur tilviljunin leitt til mikilla breytinga \u00ed t\u00ed\u00f0ni gena, jafnvel st\u00f6kkbreytinga sem eru ska\u00f0legar fyrir tegundina.<\/p>\n

N\u00e1tt\u00farulegt val er kraftur sem b\u00e6\u00f0i b\u00fdr til a\u00f0laganir og var\u00f0veitir \u00fe\u00e6r. N\u00e1tt\u00farulegt val virkar best ef stofninn er st\u00f3r og b\u00fdr \u00feannig yfir \u00feeim erf\u00f0afj\u00f6lbreytileika sem \u00fearf til a\u00f0 laga sig a\u00f0 breyttum a\u00f0st\u00e6\u00f0um og \u00fea\u00f0 sem er ekki s\u00ed\u00f0ur mikilv\u00e6gt, n\u00e6gilega st\u00f3r til a\u00f0 a\u00f0 fjarl\u00e6gja sl\u00e6mar \u00fatg\u00e1fur (sams\u00e6tur) gena.<\/p>\n

Upps\u00f6fnun ska\u00f0legra breytinga \u00ed lo\u00f0f\u00edlum \u00e1 Wrangel eyju<\/strong><\/p>\n

Rebekah Rogers og Montgomery Slatkin greindu upp \u00e1 n\u00fdtt g\u00f6gn Dalen og f\u00e9laga \u00far ra\u00f0greiningu erf\u00f0amengja lo\u00f0f\u00edlanna tveggja, fr\u00e1 S\u00edber\u00edu og Wrangel-eyju. \u00deau beindu sj\u00f3num a\u00f0 hlutfalli sl\u00e6mra breytinga og leitu\u00f0u s\u00e9rstaklega a\u00f0 breytilegum st\u00f6\u00f0um og \u00farfellingum \u00e1 genum e\u00f0a hlutum \u00feeirra. Ni\u00f0ursta\u00f0a \u00feeirra var s\u00fa a\u00f0 margskonar erf\u00f0agallar<\/a> voru algengari \u00ed Wrangel-lo\u00f0f\u00edlnum en S\u00edber\u00eduf\u00edlnum. \u00deau fundu 25% fleiri \u00farfellingar \u00ed erf\u00f0amenginu sem ey\u00f0ilag\u00f0i e\u00f0a fjarl\u00e6g\u00f0i gen, h\u00e6rra hlutfall alvarlegra st\u00f6kkbreytinga og h\u00e6rra hlutfall hoppandi gena \u00ed Wrangel-f\u00edlnum.<\/p>\n

Ni\u00f0urst\u00f6\u00f0urnar eru nokku\u00f0 sk\u00fdrar en samt ver\u00f0ur a\u00f0 sl\u00e1 varnagla. Einungis var unni\u00f0 me\u00f0 tvo einstaklinga, einn \u00far hvorum stofni. \u00dea\u00f0 er m\u00f6gulegt a\u00f0 \u00farkynja\u00f0 eintak hafi valist fr\u00e1 Wrangel-eyju og heilbrig\u00f0ur f\u00edll fr\u00e1 S\u00edber\u00edu. \u00dea\u00f0 er \u00fev\u00ed nau\u00f0synlegt a\u00f0 kanna erf\u00f0aefni fleiri lo\u00f0f\u00edla og fr\u00e1 \u00f6\u00f0rum st\u00f6\u00f0um til a\u00f0 meta hversu traust mynstri\u00f0 er.<\/p>\n

A\u00f0rir stofnerf\u00f0afr\u00e6\u00f0ilegir e\u00f0a a\u00f0fer\u00f0alegir \u00fe\u00e6ttir geta dregi\u00f0 fram \u00feau mynstur sem s\u00e1ust \u00ed g\u00f6gnunum. Helsta r\u00f6ksemdin fyrir \u00fev\u00ed a\u00f0 g\u00f6gnin s\u00e9u l\u00edklega r\u00e9tt er a\u00f0 \u00fe\u00f3tt m\u00f6gulegt s\u00e9 a\u00f0 f\u00e1 skekkju \u00ed eina m\u00e6list\u00e6r\u00f0 vegna annarra \u00fe\u00e1tta er \u00f3l\u00edklegt a\u00f0 f\u00e1 samskonar skekkju \u00ed \u00fe\u00e6r allar. Fyrst allar m\u00e6listikurnar benda \u00ed s\u00f6mu \u00e1tt er l\u00edklegt a\u00f0 mynstri\u00f0 s\u00e9 raunverulegt.<\/p>\n

Spyrja m\u00e1 hva\u00f0 getur \u00fatsk\u00fdrt \u00feessa upps\u00f6fnun ska\u00f0legra breytinga \u00ed stofninum. \u00c1st\u00e6\u00f0an er a\u00f0 \u00f6llum l\u00edkindum s\u00fa a\u00f0 stofninn var b\u00e6\u00f0i l\u00edtill og einangra\u00f0ur \u00ed margar aldir og \u00e1r\u00fe\u00fasundir. Stofninn \u00e1 Wrangel-eyju var l\u00edklega a\u00f0eins um 500-1.000 d\u00fdr vegna takmarka\u00f0s bur\u00f0ar\u00feols eyjunnar. N\u00e1tt\u00farulegt val virkar ekki sem skyldi \u00ed litlum stofnum \u00fear sem \u00fea\u00f0 n\u00e6r ekki a\u00f0 hreinsa erf\u00f0agalla \u00far stofninum. Ef stofninn er of l\u00edtill er h\u00e6tt vi\u00f0 a\u00f0 t\u00ed\u00f0ni sl\u00e6mra sams\u00e6ta \u00ed stofninum aukist me\u00f0 t\u00edmanum og einnig aukast l\u00edkur \u00e1 innr\u00e6ktun og arfhreinum erf\u00f0ag\u00f6llum.<\/p>\n

H\u00f6fundar ranns\u00f3knarinnar, Rogers og Slatkin, \u00e1lykta a\u00f0 lo\u00f0f\u00edlastofninn \u00e1 Wrangel-eyju s\u00e9 d\u00e6mi um genahrun (e. genomic meltdown) og spyrja hvort \u00fatdau\u00f0i \u00feeirra hafi veri\u00f0 \u00f3umfl\u00fdjanlegur \u00fear sem erf\u00f0amengi \u00feeirra var uppfullt af ska\u00f0legum breytingum og arfblendnin l\u00edtil.<\/p>\n

Er genahrun l\u00edklegt \u00ed \u00f6\u00f0rum stofnum og tegundum?<\/strong><\/p>\n

L\u00edfverur hafa tv\u00e6r meginlei\u00f0ir til a\u00f0 a\u00f0lagast n\u00fdju umhverfi; erf\u00f0abreytileika og sveigjanleika. Ef stofninn b\u00fdr yfir n\u00e6gilegum erf\u00f0abreytileika og er n\u00e6gilega st\u00f3r getur n\u00e1tt\u00farulegt val leitt til a\u00f0l\u00f6gunar hans a\u00f0 n\u00fdju a\u00f0st\u00e6\u00f0um. Hin lei\u00f0in er sveigjanleiki \u00ed atferli, formi e\u00f0a virkni l\u00edfvera. Sl\u00edk a\u00f0l\u00f6gunarh\u00e6fni er innbygg\u00f0 \u00ed l\u00edfverur, en mismikil eftir tegundum og h\u00f3pum. D\u00fdr geta lagast a\u00f0 breytingum \u00ed umhverfi me\u00f0 \u00fev\u00ed a\u00f0 f\u00e6ra sig til. Pl\u00f6ntur geta ekki f\u00e6rt sig en margar geta hins vegar breytt vaxtarformi s\u00ednu til a\u00f0 breg\u00f0ast vi\u00f0 n\u00fdjum a\u00f0st\u00e6\u00f0um, vaxi\u00f0 \u00e1 einn h\u00e1tt \u00ed miklum \u00feurrki og annan veg \u00ed raka. Sl\u00edkt finnst reyndar l\u00edka me\u00f0al d\u00fdra, til d\u00e6mis \u00ed bleikju sem er me\u00f0 eina sveigjanlegustu \u00feroskun sem finnst me\u00f0al hryggd\u00fdra.<\/p>\n

Genahrun eins og vir\u00f0ist hafa or\u00f0i\u00f0 \u00ed Wrangel-lo\u00f0f\u00edlunum er m\u00f6gulegt \u00ed \u00f6\u00f0rum tegundum og er l\u00edklegast \u00ed tegundum sem eru me\u00f0 mj\u00f6g litla stofnst\u00e6r\u00f0 \u00ed langan t\u00edma. Samkv\u00e6mt l\u00edkani Rogers og Slatkin er h\u00e6tt vi\u00f0 a\u00f0 stofnar sem lenda \u00ed hringi\u00f0u sm\u00e1rrar stofnst\u00e6r\u00f0ar og erf\u00f0agalla \u00feokist \u00f3hj\u00e1kv\u00e6milega \u00ed \u00e1tt a\u00f0 \u00fatdau\u00f0a.<\/p>\n

Vegna \u00e1hrifa mannsins \u00e1 vistkerfi og b\u00fasv\u00e6\u00f0i l\u00edfvera eru margar tegundir \u00ed \u00feeirri st\u00f6\u00f0u a\u00f0 teljast \u00f3gna\u00f0 e\u00f0a \u00ed beinni h\u00e6ttu \u00e1 \u00fev\u00ed a\u00f0 deyja \u00fat. L\u00edtil arfblendni eins og s\u00e1st \u00ed Wrangel-f\u00edlum s\u00e9st \u00ed \u00f6\u00f0rum tegundum \u00ed \u00fatr\u00fdmingarh\u00e6ttu eins og lj\u00f3num<\/a>, t\u00edgrum, tasman\u00eduskollum, g\u00f3rillum, blettat\u00edgrum<\/a> og \u00edsbj\u00f6rnum. Nau\u00f0synlegt er a\u00f0 framkv\u00e6ma \u00e1l\u00edka greiningar \u00e1 \u00feeim til a\u00f0 reyna a\u00f0 meta \u00e1stand tegundanna og \u00fer\u00f3unarfr\u00e6\u00f0ilegt \u00ferek.<\/p>\n

Er h\u00e6gt a\u00f0 spyrna vi\u00f0 genahruni tegunda?<\/strong><\/p>\n

L\u00edklega er besta lei\u00f0in til a\u00f0 sporna vi\u00f0 genahruni s\u00fa a\u00f0 koma \u00ed veg fyrir a\u00f0 stofnar villtra tegunda ver\u00f0i of litlir. Einnig \u00fearf a\u00f0 gera r\u00e1\u00f0stafanir til a\u00f0 draga \u00far uppskiptingu. Athafnir manna, til d\u00e6mis lagning hra\u00f0brauta e\u00f0a bygging borga, hafa rofi\u00f0 b\u00fasv\u00e6\u00f0i me\u00f0 \u00feeim aflei\u00f0ingum a\u00f0 stofnar einangrast og gen fl\u00e6\u00f0a ekki \u00e1 milli \u00feeirra. Sem d\u00e6mi eru simpansar<\/a> n\u00fa klofnir \u00ed marga sm\u00e6rri h\u00f3pa og hafa l\u00edtil samskipti, og \u00fear me\u00f0 ver\u00f0ur genabl\u00f6ndun \u00feeirra l\u00edtil. Vi\u00f0 sl\u00edkar a\u00f0st\u00e6\u00f0ur getur genagallahringi\u00f0a komist \u00ed gang og ska\u00f0legar breytingar safnast upp \u00ed litlum stofni.<\/p>\n

D\u00fdragar\u00f0afr\u00e6\u00f0ingar vita a\u00f0 innr\u00e6ktun er \u00f3gnun vi\u00f0 vi\u00f0gang tegunda. \u00cd d\u00fdrag\u00f6r\u00f0um eru haldnar \u00e6ttb\u00e6kur fyrir f\u00e1g\u00e6t d\u00fdr og \u00feau sem eru \u00ed \u00fatr\u00fdmingarh\u00e6ttu, og einstaklingar (e\u00f0a s\u00e6\u00f0i) eru fluttir gar\u00f0a og landa \u00e1 milli til a\u00f0 tryggja erf\u00f0afr\u00e6\u00f0ilegan fj\u00f6lbreytileika. Reyndar m\u00e1 spyrja hvort a\u00f0 100 g\u00f3rillur \u00ed d\u00fdrag\u00f6r\u00f0um s\u00e9u \u00ed raun g\u00f3rillur? Er tegundin var\u00f0veitt ef h\u00fan lifir ekki \u00ed s\u00ednu n\u00e1tt\u00farulega umhverfi? St\u00f3ra vandam\u00e1li\u00f0 er samt sem \u00e1\u00f0ur ey\u00f0ing b\u00fasv\u00e6\u00f0a og ofn\u00fdting jar\u00f0ar. \u00dea\u00f0 a\u00f0 flytja lj\u00f3nas\u00e6\u00f0i milli landa leysir ekki vandann.<\/p>\n

H\u00e9rlendis er vita\u00f0 um eina tegund sem hefur d\u00e1i\u00f0 \u00fat fr\u00e1 landn\u00e1mi, \u00fea\u00f0 er geirfuglinn<\/a>. \u00d6nnur tegund \u00ed mikilli h\u00e6ttu er haf\u00f6rninn<\/a>. Reyndar finnst \u00f6rninn v\u00ed\u00f0ari en \u00e1 \u00cdslandi en stofninn h\u00e9r er agnarsm\u00e1r. Kristinn Haukur Skarph\u00e9\u00f0insson \u00e1 N\u00e1tt\u00farufr\u00e6\u00f0istofnun hefur kortlagt stofnst\u00e6r\u00f0 hafarnarins \u00e1 \u00cdslandi s\u00ed\u00f0ustu \u00f6ldina. Stofninn er n\u00fa um 150 einstaklingar sem mynda um 70 p\u00f6r. Af \u00feeim verpa um 35 p\u00f6r. \u00c1 fyrri hluta s\u00ed\u00f0ustu aldar var \u00f6rninn ofs\u00f3ttur, hrei\u00f0rum var steypt og eitru\u00f0 hr\u00e6 \u00e6tlu\u00f0 refum l\u00f6g\u00f0u marga erni. F\u00e6st voru verpandi p\u00f6r innan vi\u00f0 tuttugu. Spurning er hvort stofninn h\u00e9rlendis hafi or\u00f0i\u00f0 of l\u00edtill til a\u00f0 vi\u00f0haldast. \u00dea\u00f0 ver\u00f0ur a\u00f0 rannsaka me\u00f0 \u00fev\u00ed a\u00f0 greina erf\u00f0abreytileika \u00ed stofnum h\u00e9rlendis og ytra.<\/p>\n

Samantekt<\/strong><\/p>\n