Mu kizenga yashyizwemo yonyine, ifi y’ingore yo mu bwoko bwa ‘stingray’ yarasamye ibyara izindi enye(4), nubwo bwose itigeze ihura n’ingabo. “Kubyara ari isugi” ni iki? Kandi kuki birimo kuba kenshi ku nyamaswa zashyizwe ukwa zonyine?
Ibi ni ibintu bisa n’ibirimo guhinyura amategeko kamere y’ibidukikije. Muri Gashyantare (2) 2024, ifi y’ingore ya singray yitwa Charlotte yatwitiye mu cyanya gito cy’amazi yashyizwemo ahitwa Hendersonville muri leta ya North Carolina muri Amerika – nubwo bwose iyi fi itari yaregeranye n’iy’ingabo mu myaka irenga umunani. Ibi byashyize mu ihurizo abahanga muri siyanse bo mu kigo Team Ecco Aquarium & Shark Lab.
Uko Charlotte yasamye udufi duto tune(4) two mu bwoko bwayo aho yiberaga yonyine mu kizenga nta ngabo, byabaye iyobera.
Abahanga muri siyanse bibaza ko gutwita kw’iyi fi kwaba kwaravuye ku bintu bidasanzwe bibaho gacye cyane byitwa parthenogenesis.
Iryo ni ijambo riva ku magambo abiri y’Ikigereki, parthénos, risobanuye “isugi”, na genesis risobanuye “iremwa”. Ni igihe igi ry’ingore rivamo ikiremwa ritarigeze rihura n’intanga ngabo.
Charlotte si yo nyamaswa ya mbere isamye nta ngabo. Parthenogenesis isanzwe ibaho cyane cyane mu nyamaswa z’inigwahabiri (insects), nko mu bwoko bw’utunyugunyugu twitwa ‘mayflies’, gusa ntimenyerewe mu nyamaswa zifite amagufa cyangwa uruti rw’umugongo.
Kuva mu 2001 ifi y’ingore yo mu bwoko bwa ‘bonnethead shark’ yabyara itarahuye n’ingabo, hagiye hanoneka ibindi nk’ibi mu mafi ya ‘sharks’ n’ibindi bikururanda.
Ubu birakekwa ko Charlotte ibaye ifi ya mbere ya stingray igize parthenogenesis.
Uko bigenda ngo habeho parthenogenesis biracyari iyobera. Abahanga bamwe bavuga ko ari ukugerageza “kwa nyuma” kw’inyamaswa y’ingore ngo isige ikiyikomokaho.
Kevin Feldheim umuhanga mu binyabuzima by’uturemangingo, akoresha uturemangingo-fatizo (DNA) mu kwiga amafi yo mu bwoko bwa sharks n’uburyo yororoka mu kigo Field Museum cy’i Chicago muri Amerika, agira ati:
“Intego y’irondoka ni uguha ikigukomokaho uturemangingo twawe. Ikigore gishyizwe aha cyonyine nta kigabo, aho ubusanzwe bihuza ibitsinda bikarondoka, ntikigira ayo mahirwe.”
Ntibisanzwe ko inyamaswa zifite amagufa n’uruti rw’umugongo zigira parthenogenesis, ariko iyi fi ya stingray yiswe Charlotte yo muri Amerika byayibayeho
Mu 2008, Kevin Feldheim yakoze ubundi bushakashatsi kuri parthenogenesis mu bwoko bw’amafi bwitwa zebra sharks mu kigo Shedd Aquarium cy’i Chicago. Mbere, yari yarahakanye ko nta guhuza ibitsinda kuba hagati y’amafi yo muri icyo kizenga.
Yavugaga ko nta kimenyetso cyerekana ko amafi y’ingabo ahura n’ay’ingore, gusa nanone akemeza ko ikizenga yari arimo kidafite camera zireba ayo mafi 24/7.
Yasanze kubyara muri za ‘sharks’ ari ibintu birimo amayobera menshi, kuko zimwe mu ngore zashoboraga kwibikamo intanga ngabo amezi menshi nyuma yo guhura n’ingabo.
Gusa, Feldheim yahanze uburyo bwo gupima niba ifi yavutse ifite uturemangingo-fatizo (DNA) tw’ifi y’ingabo. Ibyavuyemo ni uko ifi zavutse kuri zebra sharks zitari zifite DNA n’imwe y’ifi y’ingabo – ahubwo uturemangingo-fatizo tw’ingore gusa.
Feldheim ati: “Ikibazo cyumvikana cyari ngo ibi byabayeho bite? Urebye, igisubizo ni parthenogenesis.”
Imiserebanya yororoka nta ngabo bihuye
Mu kororoka kwinshi mu nyamaswa, amagi avukamo indi nyamaswa aremwa mu buryo bwitwa meiosis, aho uturemangingo tw’intanga ngore tumira utw’intanga ngabo bikavamo ikiremwa, gusa muri parthenogenesis igi ry’intanga ngore ryonyine ryiremamo ikiremwa cy’ibanze kizwi nka embryo ikavamo inyamaswa nshya mu buryo busa n’ubwigana kororoka gusanzwe iyo intanga ngore yahuye n’ingabo.
Madamu Kady Lyons, inzobere yiga imyororokere y’amafi yo mu bwoko bwa sharks, skates na rays mu kigo Georgia Aquarium, avuga ko parthenogenesis ari uburyo butandukanye bwo kororoka.
Gusa avuga ko amafi akomoka muri parthenogenesis aba atandukanye na za nyina mu miterere y’uturemangingo-fatizo.
Ku moko amwe n’amwe kororoka gutya nta ntanga-ngabo zijemo ni inyungu.
Urugero, mu kororoka nta ngabo byagiye biboneka mu bwoko bw’imiserebanya yitwa whiptail iboneka muri Mexico na California. Ibi byatumye umubare wayo wiyongera mu buryo budasanzwe kandi bikayirinda ibibazo nk’indwara zandurira mu mibonano mpuzabitsina.
Gusa ibi nabyo bifite ikiguzi cyabyo – muri kwa kororoka nta ngabo DNA y’iyo miserebanya igenda igira uturemangingo dufite ibibazo kurusha utwo mu yororotse bivuye mu buryo mpuzabitsina busanzwe.
Gusa, ntabwo amoko yose agubwa neza no kororoka nta ntanga ngabo nk’uko bigendekera iriya miserabanya ya whiptail. Amafi ya sharks avuka muri ubu buryo asa n’abaho igihe gito, ndetse macye cyane akageza ku gihe cyo kororoka.
Feldheim ati: “Habura urusobe rw’uturemangingo mu [nyamaswa] zavutse gutyo, ibi bishobora kuganisha ku gusubira inyuma kw’ibyitwa kororoka kuzuye.”
Mu yandi magambo, nubwo ziba zasamwe mu buryo bw’amayobera, inyamaswa zigira amagufa zivuka muri parthenogenesis zishobora kutaramba.
Lyons ari mu itsinda ry’abashakashatsi ku mibereho ya zebra sharks zavutse kuri parthenogenesis aho inyigo y’abo bahanga yasanze amafi yavutse gutyo abaho ikigereranyo cyo munsi y’umwaka umwe, kandi amenshi arangwa n’ibibazo nk’intege nke mu koga, gukata, gushinga umutwe, n’ingorane mu kurya, bigatuma ataramba.
Lyons avuga ko atatunguwe no kubona parthenogenesis mu mafi ya stingrays, nubwo kuri Charlotte ibibazo byibazwa byose bidafitiwe ibisubizo.
Agira ati: “Ikintu kimwe tutazi ni icyaba gitera kororoka gutya kw’ingore gusa nta ngabo bihuye. Ubusanzwe tuzi ko iyo ushyize abahungu n’abakobwa hamwe, baba bagomba gukora ibyabo.”
Gusa, mu gihe abahanga bakomeza kwibaza ibibazo kuri iyi myororokere y’amayobera y’izi nyamaswa, parthenogenesis yo ikomeje kubaho.
Lyons ati: “Byanze bikunze, ubuzima bushaka inzira.”
BBC
