I-Molecular Phylogenetics Ekuhlukanisweni Kwezinto Eziphilayo
Ukuhlukaniswa kwezinto eziphilayo kuwumzamo wesayensi wokuhlanganisa izinto eziphilayo ngokusekelwe kokufana kwazo nokwehluka kwazo. Sekungamakhulu eminyaka, ukuhlukaniswa kwezinhlobo zezinto eziphilayo kuncike kakhulu ezicini zomzimba—ukuma komzimba, isakhiwo sezitho, amaphethini ombala, noma ezinye izici ezibonakalayo zomzimba. Kodwa-ke, intuthuko ku-biology yama-molecule kanye nobuchwepheshe bokulandelana kwe-DNA ishintshe indlela ososayensi abaqonda ngayo ubudlelwano bezinto eziphilayo. Yilapho i-phylogenetics yama-molecule idlala khona indima ebalulekile: indlela esebenzisa idatha yama-molecule (i-DNA, i-RNA, noma amaprotheni) ukwakha kabusha umlando wokuziphendukela kwemvelo kanye nobudlelwano, bese isebenzisa le datha ukuze ithuthukise izinhlelo zokuhlukaniswa.
Kuyini i-phylogenetics yama-molecular?
I-phylogenetics yama-molecular iyigatsha le-biology yokuziphendukela kwemvelo elifunda ubudlelwano bokuziphendukela kwemvelo phakathi kwezinto eziphilayo ngokuqhathanisa ukulandelana kwama-molecule ezinto eziphilayo. Ama-molecule asetshenziswa kakhulu yi-DNA (isb., i-mitochondrial, i-chloroplast, noma izakhi zofuzo zenuzi), i-RNA, namaprotheni. Isimiso esiyisisekelo silula: izinto eziphilayo ezinezilandelana zezakhi zofuzo ezifanayo cishe zihlanganyele ukhokho ofanayo kunezinto eziphilayo ezinezilandelana zezakhi zofuzo ezihluke kakhulu.
Ngokuhlaziya umehluko kanye nokufana kokulandelana kwezakhi zofuzo, ososayensi bakha izihlahla ze-phylogenetic, imidwebo yamagatsha ekhombisa amaphethini okuhlukana kusukela kukhokho oyedwa kuya ezinhlotsheni ezahlukene zozalo. Lezi zihlahla zisebenza njengemibono yesayensi mayelana nomlando wokuziphendukela kwemvelo, engabuyekezwa njengoba kutholakala idatha entsha.
Kungani idatha yama-molecule ibalulekile ekuhlukanisweni?
Indlela yokwenza izinto inezinzuzo, kodwa futhi inemikhawulo. Izinto eziphilayo eziningi ziyashintshashintsha, ukuvela kwezici ezifanayo emaqenjini angahlobene ngenxa yokucindezeleka okuvamile kwemvelo. Isibonelo, isimo somzimba sezinhlanzi namahlengethwa esime njenge-torpedo savela njengokuzivumelanisa nokuphila emanzini, hhayi ngoba zihlobene kakhulu. Ukuhlukaniswa okusekelwe kuphela esimweni somzimba kungadukisa.
Idatha yama-molecule iyasiza ekuxazululeni le nkinga ngoba i-DNA iqukethe iminonjana ejulile yomlando wokuziphendukela kwemvelo evame ukungabonakali ngeso lenyama. Ngaphezu kwalokho, kumaqembu ezinto eziphilayo ezinezimo ezilula kakhulu noma ezifanayo (isib., amabhaktheriya, isikhunta esincane, noma izinhlobo eziyimfihlo), ukuhlaziywa kwama-molecule ngokuvamile kuyindlela kuphela yokuhlukanisa nokunquma ubudlelwano bazo.
Umthombo wedatha: yiziphi izakhi zofuzo ezisetshenziswayo?
Ukukhethwa kophawu lwezakhi zofuzo kuncike ezinhlosweni zocwaningo kanye neqembu lezinto eziphilayo ezifundwayo. Ezinye izimpawu ezisetshenziswa kakhulu zifaka:
1. I-16S rRNA yamabhaktheriya kanye ne-Archaea, ngoba lesi sakhi sofuzo sitholakala cishe kuwo wonke ama-prokaryotes futhi ukuvela kwaso kuhamba kancane ngakho-ke kufanelekile ebudlelwaneni obubanzi bobuhlobo.
2. I-18S rRNA yama-eukaryotes afana nama-protist kanye nezinye izilwane, njenge-analogue ye-16S rRNA kuma-prokaryotes.
3. I-COI (i-Cytochrome c oxidase subunit I) ku-DNA ye-mitochondrial yezilwane eziningi, yaziwa kakhulu ngendlela "yokubhalelwa kwe-DNA" yokuhlonza izinhlobo.
4. i-rbcL kanye ne-matK kuma-chloroplast ezitshalo, okuvame ukusetshenziselwa ukuhlukaniswa kwezitshalo kanye nokubhala ikhodi.
5. Ukulandelana kwe-genome ephelele manje sekungabizi kakhulu futhi kuyakwazi ukunikeza isisombululo esiphezulu, ikakhulukazi ezimweni eziyinkimbinkimbi.
Uma izakhi zofuzo zihlaziywa kakhulu, kulapho ukuqagela kobuhlobo obuvelayo kuvame ukuba namandla khona, yize ubunzima bokuhlaziya kanye nezidingo zokubala nazo zikhula.
Izindlela zokuhlaziya: kusukela ezilandelaneni kuya ezihlahleni eziguqukayo
Ngokuvamile, inqubo ye-phylogenetics yama-molecule ihilela izigaba eziningana eziyinhloko:
1. Ukuthatha amasampula kanye nokukhipha i-DNA ezintweni eziphilayo eziqondiwe.
2. Ukwandiswa kwezakhi zofuzo ezithile kusetshenziswa i-PCR (i-Polymerase Chain Reaction), noma ukulandelana okuqondile uma kusetshenziswa indlela yezakhi zofuzo.
3. Ukulandelana ukuze kutholakale ukulandelana kwe-nucleotide (A, T, C, G).
4. Ukuqondanisa ukulandelana, okungukuthi ukuhlela ukulandelana ukuze izikhundla zama-nucleotide afanayo ziqhathaniswe.
5. Yakha kabusha umuthi we-phylogenetic usebenzisa izindlela zezibalo noma zokubala ezifana nalezi:
– I-Parsimony Enkulu (ukuthola umuthi onezinguquko ezimbalwa kakhulu),
– Amathuba Aphezulu (ukuthola umuthi okungenzeka kakhulu ngokusekelwe kumodeli yokuziphendukela kwemvelo),
– I-Bayesian Inference (kusetshenziswa amathuba angemuva ukuhlola ukusekelwa kwesihlahla).
6. Hlola ukuthembeka kwesihlahla, isibonelo ngokusebenzisa i-bootstrapping, ukuze ubone ukuthi idatha isekela igatsha elithile ngamandla kangakanani.
Lezi zinyathelo ziqinisekisa ukuthi umuthi we-phylogenetic awusiwo nje umfanekiso, kodwa umphumela wokuhlaziywa okungahlolwa futhi kuphindwe.
Umthelela we-molecular phylogenetics ezinhlelweni zokuhlela
Omunye weminikelo emikhulu ye-phylogenetics yama-molecule kwakuwukuphoqa ukuhlukaniswa ukuze kubonakale kangcono i-monophyly, okungukuthi, iqembu elakhiwe ukhokho oyedwa kanye nazo zonke izizukulwane zakhe. Le ndlela ihambisana nezimiso zokuhlukaniswa kwesimanje okuvame ukubizwa ngokuthi i-phylogenetic systematics noma i-cladistics.
Ngaphambi kwenkathi yama-molecule, amanye amaqembu ayebhekwa njengento eyodwa ngenxa yokufana ngokomzimba, kodwa empeleni, ayenezinhlobo eziningana ezihlukene (i-polyphyletic). I-phylogenetics yama-molecule isiza ekuboneni nasekulungiseni la macala. Ngenxa yalokho, amagama nemingcele yamaqembu e-taxonomic ingashintsha: amanye ahlukaniswa abe yizinhlobo/izinhlobo eziningana, amanye ahlanganiswa, kanti amanye adluliselwa kwamanye amaqembu.
Izibonelo zalo mthelela obanzi zingabonakala ku:
– Ukuhlukaniswa kwama-microorganisms, okuncike kakhulu ku-16S rRNA. Amabhaktheriya amaningi ayekade eqoqwe ngokusekelwe esimweni kanye nokusetshenziswa kwawo atholakala enobuhlobo obuhlukile.
– Ubudlelwano bobuhlobo bezilwane, isibonelo ukuhlelwa kabusha kwamaqembu amaningana ngokusekelwe kudatha ye-mitochondrial neyenuzi.
– Izitshalo eziqhakazayo, lapho idatha yama-molecule isiza khona ukuxazulula ubudlelwano phakathi kwemindeni nezinhlelo, futhi icacise ukuvela kwezinhlamvu ezifana nezimbali nezithelo.
I-DNA barcode kanye nokuhlonza izinhlobo
Ngaphezu kokwakha izihlahla eziziphendukela kwemvelo, i-phylogenetics yama-molecular nayo idlala indima ekuhlonzeni ngokushesha izinhlobo nge-DNA barcode. Umqondo uwukusebenzisa izingcezu zezakhi zofuzo ezijwayelekile (isb., i-COI ezilwaneni) ukuhlonza izinhlobo, njenge-barcode emikhiqizweni. Le ndlela iwusizo ku:
– thola izinhlobo ezisesigabeni sezibungu noma izingcezu zomzimba,
- thola izinhlobo ezihlaselayo,
– ukusiza abomthetho ngokumelene nokuhweba ngezilwane zasendle,
– ukuqapha ukuhlukahluka kwezinto eziphilayo ngokusebenzisa i-DNA yemvelo (i-eDNA) emanzini, enhlabathini, noma emoyeni.
Kodwa-ke, i-barcode nayo inemikhawulo, isibonelo lapho ukwehluka kwezakhi zofuzo phakathi kwezinhlobo kuncane kakhulu noma kwenzeka ukuxutshwa okwenza imingcele yezinhlobo ifiphale.
Izinselele kanye nemikhawulo ye-molecular phylogenetics
Naphezu kwamandla ayo, i-molecular phylogenetics ayinazo izinkinga. Ezinye zezinselele ezinkulu zifaka:
1. Ukuhlanganiswa kanye nokungena ngaphakathi, ikakhulukazi ezitshalweni nakwezinye izilwane, okungaxuba izakhi zofuzo phakathi kwezinhlobo ukuze umuthi ube lula.
2. Ukuhlela uhlu lozalo olungaphelele, okuyilapho ukushintshashintsha kwezakhi zofuzo zokhokho kungazange kuhlukane kahle lapho kwakheka uhlobo olusha, ukuze izakhi zofuzo ezithile zibonise ubudlelwano obuhlukile emlandweni wangempela walolu hlobo.
3. Umehluko emazingeni okuziphendukela kwemvelo, ezinye izakhi zofuzo zishintsha ngokushesha, ezinye kancane kancane; ukukhethwa kwezakhi zofuzo okungafanele kungaholela ekuxazululweni okubi.
4. Ukudluliswa kwezakhi zofuzo okuvundlile kubhaktheriya, okwenza umqondo "womuthi" ngezinye izikhathi uchazwe ngokufanele ngokuthi "inethiwekhi" yokuziphendukela kwemvelo.
5. Ikhwalithi yedatha kanye nokusampula, ngoba imiphumela yokuhlaziya incike kakhulu ekumelelweni kwezinhlobo ezifundwe kanye nekhwalithi yochungechunge.
Ngakho-ke, izifundo eziningi zanamuhla zihlanganisa idatha yama-molecule nobunye ubufakazi obufana nokwakheka, ukuziphatha, i-ecology, kanye nerekhodi lezinsalela (indlela yokuhlanganisa).
Isiphetho
I-phylogenetics yama-molecular ishintshe kakhulu ukuhlukaniswa kwezinto eziphilayo ngokunikeza indlela enengqondo nelinganisekayo yokuhlola ubudlelwano bokuziphendukela kwemvelo. Ngokuhlaziya i-DNA, i-RNA, noma amaprotheni, ososayensi bangakha izihlahla ze-phylogenetic ezisiza ekwakheni ukuhlukaniswa okuhambisana kangcono nomlando wokuziphendukela kwemvelo. Umthelela wayo ubanzi kakhulu: kusukela ekulungisweni kwe-taxonomic kuya ekuhlonzweni kwezinhlobo nge-DNA barcode kuya ekuqondeni kangcono imvelaphi yezinto eziphilayo. Naphezu kwezinselele ezifana nokuhlanganiswa kanye nokudluliswa kwezakhi zofuzo ezivundlile, i-phylogenetics yama-molecular iyaqhubeka nokuthuthuka ngentuthuko ekulandeleni nasekusebenziseni ubuchwepheshe bekhompyutha, okwenza kube yinsika ebalulekile yebhayoloji yesimanje kanye nokulondolozwa.
Uma ufisa, ngingalungisa lesi sihloko sibe amagama ayi-1000 (ngibala amagama ngalinye ngalinye) noma ngengeze izibonelo ezithile (isib. kubantu, ezinyonini, ezitshalweni, noma emabhaktheriya) njengoba kudingeka.
