Genetic diversity and evolution of Pulmonaria angustifolia L. and Myosotis laxa sensu lato (Boraginaceae)
Failid
Kuupäev
2016-06-29
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Abstrakt
Taimeliikide püsimine looduses sõltub nende võimest kohastuda muutuvate keskkonnatingimustega, kohastumise aluseks aga on liigi geneetiline mitmekesisus. Teadmised geneetilise mitmekesisuse kohta võimaldavad välja selgitada liike mõjutavaid tegureid ning hinnata haruldaste liikide väljasuremise riski. Käesolevas doktoritöös uurisin geneetilist mitmekesisust kareleheliste (Boraginaceae) sugukonnas: sinisel kopsurohul (Pulmonaria angustifolia) ning muru-lõosilmal (Myosotis laxa s. lato). Sinine kopsurohi on areaali põhjapiiril, Eestis ja Lätis väheneva arvukusega ohustatud liik. Võrdlusmaterjalina kasutasin samas piirkonnas kasvava hariliku kopsurohu (Pulmonaria obscura Dumort.) ning sinise kopsurohu areaali keskosast (Poolast) pärit taimi. Selgus, et kõik uuritud sinise kopsurohu isendid sisaldasid hariliku kopsurohu DNA järjestusi. Sinise kopsurohu arvukuse vähenemine Eesti populatsioonides võib seega olla lokaalse hübridiseerumise tagajärg, kuid ei saa välistada, et liik tervikuna ongi hübriidne. Muru-lõosilm on morfoloogiliselt väga varieeruv liik, mille harvaesinevat teadmata päritoluga rannikuvormi on kirjeldatud ka kui balti lõosilma (Myosotis baltica Sam.). Kuigi osa muru-lõosilma rannikuvormi taimi olid morfoloogiliselt ülejäänud taimedest erinevad, geneetilist erinevust rannikuvormi ja ülejäänud taimede vahel ei olnud. Muru-lõosilma geneetiline varieeruvus populatsioonides oli positiivses korrelatsioonis populatsioone ümbritseva maastiku struktuuriga, mis näitab suunatud geenivoolu maastikul. Geenivool vee abil leviva muru-lõosilma populatsioonide vahel on tõenäoliselt suunatud kaugemalt maismaalt rannikule ega ei võimalda rannikupopulatsioonide geneetilist eristumist. Morfoloogiliste tunnuste varieeruvus muru-lõosilma populatsioonides ei olnud korrelatsioonis maastiku struktuuri ega keskkonnatingimustega. Seega ei ole rannikuvormi eristumise põhjuseks geneetiline kohastumine ega morfoloogiline plastilisus, vaid tõenäoliselt keskkonnast sõltuv taimede elutsükli epigeneetiline regulatsioon. Käesolev töö tõestab esmakordselt geneetiliste andmete põhjal sinise ja hariliku kopsurohu hübridiseerumise looduses ning toob välja, et muru- lõosilma rannikuvorm ei ole geneetiliselt eristunud takson.
The ability of plants to adapt to changing environmental conditions is strongly dependent on their genetic diversity. Knowledge of genetic diversity helps us to understand the dynamics of the species as well as the threat level in terms of extinction. This thesis aims to characterize the genetic diversity of two species in the family Boraginaceae: firstly, Pulmonaria angustifolia L. and secondly, Myosotis laxa s. lato. P. angustifolia is extremely rare and in in decline in Estonia and Latvia, on the northern border of its range. To investigate genetic diversity of P. angustifolia in Estonia and Latvia, samples of Pulmonaria obscura Dumort. from the same area and the samples of P. angustifolia from its core area (Poland) were compared. All studied individuals of P. angustifolia contained genetic material from P. obscura. Thus, local hybridization is a likely explanation for the decline in the populations of P. angustifolia in Estonia. However, a hybrid origin for the whole species is also possible. M. laxa s. lato is morphologically highly variable and has a sporadically distributed coastal form with unknown origin and phylogeny. This coastal form has been described as a separate species, Myosotis baltica Sam. The study revealed that some of the specimens of the coastal form of M. laxa differed from the others in morphological characters but not on the basis of genetic data. The genetic variation of M. laxa s. lato populations was positively correlated to the structure of the surrounding landscape, which indicates the presence of directed gene flow across the landscape. As M. laxa s. lato disperses via water, the gene flow is likely directed from the mainland populations to the coastal populations and so genetic adaptation of coastal populations is not viable. The phenotypic variation of M. laxa s. lato was correlated neither to the structure of landscape nor to the environmental conditions. Thus, the phenotypic differences of the coastal form are not caused by genetic adaptation or phenotypic plasticity but likely, by the temperature-dependent epigenetic regulation of the life cycle. This thesis confirms for the first time hybridization of P. angustifolia and P. obscura on the basis of genetic data and reveals that the coastal form of M. laxa is not genetically different from the mainland form, but likely arises due to epigenetic regulation of the life cycle of plants.
The ability of plants to adapt to changing environmental conditions is strongly dependent on their genetic diversity. Knowledge of genetic diversity helps us to understand the dynamics of the species as well as the threat level in terms of extinction. This thesis aims to characterize the genetic diversity of two species in the family Boraginaceae: firstly, Pulmonaria angustifolia L. and secondly, Myosotis laxa s. lato. P. angustifolia is extremely rare and in in decline in Estonia and Latvia, on the northern border of its range. To investigate genetic diversity of P. angustifolia in Estonia and Latvia, samples of Pulmonaria obscura Dumort. from the same area and the samples of P. angustifolia from its core area (Poland) were compared. All studied individuals of P. angustifolia contained genetic material from P. obscura. Thus, local hybridization is a likely explanation for the decline in the populations of P. angustifolia in Estonia. However, a hybrid origin for the whole species is also possible. M. laxa s. lato is morphologically highly variable and has a sporadically distributed coastal form with unknown origin and phylogeny. This coastal form has been described as a separate species, Myosotis baltica Sam. The study revealed that some of the specimens of the coastal form of M. laxa differed from the others in morphological characters but not on the basis of genetic data. The genetic variation of M. laxa s. lato populations was positively correlated to the structure of the surrounding landscape, which indicates the presence of directed gene flow across the landscape. As M. laxa s. lato disperses via water, the gene flow is likely directed from the mainland populations to the coastal populations and so genetic adaptation of coastal populations is not viable. The phenotypic variation of M. laxa s. lato was correlated neither to the structure of landscape nor to the environmental conditions. Thus, the phenotypic differences of the coastal form are not caused by genetic adaptation or phenotypic plasticity but likely, by the temperature-dependent epigenetic regulation of the life cycle. This thesis confirms for the first time hybridization of P. angustifolia and P. obscura on the basis of genetic data and reveals that the coastal form of M. laxa is not genetically different from the mainland form, but likely arises due to epigenetic regulation of the life cycle of plants.
Kirjeldus
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Märksõnad
sinine kopsurohi, kopsurohi, muru-lõosilm, geneetiline mitmekesisus, evolutsioon, Pulmonaria angustifolia, Pulmonaria, Myosotis laxa s. lato, genetic diversity, evolution