Evolution, species delimitation and diversity in myxomycetes: Arcyria and allied genera
Kuupäev
2024-10-03
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Abstrakt
Limakud mängivad ökosüsteemides olulist rolli, kuid jäävad sageli märkamatuks. Nad pole ei taimed, loomad ega seened, vaid ainulaadsed organismid keerulise elutsükliga. Limakud alustavad oma elu amööbidena mullas, kõdupuidus ja metsavarises, kus nad toituvad bakteritest ja muudest mikroorganismidest ning on ise väikeste loomade toiduks. Seejärel koonduvad amööbid nähtavateks limasteks struktuurideks – plasmoodiumideks, ja muunduvad lõpuks eoseid kandvateks viljakehadeks.
Selle töö eesmärk on täita lüngad nende evolutsiooni ja elurikkuse mõistmisel ning liikide piiritlemisel, keskendudes peamiselt sugukonnale Arcyriaceae. Kasutades nii morfoloogilisi kui multigeen-fülogeneetilist analüüsi, uuriti 33 Arcyria liike kogu maailmast. Kinnitati, et Arcyria on polüfüleetiline, koosnedes kahest eraldi klaadist.
Enamik tunnuseid, mida Arcyriaceae taksonite piiritlemiseks kasutati, esines homoplaasiat või sünplesiomorfismi. Siiski, eoste värvus oli rohkem kooskõlas fülogeneesiga ja aitas piiritleda perekondi ja sugukondi. Selle tulemusena täiendati sugukonda Arcyriaceae, loodi uus sugukond Hemitrichiaceae, kirjeldati uus perekond Spiromyxa ja taaselustati perekond Heterotrichia. Enamik uuritud liike osutus liigikompleksideks, para- või polüfüleetilisteks üksusteks.
Uurisime ka DNA triipkoodi kasutamist liikide piiritlemiseks. Üldiselt võimaldas triipkood eristada morfoloogiliste tunnuste põhjal kirjeldatud liike (DNA järjestuste liigisisesed erinevused olid väiksemad kui erinevate liikide vahel). Siiski oli erandeid, nagu krüptilised liigid, mis näevad välja sarnased, kuid on geneetiliselt erinevad, ja liigid, mis näevad välja erinevad, kuid millel on sarnane DNA. Isegi perekonna tasandil ei olnud ühtset sarnasuse läviväärtust, mis täiuslikult eraldaks järjestused liikideks.
Selle doktoritöö teine osa võtab kokku meie jõupingutused limakute elurikkuse esmaste andmete kogumisel ja avaldamisel, järgides FAIR (leitav, ligipääsetav, koostalitlusvõimeline, korduvkasutatav) põhimõtteid.
Myxomycetes (slime molds) play vital roles in ecosystems, yet remain largely unnoticed. Neither plants, animals, nor fungi, myxomycetes are unique organisms with a complex life cycle. They start as amoebas living in soil, dead wood, and litter, where they feed on bacteria and other microorganisms, and are themselves the food for small animals. Then, amoebas aggregate into visible slimy structures – plasmodia, and eventually transform into spore-bearing fruiting bodies. Despite their ecological functions, myxomycetes are often overlooked in taxonomical research. This work aimed to fill gaps in understanding their evolution, species boundaries, and biodiversity, mostly focusing on the genus Arcyria, family Arcyriaceae. We morphologically and genetically studied 33 species of Arcyria collected worldwide. Arcyria was confirmed to be polyphyletic, comprising two distant clades. Most of the traits, previously used to delimit taxa in Arcyriaceae appeared to be homoplastic or symplesiomorphic. However, the color of the spores was more consistent with the phylogeny and helped us delimit the genera and families. As a result, the family Arcyriaceae was emended, a new family Hemitrichiaceae established, a new genus Spiromyxa described, and the genus Heterotrichia resurrected. Most of examined Arcyria species turned out to be species complexes; para- or polyphyletic groups. We also explored application of DNA barcoding to delimit myxomycete species. Generally, a local barcoding gap between species was present. However, there were exceptions such as cryptic species that look alike but are genetically different, and those that look different but have similar DNA. Even at the genus level there was no single similarity threshold that would perfectly sort out sequences into species. Another part of this thesis summarizes our effort in collecting and publishing primary data on myxomycete diversity following FAIR (Findable, Accessible, Interoperable, Reusable) principles.
Myxomycetes (slime molds) play vital roles in ecosystems, yet remain largely unnoticed. Neither plants, animals, nor fungi, myxomycetes are unique organisms with a complex life cycle. They start as amoebas living in soil, dead wood, and litter, where they feed on bacteria and other microorganisms, and are themselves the food for small animals. Then, amoebas aggregate into visible slimy structures – plasmodia, and eventually transform into spore-bearing fruiting bodies. Despite their ecological functions, myxomycetes are often overlooked in taxonomical research. This work aimed to fill gaps in understanding their evolution, species boundaries, and biodiversity, mostly focusing on the genus Arcyria, family Arcyriaceae. We morphologically and genetically studied 33 species of Arcyria collected worldwide. Arcyria was confirmed to be polyphyletic, comprising two distant clades. Most of the traits, previously used to delimit taxa in Arcyriaceae appeared to be homoplastic or symplesiomorphic. However, the color of the spores was more consistent with the phylogeny and helped us delimit the genera and families. As a result, the family Arcyriaceae was emended, a new family Hemitrichiaceae established, a new genus Spiromyxa described, and the genus Heterotrichia resurrected. Most of examined Arcyria species turned out to be species complexes; para- or polyphyletic groups. We also explored application of DNA barcoding to delimit myxomycete species. Generally, a local barcoding gap between species was present. However, there were exceptions such as cryptic species that look alike but are genetically different, and those that look different but have similar DNA. Even at the genus level there was no single similarity threshold that would perfectly sort out sequences into species. Another part of this thesis summarizes our effort in collecting and publishing primary data on myxomycete diversity following FAIR (Findable, Accessible, Interoperable, Reusable) principles.
Kirjeldus
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