e-journal

Hybridization and long-distance colonization at different time scales: towards resolution of long-term controversies in the sweet vernal grasses (Anthoxanthum)

---

† Background and Aims:
Repeated hybridization and/or polyploidization confound classification and phylogenetic inference, and multiple colonizations at different time scales complicate biogeographical reconstructions. This study investigates whether such processes can explain long-term controversies in Anthoxanthum, and in particular
its debated relationship to the genus Hierochloe¨, the evolution of its conspicuously diverse floral morphology, and the origins of its strikingly disjunct occurrences. A hypothesis for recurrent polyploid formation is proposed.

† Methods:
Three plastid (trnH-psbA, trnT-L and trnL-F) and two nuclear (ITS, ETS)DNAregionswere sequenced in 57 accessions of 17 taxa (including 161 ETS clones) and Bayesian phylogenetic analyses were conducted.
Divergence times were inferred in *BEAST using a strict molecular clock.

† KeyResults:
Anthoxanthumwas inferred as monophyletic and sister to one species of Hierochloe¨ based on the plastid
data, whereas the nuclear data suggested that one section (Anthoxanthum section Anthoxanthum) is sister to a clade including the other section (Anthoxanthum section Ataxia) as sister to the genus Hierochloe¨. This could explain the variation in floral morphology; the aberrant characters in Ataxia seem to result from a Miocene hybridization event between one lineage with one fertile and two sterile florets (the Anthoxanthum lineage) and one which probably had three fertile florets as in extant Hierochloe¨. The distinct diploid A. gracile lineage originated in the Miocene; all other speciation events, manyof them involving polyploidy,were dated to the Late Pliocene to Late Pleistocene. Africawas apparently colonized twice in the Late Pliocene (from the north to afro-alpine eastern Africa, and from south-east Asia to southern Africa), whereas Macaronesia was colonized much later (Late Pleistocene) by a diploid Mediterranean lineage. The widespread European tetraploid A. odoratum originated at least twice.

†Conclusions:
Many of the controversies in Anthoxanthum can be explained by recurring hybridization and/or polyploidization
on time scales ranging from the Miocene to the Late Pleistocene. All but one of the extant species shared
most recent common ancestors in the Late Pliocene to the Late Pleistocene. The disjunct occurrences in Africa originated in the Late Pliocene via independent immigrations, whereas Macaronesia was colonized in the Late
Pleistocene.

Key words: Africa, Anthoxanthum, Ataxia, biogeography, evolution, C3 grasses, hybridization, long-distance
colonization, phylogeny, Poaceae, sweet vernal grasses.

---

Ketersediaan

Tidak ada salinan data

Informasi Detail

Judul Seri

Annals of Botany

No. Panggil

-

Penerbit

Oxford : Oxford University Press on behalf of the Annals of Botany Company., 2013

Deskripsi Fisik

Annals of Botany 112: 1015–1030, 2013

Bahasa

English

ISBN/ISSN

-

Klasifikasi

-

Tipe Isi

-

Tipe Media

-

Tipe Pembawa

-

Edisi

-

Subjek

EKOLOGI TANAMAN

Info Detail Spesifik

-

Pernyataan Tanggungjawab

agus

Versi lain/terkait

Lampiran Berkas

Komentar

---

Anda harus masuk sebelum memberikan komentar