TY - JOUR

T1 - Sympatric speciation in mountain roses (Metrosideros) on an oceanic island

AU - Osborne, Owen G

AU - Kafle, Tane

AU - Brewer, Tom

AU - Dobreva, Mariya P

AU - Hutton, Ian

AU - Savolainen, Vincent

PY - 2020/8/31

Y1 - 2020/8/31

N2 - Shifts in flowering time have the potential to act as strong prezygotic reproductive barriers in plants. We investigate the role of flowering time divergence in two species of mountain rose (Metrosideros) endemic to Lord Howe Island, Australia, a minute and isolated island in the Tasman Sea. Metrosideros nervulosa and M. sclerocarpa are sister species and have divergent ecological niches on the island but grow sympatrically for much of their range, and likely speciated in situ on the island. We used flowering time and population genomic analyses of population structure and selection, to investigate their evolution, with a particular focus on the role of flowering time in their speciation. Population structure analyses showed the species are highly differentiated and appear to be in the very late stages of speciation. We found flowering times of the species to be significantly displaced, with M. sclerocarpa flowering 53 days later than M. nervulosa. Furthermore, the analyses of selection showed that flowering time genes are under selection between the species. Thus, prezygotic reproductive isolation is mediated by flowering time shifts in the species, and likely evolved under selection, to drive the completion of speciation within a small geographical area. This article is part of the theme issue 'Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers'.

AB - Shifts in flowering time have the potential to act as strong prezygotic reproductive barriers in plants. We investigate the role of flowering time divergence in two species of mountain rose (Metrosideros) endemic to Lord Howe Island, Australia, a minute and isolated island in the Tasman Sea. Metrosideros nervulosa and M. sclerocarpa are sister species and have divergent ecological niches on the island but grow sympatrically for much of their range, and likely speciated in situ on the island. We used flowering time and population genomic analyses of population structure and selection, to investigate their evolution, with a particular focus on the role of flowering time in their speciation. Population structure analyses showed the species are highly differentiated and appear to be in the very late stages of speciation. We found flowering times of the species to be significantly displaced, with M. sclerocarpa flowering 53 days later than M. nervulosa. Furthermore, the analyses of selection showed that flowering time genes are under selection between the species. Thus, prezygotic reproductive isolation is mediated by flowering time shifts in the species, and likely evolved under selection, to drive the completion of speciation within a small geographical area. This article is part of the theme issue 'Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers'.

KW - Genetic Speciation

KW - Islands

KW - Myrtaceae/genetics

KW - New South Wales

KW - Reproductive Isolation

KW - Sympatry

U2 - 10.1098/rstb.2019.0542

DO - 10.1098/rstb.2019.0542

M3 - Article

C2 - 32654651

VL - 375

SP - 20190542

JO - Philosophical Transactions of The Royal Society B: Biological Sciences

JF - Philosophical Transactions of The Royal Society B: Biological Sciences

SN - 0962-8436

IS - 1806

ER -