Budding speciation is a process wherein a new species arises from a small,isolated population within or at the margin of an ancestral species.Well-documented cases of budding speciation are rare,and the roles of vario...Budding speciation is a process wherein a new species arises from a small,isolated population within or at the margin of an ancestral species.Well-documented cases of budding speciation are rare,and the roles of various evolutionary factors in this process remain controversial.Based on whole-genome resequencing data from 272 individuals across 27 populations,we reconstructed the evolutionary history of Rhodiola sect.Trifida and explored the relative contributions of natural selection,genetic drift,and chromosomal rearrangements as drivers of lineage divergence.We found that all samples of R.chrysanthemifolia(including R.alterna and R.sinuata)were clustered into three clades.Rhodiola liciae was sister to all other samples in the section,likely due to post-divergence gene flow and the minimal population structure of the progenitor species,while it shared the same ancestry with R.ch-I in population structure analyses.The two populations of R.sinuata were not monophyletic,instead clustering with geographically proximate populations of R.ch-III.Demographic analyses revealed that R.liciae underwent a contraction in population size following its divergence from R.ch-I approximately 0.34 million years ago(Mya),and has remained stable since around 0.1 Mya.Genomic islands and genotype-environment association analyses suggested that genetic drift and the assorting of ancestral polymorphism may have played a more significant role in the speciation of R.liciae than nature selection or chromosomal rearrangements.We propose that R.liciae diverged from R.chrysanthemifolia through budding speciation,although post-divergence gene flow has obscured its phylogenetic signal.Additionally,we identified two potential parallel budding speciation events in R.sinuata at an earlier stage than R.liciae.Our study highlights budding speciation as a prevalent yet poorly characterized mode of plant speciation,with assorting of ancestral polymorphism as a key stochastic mechanism in the process.展开更多
Examining the pollination biology of plant species is not only crucial for enhancing our understanding of their reproductive biology,but also essential for elucidating their adaptation and evolutionary history.Here,we...Examining the pollination biology of plant species is not only crucial for enhancing our understanding of their reproductive biology,but also essential for elucidating their adaptation and evolutionary history.Here,we investigated the breeding system and pollination biology of two closely related species in Actaea.The flower of A.purpurea is unique in the genus with purple and chartaceous(paper-like)sepals,fewer stamens with yellow anthers and purple filaments.Through three seasons of field observation and exclusion experiments,we determined that A.purpurea was primarily pollinated by a hornet species,Vespa bicolor,which also served as the most efficient pollinator.In contrast,A.japonica was primarily pollinated by large flies.Actaea purpurea exhibited a significantly higher cumulative nectar volume than A.japonica,which could be a crucial factor in attracting V.bicolor.A control experiment further demonstrated that removing the nectar leaf(petal)significantly decreased the visiting frequency of V.bicolor.Breeding system studies revealed that both species were self-compatible,yet they primarily underwent outcrossing in natural habitats.Our study presents a compelling case of possible pollinator shift in A.purpurea accompanied by morphological divergence.A more in-depth investigation of this system would offer crucial insights into the extent to which pollinators are involved in the plant speciation process and whether they contribute to reproductive isolation between closely related species.展开更多
基金supported by the National Natural Science Foundation of China(grant nos.:32070236 and 32370226)the Innovation Capability Support Program of Shaanxi(No.2023KJXX-019)the Fundamental Research Funds for the Central Universities(No.GK202301008 to J.Q.Zhang,and No.LHRCCX23183 to L.Huang).
文摘Budding speciation is a process wherein a new species arises from a small,isolated population within or at the margin of an ancestral species.Well-documented cases of budding speciation are rare,and the roles of various evolutionary factors in this process remain controversial.Based on whole-genome resequencing data from 272 individuals across 27 populations,we reconstructed the evolutionary history of Rhodiola sect.Trifida and explored the relative contributions of natural selection,genetic drift,and chromosomal rearrangements as drivers of lineage divergence.We found that all samples of R.chrysanthemifolia(including R.alterna and R.sinuata)were clustered into three clades.Rhodiola liciae was sister to all other samples in the section,likely due to post-divergence gene flow and the minimal population structure of the progenitor species,while it shared the same ancestry with R.ch-I in population structure analyses.The two populations of R.sinuata were not monophyletic,instead clustering with geographically proximate populations of R.ch-III.Demographic analyses revealed that R.liciae underwent a contraction in population size following its divergence from R.ch-I approximately 0.34 million years ago(Mya),and has remained stable since around 0.1 Mya.Genomic islands and genotype-environment association analyses suggested that genetic drift and the assorting of ancestral polymorphism may have played a more significant role in the speciation of R.liciae than nature selection or chromosomal rearrangements.We propose that R.liciae diverged from R.chrysanthemifolia through budding speciation,although post-divergence gene flow has obscured its phylogenetic signal.Additionally,we identified two potential parallel budding speciation events in R.sinuata at an earlier stage than R.liciae.Our study highlights budding speciation as a prevalent yet poorly characterized mode of plant speciation,with assorting of ancestral polymorphism as a key stochastic mechanism in the process.
基金supported by the National Natural Science Foundation of China(31870194)the Innovation Capability Support Program of Shaanxi(Program No.2023KJXX-019)the Fundamental Research Funds for the Central Universities(GK202301008 to J.Q.Zhang).
文摘Examining the pollination biology of plant species is not only crucial for enhancing our understanding of their reproductive biology,but also essential for elucidating their adaptation and evolutionary history.Here,we investigated the breeding system and pollination biology of two closely related species in Actaea.The flower of A.purpurea is unique in the genus with purple and chartaceous(paper-like)sepals,fewer stamens with yellow anthers and purple filaments.Through three seasons of field observation and exclusion experiments,we determined that A.purpurea was primarily pollinated by a hornet species,Vespa bicolor,which also served as the most efficient pollinator.In contrast,A.japonica was primarily pollinated by large flies.Actaea purpurea exhibited a significantly higher cumulative nectar volume than A.japonica,which could be a crucial factor in attracting V.bicolor.A control experiment further demonstrated that removing the nectar leaf(petal)significantly decreased the visiting frequency of V.bicolor.Breeding system studies revealed that both species were self-compatible,yet they primarily underwent outcrossing in natural habitats.Our study presents a compelling case of possible pollinator shift in A.purpurea accompanied by morphological divergence.A more in-depth investigation of this system would offer crucial insights into the extent to which pollinators are involved in the plant speciation process and whether they contribute to reproductive isolation between closely related species.
