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Evidence of whole-genome duplications (WGDs) and subsequent karyotype changes has been detected in most major lineages of living organisms on Earth. To clarify the complex resulting multi-layered patterns of gene collinearity in genome analyses, there is a need for convenient and accurate toolkits. To meet this need, we developed WGDI (Whole-Genome Duplication Integrated analysis), a Python-based command-line tool that facilitates comprehensive analysis of recursive polyploidization events and cross-species genome alignments. WGDI supports three main workflows (polyploid inference, hierarchical inference of genomic homology, and ancestral chromosome karyotyping) that can improve the detection of WGD and characterization of WGD-related events based on high-quality chromosome-level genomes. Significantly, it can extract complete synteny blocks and facilitate reconstruction of detailed karyotype evolution. This toolkit is freely available at GitHub (https://github.com/SunPengChuan/wgdi). As an example of its application, WGDI convincingly clarified karyotype evolution in Aquilegia coerulea and Vitis vinifera following WGDs and rejected the hypothesis that Aquilegia contributed as a parental lineage to the allopolyploid origin of core dicots. This work reports an integrated and user-friendly toolkit, WGDI,for polyploid inference, hierarchical inference of genomic homology, and ancestral chromosome karyotyping. WGDI can improve the detection of whole-genome duplication and facilitates dynamic illumination of karyotype evolution. [ABSTRACT FROM AUTHOR]

It is increasingly realized that homoploid hybrid speciation (HHS), which involves no change in chromosome number, is an important mechanism of speciation. HHS will likely increase in frequency as ecological and geographical barriers between species are continuing to be disrupted by human activities. HHS requires the establishment of reproductive isolation between a hybrid and its parents, but the underlying genes and genetic mechanisms remain largely unknown. In this study, we reveal by integrated approaches that reproductive isolation originates in one homoploid hybrid plant species through the inheritance of alternate alleles at genes that determine parental premating isolation. The parent species of this hybrid species are reproductively isolated by differences in flowering time and survivorship on soils containing high concentrations of iron. We found that the hybrid species inherits alleles of parental isolating major genes related to flowering time from one parent and alleles of major genes related to iron tolerance from the other parent. In this way, it became reproductively isolated from one parent by the difference in flowering time and from the other by habitat adaptation (iron tolerance). These findings and further modeling results suggest that HHS may occur relatively easily via the inheritance of alternate parental premating isolating genes and barriers. Using integrated approaches, the authors reveal that reproductive isolation originated in one homoploid hybrid plant species (Ostryopsis intermedia) through the inheritance of alternate alleles at genes that determine parental premating isolation (flowering time and habitat adaptation, i.e., iron tolerance). Their findings and further modeling results suggest that homoploid hybrid speciation can occur easily via the inheritance of alternate, pre-existing, parental reproductive isolations. [ABSTRACT FROM AUTHOR]

Parallel evolution of reproductive isolation (PERI) provides strong evidence for natural selection playing a fundamental role in the origin of species. However, PERI has been rarely demonstrated for well established species drawn from different genera. In particular, parallel molecular signatures for the same genes in response to similar habitat divergence in such different lineages is lacking. Here, based on whole-genome sequencing data, we first explore the speciation process in two sister species of Carpinus (Betulaceae) in response to divergence for temperature and soil-iron concentration in habitats they occupy in northern and southwestern China, respectively. We then determine whether parallel molecular mutations occur during speciation in this pair of species and also in another sister-species pair of the related genus, Ostryopsis , which occupy similarly divergent habitats in China. We show that gene flow occurred during the origin of both pairs of sister species since approximately 9.8 or approximately 2 million years ago, implying strong natural selection during divergence. Also, in both species pairs we detected concurrent positive selection in a gene ( LHY ) for flowering time and in two paralogous genes ( FRO4 and FRO7 ) of a gene family known to be important for iron tolerance. These changes were in addition to changes in other major genes related to these two traits. The different alleles of these particular candidate genes possessed by the sister species of Carpinus were functionally tested and indicated likely to alter flowering time and iron tolerance as previously demonstrated in the pair of Ostryopsis sister species. Allelic changes in these genes may have effectively resulted in high levels of prezygotic reproductive isolation to evolve between sister species of each pair. Our results show that PERI can occur in different genera at different timescales and involve similar signatures of molecular evolution at genes or paralogues of the same gene family, causing reproductive isolation as a consequence of adaptation to similarly divergent habitats., Competing Interests: The authors declare no competing interests., (© 2022 The Author(s).)