A new species of Populus and the extensive hybrid speciation arising from it on the Qinghai-Tibet Plateau.

While the diversity of species formation is broadly acknowledged, significant debate exists regarding the universal nature of hybrid species formation. Through an 18-year comprehensive study of all Populus species on the Qinghai-Tibet Plateau, 23 previously recorded species and 8 new species were identified. Based on morphological characteristics, these can be classified into three groups: species in section Leucoides, species with large leaves, and species with small leaves in section Tacamahaca. By conducting whole-genome re-sequencing of 150 genotypes from these 31 species, 2.28 million single nucleotide polymorphisms (SNPs) were identified. Phylogenetic analysis utilizing these SNPs not only revealed a highly intricate evolutionary network within the large-leaf species of section Tacamahaca but also confirmed that a new species, P. curviserrata, naturally hybridized with P. cathayana, P. szechuanica, and P. ciliata, resulting in 11 hybrid species. These findings indicate the widespread occurrence of hybrid species formation within this genus, with hybridization serving as a key evolutionary mechanism for Populus on the plateau. A novel hypothesis, "Hybrid Species Exterminating Their Ancestral Species (HSEAS)," is introduced to explain the mechanisms of hybrid species formation at three different scales: the entire plateau, the southeastern mountain region, and individual river valleys.

Novel IKZF3 transcriptomic signature correlates with positive outcomes of skin cutaneous melanoma: A pan-cancer analysis.

To investigate the potential relationship between Ikaros family genes and skin cutaneous melanoma (SKCM), we undertook a pan-cancer analysis of the transcriptional signature and clinical data of melanoma through multiple databases. First, 10,327 transcriptomic samples from different cancers were included to determine the overall characteristics and clinical prognoses associated with Ikaros gene expression across cancer types. Second, differentially expressed genes analysis, prognostic evaluation, and gene set enrichment analysis were employed to investigate the role of Ikaros (IKZF) genes in SKCM. Third, we evaluated the relationship between Ikaros family genes and SKCM immune infiltrates and verified the findings using the GEO single-cell sequencing dataset. The results show that Ikaros genes were widely expressed among different cancer types with independently similar patterns as follows: 1. IKZF1 and IKZF3, and 2. IKZF2 and IKZF4-5. IKZF2 and IKZF5 were downregulated in the primary tumor, and IKZF1-3 expression decreased significantly as the T-stage or metastasis increased in SKCM. Moreover, high IKZF1-3 expression was associated with better overall survival, disease-specific survival, and progression-free interval. IKZF3 is an independent prognostic factor of SKCM. Among Ikaros genes, the expression of IKZF1 and IKZF3 positively correlated with the infiltration level of CD4+ T cells and CD8+ T cells, B cells, and Tregs in SKCM and negatively correlated with the infiltration level of M0 and M1 macrophages. Moreover, single-cell sequencing data analysis revealed that IKZF1 and IKZF3 were mainly expressed by immune cells. Correlation analysis shows the immune factors and drug responses associated with IKZF3 expression. In conclusion, the present study is the first, to our knowledge, to identify a pan-cancer genomic signature of the Ikaros gene family among different cancers. Expression of these family members, particularly high levels of IKZF3, indicate positive immunological status and beneficial clinical outcomes of SKCM. IKZF3 may therefore serve as potential targets for immunotherapy of melanoma.