Käfer, J. | bioRxiv Science

bioRxiv2026

Genomic insights into sex-linked regions and dioecy in the ivory palm (Phytelephas aequatorialis)

Background and Aims: Dioecy has evolved independently multiple times in Palms, yet the genetic mechanisms underlying sex determination remain poorly understood across the family. Current knowledge is limited to genera from the subfamily Coryphoideae, in which Phoenix and Kerriodoxa independently recruited the same genomic region as the sex determining locus, suggesting a potentially convergent evolutionary pathway. Whether this pattern extends across the family remains unknown. Here, we investigate the genetic basis of sex determination in Phytelephas aequatorialis, from the Ceroxyloideaea palm subfamily, to identify its sex chromosome system, sex-linked genomic region, and candidate sex-determining genes. Methods: Using exon capture sequencing data from male and female individuals of P. aequatorialis, we analyzed genome wide sequence polymorphisms to detect signatures of sex linkage. Key Results: Our analyses reveal an XY sex chromosome system in Phytelephas, similar to that reported in the few dioecious palm species investigated to date. However, sex linkage maps to a distinct genomic region, indicating an independent origin of the sex-determining locus. We further identified 16 high confidence sex-linked genes with key roles in developmental processes and hormone signaling pathways, making them key candidates for involvement in sex determination. Sex-specific genetic markers were successfully developed from a subset of these genes. Conclusions: Our study suggests that in P. aequatorialis, the independent evolution of sex separation has relied on distinct genomic regions and genes, highlighting multiple evolutionary pathways leading to dioecy across the palm family. Comparative genomic analyses across additional lineages will be essential to reconstruct the evolutionary history of sex chromosomes and sex separation in this family.

plant biology↗

bioRxiv2022

Trait-dependent diversification in angiosperms: patterns, models and data

Variation in species richness across the tree of life, accompanied by the incredible variety of ecological and morphological characteristics found in nature, has inspired many studies to link traits with species diversification. Angiosperms are a highly diverse group that has fundamentally shaped life on earth since the Cretaceous, and illustrate how species diversification affects ecosystem functioning. Numerous traits and processes have been linked to differences in species richness within this group, but we know little about how these interact and their relative importance. Here, we synthesized data from 152 studies that used state-dependent speciation and extinction (SSE) models on angiosperm clades. Intrinsic traits related to reproduction and morphology were often linked to diversification but a set of universal drivers did not emerge as traits did not have consistent effects across clades. Importantly, dataset properties were correlated to SSE model results - trees that were larger, older, or less well-sampled tended to yield trait-dependent outcomes. We compared these properties to recommendations for SSE model use and provide a set of best practices to follow when designing studies and reporting results. Finally, we argue that SSE model inferences should be considered in a larger context incorporating species ecology, demography and genetics.

evolutionary biology↗