Sex chromosome evolution in Salix

NAISS 2024/5-174


NAISS Medium Compute

Principal Investigator:

Sophie Karrenberg


Uppsala universitet

Start Date:


End Date:


Primary Classification:

10615: Evolutionary Biology

Secondary Classification:

10609: Genetics (medical to be 30107 and agricultural to be 40402)




The evolution of separate sexes is of fundamental importance in biology. Sex determining mechanisms are highly variable and labile and sex chromosomes often degenerate; however, the underlying evolutionary mechanisms are unclear. Theoretical studies predict that sex chromosome evolution is driven by sex ratio selection and/or by different forms of genetic conflict, for example, between males and females or between cytoplasm and nucleus. Empirical evidence for these predictions is scarce, in part because the best-studied systems are animals with ancient sex chromosomes. This project investigates a plant family with separate sexes (Salicaeae, willows and poplars) where a high turnover of recently emerged sex chromosomes has been suggested and sex ratio bias is common. The project has three main objectives: (1) identify the mechanisms for sex determination and sex ratio bias, (2) analyze signs of degeneration in sex-associated region(s), and (3) investigate the evolutionary history and dynamics of genomic region(s) associated with sex-determination and sex-ratio bias. We will combine sex ratio analysis in natural populations and transmission analysis of sex-associated polymorphisms in controlled crosses with whole-genome sequencing, comparative population genomic analyses and theoretical modeling. This comprehensive approach will allow us to gain novel insights into sex chromosome evolution and evolutionary processes at large.