Sex chromosomes can evolve when recombination is halted between a pair of chromosomes, and this can lead to degeneration of the sex-limited chromosome. In the early stages of differentiation sex chromosomes are homomorphic, and even though homomorphic sex chromosomes are very common throughout animals and plants, we know little about the evolutionary forces shaping these types of sex chromosome...

Related species share genetic and developmental backgrounds. Therefore, separate-sex species that share recent common ancestors with hermaphroditic species may have hidden genetic variation for sex determination that causes some level of lability of expression of gender. Worms of the polychaete species Ophryotrocha labronica have separate, dimorphic sexes and their ancestor was hermaphroditic. ...

Recent evidence has suggested that clades of dioecious angiosperms have fewer extant species on average than those of cosexual (hermaphroditic and monoecious) relatives. Reasons for the decrease in speciation rates and/or increase in extinction rates are only beginning to be investigated. One possibility is that dioecious species suffer a competitive disadvantage with cosexuals because only hal...

a 5 # Equal contribution 6 Departments of a Botany, 19 Supplementary information: All supplementary files will be made available upon request. 20 Data Accessibility: All sequence data will be deposited on Genbank and SRA and all 21 other data files on Dryad. 22 23 peer-reviewed) is the author/funder. All rights reserved. No reuse allowed without permission. Abstract 24 All species of the genus ...

All species of the genus Populus (poplar, aspen) are dioecious, suggesting an ancient origin of this trait. Despite some empirical counter examples, theory suggests that nonrecombining sex-linked regions should quickly spread, eventually becoming heteromorphic chromosomes. In contrast, we show using whole-genome scans that the sex-associated region in Populus trichocarpa is small and much young...

Sexual systems are highly variable in flowering plants and an important contributor to floral diversity. The ranunculid genus Thalictrum is especially well-suited to study evolutionary transitions in sexual systems. Homeotic transformation of sexual organs (stamens and carpels) is a plausible mechanism for the transition from hermaphroditic to unisexual flowers in this lineage because flowers o...

Abstract Tertiary relicts often show evolutionary stasis in morphology and ecology have been hypothesized to retain stable population sizes refugia. However, recent studies reported that some evolutionarily shifted their physiology, ecology, experienced various patterns of demography. To understand the historical survival relict plants, a multidimensional study investigating evolution ecologica...