Evol Ecol Res 19: 365-386 (2018)     Full PDF if your library subscribes.

Differences and similarities of sex ratios between dioecious angiosperms and dioicous bryophytes

Tom J. de Jong1, Heinjo J. During2 and Avi Shmida3

1Leiden University, Leiden, The Netherlands,  2Utrecht University, Utrecht, The Netherlands and 3Center for Rationality and Department of Ecology, Evolution and Behavior, The Hebrew University of Jerusalem, Jerusalem, Israel

Correspondence: T.J. de Jong, Leiden University, PO Box 9516, 2300 RA Leiden, The Netherlands. email: tomdejong@yahoo.com


Observation: For plant species with separate sexes, the average population sex ratio is female biased in mosses and liverworts, male biased in trees and shrubs, and unbiased in short-lived herbs.

Key assumption: When fertilization occurs, female investment in reproduction greatly outweighs male investment.

Questions: Can we explain the general pattern in population sex ratios from primary sex ratios in seeds or spores? What does genomic conflict theory predict for sex ratios of angiosperms and bryophytes? Are there other explanatory factors?

Data studied: Literature review of variation in sex ratio found in seeds and spores and of male and female performance.

Conclusion: Primary sex ratios were often variable, suggesting genomic conflict involving both cytoplasmic factors and sex-linked drive. Even though theory predicts some differences, primary sex ratios of angiosperms and bryophytes were remarkably similar. Males sometimes perform worse than females in the pre-reproductive phase and this may result in a female bias before reproduction occurs. In the reproductive stage, females invest more than males and may suffer greater mortality. The sex ratio of a cohort may then slowly change from female to male bias. This might explain the different population sex ratios of short-lived (herbs) and long-lived angiosperms (trees). In bryophytes, low fertilization rates, reducing female allocation to reproduction, could shift the balance towards consistent female bias in their populations.

Keywords: cytoplasmic DNA, dioecy, gene drive, genomic conflict, sex allocation theory.

IF you are connected using the IP of a subscribing institution (library, laboratory, etc.)
or through its VPN.


        © 2018 Tom J. de Jong. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.

       Subscribing institutions/libraries may grant individuals the privilege of making a single copy of an EER article for non-commercial educational or non-commercial research purposes. Subscribing institutions/libraries may also use articles for non-commercial educational purposes by making any number of copies for course packs or course reserve collections. Subscribing institutions/libraries may also loan single copies of articles to non-commercial libraries for educational purposes.

       All copies of abstracts and articles must preserve their copyright notice without modification.