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In between breeding systems: neither dioecy nor androdioecy explains sexual polymorphism in functionally dioecious
M Cristina Lorenzi1, Gabriella Sella
1Università di Torino, Department of Life Sciences and Systems Biology, University of Turin, via Accademia Albertina 13, 10123 Torino, Italy.
Integrative and Comparative Biology
|May 11, 2013
Summary
The study on Ophryotrocha labronica reveals hidden genetic variation for sex determination, showing intermediate sexual phenotypes between separate sexes and hermaphroditism in different populations.
Area of Science:
- Evolutionary biology
- Genetics
- Marine biology
Background:
- Related species share genetic backgrounds, suggesting potential for hidden variation in sex determination.
- The polychaete worm Ophryotrocha labronica, with separate sexes, evolved from a hermaphroditic ancestor.
- Geographic populations of O. labronica may exhibit varying degrees of gender specialization.
Purpose of the Study:
- To analyze the extent of fixed versus labile gender expression in Ophryotrocha labronica.
- To investigate the variation in sexual phenotypes across geographically distinct populations.
- To understand the continuum between androdioecy and dioecy in breeding systems.
Main Methods:
- Phenotypic analysis of sexual morphs in three geographically distinct populations.
- Observation of sexual dimorphism and gamete presence in O. labronica.
- Assessment of functional hermaphroditism and gamete usage for reproduction.
Main Results:
- Up to four sexual phenotypes were identified: pure males, males with oocytes, pure females, and females with sperm.
- The frequency of these sexual phenotypes varied significantly among the studied populations.
- Less dioecious-like populations showed weaker sexual dimorphism and traits indicative of hermaphroditism, such as plastic female allocation.
Conclusions:
- Ophryotrocha labronica populations represent novel intermediate states between androdioecy and dioecy.
- Sexual development in this species exhibits a gradient rather than distinct categories.
- The findings contribute to a broader understanding of the evolution of breeding systems.
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