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Why do schistosomes have separate sexes?
1Department of Health Research and Policy, Stanford University School of Medicine, Stanford, CA 94305, USA.
Parasitology Today (Personal Ed.)
|May 1, 1990
Summary
Schistosoma evolved from hermaphroditic ancestors, leading to sexual dimorphism in modern flukes. Male schistosomes retain ancestral traits and support females, who have lost key structures for reproductive efficiency.
Area of Science:
- Evolutionary biology
- Parasitology
- Reproductive biology
Background:
- The evolution of Schistosoma from hermaphroditic ancestors is proposed.
- Hermaphroditism in ancestral blood flukes offered reproductive advantages.
- The transition to warm-blooded hosts influenced fluke evolution.
Purpose of the Study:
- To explore the evolutionary pathway of Schistosoma from hermaphroditic flukes.
- To understand the development of sexual dimorphism in Schistosoma.
- To investigate the persistent ancestral genome fragments in male Schistosoma.
Main Methods:
- Comparative genomic analysis of ancestral and present-day Schistosoma.
- Analysis of reproductive strategies and genome remnants.
- Morphological and functional comparison between male and female Schistosoma.
Main Results:
- Sexual separation and dimorphism arose from reproductive advantages in hermaphroditic ancestors.
- Male Schistosoma retain significant fragments of the ancestral contrasex genome.
- Female Schistosoma exhibit a more complete loss of the male-specific genome, sacrificing structural elements.
Conclusions:
- Modern Schistosoma exhibit sexual dimorphism driven by evolutionary optimization of reproduction.
- Males play a compensatory role, facilitating female survival and reproduction through transport and physiological support.
- The evolutionary trajectory highlights the trade-offs between reproductive efficiency and structural integrity.