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Coexisting cyclic parthenogens comprise a holocene species flock in Eubosmina
Markéta Faustová1, Veronika Sacherová, H David Sheets
1Department of Biological Sciences, State University of New York at Buffalo, Buffalo, New York, United States of America. marfaustova@hotmail.com
Plos One
|July 28, 2010
Summary
Cyclic parthenogens like Eubosmina may form distinct species despite asexual reproduction. Genetic and morphometric analyses reveal reproductive barriers, suggesting young species are actively diverging.
Area of Science:
- Evolutionary Biology
- Genetics
- Limnology
Background:
- Mixed breeding systems with extended clonal phases and weak sexual recruitment are common but thought to hinder species formation.
- Cyclic parthenogens, such as cladocerans, may face challenges in establishing discrete species.
- The cladoceran Eubosmina presents a unique case with proposed sympatric species and a Holocene fossil record, making it ideal for studying speciation.
Purpose of the Study:
- To test the hypothesis that Eubosmina represents a single polymorphic species in four northern European lakes.
- To investigate the evolutionary significance of morphotypic variation in Eubosmina under natural coexistence.
- To determine if extended clonal phases and weak sexual recruitment inhibit speciation in Eubosmina.
Main Methods:
- Nuclear and mitochondrial DNA sequencing of coexisting Eubosmina morphotypes.
- Morphometric analysis of Eubosmina populations from four northern European lakes.
- Comparative analysis of genetic differentiation and morphometric variation.
Main Results:
- Significant genetic differentiation was observed between coexisting Eubosmina morphotypes.
- Genealogical exclusivity was demonstrated for the studied morphotypes.
- Distinct morphometric differences were found, supporting reproductive isolation.
Conclusions:
- The studied Eubosmina morphotypes represent young, diverging species.
- Apparent reproductive barriers exist despite sympatric coexistence in the freshwater pelagic zone.
- Speciation is occurring in Eubosmina, challenging previous assumptions about cyclic parthenogens.
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