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Phylogenetic analysis of cryptic speciation in the polychaete Pygospio elegans
Ecology and Evolution
|July 28, 2012
Summary
Poecilogony, the presence of multiple developmental modes within one species, was confirmed in the marine worm Pygospio elegans. Genetic analysis revealed this variation is not due to cryptic speciation but is a true characteristic of the species.
Area of Science:
- Marine Biology
- Evolutionary Biology
- Genetics
Background:
- Marine invertebrates exhibit diverse developmental modes, usually uniform within a species.
- Poecilogony, multiple developmental modes in one species, is rare and often mistaken for cryptic speciation.
- The marine polychaete worm Pygospio elegans presents a case for studying true poecilogony.
Purpose of the Study:
- To investigate if poecilogony in Pygospio elegans is a result of cryptic speciation.
- To analyze the genetic diversity and population structure of Pygospio elegans across different developmental modes.
Main Methods:
- Phylogenetic analysis using mitochondrial cytochrome c oxidase subunit I (COI) gene sequences.
- Sampling of 279 individual Pygospio elegans worms across diverse geographic and environmental scales.
- Analysis of sequence variation, haplotype diversity, and population structure.
Main Results:
- Low genetic divergence (1.7%) among European Pygospio elegans populations, with most variation occurring within populations.
- Widespread common haplotypes found across populations, including those with different developmental modes.
- Predominantly planktonic populations exhibited higher numbers of population-specific, low-frequency haplotypes compared to brooded populations.
Conclusions:
- The study supports true poecilogony in Pygospio elegans, refuting the hypothesis of cryptic speciation.
- Developmental mode variation within Pygospio elegans is an intrinsic species trait.
- Planktonic developmental modes correlate with higher genetic diversity, consistent with interspecies patterns.
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