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In Situ Hybridization Techniques for Paraffin-Embedded Adult Coral Samples
Published on: August 31, 2018
Introgression despite substantial divergence in a broadcast spawning marine invertebrate
Marie L Nydam1, Richard G Harrison
1Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York 14853, USA. mln32@cornell.edu
Evolution; International Journal of Organic Evolution
|November 4, 2010
Summary
Marine broadcast spawners, like Ciona intestinalis, show evidence of hybridization even at high genetic divergence. This suggests weaker reproductive barriers may exist between these species than previously thought.
Area of Science:
- Marine biology
- Speciation research
- Evolutionary genetics
Background:
- Understanding speciation requires knowledge of reproductive isolation and divergence times.
- Marine broadcast spawners are understudied regarding hybridization and divergence.
- Cryptic species within Ciona intestinalis present an opportunity to study these relationships.
Purpose of the Study:
- Investigate sympatric distribution of Ciona intestinalis types A and B.
- Determine evidence of hybridization and introgression between C. intestinalis types.
- Analyze reproductive isolation versus divergence patterns in marine broadcast spawners.
Main Methods:
- Field surveys to identify sympatric populations of Ciona intestinalis.
- Genetic analysis (mtCOI sequencing) to assess divergence and introgression.
- Comparative analysis with existing data on marine broadcast spawners.
Main Results:
- Ciona intestinalis types A and B were found sympatrically.
- 21 out of ~500 individuals showed evidence of introgression.
- Types A and B exhibit 12.4% mitochondrial COI divergence, near the limit for introgression.
Conclusions:
- Hybridization and introgression occur in marine broadcast spawners at significant genetic divergence levels.
- The findings question the strength of postmating prezygotic reproductive barriers in these species.
- Further research is needed to understand speciation mechanisms in marine broadcast spawners.
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