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Relative fitness components measured with competitive PCR
L M Wooninck1, R R Warner, R C Fleischer
1Department of Ecology, Evolution and Marine Biology, University of California, Santa, Barbara, CA, 93106, USA. wooninck@lifesci.ucsb.edu
Molecular Ecology
|September 6, 2000
Summary
A new competitive PCR method accurately measures relative sperm output and estimates paternity in species with sperm competition. This technique reveals ejaculate size alone does not predict paternity outcomes.
Area of Science:
- Reproductive Biology
- Molecular Ecology
- Behavioral Ecology
Background:
- Sperm competition is common in many species, making paternity determination crucial.
- Existing DNA-based paternity methods are often costly, labor-intensive, and challenging for highly fecund species.
- Understanding the link between sperm number and paternity is a key objective in reproductive studies.
Purpose of the Study:
- To develop a novel, efficient method for assessing relative sperm output and paternity in sperm competition.
- To simultaneously estimate paternity distributions for numerous offspring from large mating events.
- To investigate the relationship between male ejaculate size and realized paternity.
Main Methods:
- Development of a competitive polymerase chain reaction (PCR) protocol combined with automated sequencing.
- Calibration of the competitive PCR technique using a microsatellite locus in the bluehead wrasse (Thalassoma bifasciatum).
- Application of the method to estimate paternity distributions in multiple larvae from natural mating events.
Main Results:
- The competitive PCR protocol accurately reflected initial DNA template proportions, validating its use for quantifying relative sperm contributions.
- Paternity distributions estimated using the new PCR method closely matched those obtained by traditional individual-based analyses.
- Comparison of paternity with sperm contribution revealed that ejaculate size alone is not a sole predictor of a male's share of paternity.
Conclusions:
- The developed competitive PCR technique offers a robust and efficient tool for studying sperm competition and paternity.
- This method overcomes limitations of traditional techniques, particularly for highly fecund species.
- Male reproductive success in sperm competition is influenced by factors beyond just ejaculate volume.