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Population-level mating patterns and fluctuating asymmetry in swordtail hybrids
Zachary W Culumber1, Gil G Rosenthal
1Centro de Investigaciones Biológicas, Universidad Autónoma del Estado de Hidalgo, Pachuca, Hidalgo, Mexico. zculumber@gmail.com
Die Naturwissenschaften
|June 19, 2013
Summary
Structured populations of swordtail fish show lower fluctuating asymmetry (FA) in their vertical bars. This indicates that non-random mating patterns, not hybridization itself, influence this measure of developmental stability.
Area of Science:
- Evolutionary biology
- Animal behavior
- Genetics
Background:
- Morphological symmetry is linked to fitness and mate choice across many species.
- Fluctuating asymmetry (FA), a measure of developmental instability, is expected to decrease under strong sexual selection.
- Hybrid populations of swordtails (Xiphophorus birchmanni and Xiphophorus malinche) exhibit a spectrum from panmictic to highly structured, with maintained reproductive isolation.
Purpose of the Study:
- To investigate the relationship between population structure, mating patterns, and fluctuating asymmetry (FA) in swordtail fish.
- To determine if FA in sexually selected traits differs between structured and unstructured hybrid populations and parental species.
Main Methods:
- Quantified fluctuating asymmetry (FA) in the vertical bars of Xiphophorus swordtails.
- Compared FA levels across parental species, unstructured hybrid populations, and structured hybrid populations.
- Correlated FA with observed mating patterns within these populations.
Main Results:
- Fluctuating asymmetry (FA) in vertical bars was significantly lower in structured hybrid populations compared to parental and unstructured hybrid populations.
- No significant difference in FA was found between parental species and unstructured hybrid populations.
- These findings suggest hybridization itself does not impact FA, but rather population structure and associated mating patterns do.
Conclusions:
- Population structure, specifically non-random mating in structured populations, is a key driver of reduced fluctuating asymmetry (FA) in sexually selected traits.
- The study highlights the role of mating systems in shaping developmental stability and morphological traits in hybridizing species.
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