Hybridization and Introgression in Two Ecologically Dissimilar Fundulus Hybrid Zones
Hybridization and introgression appear more common in rapidly evolving groups, suggesting an important role in the evolutionary process. Detailed studies of how extrinsic or intrinsic forces regulate hybridization and introgression have the potential for broadening our understanding of mechanisms generating diversity. Species in the Fundulus notatus species complex have broad overlapping ranges and occur in replicated hybrid zones along predictable stream gradients. Typical hybrid zone structure has Fundulus olivaceus in headwaters, F. notatus downstream, and hybrid zones near confluences or abrupt shifts in habitat. Rarely, the typical upstream-downstream orientation is reversed raising questions as to how hybrid zones are formed and maintained. We used next-generation sequencing data to study hybridization and introgression in hybrid zones in neighboring drainages that differ in orientation (typical and reversed). We predicted extrinsic forces linked to stream gradients would result in noticeable differences between the two. Contrary to predictions, the data indicate the hybrid zones are remarkably similar. We used individual-based simulations to explore the potential role of intrinsic and extrinsic forces in generating and maintaining typical and reversed hybrid zones. Simulation results were consistent with reversed hybrid zones being formed from stochastic processes combined with strong intrinsic forces and weak extrinsic forces.
J. F. Schaefer et al., "Hybridization and Introgression in Two Ecologically Dissimilar Fundulus Hybrid Zones," Evolution, vol. 70, no. 5, pp. 1051-1063, Society for the Study of Evolution, May 2016.
The definitive version is available at https://doi.org/10.1111/evo.12920
Keywords and Phrases
Fundulus; Fundulus notatus; Fundulus olivaceus; animal; biological model; computer simulation; Fundulidae; genetic variation; genetics; hybridization; Markov chain; reproductive isolation; river; Animals; Genetic; Models; Rivers; Stochastic Processes; Extrinsic selection; Intrinsic selection; Population genomics; Simulation; SNP; Unified neutral theory of biodiversity
International Standard Serial Number (ISSN)
Article - Journal
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