Hybridization and Reproductive Isolation among Syntopic Populations of the Topminnows Fundulus Notatus and F. Olivaceus


Fundulus notatus and Fundulus olivaceus are two closely related topminnow species that exhibit similar ecological niches and broad, largely overlapping, North American ranges extending throughout much of the Mississippi River drainage as well as the coastal drainages of the Gulf of Mexico. Previous studies have suggested that these two species are reproductively compatible despite cytogenetic differences and will hybridize when syntopic. We used nuclear and mtDNA loci to assess levels of hybridization and test for introgression in syntopic populations of these two species in four drainages in southern Illinois. Although hybridization was detected in all syntopic populations, an assessment of the proportion of hybrid individuals indicated a deficiency of hybrids relative to expectations under random mating. We determined that, although mtDNA introgression was prevalent and extended beyond the zones of contact, evidence of nuclear introgression was limited to the zone of sympatry.


Biological Sciences

Keywords and Phrases

microsatellite DNA; mitochondrial DNA; primer DNA; fish; hybrid zone; hybridization; introgression; reproductive isolation; sympatry; animal; Bayes theorem; biological model; cluster analysis; comparative study; Cyprinodontiformes; DNA sequence; gene frequency; genetics; molecular genetics; nucleotide sequence; phylogeny; polymerase chain reaction; population genetics; reproduction; restriction fragment length polymorphism; species differentiation; United States; Animals; Base Sequence; DNA Primers; DNA; Mitochondrial; Fundulidae; Genetic Speciation; Population; Genetic; Microsatellite Repeats; Models; Molecular Sequence Data; Polymorphism; Restriction Fragment Length; Sequence Analysis; Illinois; North America; Fundulus heteroclitus; Fundulus notatus; Fundulus olivaceus; Cytochrome b; Killifish; Microsatellite; Nuclear; SNP

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Article - Journal

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© 2007 Wiley-Blackwell, All rights reserved.

Publication Date

01 Sep 2007