title: Hybridization and reproductive isolation among syntopic populations of the topminnows Fundulus notatus and F. olivaceus.
abstract: 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.
authors.affiliation: Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL 62026, USA. dduvern@siue.edu
authors.forename: D D
authors.initials: DD
authors.lastname: Duvernell
authors.forename: J F
authors.initials: JF
authors.lastname: Schaefer
authors.forename: D C
authors.initials: DC
authors.lastname: Hancks
authors.forename: J A
authors.initials: JA
authors.lastname: Fonoti
authors.forename: A M
authors.initials: AM
authors.lastname: Ravanelli
mesh_terms: D000818:Animals; D001483:Base Sequence; D001499:Bayes Theorem; D016000:Cluster Analysis; D017931:DNA Primers; D004272:DNA, Mitochondrial / Q000235:genetics; D023781:Fundulidae / Q000235:genetics*; D005787:Gene Frequency; D049810:Genetic Speciation; D005828:Genetics, Population; D006824:Hybridization, Genetic; D018895:Microsatellite Repeats / Q000235:genetics; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012098:Reproduction / Q000235:genetics*; D017422:Sequence Analysis, DNA; D014481:United States
chemical_list: D017931:DNA Primers; D004272:DNA, Mitochondrial