Population Genetics of Fundulus Heterclitus in the Hudson river and North New Jersey Estuaries: Evaluation of Subspecies Boundary and Hybridization with F. Diopaanus
The mummichog Fundulus heteroclitus is a common estuarine fish, chiefly occupying marshes from Newfoundland to Florida. It consists of two subspecies, very similar by adult morphology, but different genetically, in egg morphology and spawning site preference. According to DNA sequence analyses, thes...
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Hudson River Foundation
1995
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| Online Access: | https://dx.doi.org/10.7282/t3sn084w https://rucore.libraries.rutgers.edu/rutgers-lib/35266/ |
| Summary: | The mummichog Fundulus heteroclitus is a common estuarine fish, chiefly occupying marshes from Newfoundland to Florida. It consists of two subspecies, very similar by adult morphology, but different genetically, in egg morphology and spawning site preference. According to DNA sequence analyses, these two taxa diverged between 0.5-1.0 million y.a. To reveal the boundary zone between subspecies, murnmichogs were sampled in 24 sites between Tuckerton, NJ, New Haven, CT, and Tivoli Bay on the Hudson River. Allozymes were resolved using horizontal starch gel electrophoresis. RFLP analysis of the peR-amplified mitochondrial DNA regulatory region was performed to reveal mtDNA haplotype frequencies. Our results indicate that these two subspecies are now isolated by a 120 -150 km area between the Wreck Pond (Sea Girt, NJ) and downriver parts of the Hudson and Hackensack river estuaries, occupied by another subspecies - Fundulus heteroclitus intermedius ssp. n. - taxon with clear hybrid origin, but yet genetically distinct from both parent subspecies. F. h. heteroclitus and F. h. intermedius are now separated by a 5 km long strip of sand beaches between Sea Girt and Belmar, NJ, where a sharp shift in Mdh-A and mtDNA haplotypes frequencies occurs. The heterozygote deficiency for Mdh-A allele in two sites on the Hudson and Hackensack rivers indicates that the highly polymorphic F. h. intermedius in NYINJ Harbor estuaries has become reproductively isolated from F. h. macrolepidorus. As a second part of the study, hybridization zones between F. h. macrolepidotus and freshwater F. diaphanus have been found and characterized in two locations on the Hudson River. |
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