A few traditionally applied diagnostic characters of color pattern were compared with an additional set of morphological and genetic characters to evaluate differences between Nerodia sipedon and N. fasciata and to study the dynamics across their hybrid zone in the Carolinas. Many of the morphological characters exhibited significant interspecific differences, although only the number of dorsally complete crossbands (CBa) was diagnostic by itself. A discriminant function analysis of morphological characters was successful in separating both taxa. Species-specific nuclear markers, identified by the AFLP (Amplified Fragment Length Polymorphism) technique were nearly fixed and served as diagnostic markers. They revealed extensive introgression between the two species not recognizable morphologically. Markers for N. sipedon and F1 hybrids, backcrossed to a parental species exhibiting more than one introgressive marker, were less frequent than expected at Hardy-Weinberg equilibrium, implying selection against N. sipedon and hybrids with an increased introgression, respectively. This is consistent with a pronounced genetic and morphological dominance of N. fasciata in the hybrid zone. The genetic results show that the two taxa are independent entities and qualify for species status under both the Phylogenetic Species Concept and the Evolutionary Species Concept. N. fasciata and N. sipedon segregate ecologically along ecotones of salinity, temperature, and water current. Variation in the width of these ecotones is reflected in the width of hybrid zones.
","abstract_html":"<p>A few traditionally applied diagnostic characters of color pattern were compared with an additional set of morphological and genetic characters to evaluate differences between <em>Nerodia sipedon</em> and <em>N. fasciata</em> and to study the dynamics across their hybrid zone in the Carolinas. Many of the morphological characters exhibited significant interspecific differences, although only the number of dorsally complete crossbands (CBa) was diagnostic by itself. A discriminant function analysis of morphological characters was successful in separating both taxa. Species-specific nuclear markers, identified by the AFLP (Amplified Fragment Length Polymorphism) technique were nearly fixed and served as diagnostic markers. They revealed extensive introgression between the two species not recognizable morphologically. Markers for <em>N. sipedon</em> and F1 hybrids, backcrossed to a parental species exhibiting more than one introgressive marker, were less frequent than expected at Hardy-Weinberg equilibrium, implying selection against <em>N. sipedon</em> and hybrids with an increased introgression, respectively. This is consistent with a pronounced genetic and morphological dominance of <em>N. fasciata</em> in the hybrid zone. The genetic results show that the two taxa are independent entities and qualify for species status under both the Phylogenetic Species Concept and the Evolutionary Species Concept. <em>N. fasciata</em> and <em>N. sipedon</em> segregate ecologically along ecotones of salinity, temperature, and water current. Variation in the width of these ecotones is reflected in the width of hybrid zones.</p>","abstract_has_math":false,"creators":["Mebert, Konrad"],"institution":null,"degree_name":"Doctor of Philosophy (PhD)","degree_level":"Dissertation","degree_discipline":"Biological Sciences","degree_department":null,"school":null,"contributors":["Alan H. Savitzky","Richard G. Whittecar","John R. Holsinger","Robert K. Rose"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2003,"date_issued":"2003-04-01T08:00:00Z","date_published":"2003-04-01T08:00:00Z","updated_at":"2026-07-24T03:34:39Z","subjects":["Carolinas","Hybridization","Nerodia fasciata","Nerodia sipedon","Watersnakes","Anatomy","Molecular Biology","Physiology","Zoology"],"languages":[],"rights":["In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
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"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["9780496511266","https://digitalcommons.odu.edu/biology_etds/36"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["A few traditionally applied diagnostic characters of color pattern were compared with an additional set of morphological and genetic characters to evaluate differences between Nerodia sipedon and N. fasciata and to study the dynamics across their hybrid zone in the Carolinas. Many of the morphological characters exhibited significant interspecific differences, although only the number of dorsally complete crossbands (CBa) was diagnostic by itself. A discriminant function analysis of morphological characters was successful in separating both taxa. Species-specific nuclear markers, identified by the AFLP (Amplified Fragment Length Polymorphism) technique were nearly fixed and served as diagnostic markers. They revealed extensive introgression between the two species not recognizable morphologically. Markers for N. sipedon and F1 hybrids, backcrossed to a parental species exhibiting more than one introgressive marker, were less frequent than expected at Hardy-Weinberg equilibrium, implying selection against N. sipedon and hybrids with an increased introgression, respectively. This is consistent with a pronounced genetic and morphological dominance of N. fasciata in the hybrid zone. The genetic results show that the two taxa are independent entities and qualify for species status under both the Phylogenetic Species Concept and the Evolutionary Species Concept. N. fasciata and N. sipedon segregate ecologically along ecotones of salinity, temperature, and water current. Variation in the width of these ecotones is reflected in the width of hybrid zones.
"]},{"key":"dc:title","label":"Title","values":["Hybridization Between the Watersnakes Nerodia sipedon and Nerodia fasciata, in the Carolinas: A Morphological and Molecular Approach"]}]}],"canonical_facts":{"dc:contributor":["Alan H. Savitzky","Richard G. Whittecar","John R. Holsinger","Robert K. Rose"],"dc:creator":["Mebert, Konrad"],"dc:date.available":["2019-04-18T07:00:00Z"],"dc:description.abstract":["A few traditionally applied diagnostic characters of color pattern were compared with an additional set of morphological and genetic characters to evaluate differences between Nerodia sipedon and N. fasciata and to study the dynamics across their hybrid zone in the Carolinas. Many of the morphological characters exhibited significant interspecific differences, although only the number of dorsally complete crossbands (CBa) was diagnostic by itself. A discriminant function analysis of morphological characters was successful in separating both taxa. Species-specific nuclear markers, identified by the AFLP (Amplified Fragment Length Polymorphism) technique were nearly fixed and served as diagnostic markers. They revealed extensive introgression between the two species not recognizable morphologically. Markers for N. sipedon and F1 hybrids, backcrossed to a parental species exhibiting more than one introgressive marker, were less frequent than expected at Hardy-Weinberg equilibrium, implying selection against N. sipedon and hybrids with an increased introgression, respectively. This is consistent with a pronounced genetic and morphological dominance of N. fasciata in the hybrid zone. The genetic results show that the two taxa are independent entities and qualify for species status under both the Phylogenetic Species Concept and the Evolutionary Species Concept. N. fasciata and N. sipedon segregate ecologically along ecotones of salinity, temperature, and water current. Variation in the width of these ecotones is reflected in the width of hybrid zones.
"],"dc:identifier":["9780496511266","https://digitalcommons.odu.edu/biology_etds/36"],"dc:rights":["In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
"],"dc:subject":["Carolinas","Hybridization","Nerodia fasciata","Nerodia sipedon","Watersnakes","Anatomy","Molecular Biology","Physiology","Zoology"],"dc:title":["Hybridization Between the Watersnakes Nerodia sipedon and Nerodia fasciata, in the Carolinas: A Morphological and Molecular Approach"],"thesis:degree_discipline":["Biological Sciences"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Doctor of Philosophy (PhD)"]},"updated_at":"2026-07-24T03:34:39Z"}