Genetic variation and biogeography of the spotted gar Lepisosteus oculatus from core and peripheral populations

• Published in: Journal of experimental zoology. Part B, Molecular and developmental evolution Vol. 328; no. 7; pp. 596 - 606
• Main Authors: David, Solomon R., Wright, Jeremy J.
• Format: Journal Article
• Language: English
• Published: United States 01.11.2017
• Subjects: Animal Distribution; Animals; biogeography; conservation genetics; ecology; Fishes - genetics; Genetic Variation; molecular ecology; Phylogeography; spotted gar; United States; ecology; molecular ecology; biogeography; spotted gar; conservation genetics
• DOI: 10.1002/jez.b.22772
• ISSN: 1552-5007

The spotted gar (Lepisosteus oculatus) shows a disjunct natural distribution, with a core population extending from the central Mississippi River Basin to the U.S. gulf coast and a peripheral population in the southern Great Lakes Basin. Despite significant conservation concerns for this species in the Great Lakes watersheds where it occurs, few genetic examinations and comparisons of these populations have been performed. We investigated inter‐ and intrapopulational variation in several mitochondrial genetic markers (cytochrome oxidase subunit I, COI; cytochrome oxidase subunit II, COII; and 16S rRNA, 16S) from spotted gars taken from core and peripheral populations. Genetic diversity was highest in the Mississippi River Basin and lowest in the Great Lakes Basin, while the Nueces River Basin (Texas) population showed the greatest level of divergence from other populations. Average genetic distance among core and peripheral populations was over an order of magnitude less than that seen between L. oculatus and its sister species, the Florida gar (L. platyrhincus), although a significant correlation was found between genetic and geographical distance in L. oculatus. Genetic divergence in spotted gars is likely to be related to a combination of geographic isolation and founder effects associated with recent colonization following glacial retreat. Despite its apparent lack of significant genetic differentiation or haplotype diversity, the Great Lakes population of spotted gars has previously been shown to be a unique component of the species, and additional studies are needed to determine the genetic mechanisms underlying regional adaptations as well as potential morphological differentiation among spotted gar populations. GRAPHICAL ABSTRACT We investigated inter‐ and intrapopulational variation in several mitochondrial genetic markers from spotted gars taken from core and peripheral populations. Genetic diversity was highest in the Mississippi River Basin, lowest in the Great Lakes Basin, and most divergent in the western Gulf Coast Basin. Average genetic distance between core and peripheral populations was over an order of magnitude less than that seen between Lepisosteus oculatus and its sister species, L. platyrhincus, although a significant correlation was found between genetic and geographical distance in L. oculatus. Genotypic divergence in spotted gars is likely to be related to a combination of geographic isolation and founder effects associated with recent colonization following glacial retreat. Despite its apparent lack of significant genetic differentiation or diversity, the Great Lakes population of spotted gars has previously been shown to be a unique component of the species, being adapted to life at higher latitudes with shorter growing seasons.