To all the gar I loved before: range-wide population genetic structure in Alligator gar

• Published in: Conservation genetics Vol. 24; no. 4; pp. 501 - 521
• Main Authors: Bohn, Sandra E., Kreiser, Brian R., Williford, Damon, Anderson, Joel, Karel, William
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-08-2023; Springer Nature B.V
• Subjects: Animal Genetics and Genomics; Aquatic reptiles; Atractosteus spatula; Biodiversity; Biomedical and Life Sciences; Coastal zone; Conservation Biology/Ecology; Demographics; Demography; Ecology; Evolutionary Biology; Genetic diversity; Genetic structure; Genotypes; Haplotypes; Information management; Life Sciences; Microsatellites; Plant Genetics and Genomics; Population genetics; Population number; Populations; Reintroduction; Research Article; River basins; River systems; Rivers; Gar; Population structure; Mitochondrial DNA; Microsatellites; Phylogeography
• ISSN: 1566-0621; 1572-9737
• DOI: 10.1007/s10592-023-01516-3

Managers and researchers have taken an increasing interest in Alligator gar (
Atractosteus spatula
). Conservation efforts are needed across much of the range where there are either declining populations or a growing popularity of Alligator gar as a trophy fish. Understanding the spatial patterns of genetic diversity and differentiation is necessary to guide management efforts. This study provides the most comprehensive examination to date of the range-wide genetic structure in Alligator gar with microsatellite genotype data for 935 individuals and mitochondrial control region sequence data from 696 individuals. Analysis of the microsatellite data identified 11 genetic groups representing three regional assemblages of populations. Two groups were from coastal areas or river systems, with the extreme western sites representing one of these groups. The third group comprised the interior portion of the range within the Mississippi River basin. The interior and peripheral coastal sites possessed lower levels of genetic diversity and estimates of effective population size. The mitochondrial data revealed similar patterns of genetic structure and diversity. Of the three haplogroups, one was widespread while the other two were either found in coastal sites and drainages or were restricted to the western portion of the range. Demographic analyses found evidence of demographic expansion in the two most widespread haplogroups, and haplotype diversity was lowest in interior sites. While there were still sampling gaps in our study, these results provide important baseline information for the management of Alligator gar populations and can serve to guide hatchery propagation and reintroduction programs.