The Alligator Gar Atractosteus spatula (AG) is a long‐lived fish of growing management and conservation interest. Situated on the border of Texas and Oklahoma, Lake Texoma supports one of the last robust AG populations in Oklahoma; however, a genetic evaluation of this population is lacking. We genotyped AG individuals with 17 microsatellite loci, 7 of which also cross‐amplified in three sympatric Lepisosteus species: the Longnose Gar L. osseus (LN), Shortnose Gar L. platostomus (SN), and Spotted Gar L. oculatus (SP). Bayesian assignment analyses conducted in STRUCTURE and NewHybrids confirmed that a field‐identified hybrid was an F₁ AG × LN and identified five other individuals that were suspected backcrosses (three LN × SN; two SN × SP). Alligator Gar had the lowest observed heterozygosity (0.179) and the lowest allelic richness (1.682) among the nonhybrid individuals of the four gar species examined. We also examined the potential for population structure and differences in pairwise relatedness (r) between two areas where AG are commonly encountered within Lake Texoma: the Red River and Washita River arms. No population structure was detected using noninformative or location priors in STRUCTURE, and estimates of r produced by the TrioML estimator in COANCESTRY were not significantly different between arms (overall mean r = 0.199). Point estimates of effective population size ranging from 16.3 to 29.2 suggested that the AG population may be vulnerable to the effects of inbreeding depression and random genetic drift. Results provide a genetic status assessment of AG in Lake Texoma and a baseline for future management and conservation decisions within Lake Texoma and surrounding regions.

中文翻译：

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德克马湖扬子鳄的杂交与种群遗传

鳄雀鳝Atractosteus压舌板（AG）越来越多的管理和保护利益的长寿鱼。得克萨斯湖位于得克萨斯州和俄克拉荷马州的边界，是俄克拉荷马州最后一批健壮的农业人口之一。然而，缺乏对该人群的遗传评估。我们对具有17个微卫星基因座的AG个体进行了基因分型，其中7个在三个同伴的Lepisosteus物种中得到了交叉扩增：Longnose Gar L. osseus（LN），Shortnose Gar L. platostomus（SN）和Spoted Gar L. oculatus（SP） 。在STRUCTURE和NewHybrids中进行的贝叶斯指派分析证实，现场识别的杂种是F ₁AG×LN并确定了其他五个涉嫌回交的个人（三个LN×SN；两个SN×SP）。在所研究的四种种的非杂种个体中，扬子鳄的杂合度最低（0.179），等位基因丰富度最低（1.682）。我们还研究了人口结构的潜力以及在德克马湖中最常遇到AG的两个区域之间的成对相关性（r）之间的差异：红河和华盛顿河两岸。在结构中使用非信息性或位置先验的方法未检测到种群结构，并且 TrioML估计器在COANCESTRY中产生的r估计在两臂之间无显着差异（总体平均r  = 0.199）。对有效种群数量的点估计值范围为16.3至29.2，这表明AG种群可能容易受到近亲衰退和随机遗传漂移的影响。结果提供了德克索马湖中AG的遗传状态评估，并为德克索马湖及周边地区未来的管理和保护决策提供了基线。