Texas A&M University, 3528 TAMU, College Station, TX, 77843, USA.
Department of Psychology, Franklin and Marshall College, Lancaster, PA, 17603, USA.
Sci Rep. 2023 Jul 5;13(1):10866. doi: 10.1038/s41598-023-37379-4.
Hybrid zones can be used to identify traits that maintain reproductive isolation and contribute to speciation. Cognitive traits may serve as post-mating reproductive isolating barriers, reducing the fitness of hybrids if, for example, misexpression occurs in hybrids and disrupts important neurological mechanisms. We tested this hypothesis in a hybrid zone between two subspecies of Swainson's thrushes (Catharus ustulatus) using two cognitive tests-an associative learning spatial test and neophobia test. We included comparisons across the sexes and seasons (spring migration and winter), testing if hybrid females performed worse than males (as per Haldane's rule) and if birds (regardless of ancestry or sex) performed better during migration, when they are building navigational maps and encountering new environments. We documented reduced cognitive abilities in hybrids, but this result was limited to males and winter. Hybrid females did not perform worse than males in either season. Although season was a significant predictor of performance, contrary to our prediction, all birds learned faster during the winter. The hypothesis that cognitive traits could serve as post-mating isolating barriers is relatively new; this is one of the first tests in a natural hybrid zone and non-food-caching species. We also provide one of the first comparisons of cognitive abilities between seasons. Future neurostructural and neurophysiological work should be used to examine mechanisms underlying our behavioral observations.
杂种区可用于识别维持生殖隔离并有助于物种形成的特征。认知特征可能成为交配后生殖隔离的屏障，如果杂种中发生错误表达并破坏重要的神经机制，例如，会降低杂种的适应性。我们在两种斯温森氏画眉亚种（Catharus ustulatus）的杂种区使用两项认知测试——联想学习空间测试和新物恐惧测试，检验了这一假说。我们进行了跨性别和季节（春季迁徙和冬季）的比较，检验杂种雌鸟是否比雄鸟表现更差（如哈代定律），以及无论祖先或性别如何，鸟类在迁徙时是否表现更好，因为它们正在构建导航图并遇到新环境。我们记录了杂种认知能力的下降，但这一结果仅限于雄性和冬季。杂种雌鸟在任何季节的表现都不比雄鸟差。尽管季节是性能的重要预测因素，但与我们的预测相反，所有鸟类在冬季学习得更快。认知特征可能成为交配后隔离屏障的假说相对较新；这是在自然杂种区和非食虫物种中的首次测试之一。我们还首次比较了不同季节的认知能力。未来的神经结构和神经生理学研究应用于研究我们行为观察的潜在机制。
