Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, 1102 S. Goodwin Ave, Urbana, IL, 61801, USA.
Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, 1630 Linden Dr, Madison, WI, 53706, USA.
Oecologia. 2020 May;193(1):15-26. doi: 10.1007/s00442-020-04626-8. Epub 2020 Mar 22.
Animals are predicted to prefer high-quality over low-quality habitats, but adaptive habitat selection is less straightforward than often assumed. Preferences may improve only specific fitness metrics at particular spatial scales, with variation across time or between sexes. Preferences sometimes even reduce fitness. We investigated the context specificity of adaptive habitat selection, studying dickcissels (Spiza americana)-a polygynous songbird-as a model. From 2014 to 2015, we measured male and female habitat preferences at two scales (territories and landscape patches) on 21 grassland patches in Ringgold County, Iowa, USA. We tested whether preferences improved four fitness metrics-polygyny, avoidance of brood parasitism by brown-headed cowbirds (Molothrus ater), fledgling productivity, and offspring condition. Both sexes preferred territories where offspring attained superior condition and patches where parasitism was infrequent. Females preferred patches where nests produced more fledglings, and in 2014, males on preferred (i.e., early-established) territories attracted more mates and produced more fledglings. However, males on non-preferred (i.e., late-established) territories were more successful in 2015. This inconsistency may have arisen because females were abundant and nest-predation rates were low in May-June 2014, allowing early-settling males to produce many young. In 2015, however, females were more abundant and nests more successful later in the breeding season. Our results show that habitat preferences do not uniformly improve fitness, and some benefits differ between sexes. Moreover, preference-fitness relationships only manifest at specific scales, and annual variation in population and predation dynamics can limit consistency. Detecting adaptive habitat selection thus requires multi-year measurements and careful consideration of relevant scales.
动物被预测会偏好高质量的栖息地而非低质量的栖息地，但适应性的栖息地选择并不像人们通常认为的那样简单。偏好可能仅在特定的空间尺度上提高特定的适应度指标，并且在时间或性别之间存在变化。偏好有时甚至会降低适应度。我们研究了适应性栖息地选择的情境特异性，以迪克西雀（Spiza americana）——一种多配偶的鸣禽——作为模型。在 2014 年至 2015 年期间，我们在美国爱荷华州林金县的 21 个草原斑块上的两个尺度（领地和景观斑块）上测量了雄性和雌性的栖息地偏好。我们测试了偏好是否改善了四个适应度指标——多配偶制、避免棕色头牛鹂（Molothrus ater）的巢寄生、雏鸟生产力和后代状况。雌雄两性都偏好后代状况较好的领地和寄生虫较少的斑块。雌性偏好产生更多雏鸟的斑块，而在 2014 年，雄性在偏好的（即早期建立的）领地上吸引了更多的配偶并产生了更多的雏鸟。然而，在 2015 年，非偏好的（即后期建立的）领地上的雄性更为成功。这种不一致可能是由于 2014 年 5 月至 6 月雌性数量丰富且巢捕食率较低，使得早期定居的雄性能够繁殖很多后代。然而，在 2015 年，雌性数量更多，并且在繁殖季节后期巢的成功率更高。我们的结果表明，栖息地偏好并不一致地提高适应度，并且一些好处在性别之间存在差异。此外，偏好-适应度关系仅在特定的尺度上表现出来，并且种群和捕食动态的年度变化会限制一致性。因此，检测适应性栖息地选择需要多年的测量并仔细考虑相关的尺度。
