Borthwick Richard, de Flamingh Alida, Hesselbarth Maximilian H K, Parandhaman Anjana, Wagner Helene H, Abdel Moniem Hossam E M
Department of Biological and Environmental Sciences, Alabama A&M University, Normal, AL, United States.
Program in Ecology, Evolution, and Conservation Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States.
Front Genet. 2020 Mar 31;11:307. doi: 10.3389/fgene.2020.00307. eCollection 2020.
Rapid progression of human socio-economic activities has altered the structure and function of natural landscapes. Species that rely on multiple, complementary habitat types (i.e., landscape complementation) to complete their life cycle may be especially at risk. However, such landscape complementation has received little attention in the context of landscape connectivity modeling. A previous study on flower longhorn beetles (: ) integrated landscape complementation into a continuous habitat suitability 'surface', which was then used to quantify landscape connectivity between pairs of sampling sites using gradient-surface metrics. This connectivity model was validated with molecular genetic data collected for the banded longhorn beetle () in Indiana, United States. However, this approach has not been compared to alternative models in a landscape genetics context. Here, we used a discrete land use/land cover map to calculate landscape metrics related to landscape complementation based on a patch mosaic model (PMM) as an alternative to the previously published, continuous habitat suitability model (HSM). We evaluated the HSM surface with gradient surface metrics (GSM) and with two resistance-based models (RBM) based on least cost path (LCP) and commute distance (CD), in addition to an isolation-by-distance (IBD) model based on Euclidean distance. We compared the ability of these competing models of connectivity to explain pairwise genetic distances ( ) previously calculated from ten microsatellite genotypes of 454 beetles collected from 17 sites across Indiana, United States. Model selection with maximum likelihood population effects (MLPE) models found that GSM were most effective at explaining pairwise genetic distances as a proxy for gene flow across the landscape, followed by the landscape metrics calculated from the PMM, whereas the LCP model performed worse than both the CD and the isolation by distance model. We argue that the analysis of a continuous HSM with GSM might perform better because of their combined ability to effectively represent and quantify the continuous degree of landscape complementation (i.e., availability of complementary habitats in vicinity) found at and in-between sites, on which these beetles depend. Our findings may inform future studies that seek to model habitat connectivity in complex heterogeneous landscapes as natural habitats continue to become more fragmented in the Anthropocene.
人类社会经济活动的快速发展改变了自然景观的结构和功能。依赖多种互补栖息地类型（即景观互补性）来完成其生命周期的物种可能尤其面临风险。然而，在景观连通性建模的背景下，这种景观互补性很少受到关注。先前一项关于花长角甲虫（：）的研究将景观互补性整合到一个连续的栖息地适宜性“表面”中，然后使用梯度表面度量来量化成对采样点之间的景观连通性。这个连通性模型通过在美国印第安纳州为带状长角甲虫（）收集的分子遗传数据进行了验证。然而，在景观遗传学背景下，这种方法尚未与其他模型进行比较。在这里，我们使用离散的土地利用/土地覆盖图，基于斑块镶嵌模型（PMM）计算与景观互补性相关的景观度量，作为先前发表的连续栖息地适宜性模型（HSM）的替代方法。除了基于欧几里得距离的距离隔离（IBD）模型外，我们还使用梯度表面度量（GSM）以及基于最小成本路径（LCP）和通勤距离（CD）的两个基于抗性的模型（RBM）来评估HSM表面。我们比较了这些相互竞争的连通性模型解释先前从美国印第安纳州17个地点收集的454只甲虫的十个微卫星基因型计算出的成对遗传距离（）的能力。使用最大似然种群效应（MLPE）模型进行模型选择发现，GSM在解释成对遗传距离作为景观中基因流的代理方面最有效，其次是从PMM计算出的景观度量，而LCP模型的表现比CD模型和距离隔离模型都差。我们认为，使用GSM对连续的HSM进行分析可能表现更好，因为它们能够有效表示和量化这些甲虫所依赖的站点及其之间发现的景观互补性的连续程度（即附近互补栖息地的可用性）。我们的研究结果可能为未来的研究提供参考，这些研究旨在模拟复杂异质景观中的栖息地连通性，因为在人类世，自然栖息地继续变得更加破碎化。
