Research School of Biology and Center for Biodiversity Analysis, The Australian National University, Canberra, ACT, Australia.
Department of Environment, Parks and Water Security, Northern Territory Government, Darwin, Northern Territory, Australia.
Mol Ecol. 2022 Feb;31(4):1076-1092. doi: 10.1111/mec.16310. Epub 2021 Dec 17.
Landscape genetics commonly focuses on the effects of environmental resistance on animal dispersal patterns, but there is an emerging focus on testing environmental effects on emigration and settlement choices. In this study, we used landscape genetics approaches to quantify dispersal patterns in the world's largest crocodilian, the saltwater crocodile (Crocodylus porosus), and demonstrated environmental influences on three processes that comprise dispersal: emigration, movement and settlement. We found that both environmental resistance and properties of the source and destination catchments (proportion of breeding habitat) were important factors influencing observed dispersal events. Our habitat quality variables related to hypotheses about resource competition and represented the ratio of breeding habitat (which limits carrying capacity), suggesting that competition for habitat influences emigration and settlement choices, together with the strong effect of environmental resistance to movement (where high-quality habitat was associated with greatest environmental permeability). Approximately 42% of crocodiles were migrants from populations other than their sampling locations and some outstandingly productive populations had a much higher proportion of emigration rather than immigration. The distance most commonly travelled between source and destination was 150-200 km although a few travelled much longer distances, up to 600-700 km. Given the extensive dispersal range, individual catchments or hydrographic regions that combine two or three adjacent catchments are an appropriate scale for population management.
景观遗传学通常侧重于环境阻力对动物扩散模式的影响，但现在越来越关注测试环境对移民和定居选择的影响。在这项研究中，我们使用景观遗传学方法来量化世界上最大的鳄鱼——咸水鳄（Crocodylus porosus）的扩散模式，并证明了三个构成扩散过程的环境影响：移民、移动和定居。我们发现，环境阻力以及源和目的地流域的特性（繁殖栖息地的比例）都是影响观察到的扩散事件的重要因素。我们的栖息地质量变量与关于资源竞争的假设有关，并代表繁殖栖息地（限制承载能力）的比例，这表明对栖息地的竞争会影响移民和定居的选择，同时环境阻力对移动的影响也很大（高质量的栖息地与最大的环境渗透性相关）。大约 42%的鳄鱼是从其采样地点以外的种群中移民而来的，一些生产力极高的种群的移民比例远远高于移民比例。源和目的地之间最常见的旅行距离是 150-200 公里，尽管有一些旅行距离要长得多，可达 600-700 公里。鉴于广泛的扩散范围，个体流域或包含两个或三个相邻流域的水文区域是进行种群管理的适当规模。
