Deere Jacques A, Coulson Tim, Cubaynes Sarah, Smallegange Isabel M
Department of Zoology, University of Oxford, The Tinbergen Building, South Parks Road, Oxford, OX1 3PS, UK.
Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O. Box 94248, 1090 GE Amsterdam, The Netherlands.
Ecol Modell. 2017 Dec 24;366:37-47. doi: 10.1016/j.ecolmodel.2017.10.010.
Individuals that disperse from one habitat to another has consequences for individual fitness, population dynamics and gene flow. The fitness benefits accrued in the new habitat are traded off against costs associated with dispersal. Most studies focus on costs at settlement and effects on settlement populations; the influence of dispersal to natal populations is assessed by monitoring change in numbers due to emigration. However, the extent to which natal populations are affected when individuals that invest in dispersal fail to disperse/emigrate is unclear. Here, we use an Integral Projection Model (IPM) to assess how developing into a disperser affects natal population structure and growth. We do so using the bulb mite () as a study system. Bulb mites, in unfavourable environments, develop into a dispersal (deutonymph) stage during ontogeny; these individuals are called dispersers with individuals not developing into this stage called non-dispersers. We varied disperser expression and parameterised IPMs to describe three simulations of successful and unsuccessful dispersal: (i) 'no dispersal' - dispersal stage is excluded and demographic data are from non-disperser individuals; (ii) 'false dispersal' - dispersal stage included and demographic data from non-disperser individuals are used; (iii) 'true dispersal' - dispersal stage included and demographic data are from individuals that go through the dispersal stage and from non-disperser individuals. We found that the type of dispersal simulation (no dispersal < false dispersal < true dispersal) and disperser expression increases generation time and reduces lifetime reproductive success and population growth rate. Our findings show that disperser individuals that fail to leave, can change the structure and growth of natal populations.
从一个栖息地扩散到另一个栖息地的个体，会对个体适合度、种群动态和基因流动产生影响。在新栖息地获得的适合度益处会与扩散相关的成本进行权衡。大多数研究关注定居时的成本以及对定居种群的影响；通过监测因迁出导致的数量变化来评估扩散对出生种群的影响。然而，当投入扩散的个体未能扩散/迁出时，出生种群受到影响的程度尚不清楚。在这里，我们使用积分投影模型（IPM）来评估发育成为扩散者如何影响出生种群结构和增长。我们以球螨（）作为研究系统来进行此项研究。在不利环境中，球螨在个体发育过程中会发育到扩散（若螨）阶段；这些个体被称为扩散者，未发育到这个阶段的个体则称为非扩散者。我们改变扩散者的表现形式，并对IPM进行参数化，以描述成功和不成功扩散的三种模拟情况：（i）“无扩散”——排除扩散阶段，人口统计数据来自非扩散者个体；（ii）“假扩散”——包括扩散阶段，使用来自非扩散者个体的人口统计数据；（iii）“真扩散”——包括扩散阶段，人口统计数据来自经历扩散阶段的个体和非扩散者个体。我们发现，扩散模拟的类型（无扩散 < 假扩散 < 真扩散）和扩散者表现形式会增加世代时间，并降低终生繁殖成功率和种群增长率。我们的研究结果表明，未能离开的扩散者个体可以改变出生种群的结构和增长。
