Department of Mathematics, Heriot-Watt University, Edinburgh, UK.
Proc Biol Sci. 2013 Jan 16;280(1754):20122714. doi: 10.1098/rspb.2012.2714. Print 2013 Mar 7.
Seasonality is an important component in many population systems, and factors such as latitude, altitude and proximity to the coastline affect the extent of the seasonal fluctuations. In this paper, we ask how changes in seasonal fluctuations impact on the population cycles. We use the Fennoscandian vole system as a case study, focusing on variations in the length of the breeding season. We use a predator-prey model that includes generalist and specialist predation alongside seasonal forcing. Using a combination of bifurcation analysis and direct simulations, we consider the effects of varying both the level of generalist predation and the length of the breeding season; these are the main changes that occur over a latitudinal gradient in Fennoscandia. We predict that varying the breeding season length leads to changes in the period of the multi-year cycles, with a higher period for shorter breeding season lengths. This concurs with the gradient of periodicity found in Fennoscandia. The Fennoscandian vole system is only one of many populations that are affected by geographical and temporal changes in seasonality; thus our results highlight the importance of considering these changes in other population systems.
季节性是许多种群系统的一个重要组成部分，纬度、海拔和靠近海岸线等因素会影响季节性波动的程度。在本文中，我们探讨季节性波动的变化如何影响种群周期。我们以芬诺斯堪的亚田鼠系统为例，重点研究繁殖季节长度的变化。我们使用一个包含广义捕食者和专业捕食者以及季节性驱动的捕食者-猎物模型。通过分支分析和直接模拟的结合，我们考虑了广义捕食者捕食水平和繁殖季节长度这两个变量的变化；这些是在芬诺斯堪的亚地区的纬度梯度上发生的主要变化。我们预测，改变繁殖季节的长度会导致多年周期的周期变化，较短的繁殖季节长度会导致更高的周期。这与在芬诺斯堪的亚发现的周期性梯度一致。芬诺斯堪的亚田鼠系统只是受季节性的地理和时间变化影响的众多种群之一；因此，我们的结果强调了在其他种群系统中考虑这些变化的重要性。
