Evolutionary Biology Laboratory, Evolutionary and Organismal Biology Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur PO, Bangalore, India.
Sci Rep. 2013;3:1405. doi: 10.1038/srep01405.
Constant immigration can stabilize population size fluctuations but its effects on extinction remain unexplored. We show that constant immigration significantly reduced extinction in fruitfly populations with relatively stable or unstable dynamics. In unstable populations with oscillations of amplitude around 1.5 times the mean population size, persistence and constancy were unrelated. Low immigration enhanced persistence without affecting constancy whereas high immigration increased constancy without enhancing persistence. In relatively stable populations with erratic fluctuations of amplitude close to the mean population size, both low and high immigration enhanced persistence. In these populations, the amplitude of fluctuations relative to mean population size went down due to immigration, and their dynamics were altered to low-period cycles. The effects of immigration on the population size distribution and intrinsic dynamics of stable versus unstable populations differed considerably, suggesting that the mechanisms by which immigration reduced extinction risk depended on underlying dynamics in complex ways.
持续的移民可以稳定人口规模的波动，但它对灭绝的影响仍未得到探索。我们表明，持续的移民显著降低了果蝇种群的灭绝风险，这些种群的动态相对稳定或不稳定。在不稳定的种群中，振幅围绕平均种群大小的 1.5 倍左右波动，持久性和恒定性没有关系。低移民增加了持久性而不影响恒定性，而高移民增加了恒定性而不增加持久性。在相对稳定的种群中，振幅波动不规则，接近平均种群大小，低移民和高移民都增加了持久性。在这些种群中，由于移民的影响，相对于平均种群大小的波动幅度下降，其动态也转变为低周期循环。移民对稳定与不稳定种群的种群规模分布和内在动态的影响有很大差异，这表明移民降低灭绝风险的机制以复杂的方式取决于潜在的动态。
