Data from: Cryptic inbreeding depression in a growing population of a long-lived species

Genetic effects are often overlooked in endangered species monitoring, and populations showing positive growth are often assumed to be secure. However, the continued reproductive success of a few individuals may mask issues such as inbreeding depression, especially in long-lived species. Here, we test for inbreeding depression in little spotted kiwi (Apteryx owenii) by comparing a population founded with two birds to one founded with 40 birds, both from the same source population and both showing positive population growth. We used a combination of microsatellite genotypes, nest observations and modelling to examine the consequences of assessing population viability exclusively via population growth. We demonstrate (i) significantly lower hatching success despite significantly higher reproductive effort in the population with two founders; (ii) positive growth in the population with two founders is mainly driven by ongoing chick production of the founding pair; and (iii) a substantial genetic load in the population founded with two birds (10–15 diploid lethal equivalents). Our results illustrate that substantial, cryptic inbreeding depression may still be present when a population is growing, especially in long-lived species with overlapping generations.

濒危物种监测工作中，遗传效应常被忽视，而种群增长为正的种群通常被默认是安全的。然而，少数个体持续的繁殖成功可能掩盖近交衰退（inbreeding depression）等问题，在长寿命物种中这一现象尤为突出。本研究以小斑点几维鸟（Apteryx owenii）为研究对象，通过对比两个来源种群相同、均呈现正增长的建立种群——一个由2只个体建立，另一个由40只个体建立——来检验近交衰退效应。研究结合微卫星基因型（microsatellite genotypes）检测、巢箱观测与模型模拟，探究仅通过种群增长评估种群生存力所带来的后果。结果表明：（1）尽管由2只个体建立的种群繁殖投入显著更高，但其孵化成功率却显著更低；（2）该种群的正增长主要由创始配对持续繁育的雏鸟所驱动；（3）由2只个体建立的种群存在显著的遗传负荷，携带10~15个二倍体致死当量（diploid lethal equivalents）。本研究结果显示，即便种群处于增长状态，仍可能存在显著的隐蔽近交衰退，这一情况在具有世代重叠的长寿命物种中尤为明显。