Tiago Antao
Brian K. Hand
Clint C. Muhlfeld
Matthew C. Boyer
Ted Corsart
Brian Trethewey
Robert K. Al-Chokhachy
Robin S. Waples
Gordon Luikart
2021
<p><span>Estimating the effective population size and effective number of breeders per year (</span><i>N</i><sub>b</sub><span>) can facilitate early detection of population declines. We used computer simulations to quantify bias and precision of the one-sample </span><span class="smallCaps">LDNe</span><span> estimator of </span><i>N</i><sub>b</sub><span> in age-structured populations using a range of published species life history types, sample sizes, and DNA markers. </span><i>N</i><sub>b</sub><span> estimates were biased by ~5%–10% when using SNPs or microsatellites in species ranging from fishes to mosquitoes, frogs, and seaweed. The bias (high or low) was similar for different life history types within a species suggesting that life history variation in populations will not influence </span><i>N</i><sub>b</sub><span> estimation. Precision was higher for 100 SNPs (</span><i>H</i><span> ≈ 0.30) than for 15 microsatellites (</span><i>H</i><span> ≈ 0.70). Confidence intervals (CIs) were occasionally too narrow, and biased high when </span><i>N</i><sub>b</sub><span> was small (</span><i>N</i><sub>b</sub><span> < 50); however, the magnitude of bias would unlikely influence management decisions. The CIs (from </span><span class="smallCaps">LDNe</span><span>) were sufficiently narrow to achieve high statistical power (≥0.80) to reject the null hypothesis that </span><i>N</i><sub>b</sub><span> = 50 when the true </span><i>N</i><sub>b</sub><span> = 30 and when sampling 50 individuals and 200 SNPs. Similarly, CIs were sufficiently narrow to reject </span><i>N</i><sub>b</sub><span> = 500 when the true </span><i>N</i><sub>b</sub><span> = 400 and when sampling 200 individuals and 5,000 loci. Finally, we present a linear regression method that provides high power to detect a decline in </span><i>N</i><sub>b</sub><span> when sampling at least five consecutive cohorts. This study provides guidelines and tools to simulate and estimate </span><i>N</i><sub>b</sub><span> for age structured populations (</span>https://github.com/popgengui/agestrucnb/<span>), which should help biologists develop sensitive monitoring programmes for early detection of changes in </span><i>N</i><sub>b</sub><span> and population declines.</span></p>
application/pdf
10.1111/1755-0998.13251
en
Wiley
Detecting population declines via monitoring the effective number of breeders (Nb)
article