1 Citation 143 Views 3 Downloads
Population bottlenecks can reduce genetic diversity and may lead to
inbreeding depression. However, some studies have provided evidence that
long lifespans buffer negative genetic effects of bottlenecks. Others have
cautioned that longevity might merely mask the effects of genetic drift,
which will still affect long-term population viability. We used
microsatellite data from actual populations of tuatara (Sphenodon
punctatus) and eastern massasaugas (Sistrurus catenatus) as a starting
point for simulated population declines to evaluate the performance of
bottleneck tests under a range of scenarios. We quantified losses in
genetic diversity for each scenario and assessed the power of commonly
used tests (i.e., M-ratio, heterozygosity excess, and mode-shift) to
detect known bottlenecks in these moderate- to long-lived species.
Declines in genetic diversity were greater in bottlenecks simulated for
eastern massasaugas, the shorter-lived species, and mode-shift and
heterozygosity excess tests were more sensitive to population declines in
this species. Conversely, M-ratio tests were more sensitive to bottlenecks
simulated in tuatara. Despite dramatic simulated population declines,
heterozygosity excess and mode-shift tests often failed to detect
bottlenecks in both species, even when large losses in genetic diversity
had occurred (both allelic diversity and heterozygosity). While not
eliminating type II error, M-ratio tests generally performed best and were
most reliable when a critical value (Mc) of 0.68 was used. However, in
tuatara simulations, M-ratio tests had high rates of type I error when Mc
was calculated assuming θ = 10. Our results suggest that reliance on these
tests could lead to misguided species management decisions.
143 views reported since publication in 2021.