RT Journal Article
SR Electronic
T1 Genome size and the extinction of small populations
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 173690
DO 10.1101/173690
A1 Thomas LaBar
A1 Christoph Adami
YR 2017
UL http://biorxiv.org/content/early/2017/08/08/173690.abstract
AB Species extinction is ubiquitous throughout the history of life. Understanding the factors that cause some species to go extinct while others survive will help us manage Earth’s present-day biodiversity. Most studies of extinction focus on inferring causal factors from past extinction events, but these studies are constrained by our inability to observe extinction events as they occur. Here, we use digital experimental evolution to avoid these constraints and study “extinction in action”. Previous digital evolution experiments have shown that strong genetic drift in small populations led to larger genomes, greater phenotypic complexity, and high extinction rates. Here we show that this elevated extinction rate is a consequence of genome expansions and a concurrent increase in the genomic mutation rate. High genomic mutation rates increase the lethal mutation rate, leading to an increase the likelihood of a mutational meltdown. Genome expansions contribute to this lethal mutational load because genome expansions increase the likelihood of lethal mutations. We further find that an increased phenotypic complexity does not contribute to an increased risk of extinction. These results have implications for the causes of extinction in small populations and suggest that complexity increases in small populations may be limited by high rates of extinction.