Why polyploid exceptionalism is not accompanied by reduced extinction rates

Abstract

In spite of their success during the past several millions of years, recent analyses indicate that polyploid species may have higher extinction rates than their diploid relatives. The idea that neopolyploid species are relatively short-lived is antithetical to the notion of polyploid exceptionalism. I propose that young, established polyploid species have unusually high extinction rates due to demographic and genetic challenges and that early demise accounts for the elevated extinction of polyploid species as a whole. Polyploid species are composed of conspecific lineages (each of an independent origin). Each origin is associated with a genetic and demographic bottleneck which reduces their abilities to cope with environment perturbations. The greater the number of independently originated lineages, the longer a polyploid species is likely to persist, given that the lineages are genetically/ecologically divergent. Autopolyploids appear to have much higher extinction rates than allopolyploids, even though the formation frequency in autopolyploids may be orders of magnitude greater. Niche differences between polyploids and their progenitors may be enhanced via the differential survival of the most divergent polyploids relative to their progenitors. It seems to be the rarely successful polyploid that flourishes during times of environmental alteration and that leaves an enduring genomic legacy.