Inbreeding depression in polyploid species: a meta-analysis

Whole-genome duplication (WGD) is a common mutation in eukaryotes with
far-reaching phenotypic effects. Morphological and fitness consequences of
WGD and their effects on the survival of novel polyploid lineages are
intensively studied. Another important factor that may also determine the
probability of establishment and success of polyploid lineages is
inbreeding depression. Inbreeding depression is expected to play an
important role in the establishment of neopolyploid lineages, their
capacity to colonize new environments, and in the simultaneous evolution
of ploidy and other life-history traits such as self-fertilization. Both
theoretically and empirically, there is no consensus on the consequences
of polyploidy on inbreeding depression. Here, we investigated the effect
of polyploidy on the evolution of inbreeding depression by performing a
meta-analysis within angiosperm species. The main results of our study are
that the consequences of polyploidy on inbreeding depression are complex
and depend on the time since polyploidization. We found that newly formed
polyploid lineages have a much lower amount of inbreeding depression than
their diploid relatives. Natural established polyploid lineages are
intermediate, exhibiting a higher amount of inbreeding depression than
synthetic neopolyploids, but smaller than diploids, suggesting that the
negative effect of polyploidy on inbreeding depression decreases with time
since polyploidization.