Zaveska, E. | bioRxiv Science

bioRxiv2022

Niche differentiation following whole-genome duplication? The importance of considering the intricate evolutionary history of polyploids when assessing climatic niche evolution

AimAlthough whole genome duplication (WGD) is an important speciation force, we still lack a consensus on the role of niche differentiation in polyploid evolution. In addition, the role of genome doubling per se vs. later divergence on polyploids niche evolution remains obscure. One reason for this might be that the intraspecific genetic structure of polyploid complexes and interploidy gene flow is often neglected in ecological studies. Here, we aim to investigate to which extent these evolutionary processes impact our inference on niche differentiation of autopolyploids. LocationEurope TaxonArabidopsis arenosa (Brassicaceae) MethodsLeveraging a total of 352 cytotyped populations of diploid-autotetraploid A. arenosa, we examined differences among climatic niches of diploid and tetraploid lineages both globally, and independently for each tetraploid lineage with respect to the niche of its evolutionary closest relative. Then, we tested if there was an effect of additional interploidy introgression from other sympatric but more ancestral diploid lineages of A. arenosa on climatic niches of tetraploids. ResultsEcological niche shift of tetraploids is only detected when the assignment of populations to intraspecific genetic lineages is considered. We found different patterns of climatic niche evolution (i.e. niche conservatism, contraction or expansion) in each tetraploid lineage when compared to its evolutionary closest relatives. We observed an effect of interploidy gene flow in patterns of climatic niche evolution of tetraploid ruderal plants of A. arenosa. Main conclusionsThe niche shift of tetraploids in A. arenosa is not driven by WGD per se but rather reflects dynamic post-WGD evolution in the species, involving tetraploid migration out of their ancestral area and interploidy introgression with other diploid lineages. Our study supports that evolutionary processes following WGD - which usually remain undetected by studies neglecting evolutionary history of polyploids - may play a key role in the adaptation of polyploids to challenging environments.

plant biology↗

bioRxiv2020

Partial endoreplication stimulates diversification in the species-richest lineage of orchids

Some of the most burning questions in biology in recent years concern differential diversification along the tree of life and its causes. Among others, it could be triggered by the evolution of novel phenotypes accelerating diversification in lineages that bear them. In the Pleurothallidinae, the most species-rich subtribe of plants on Earth with 46 genera and [~]5,500 species, we constructed a completely new phylogeny and mapped on to it the type of endoreplication intending to trace how the phenomenon of partial endoreplication, which is unique to orchids, affects the differential diversification of lineages. We have used NGS based target enrichment HybSeq approach for the reconstruction of the phylogeny and the flow cytometry to estimate the type of endoreplication. The BAMM and BiSSE analyses have been used to assess diversification rates and to trace the phenotype changes. We have found that three of six changes in diversification rates are associated with changes in the endoreplication type and the clades bearing taxa with partial endoreplication showed higher net diversification rates. Our results demonstrate that multiple evolution of partial endoreplication within the subtribe considerably shapes the patterns of diversity and that partial endoreplication is a trait with an evolutionary significance.

evolutionary biology↗