Modern Species Evolution from Reconstructed Extinct Ancestors.

During the last decade, technological improvements led to the development of large sets of genomic resources permitting the emergence of high-resolution comparative genomic studies in both plant and animal lineages. In an attempt to unravel the structure and evolution of their ancestral founder genomes we have re-assed the synteny and duplications of plant and animal genomes to identify and characterize shared duplications. We combined the data on the intra-genomic duplications with those on the colinear blocks that allowed us to propose a model in which the plant and animal genomes have evolved from a common ancestors with respectively a basic number of 5 to 13 chromosomes through whole genome duplications (i.e. paleopolyploidization) and translocations followed by lineage specific segmental duplications, chromosome fusions and translocations. Based on the comparison of the plant and animal genome paleohistory, some major differences are unveiled in (i) evolutionary mechanisms (i.e. polyploidization and diploidization processes), (ii) genome conservation (i.e. coding and non-coding sequence maintenance), and (iii) modern genome architecture (i.e. genome organization including repeats expansion and contraction phenomena). These data demonstrates how extant animal and plant genomes are the result of inherently different rates and modes of genome evolution resulting in relatively stable animal and much more dynamic and plastic plant genomes.