Figure 2.

The pre‐mitochondrion symbioses hypothesis. (A) Putative ecto‐ (yellow oval) or endo‐symbioses (orange oval) could have been established by the host (large oval) before the advent of the proto‐mitochondrion (red oval). For simplicity, only one of each of these types of symbioses is represented but the hypothesis is not binding to any particular number of symbiosis or their specific type. (B) If these earlier symbiosis involved symbionts of different phylogenetic origins and they promoted the transfer of genes to the increasingly chimeric host genome, these would result in particular phylogenetic patterns of the LECA proteome in which (i) the phylogenetic nature of the LECA protein would be heterogeneous, containing more than two distinct types of phylogenetic origins and (ii) protein families of different phylogenetic origins would tend to show different stem lengths.