Fig. 2.

Current challenges of ortholog-based research. The logo of the EBP is used to symbolize large, targeted sequencing projects. The world map in the bottom half shows the sampling distribution of 13,174 metagenomes from 14 habitats as an example of a large-scale metagenome project [Figure adapted from Coelho et al. (2022)]. The bottle shape represents the large number of available datasets which present several new challenges. As the first challenge, all new datasets must pass through the genome annotation bottleneck (C1). Challenges regarding technical aspects of orthology prediction are presented in boxes C2-4. Finally, orthology assignments should be FAIR (C5) (Wilkinson et al. 2016).