Gone with the Species: From Gene Loss to Gene Extinction.

Background: Vertebrae protein-coding genes exhibit remarkable diversity and are organized into many gene families. These gene families have emerged through various gene duplication events, the most prominent being the two rounds of whole-genome duplication (WGD). The current research project analyzed a unique class of genes called "singletons". Notably, we introduce the concept of "super-singletons": genes that stand as the last representatives of their ancestral families and the sole representatives of their genetic makeup with no ortholog in any other species.

Methods: We used the Ensembl/Biomart pipeline to identify duplicated and unduplicated protein-coding genes in different vertebrate species and found orthologs of human genes.

Results: We showed the frequency of duplicated genes and singletons, demonstrating that singletons are more vulnerable to evolutionary loss than duplicated genes. Additionally, we found that contractions in vertebrate gene families are more prevalent than expansion.

Conclusion: Our study provides insight into the evolution of gene families and presents a novel scenario where the extinction of species would lead to the extinction of a gene, ultimately shifting the narrative from the impact of genetics on species extinction to the extinction of genes.