Contrasting Satellitomes in New World and African Trogons (Aves, Trogoniformes)

Satellite DNAs (satDNAs) are tandemly repeated sequences that play essential roles in chromosome structure, genome organization, and evolution. Despite their importance, the satellitome (the complete collection of satDNAs) of most avian lineages remains unexplored. We sought to describe the repeatome of three trogonid species, Trogon surrucura, T. melanurus, and Apaloderma vittatum with a focus on the satellitome to evaluate the general features of this lineage.

Herein, we provide the first comparative characterization of the repeatome, with a particular focus on the comparative characterization of satDNAs in three trogonid species: T. surrucura, T. melanurus, and A. vittatum. Using a combination of bioinformatic pipelines and cytogenetic approaches.

We identified 16 satDNA families in T. surrucura, 15 in T. melanurus, and only 3 in A. vittatum. Sequence comparisons revealed that five families are shared between the two Trogon species, consistent with the library hypothesis, whereas no satDNAs were shared with A. vittatum. While both Trogon species exhibited a predominance of GC-rich repeats, A. vittatum represents the first bird described with a satellitome dominated by AT-rich satDNAs. In situ mapping in T. surrucura revealed chromosome-specific satDNAs restricted to pairs 1 and 2 and a Z-specific repeat that was strongly accumulated on its long arms, an atypical feature among birds. Conversely, the W chromosome showed a surprisingly low number of satDNAs, limited to centromeric signals.

Our results reveal highly divergent satellitome landscapes among trogonids, characterized by lineage-specific differences in repeat composition, abundance, and chromosomal distribution. These findings support the view that satDNAs are dynamic genomic elements, whose amplification, loss, and chromosomal redistribution can influence genome architecture and play a role in avian speciation.