Hybridization, Maternal Inheritance, and Evolutionary Time of Divergence of Endangered Species of Hypancistrus (Siluriformes: Loricariidae) in the Xingu River

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Abstract
Catfishes of the genus Hypancistrus are among the most emblematic endemic species of the Xingu River rapids, a biodiversity hotspot of the Amazon Basin. In the unique Volta Grande region, the distribution of Hypancistrus zebra , Hypancistrus seideli , and Hypancistrus yudja overlap, creating a potential zone of biological interaction, and previous morphological analyses suggest the occurrence of hybridization between H. seideli and H. yudja . We investigated maternal inheritance and phylogenetic relationships among the three species and hybrids using complete mitochondrial genomes and nuclear genome size estimates. Phylogenetic analyses revealed that hybrids carried maternal lineages exclusively from H. zebra and H. seideli , with no evidence of contribution from H. yudja . Nuclear genome size analyses support this pattern, with hybrids exhibiting intermediate values consistent with additive inheritance. Divergence time estimates indicated a very recent evolutionary radiation (< 0.5 Ma), explaining the persistence of reproductive compatibility among the species. These findings raise conservation concerns, particularly for the zebra pleco H. zebra , a critically endangered species at risk of genetic introgression. Our study provides the first complete mitochondrial genome data for these species and emphasizes the importance of integrating morphological and genomic approaches to understand hybridization dynamics and guide conservation strategies in the Xingu River.
Funding Information
  • Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (88887.706125/2022‐00)

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