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Genome-wide analyses reveal drivers of penguin diversification
Juliana A Vianna1, Flávia A N Fernandes2, María José Frugone3
1Departamento de Ecosistemas y Medio Ambiente, Facultad de Agronomía e Ingeniería Forestal, Pontificia Universidad Católica de Chile, 782-0436 Santiago, Chile; jvianna@uc.cl bowie@berkeley.edu.
Summary
Penguin evolution originated in New Zealand and Australia, not Antarctica. Climate change and ocean currents drove penguin diversification and adaptation, impacting their population sizes throughout history.
Area of Science:
- Evolutionary Biology
- Genomics
- Paleoclimatology
Background:
- Penguins are flightless diving birds with diverse species across the Southern Hemisphere.
- Their evolutionary history, diversification, and adaptation to various environments are subjects of ongoing scientific debate.
Purpose of the Study:
- To reconstruct the evolutionary timeline, geographic origins, and diversification patterns of penguins.
- To investigate changes in penguin thermal niches and associated genomic adaptations.
- To test hypotheses regarding the drivers of penguin diversification and population dynamics.
Main Methods:
- Phylogenomic analysis using 22 new genomes from 18 penguin species.
- Reconstruction of historical climate and oceanographic changes, including the Antarctic Circumpolar Current (ACC).
- Analysis of gene adaptation related to thermoregulation and oxygen metabolism.
Main Results:
- The penguin crown-group originated in the Miocene in New Zealand and Australia, with *Aptenodytes* as the sister group to all other species.
- Lineage diversification was significantly influenced by climate shifts and the opening of the Drake Passage, intensifying the ACC.
- Penguin species exhibited introgressive hybridization, potentially facilitated by the ACC, and showed adaptations in thermoregulation and oxygen metabolism genes.
- Population size estimates revealed sensitivity to climate shifts, with a common pattern of increase followed by a decline during the Last Glacial Maximum due to reduced marine productivity.
Conclusions:
- Penguin origins and diversification are linked to paleoclimatic events and geographic changes, challenging previous Antarctic-centric theories.
- Genomic adaptations reflect responses to environmental pressures, particularly concerning thermoregulation and oxygen use.
- Penguin populations demonstrate a clear sensitivity to climate fluctuations, impacting their demographic trajectories over evolutionary timescales.
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