2005/10/04 by Allan J. Baker, Sérgio L. Pereira, Oliver Haddrath +1 · 2 citations
Biochemistry, Genetics and Molecular Biology · Earth and Planetary Sciences · #Genetic diversity and population structure #Genomics and Phylogenetic Studies #Evolution and Paleontology Studies #Southern Hemisphere #Taxon #Global cooling #Biogeography #Temperate climate #Extant taxon #Extinction event #Paleontology #Circumpolar star #Extinction (optical mineralogy) #Latitude #Oceanography #Ecology #Climate change #Geology #Biology #Evolutionary biology #Biological dispersal
paper · doi:10.1098/rspb.2005.3260
openalex publication_date 2005/10/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Classic problems in historical biogeography are where did penguins originate, and why are such mobile birds restricted to the Southern Hemisphere? Competing hypotheses posit they arose in tropical-warm temperate waters, species-diverse cool temperate regions, or in Gondwanaland approximately 100 mya when it was further north. To test these hypotheses we constructed a strongly supported phylogeny of extant penguins from 5851 bp of mitochondrial and nuclear DNA. Using Bayesian inference of ancestral areas we show that an Antarctic origin of extant taxa is highly likely, and that more derived taxa occur in lower latitudes. Molecular dating estimated penguins originated about 71 million years ago in Gondwanaland when it was further south and cooler. Moreover, extant taxa are inferred to have originated in the Eocene, coincident with the extinction of the larger-bodied fossil taxa as global climate cooled. We hypothesize that, as Antarctica became ice-encrusted, modern penguins expanded via the circumpolar current to oceanic islands within the Antarctic Convergence, and later to the southern continents. Thus, global cooling has had a major impact on penguin evolution, as it has on vertebrates generally. Penguins only reached cooler tropical waters in the Galapagos about 4 mya, and have not crossed the equatorial thermal barrier.