Hybridization masks speciation in the evolutionary history of the Galápagos marine iguana
2015/06/03 by Amy MacLeod, Ariel Rodríguez, Miguel Vences +9 · 91 citations
Biochemistry, Genetics and Molecular Biology · Earth and Planetary Sciences · Environmental Science · #Allopatric speciation #Biology #Clade #Ecology #Evolution and Paleontology Studies #Evolutionary biology #Fish biology, ecology, and behavior #Gene #Gene flow #Genetic algorithm #Genetic diversity and population structure #Genetic variation #Genetics #Hybrid zone #Iguana #Incipient speciation #Phylogenetic tree #Population #Sister group #Zoology
paper · pdf · doi:10.1098/rspb.2015.0425
published in Proceedings of the Royal Society B Biological Sciences 282(1809), 20150425 (Royal Society)
openalex publication_date 2015/06/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Abstract
The effects of the direct interaction between hybridization and speciation-two major contrasting evolutionary processes--are poorly understood. We present here the evolutionary history of the Galápagos marine iguana (Amblyrhynchus cristatus) and reveal a case of incipient within--island speciation, which is paralleled by between-island hybridization. In-depth genome-wide analyses suggest that Amblyrhynchus diverged from its sister group, the Galápagos land iguanas, around 4.5 million years ago (Ma), but divergence among extant populations is exceedingly young (less than 50,000 years). Despite Amblyrhynchus appearing as a single long-branch species phylogenetically, we find strong population structure between islands, and one case of incipient speciation of sister lineages within the same island--ostensibly initiated by volcanic events. Hybridization between both lineages is exceedingly rare, yet frequent hybridization with migrants from nearby islands is evident. The contemporary snapshot provided by highly variable markers indicates that speciation events may have occurred throughout the evolutionary history of marine iguanas, though these events are not visible in the deeper phylogenetic trees. We hypothesize that the observed interplay of speciation and hybridization might be a mechanism by which local adaptations, generated by incipient speciation, can be absorbed into a common gene pool, thereby enhancing the evolutionary potential of the species as a whole.
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