title: Multiple invasions into freshwater by pufferfishes (teleostei: tetraodontidae): a mitogenomic perspective.
abstract: Pufferfishes of the Family Tetraodontidae are the most speciose group in the Order Tetraodontiformes and mainly inhabit coastal waters along continents. Although no members of other tetraodontiform families have fully discarded their marine lives, approximately 30 tetraodontid species spend their entire lives in freshwaters in disjunct tropical regions of South America, Central Africa, and Southeast Asia. To investigate the interrelationships of tetraodontid pufferfishes and thereby elucidate the evolutionary origins of their freshwater habitats, we performed phylogenetic analysis based on whole mitochondrial genome sequences from 50 tetraodontid species and closely related species (including 31 newly determined sequences). The resulting phylogenies reveal that the family is composed of four major lineages and that freshwater species from the different continents are independently nested in two of the four lineages. A monophyletic origin of the use of freshwater habitats was statistically rejected, and ancestral habitat reconstruction on the resulting tree demonstrates that tetraodontids independently entered freshwater habitats in different continents at least three times. Relaxed molecular-clock Bayesian divergence time estimation suggests that the timing of these invasions differs between continents, occurring at 0-10 million years ago (MA) in South America, 17-38 MA in Central Africa, and 48-78 MA in Southeast Asia. These timings are congruent with geological events that could facilitate adaptation to freshwater habitats in each continent.
authors.affiliation: Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, Chiba, Japan. yamanouey@yahoo.co.jp
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Yamanoue
authors.forename: Masaki
authors.initials: M
authors.lastname: Miya
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Doi
authors.forename: Kohji
authors.initials: K
authors.lastname: Mabuchi
authors.forename: Harumi
authors.initials: H
authors.lastname: Sakai
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Nishida
mesh_terms: D000350:Africa, Central; D000818:Animals; D001210:Asia, Southeastern; D017753:Ecosystem; D005618:Fresh Water / Q000469:parasitology; D049810:Genetic Speciation; D054629:Genome, Mitochondrial / Q000502:physiology*; D023281:Genomics / Q000379:methods; D058865:Introduced Species; D008954:Models, Biological; D010802:Phylogeny; D013020:South America; D023721:Tetraodontiformes / Q000145:classification / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D013997:Time Factors