Recent diversification of a marine genus (Tursiops spp.) tracks habitat preference and environmental change.
Understanding the evolution of diversity and the resulting systematics in marine systems is confounded by the lack of clear boundaries in oceanic habitats, especially for highly mobile species like marine mammals. Dolphin populations and sibling species often show differentiation between coastal and offshore habitats, similar to the pelagic/littoral or benthic differentiation seen for some species of fish. Here we test the hypothesis that lineages within the polytypic genus Tursiops track past changes in the environment reflecting ecological drivers of evolution facilitated by habitat release. We used a known recent time point for calibration (the opening of the Bosphorus) and whole mitochondrial genome (mitogenome) sequences for high phylogenetic resolution. The pattern of lineage formation suggested an origin in Australasia and several early divisions involving forms currently inhabiting coastal habitats. Radiation in pelagic environments was relatively recent, and was likely followed by a return to coastal habitat in some regions. The timing of some nodes defining different ecotypes within the genus clustered near the two most recent interglacial transitions. A signal for an increase in diversification was also seen for dates after the last glacial maximum. Together these data suggest the tracking of habitat preference during geographic expansions, followed by transition points reflecting habitat shifts, which were likely associated with periods of environmental change.
School of Biological and Biomedical Sciences, Durham University, South Road, DH1 3LE, UK; Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen K, Denmark; Biological Department, UAE University, P.O.Box 17551, Al Ain, UAE; and School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001, Australia.
Andre E
AE
Moura
Sandra C A
SC
Nielsen
Julia T
JT
Vilstrup
J Victor
JV
Moreno-Mayar
M Thomas P
MT
Gilbert
Howard W I
HW
Gray
Ada
A
Natoli
Luciana
L
Möller
A Rus
AR
Hoelzel
D000818:Animals; D059001:Aquatic Organisms / Q000145:classification / Q000235:genetics; D044822:Biodiversity; D004272:DNA, Mitochondrial / Q000235:genetics; D004289:Dolphins / Q000145:classification* / Q000235:genetics*; D017753:Ecosystem; D004777:Environment; D054629:Genome, Mitochondrial / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny
D004272:DNA, Mitochondrial