Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 8514
Title: Geographic and temporal dynamics of a global radiation and diversification in the killer whale
Author: Phillip A. Morin, Michael J. Ford
Publication Year: 2015
Journal: Molecular Ecology
Volume: 24
Pages: 3964-3979
DOI: 10.1111/mec.13284
Keywords: cetacean,mitogenomics,phylogeography,speciation,killer whale


Global climate change during the Late Pleistocene periodically encroached and then released habitat during the glacial cycles, causing range expansions and contractions in some species. These dynamics have played a major role in geographic radiations, diversification and speciation. We investigate these dynamics in the most widely dis- tributed of marine mammals, the killer whale (Orcinus orca), using a global data set of over 450 samples. This marine top predator inhabits coastal and pelagic ecosystems ranging from the ice edge to the tropics, often exhibiting ecological, behavioural and morphological variation suggestive of local adaptation accompanied by reproductive isolation. Results suggest a rapid global radiation occurred over the last 350 000 years. Based on habitat models, we estimated there was only a 15% global contraction of core suitable habitat during the last glacial maximum, and the resources appeared to sus- tain a constant global effective female population size throughout the Late Pleistocene. Reconstruction of the ancestral phylogeography highlighted the high mobility of this species, identifying 22 strongly supported long-range dispersal events including inter- oceanic and interhemispheric movement. Despite this propensity for geographic dis- persal, the increased sampling of this study uncovered very few potential examples of ancestral dispersal among ecotypes. Concordance of nuclear and mitochondrial data further confirms genetic cohesiveness, with little or no current gene flow among sym- patric ecotypes. Taken as a whole, our data suggest that the glacial cycles influenced local populations in different ways, with no clear global pattern, but with secondary contact among lineages following long-range dispersal as a potential mechanism driv- ing ecological diversification. 

Theme: Recovery and rebuilding of marine and coastal species
Foci: Characterize the population biology of species, and develop and improve methods for predicting the status of populations.
Official Citation:

Morin PA, Parsons KM, Archer FI, Avila-Arcos MC, Barrett-Lennard LG, Dalla Rosa L, Duchene S, Durban JW, Ellis GM, Ferguson SH, Ford JK, Ford MJ, Garilao C, Gilbert MT, Kaschner K, Matkin CO, Petersen SD, Robertson KM, Visser IN, Wade PR, Ho SYW, Foote AD.  2015.  Geographic and temporal dynamics of a global radiation and diversification in the killer whale.  Molecular Ecology 24: 3964-3979.