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Makelainen P.,University of Helsinki | Esteban R.,Conservation Information and Research on Cetaceans | Foote A.D.,Copenhagen University | Kuningas S.,University of St. Andrews | And 6 more authors.
Journal of the Marine Biological Association of the United Kingdom | Year: 2014

Here we present a comparison of saddle and eye patch patterns of killer whales from Norwegian, Icelandic, British, Spanish and Greenlandic waters. We found only a small amount of variation in saddle patch shapes, which may reflect a recent phylogenetic divergence from the most recent common ancestor. Eye patch shapes were more variable than saddle patches in small details. Most individuals had eye patches with parallel orientation, with the exception of a small group of killer whales from the Hebrides, which, as previously reported, had sloping eye patches that sloped downward at the posterior end. This differentiation in pigmentation patterns of the Hebridean killer whales from neighbouring populations could reflect one or more of several evolutionary processes, including a deeper phylogenetic divergence, low gene flow with other local populations and drift. © Marine Biological Association of the United Kingdom 2014.

Beck S.,Bangor University | Kuningas S.,University of St. Andrews | Esteban R.,Conservation Information and Research on Cetaceans | Foote A.D.,University of Aberdeen | Foote A.D.,Copenhagen University
Behavioral Ecology | Year: 2012

The persistence and size of social groups can be plastic and governed by ecological selection or be under greater genetic control and constrained by phylogenetic inertia. Comparing sociality of phylogenetically divergent populations under the same ecological conditions or between groups within a population under different ecological conditions can identify the relative influence of ecological selection on group formation. Here, we compare the size and persistence of social groups within a community of Atlantic killer whales, comparing between data collected from an area around Scotland where the whales have mainly been seen to hunt seals and data collected from an area around Iceland where the whales have mainly been seen to hunt herring. Additionally, we compare the observed social structure with that of previously studied Pacific ecotypes. Atlantic killer whale groups in both locations had a stable long-term primary social tier (association index level > 0.8) similar to that of Pacific killer whales. However, associations between these groups were much lower when hunting for seals than for fish in both the Atlantic and the Pacific. The occurrence of these differences in sociality between Atlantic groups, which are linked in a single social network, suggests that ecological selection partially determines sociality in this species. Furthermore, if sociality was constrained by phylogenetic inertia, then the Atlantic killer whales would all be expected to be more similar to the Pacific fish-eating ecotype than the more phylogenetically distant Pacific mammal-eating ecotype. Our study suggests that sociality in killer whales is to some extent plastic and can be adapted to the local ecological conditions. © The Author 2011.

Esteban R.,Conservation Information and Research on Cetaceans | Verborgh P.,Conservation Information and Research on Cetaceans | Gauffier P.,Conservation Information and Research on Cetaceans | Gimenez J.,Gema Inc | And 7 more authors.
Journal of the Marine Biological Association of the United Kingdom | Year: 2014

Killer whales have been described in the Gulf of Cadiz, southern Spain, in spring and in the Strait of Gibraltar in summer. A total of 11,276 cetaceans sightings coming from different sources (dedicated research surveys, whale watching companies and opportunistic observations) were used to create two presence-'pseudo-absence' predictive generalized additive models (GAM), where presence data were defined as sightings of killer whales and 'pseudo-absence' data as sightings of other cetacean species. One model was created using spring data when killer whales' main prey, Atlantic bluefin tuna, enter the Mediterranean Sea, and the other model used summer data when Atlantic bluefin tuna return to the Atlantic Ocean. Both model predictions show that killer whales are highly associated with a probable distribution of bluefin tuna during their migration throughout the study area, constraining their distribution to the Gulf of Cadiz in spring and the Strait of Gibraltar in spring and summer. Knowledge of the distribution of killer whales in the study area is essential to establish conservation measures for this population. © 2013 Marine Biological Association of the United Kingdom .

Vilstrup J.T.,Copenhagen University | Ho S.Y.W.,University of Sydney | Foote A.D.,Copenhagen University | Morin P.A.,Southwest Fisheries Science Center | And 11 more authors.
BMC Evolutionary Biology | Year: 2011

Background. Previous DNA-based phylogenetic studies of the Delphinidae family suggest it has undergone rapid diversification, as characterised by unresolved and poorly supported taxonomic relationships (polytomies) for some of the species within this group. Using an increased amount of sequence data we test between alternative hypotheses of soft polytomies caused by rapid speciation, slow evolutionary rate and/or insufficient sequence data, and hard polytomies caused by simultaneous speciation within this family. Combining the mitogenome sequences of five new and 12 previously published species within the Delphinidae, we used Bayesian and maximum-likelihood methods to estimate the phylogeny from partitioned and unpartitioned mitogenome sequences. Further ad hoc tests were then conducted to estimate the support for alternative topologies. Results. We found high support for all the relationships within our reconstructed phylogenies, and topologies were consistent between the Bayesian and maximum-likelihood trees inferred from partitioned and unpartitioned data. Resolved relationships included the placement of the killer whale (Orcinus orca) as sister taxon to the rest of the Globicephalinae subfamily, placement of the Risso's dolphin (Grampus griseus) within the Globicephalinae subfamily, removal of the white-beaked dolphin (Lagenorhynchus albirostris) from the Delphininae subfamily and the placement of the rough-toothed dolphin (Steno bredanensis) as sister taxon to the rest of the Delphininae subfamily rather than within the Globicephalinae subfamily. The additional testing of alternative topologies allowed us to reject all other putative relationships, with the exception that we were unable to reject the hypothesis that the relationship between L. albirostris and the Globicephalinae and Delphininae subfamilies was polytomic. Conclusion. Despite their rapid diversification, the increased sequence data yielded by mitogenomes enables the resolution of a strongly supported, bifurcating phylogeny, and a chronology of the divergences within the Delphinidae family. This highlights the benefits and potential application of large mitogenome datasets to resolve long-standing phylogenetic uncertainties. © 2011 Vilstrup et al; licensee BioMed Central Ltd.

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