Seasonal movements of killer whales between Iceland and Scotland

Samarra, Filipa I. P.; Foote, Andrew D.

doi:10.3354/ab00637

Cited by 27 publications

(21 citation statements)

References 12 publications

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“…Samples were selected from a global data set of 452 individuals that best represented the known global geographic and genetic diversity of this species (Morin et al, 2015). Where possible, we selected identifiable individuals from longitudinally studied populations, e.g., Crozet Archipelago (Guinet & Tixier, 2011), Gibraltar (Esteban et al, 2016), Iceland (Samarra & Foote, 2015) and Scotland (Beck et al, 2014).…”

Section: Library Building Sequencing and Mappingmentioning

confidence: 99%

Killer whale genomes reveal a complex history of recurrent admixture and vicariance

et al. 2019

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Reconstruction of the demographic and evolutionary history of populations assuming a consensus tree‐like relationship can mask more complex scenarios, which are prevalent in nature. An emerging genomic toolset, which has been most comprehensively harnessed in the reconstruction of human evolutionary history, enables molecular ecologists to elucidate complex population histories. Killer whales have limited extrinsic barriers to dispersal and have radiated globally, and are therefore a good candidate model for the application of such tools. Here, we analyse a global data set of killer whale genomes in a rare attempt to elucidate global population structure in a nonhuman species. We identify a pattern of genetic homogenisation at lower latitudes and the greatest differentiation at high latitudes, even between currently sympatric lineages. The processes underlying the major axis of structure include high drift at the edge of species' range, likely associated with founder effects and allelic surfing during postglacial range expansion. Divergence between Antarctic and non‐Antarctic lineages is further driven by ancestry segments with up to four‐fold older coalescence time than the genome‐wide average; relicts of a previous vicariance during an earlier glacial cycle. Our study further underpins that episodic gene flow is ubiquitous in natural populations, and can occur across great distances and after substantial periods of isolation between populations. Thus, understanding the evolutionary history of a species requires comprehensive geographic sampling and genome‐wide data to sample the variation in ancestry within individuals.

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Section: Library Building Sequencing and Mappingmentioning

confidence: 99%

Killer whale genomes reveal a complex history of recurrent admixture and vicariance

et al. 2019

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“…Genetic units 1 and 2 had a significant predominance of mtDNA haplotype 33 and the majority of its individuals were seen year-round in Iceland. Contrarily, nearly all individuals in genetic unit 3 had mtDNA haplotype 34 and were seen only seasonally in Iceland; some of them are known to travel to Scotland where they were seen feeding upon marine mammals (Samarra & Foote, 2015;Samarra, Vighi, et al, 2017). It is important to acknowledge that since the time lapse during which the stable isotopic signal of a given diet remains in skin is only a few weeks (Browning, Dold, I-Fan, & Worthy, 2014;Giménez, Ramírez, Almunia, Forero, & de Stephanis, 2016), individual isotopic signatures might not represent the entire diet patterns of individuals.…”

Section: Fine-scale Genetic Structurementioning

confidence: 99%

“…Photo‐identification of killer whales in Icelandic herring overwintering‐ and summer‐spawning grounds showed that some individuals are sighted in both summer and winter seasons but others are seen only seasonally (Samarra, Tavares, et al, ). Also, some individuals observed only in the winter season were seen moving to Scotland in the summer, where they were seen feeding upon marine mammals (Samarra & Foote, ). Isotopic analyses of biopsy sampled individuals with different observed movement patterns show that these largely correspond to different isotopic niche widths (Samarra, Vighi, Aguilar, & Víkingsson, ).…”

Section: Introductionmentioning

confidence: 99%

Killer whales (Orcinus orca) in Iceland show weak genetic structure among diverse isotopic signatures and observed movement patterns

Tavares

Samarra

Pascoal

et al. 2018

Ecology and Evolution

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Local adaption through ecological niche specialization can lead to genetic structure between and within populations. In the Northeast Pacific, killer whales (Orcinus orca) of the same population have uniform specialized diets that are non‐overlapping with other sympatric, genetically divergent, and socially isolated killer whale ecotypes. However, killer whales in Iceland show intrapopulation variation of isotopic niches and observed movement patterns: some individuals appear to specialize on herring and follow it year‐round while others feed upon herring only seasonally or opportunistically. We investigated genetic differentiation among Icelandic killer whales with different isotopic signatures and observed movement patterns. This information is key for management and conservation purposes but also for better understanding how niche specialization drives genetic differentiation. Photo‐identified individuals (N = 61) were genotyped for 22 microsatellites and a 611 bp portion of the mitochondrial DNA (mtDNA) control region. Photo‐identification of individuals allowed linkage of genetic data to existing data on individual isotopic niche, observed movement patterns, and social associations. Population subdivision into three genetic units was supported by a discriminant analysis of principal components (DAPC). Genetic clustering corresponded to the distribution of isotopic signatures, mtDNA haplotypes, and observed movement patterns, but genetic units were not socially segregated. Genetic differentiation was weak (F ST < 0.1), suggesting ongoing gene flow or recent separation of the genetic units. Our results show that killer whales in Iceland are not as genetically differentiated, ecologically discrete, or socially isolated as the Northeast Pacific prey‐specialized killer whales. If any process of ecological divergence and niche specialization is taking place among killer whales in Iceland, it is likely at a very early stage and has not led to the patterns observed in the Northeast Pacific.

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“…Where possible, we selected identifiable individuals from longitudinally studied populations, e.g. Crozet Archipelago (Guinet & Tixier, 2011); Gibraltar (Esteban et al, 2016); and Iceland (Samarra & Foote, 2015). DNA was extracted from skin biopsies, with the exception of the recently described type D morphotype (Pitman et al, 2011), from which dry soft tissue and powdered tooth were sampled from a specimen (#1077) which stranded on Paraparaumu Beach, New Zealand in 1955, and is now part of the collections of the Museum of New Zealand, Te Papa Tongarewa, Wellington.…”

Section: Library Building Sequencing and Mappingmentioning

confidence: 99%

Killer whale genomes reveal a complex history of recurrent admixture and vicariance

Foote

Martin

Louis

et al. 2019

Preprint

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Reconstruction of the demographic and evolutionary history of populations assuming a consensus tree-like relationship can mask more complex scenarios, which are prevalent in nature. An emerging genomic toolset, which has been most comprehensively harnessed in the reconstruction of human evolutionary history, enables molecular ecologists to elucidate complex population histories. Killer whales have limited extrinsic barriers to dispersal and have radiated globally, and are therefore a good candidate model for the application of such tools. Here, we analyse a global dataset of killer whale genomes in a rare attempt to elucidate global population structure in a non-human species. We identify a pattern of genetic homogenisation at lower latitudes and the greatest differentiation at high latitudes, even between currently sympatric lineages. The processes underlying the major axis of structure include high drift at the edge of species' range, likely associated with founder effects and allelic surfing during post-glacial range expansion. Divergence between Antarctic and non-Antarctic lineages is further driven by ancestry segments with up to four-fold older coalescence time than the genome-wide average; relicts of a previous vicariance during an earlier glacial cycle. Our study further underpins that episodic gene flow is ubiquitous in natural populations, and can occur across great distances and after substantial periods of isolation between populations.Thus, understanding the evolutionary history of a species requires comprehensive geographic sampling and genome-wide data to sample the variation in ancestry within individuals.

show abstract

Seasonal movements of killer whales between Iceland and Scotland

Cited by 27 publications

References 12 publications

Killer whale genomes reveal a complex history of recurrent admixture and vicariance

Killer whale genomes reveal a complex history of recurrent admixture and vicariance

Killer whales (Orcinus orca) in Iceland show weak genetic structure among diverse isotopic signatures and observed movement patterns

Killer whale genomes reveal a complex history of recurrent admixture and vicariance

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