Intra-population variation in isotopic niche in herring-eating killer whales off Iceland

Samarra, Filipa I. P.; Vighi, Morgana; Aguilar, Àlex; Víkingsson, Gísli A.

doi:10.3354/meps11998

Cited by 37 publications

(64 citation statements)

References 74 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Stable isotope ratios were available for all 21 individuals of genetic unit 1, for 23/25 individuals of genetic unit 2 and for 12/15 individuals of genetic unit 3, including 5/6 individuals matched to Scotland in the summer (Samarra, Vighi, et al, ). Overall, individuals from genetic unit 3 had higher values of δ 15 N (Figure ) and a significantly larger SEA C than individuals from the two other genetic units (Figure ; unit 3 vs. unit 1: 0.98 vs. 0.16‰ 2 , p ‐value < 0.0001; unit 3 vs. unit 2: 0.98 vs. 0.29‰ 2 , p ‐value < 0.001).…”

Section: Resultsmentioning

confidence: 99%

“…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, ). Individuals seen in both seasons had lower nitrogen stable isotope ratios ( 15 N/ 14 N, represented as δ 15 N), consistent with a diet predominantly composed of herring, while killer whales only seen seasonally (including sampled individuals that travel between Iceland and Scotland) exhibited larger variation in δ 15 N, suggesting that some individuals have a diet including other prey (Samarra, Vighi, et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…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, ). Individuals seen in both seasons had lower nitrogen stable isotope ratios ( 15 N/ 14 N, represented as δ 15 N), consistent with a diet predominantly composed of herring, while killer whales only seen seasonally (including sampled individuals that travel between Iceland and Scotland) exhibited larger variation in δ 15 N, suggesting that some individuals have a diet including other prey (Samarra, Vighi, et al, ). However, there is no social isolation between individuals with different observed movement patterns and isotopic signatures, that is, putative herring‐specialists remaining year‐round in Iceland have been photographed in close proximity with Icelandic‐Scottish killer whales (Tavares, Samarra, & Miller, ).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

View full text Add to dashboard Cite

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.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

View full text Add to dashboard Cite

show abstract

“…In combination with studies on 632 stable isotopes, these differences in individual movement patterns suggest a mosaic of 633 foraging preferences (Samarra et al 2017b). Importantly, such differences in 634 movement patterns and feeding preferences are not reflected in social isolation 635 (Tavares et al 2017), thus suggesting that these differences may occur in the absence 636 of reproductive isolation.…”

Section: Adaptation To Long-term Changes In Prey Distribution 517mentioning

confidence: 95%

“…Because observational data alone 643 cannot accurately reflect their feeding ecology (Samarra et al 2017b …”

Section: Adaptation To Long-term Changes In Prey Distribution 517mentioning

confidence: 99%

Movements and site fidelity of killer whales (Orcinus orca) relative to seasonal and long-term shifts in herring (Clupea harengus) distribution

et al. 2017

View full text Add to dashboard Cite

. (2017) Movements and site fidelity of killer whales (Orcinus orca) relative to seasonal and long-term shifts in herring (Clupea harengus) distribution. Marine Biology, 164 (8). Article:159.Downloaded from: http://insight.cumbria.ac.uk/id/eprint/3080/ Usage of any items from the University of Cumbria's institutional repository 'Insight' must conform to the following fair usage guidelines.Any item and its associated metadata held in the University of Cumbria's institutional repository Insight (unless stated otherwise on the metadata record) may be copied, displayed or performed, and stored in line with the JISC fair dealing guidelines (available here) for educational and not-for-profit activities provided that• the authors, title and full bibliographic details of the item are cited clearly when any part of the work is referred to verbally or in the written form• a hyperlink/URL to the original Insight record of that item is included in any citations of the work • the content is not changed in any way• all files required for usage of the item are kept together with the main item file. You may not• sell any part of an item• refer to any part of an item without citation • amend any item or contextualise it in a way that will impugn the creator's reputation• remove or alter the copyright statement on an item.The full policy can be found here. Alternatively contact the University of Cumbria Repository Editor by emailing insight@cumbria.ac.uk. Predators specialising on migratory prey that frequently change migration route 18 face the challenge of finding prey with an unpredictable distribution. Here, we 19 used photo-identification data to investigate whether killer whales observed in 20 herring overwintering and spawning grounds off Iceland follow herring year-21 round, as previously proposed, and have the ability to adapt to long-term changes 22 in herring distribution. Of 327 identified whales seen more than once, 45% were 23 seen in both grounds, and were thus presumed herring-specialists, likely following 24 herring year-round, while others were only seen on one of the grounds, possibly 25 following herring to unsampled grounds or moving to other locations and 26 exploiting different prey. High seasonal site fidelity to herring grounds, long-term 27 site fidelity to herring spawning grounds, and matches of individual whales 28 between past and recently occupied herring overwintering grounds showed an 29 ability to adapt to long-term changes in prey distribution as well as diversity of 30 movement patterns which are maintained over time, likely as socially-learnt 31traditions. Such population structuring shows that the movement patterns and 32 foraging ecology of herring-eating killer whales are more complex than previously 33 assumed and must be taken into account in future population assessments. 34Identifying the factors driving these differences in movements and resource use 35 will be relevant towards our understanding of how prey predictability may drive 36 specialization in this and other top predator speci...

show abstract

Behavioural heterogeneity across killer whale social units in their response to feeding opportunities from fisheries

Auguin,

Guinet,

Mourier

et al. 2024

Ecology and Evolution

View full text Add to dashboard Cite

Intra‐population heterogeneity in the behavioural response of predators to changes in prey availability caused by human activities can have major evolutionary implications. Among these activities, fisheries, while extracting resources, also provide new feeding opportunities for marine top predators. However, heterogeneity in the extent to which individuals have responded to these opportunities within populations is poorly understood. Here, we used 18 years of photo‐identification data paired with statistical models to assess variation in the way killer whale social units within a subantarctic population (Crozet Islands) interact with fisheries to feed on fish caught on fishing gear (i.e., depredation behaviour). Our results indicate large heterogeneity in both the spatial and temporal extents of depredation across social units. While some frequently depredated on fishery catches over large areas, others sporadically did so and in small areas consistently over the years. These findings suggest that killer whale social units are exposed to varying levels of impacts of depredation, both negative (potential retaliation from fishers) and positive (food provisioning), on their life history traits, and may explain the contrasted demographic patterns observed within the declining population at Crozet but also potentially within the many other killer whale populations documented depredating on fisheries catches worldwide.

show abstract

Intra-population variation in isotopic niche in herring-eating killer whales off Iceland

Cited by 37 publications

References 74 publications

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

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

Movements and site fidelity of killer whales (Orcinus orca) relative to seasonal and long-term shifts in herring (Clupea harengus) distribution

Behavioural heterogeneity across killer whale social units in their response to feeding opportunities from fisheries

Contact Info

Product

Resources

About