Assessment of genetic structure among eastern North Pacific gray whales on their feeding grounds

Lang, Aimée R.; Calambokidis, John; Scordino, Jonathan J.; Pease, Victoria; Klimek, Amber; Burkanov, Vladimir N.; Gearin, Pat; Литовка, Д. И.; Robertson, Kelly M.; Mate, Bruce R.; Jacobsen, Jeff K.; Taylor, Barbara L.

doi:10.1111/mms.12129

Cited by 36 publications

(45 citation statements)

References 69 publications

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“…Other whale species with common wintering grounds but long-term fidelity to different feeding areas in the North Pacific exhibit female-mediated population structure (e.g. humpback and gray whales, [40, 41]), but arguably these feeding areas are spread over greater geographic distances than seen here, and have geographically distinct migratory routes. Even without genetic divergence between geographic sites, differences in the frequencies of maternally inherited haplotypes between sites can be expected due to the long-term, maternally influenced fidelities of females to particular feeding areas.…”

Section: Discussionmentioning

confidence: 76%

Estimates of Abundance and Trend of Chilean Blue Whales off Isla de Chiloé, Chile

et al. 2017

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Since 1970, blue whales (Balaenoptera musculus) have been seen feeding in the waters off southern Chile during the summer and autumn (December to May). Investigation of the genetic, acoustic and morphological characteristics of these blue whales shows that they are a distinct but unnamed subspecies, called the Chilean blue whales. Photo-identification surveys have been conducted in the waters off northwestern Isla Grande de Chiloé, southern Chile from 2004–2012 and Isla Chañaral, central Chile in 2012. Over this time, 1,070 blue whales were encountered yielding, after photo-quality control, 318 and 267 unique photographs of the left and right side of the flank respectively. Using mark-recapture analysis of left and right side photographs collected from Isla Grande de Chiloé (2004–2012), open population models estimate that ~570–760 whales are feeding seasonally in this region. POPAN superpopulation abundance estimates for the same feeding ground in 2012 are 762 (95% confidence intervals, CI = 638–933) and 570 (95% CI 475–705) for left and right side datasets respectively, very similar to results from closed population models. Estimates of trend revealed strong variation in abundance, peaking in 2009 and [suggesting] fluctuating use in the survey area over time, likely related to the density of their prey. High inter-annual return rates suggest a degree of site-fidelity of individuals to Isla Grande de Chiloé and that the number of whales using this feeding ground is relatively small.

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Section: Discussionmentioning

confidence: 76%

Estimates of Abundance and Trend of Chilean Blue Whales off Isla de Chiloé, Chile

et al. 2017

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“…Among globally‐distributed large whales, most baleen whales exhibit high mtDNA diversity relative to toothed whales and are divided into multiple subspecies and genetically distinct populations (e.g., fin, humpback, grey and blue whales; Archer et al., ; Baker et al., ; Jackson et al., ; Lang et al., ; Leduc et al., ). Among toothed whales, however, unusually low mitochondrial DNA (mtDNA) diversity in some of the social odontocetes (e.g., sperm, pilot, killer and false‐killer whales; Alexander et al., , ; Hoelzel et al., ; Martien et al., ; Van Cise et al., ) has limited power to infer population structure, phylogeography and historical demography using traditional genetic tools.…”

Section: Introductionmentioning

confidence: 99%

Demography or selection on linked cultural traits or genes? Investigating the driver of low mtDNA diversity in the sperm whale using complementary mitochondrial and nuclear genome analyses

et al. 2018

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Mitochondrial DNA has been heavily utilized in phylogeography studies for several decades. However, underlying patterns of demography and phylogeography may be misrepresented due to coalescence stochasticity, selection, variation in mutation rates and cultural hitchhiking (linkage of genetic variation to culturally-transmitted traits affecting fitness). Cultural hitchhiking has been suggested as an explanation for low genetic diversity in species with strong social structures, counteracting even high mobility, abundance and limited barriers to dispersal. One such species is the sperm whale, which shows very limited phylogeographic structure and low mtDNA diversity despite a worldwide distribution and large population. Here, we use analyses of 175 globally distributed mitogenomes and three nuclear genomes to evaluate hypotheses of a population bottleneck/expansion vs. a selective sweep due to cultural hitchhiking or selection on mtDNA as the mechanism contributing to low worldwide mitochondrial diversity in sperm whales. In contrast to mtDNA control region (CR) data, mitogenome haplotypes are largely ocean-specific, with only one of 80 shared between the Atlantic and Pacific. Demographic analyses of nuclear genomes suggest low mtDNA diversity is consistent with a global reduction in population size that ended approximately 125,000 years ago, correlated with the Eemian interglacial. Phylogeographic analysis suggests that extant sperm whales descend from maternal lineages endemic to the Pacific during the period of reduced abundance and have subsequently colonized the Atlantic several times. Results highlight the apparent impact of past climate change, and suggest selection and hitchhiking are not the sole processes responsible for low mtDNA diversity in this highly social species.

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“…These migratory baleen whales spend approximately half of the year in Arctic and sub-Arctic regions, where climate change is rapidly reshaping ecosystems, and a northward shift in feeding range, among other population changes, has been attributed to climate impacts on benthic habitats (Moore et al 2003;Moore 2008). Today, gray whales survive in geographically separate eastern and western populations in the North Pacific Ocean, with subtle genetic structure observed both between these populations (LeDuc et al 2002) and among feeding (Lang et al 2014) and breeding ) groups in the eastern Pacific. However, radiometric dating of subfossil remains shows that gray whales were also present in the Atlantic Ocean during the Holocene (Bryant 1995) and Pleistocene (Noakes et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Climate impacts on transocean dispersal and habitat in gray whales from the Pleistocene to 2100

et al. 2015

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Arctic animals face dramatic habitat alteration due to ongoing climate change. Understanding how such species have responded to past glacial cycles can help us forecast their response to today's changing climate. Gray whales are among those marine species likely to be strongly affected by Arctic climate change, but a thorough analysis of past climate impacts on this species has been complicated by lack of information about an extinct population in the Atlantic. While little is known about the history of Atlantic gray whales or their relationship to the extant Pacific population, the extirpation of the Atlantic population during historical times has been attributed to whaling. We used a combination of ancient and modern DNA, radiocarbon dating and predictive habitat modelling to better understand the distribution of gray whales during the Pleistocene and Holocene. Our results reveal that dispersal between the Pacific and Atlantic was climate dependent and occurred both during the Pleistocene prior to the last glacial period and the early Holocene immediately following the opening of the Bering Strait. Genetic diversity in the Atlantic declined over an extended interval that predates the period of intensive commercial whaling, indicating this decline may have been precipitated by Holocene climate or other ecological causes. These first genetic data for Atlantic gray whales, particularly when combined with predictive habitat models for the year 2100, suggest that two recent sightings of gray whales in the Atlantic may represent the beginning of the expansion of this species' habitat beyond its currently realized range.

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Assessment of genetic structure among eastern North Pacific gray whales on their feeding grounds

Cited by 36 publications

References 69 publications

Estimates of Abundance and Trend of Chilean Blue Whales off Isla de Chiloé, Chile

Estimates of Abundance and Trend of Chilean Blue Whales off Isla de Chiloé, Chile

Demography or selection on linked cultural traits or genes? Investigating the driver of low mtDNA diversity in the sperm whale using complementary mitochondrial and nuclear genome analyses

Climate impacts on transocean dispersal and habitat in gray whales from the Pleistocene to 2100

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