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  • 1
    ISSN: 1573-5117
    Keywords: Heteronemertea ; genetic differentiation ; North Atlantic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Specimens of the common intertidal nemerteans Lineus ruber and L. viridis were collected fromsites along the west and Southwest coasts of Britain,northern France and North America. Allele frequenciesof up to 13 putative enzyme loci were estimated forall populations of L. ruber and L.viridis. Estimates of genetic variation were low forpopulations of L. ruber (Hobs 0.008–0.052)but were higher for populations of L. viridis(Hobs 0.068–0.153). Exacttests for conformity of observed genotype frequenciesto those expected under Hardy-Weinberg equilibriumfailed to detect significant deviations for L.ruber or L. viridis. F-statistics wereaffected by small sample size and low expected valuesin some populations, but, FST wassignificantly different from zero for most lociexamined for both Lineus ruber and L.viridis. This indicated a significant degree ofpopulation structuring for both species (only amoderate level of gene-flow). Intraspecificcomparisons of genetic distance and genetic identityshowed little evidence of genetic differentiationbetween populations separated by large geographicdistances (1000s of km). There was no apparentrelationship between genetic distance betweenpopulations and the geographic distance separatingthem. Possible explanations for this lack of geneticdifferentiation between populations of L. ruberand L. viridis are discussed. These include alack of variation in the enzyme loci sampled caused bypopulation dynamics, balancing selection in the enzymeloci sampled, large introductions between populationsand passive dispersal.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2022-05-26
    Description: © The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Scientific Reports 4 (2014): 5024, doi:10.1038/srep05024.
    Description: Climate change is a major threat to global biodiversity. Antarctic ecosystems are no exception. Investigating past species responses to climatic events can distinguish natural from anthropogenic impacts. Climate change produces ‘winners’, species that benefit from these events and ‘losers’, species that decline or become extinct. Using molecular techniques, we assess the demographic history and population structure of Pygoscelis penguins in the Scotia Arc related to climate warming after the Last Glacial Maximum (LGM). All three pygoscelid penguins responded positively to post-LGM warming by expanding from glacial refugia, with those breeding at higher latitudes expanding most. Northern (Pygoscelis papua papua) and Southern (Pygoscelis papua ellsworthii) gentoo sub-species likely diverged during the LGM. Comparing historical responses with the literature on current trends, we see Southern gentoo penguins are responding to current warming as they did during post-LGM warming, expanding their range southwards. Conversely, Adélie and chinstrap penguins are experiencing a ‘reversal of fortunes’ as they are now declining in the Antarctic Peninsula, the opposite of their response to post-LGM warming. This suggests current climate warming has decoupled historic population responses in the Antarctic Peninsula, favoring generalist gentoo penguins as climate change ‘winners’, while Adélie and chinstrap penguins have become climate change ‘losers’.
    Description: We thank the Zoological Society of London, Quark Expeditions, Exodus Travels ltd., Oceanites, the Holly Hill Charitable Trust, the Charities Advisory Trust and an U.S. National Science Foundation (NSF) Office of Polar Programs grant (ANT-0739575) for funding.
    Keywords: Climate-change ecology ; Molecular ecology ; Molecular evolution ; Population genetics
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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