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  • 1
    Electronic Resource
    Electronic Resource
    Genetic differentiation of populations of the common intertidal nemerteans Lineus ruber and Lineus viridis (Nemertea, Anopla) (1997)
    Springer
    Hydrobiologia 365 (1997), S. 1-11 
    Details
    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
    URL: http://dx.doi.org/10.1023/A:1003110022640
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Enzyme electrophoresis, genetic identity and description of a new genus and species of heteronemertean (Nemertea, Anopla) from northwestern Spain and North Wales (1993)
    Springer
    Hydrobiologia 266 (1993), S. 219-238 
    Details
    ISSN: 1573-5117
    Keywords: Heteronemertea ; genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The anoplan order Heteronemertea, particularly the genera Cerebratulus, Lineus and Micrura, contains a very large number of nominate species, many of which are inadequately described. As a consequence, systematic difficulties are encountered with the identification of many taxa in this group, especially those originally established primarily on the basis of their external features. The present paper concerns heteronemerteans collected from two locations, the Foz Estuary (north-western Spain) and Llandudno (North Wales). The Spanish collection included specimens identified as Lineus longissimus (Gunnerus), whilst samples from Llandudno contained large numbers of Lineus viridis (Müller); samples of a third similar but apparently undescribed species were found at both locations. Starch gel electrophoresis showed that samples of the apparent third species were genetically almost identical from each of the two locations, but were clearly different from the two described Lineus species. Histological studies of the unknown specimens revealed anatomical characters, including the unique feature of a proboscis epithelium ciliated throughout its length, which exclude it from any known heteronemertean taxon; it is accordingly placed in a new genus and species, for which the name Riseriellus occultus is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00013370
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    Paper (German National Licenses)
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  • 3
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    Low connectivity between ‘scaly-foot gastropod’ (Mollusca: Peltospiridae) populations at hydrothermal vents on the Southwest Indian Ridge and the Central Indian Ridge (2015)
    Springer
    In:  Organisms Diversity & Evolution, 15 (4). pp. 663-670.
    Details
    Publication Date: 2018-01-19
    Description: Hydrothermal vents on mid-oceanic ridges are patchily distributed and host many taxa endemic to deep-sea chemosynthetic environments, whose dispersal may be constrained by geographical barriers. The aim of this study was to investigate the connectivity of three populations of the ‘scaly-foot gastropod’ (Chrysomallon squamiferum Chen et al., 2015), a species endemic to hydrothermal vents in the Indian Ocean, amongst two vent fields on the Central Indian Ridge (CIR) and Longqi field, the first sampled vent field on the Southwest Indian Ridge (SWIR). Connectivity and population structure across the two mid-oceanic ridges were investigated using a 489-bp fragment of the cytochrome oxidase c subunit I (COI) gene. Phylogeographical approaches used include measures of genetic differentiation (FST), reconstruction of parsimony haplotype network, mismatch analyses and neutrality tests. Relative migrants per generation were estimated between the fields. Significant differentiation (FST = 0.28–0.29, P 〈 0.001) was revealed between the vent field in SWIR and the two in CIR. Signatures were detected indicating recent bottleneck events followed by demographic expansion in all populations. Estimates of relative number of migrants were relatively low between the SWIR and CIR, compared with values between the CIR vent fields. The present study is the first to investigate connectivity between hydrothermal vents across two mid-ocean ridges in the Indian Ocean. The phylogeography revealed for C. squamiferum indicates low connectivity between SWIR and CIR vent populations, with implications for the future management of environmental impacts for seafloor mining at hydrothermal vents in the region, as proposed for Longqi.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s13127-015-0224-8
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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