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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 49 (1978), S. 27-32 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The common subtidal marine bryozoan Alcyonidium gelatinosum (L.) is one of the most confusing species of a taxonomically very difficult genus. It shows massive variation for almost all morphological characters. A number of sympatric colonies collected off the coast of Lundy (Bristol Channel) could be clearly divided on morphological grounds into two quite distinct types. Using starch gel electrophoresis the products of a range of genetic enzyme loci were compared between the two morphotypes and also between these and other Bristol Channel populations of A. gelatinosum. Minimal differences were observed between one Lundy morphotype and the other allopatric populations, which it was consequently concluded were conspecific. The second morphotype showed considerable genetic differentiation [genetic identity (Nei, 1972) =0.417] from the other Lundy population, with no common alleles at some loci. The probability of obtaining the observed results by chance in a single population is significantly low (P〈10−14). It is therefore concluded that the two morphotypes of A. gelatinosum from Lundy are not conspecific.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 35 (1976), S. 139-147 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Electrophoretic analysis of loci controlling a variety of enzymes has been applied to samples of the “Padstow mussel” and typical Mytilus edulis L. living strictly sympatrically at Rock, Cornwall, England, in order to resolve the disputed status of the “Padstow mussel”. Small samples indicated similar monomorphic states at the αGPDH, TO, MDH-2 loci and weak polymorphism at the 6 PGD locus in both types of mussel. The MDH-1 locus may be weakly polymorphic in the “Padstow mussel” and monomorphic in M. edulis. Large samples assayed for AP, LAP, PGM, and PHI produced data showing very large and highly significant differences in allele frequencies at three of these loci between the two groups of mussels separated on anatomical characters. At the LAP locus, significant deficiencies of heterozygotes were observed in both groups of mussels. A small percentage of mussels from Rock are difficult to assign with certainty to one or other group on anatomical and morphological criteria, but the genetic evidence indicates that most, if not all, such specimens are M. edulis. These genetic differences make it highly improbable that any significant degree of genetic exchange occurs between the two groups in nature and, taken together with the evidence of genetic resemblance of the Padstow mussel to M. galloprovincialis from Venice and that of Rock M. edulis to M. edulis, from the Gower peninsula of Wales we conclude that the “Padstow mussel” is indeed M. galloprovincialis.
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  • 3
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Allozyme electrophoretic analysis of seven polymorphic enzyme loci suggested that 1261 samples of Palythoa collected along 1765 km of the Great Barrier Reef during 1992–1993 were members of a single taxon, identified as Palythoa caesia Dana, 1846, with high external morphological variability and possibly encompassing several previously described species. Populations were slightly genetically differentiated (standardized genetic variance, F ST=0.010, p〈0.05), but there was no evidence of isolation by distance, or of the particular genetic distinction of geographic sets of reefs such as the Swains, as has been observed in other invertebrates. Differentiation was thought to be the result of random selection acting on patches of larvae, not the consequences of long-term reproductive isolation of populations.
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  • 4
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Specimens of the deep-sea brittle-star Ophiomusium lymani were collected from six sites in the Rockall Trough (northeast Atlantic_. Four monomorphic and four polymorphic loci were detected, with up to 75 individuals screened at any one locus. The results showed little difference in allele frequencies between sites and, consequently, estimates of genetic identity indicated no significant genetic differentiation between the populations sampled. Deficits of heterozygotes were observed at all polymorphic loci, but the deficiencies were only significant at the phosphoglucose isomerase locus from two locations. The deficit of heterozygotes was not the same across loci, suggesting that inbreeding is not the cause of the excess homozygosity. No relationship between heterozygosity and depth was observed.
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  • 5
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Samples of an intertidal zoanthid, Zoanthus coppingeri, Haddon and Shackelton, 1891, were collected from three localities in the Great Barrier Reef region during 1992–1993, and subjected to allozyme electrophoretic analysis at seven polymorphic loci. The reduced ratio of observed to expected genotypic diversity indicated that populations were partly clonal, but they were not dominated by a few clones as occurs in some other cnidarians. Regular disturbance by wave action is postulated to prevent the formation of large stands of particular clones by clearing space and mixing genotypes over small scales. The sexual origin of clonal genotypes was confirmed by conformance to Hardy-Weinberg predictions of genotype frequencies at all but one locus. Values of the standardised genetic variance among populations, F ST , were highly significant between localities and between replicate sites within localities separated by only 50 m. Strong genetic structure has not previously been described in a Great Barrier Reef invertebrate species, and is considered to be the consequence of stochastic changes in gene frequencies as a result of low levels of gene flow. High clonal longevity and low recruitment rates may maintain genetic differences over long periods. Similar effects may be seen in other Great Barrier Reef invertebrate species with comparable reproductive patterns.
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  • 6
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A scanning electron microscopy (SEM) study of bisexual Artemia populations revealed that populations representing the species A. franciscana, A. persimilis, A. urmiana, A. sinica and a recently described species from Kazakhstan have a pair of spine-like outgrowths at the basal parts of their penes, whereas populations from southern Europe and North Africa (i.e. Mediterranean populations) lack these spine-like outgrowths. Allozyme and DNA polymorphisms, detected by allozyme starch gel electrophoresis and AFLP fingerprinting, respectively, suggested conspecificity of the studied populations from the broader Mediterranean basin. Male specimens from the collection of the Natural History Museum of London (UK) of the extinct A. salina population from Lymington lack spine-like outgrowths at the basal parts of the penes. This finding, based on a taxonomic character which is quite reliable, suggests conspecificity of A. salina from Lymington and the present bisexual Artemia populations from the Mediterranean basin, grouped under the binomen A. tunisiana.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 49 (1978), S. 343-350 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract For many years the taxonomic position of the marine ctenostome bryozoan Alcyonidium mytili Dalyell (1848) has been in doubt, with some authorities regarding it as being conspecific with A. polyoum (Hassall). We have set out to resolve this problem using enzyme electrophoresis to examine the genetics of the population structure in the two “species”. The results show beyond reasonable doubt that sympatric populations of the two species are indeed from quite separate and non-interbreeding gene pools. An examination of various allopatric populations shows a new species of “A. mytili” to exist sympatrically with the other at Langstone Harbour, Hampshire, England. This species can be readily distinguished on morphological as well as genetic ground. Samples of “A. mytili” from Guernsey also show substantial genetic differences from other populations examined. It is tentatively concluded that this population also represents a separate gene pool and consequently should be recognised as a third species of “A. mytili”.
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  • 8
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 183 (1959), S. 1833-1834 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Table 1. OBSERVED AND EXPECTED DISTRIBUTION OF DIFFERENT MATINGS IN A MIXED BLUE AND SNOW GOOSE POPULATION Type of mating Two snow birds Two blue birds One blue, one snow Total No. observed Ko. expected 373 330-4 64 21-4 83 168-2 520 520 The x2 value for the deviations from expected is very ...
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  • 9
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 190 (1961), S. 1135-1136 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] About forty etherized D. melanogaster were placed in a tube connecting two half-pint milk bottles. In one bottle was a spoon with food containing an adulterant, in the other was a spoon with normal food. The number of flies in each bottle was recorded after 1 hr. and after 24 hr., at which time the ...
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  • 10
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 189 (1961), S. 162-163 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Additive genetic variance in each of the four populations was estimated in the following way. Virgin flies were collected and mated assortatively for the number of chsetse on the fifth sternite. Two samples of five flies of each sex were drawn from each culture and the chsetse on the fifth sternite ...
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