Genetic differentiation among populations of Minona ileanae (Platyhelminthes: Proseriata) from the Red Sea and the Suez Canal

The phenomenon of Lessepsian migration has stimulated the interest of biologists ever since the opening of the Suez Canal in 1869, concerning, in particular, the possible effects of migrants on Mediterranean autochthonous communities. So far, most attention has been devoted to macrofaunal taxa - yet, the nature of the sandy shores of the Canal may constitute an ideal habitat for many interstitial taxa. However, studies on these organisms, and especially on “inconspicuous” taxa, such as the microturbellaria, are almost completely lacking. A recent sampling campaign along the shores of the Suez Canal, aimed at studying the composition and distribution of free-living Platyhelminthes in the area, potential invaders of the Mediterranean Sea, revealed the occurrence of the interstitial species Minona ileanae (Neoophora: Proseriata), first described on specimens collected in the Gulf of Eilat-Aqaba (Red Sea). The presence of a significant population of this species in the Suez area, a possible source of colonizers of the Canal, allowed comparison between its genetic pattern and those obtained from three populations collected in the Canal. Their genetic structure was surveyed by means of ISSR (Inter-Simple Sequence Repeat) molecular markers. UPGMA cluster analysis based on the matrix of interindividual dissimilarity (1-relatedness) and the assignment test revealed sharp genetic divergence among the four samples with a highly significant F_ST value (0.155, P < 0.001). The significant genetic differentiation may be related to a post-1869 colonisation of the Canal with swift genetic divergence, due to either different pressure selection of the habitats and/or the short life cycle of M. ileanae, or, more convincingly, to an early migration to the Isthmus in pre-Lessepsian periods, during i) the Last Interglacial Optimum, ii) the Holocene Climatic Optimum, or iii) across the artificial waterways built by the ancient Egyptians from the 13th century B.C. onwards. The remarkable tolerance shown in laboratory of the species to salinity values ranging from as low as 10‰ to 80‰ supports the possibility that M. ileanae may have survived in the water bodies of the Isthmus in pre-Lessepsian times.     

Genetic diversity of Shiraia bambusicola from East China assessed using ISSR markers

To understand the genetic differentiation of the medicinal fungus Shiraia bambusicola, the genetic diversity of 107 individuals from eight populations collected from Jiangsu, Anhui and Zhejiang provinces were studied using inter-simple sequence repeat (ISSR) analysis. The results revealed that the 11 employed primers produced a total of 241 ISSR loci, of which 240 loci (PPB = 99.6%) were polymorphic. Both Nei's gene diversity indexes and Shannon's gene diversity indexes showed that the genetic differentiation of S. bambusicola primarily occurred within the populations. AMOVA revealed that the variation among populations was 40.0%, and the variation within populations was 60.0%. The results of an unweighted pair group method arithmetic average (UPGMA) analysis and a principal coordinate analysis (PCA) revealed that the populations with minimal geographic separations frequently exhibited regional characteristics. These findings revealed that the relationship between sibship and geographical distribution was intensive.     

Identification of endangered Mediterranean cyprinodontiform fish by means of DNA inter-simple sequence repeats (ISSRs)

We used inter-simple sequence repeat (ISSR) technique to obtain species-specific molecular markers for the cyprinodontiform fish Valencia hispanica, Valencia letourneuxi and Aphanius fasciatus. The aims were (i) to assess the effectiveness of ISSRs in discriminating the three species and (ii) to identify tissues of two unidentified fish suspected to belong to one of the three above species by comparing ISSR genotypes. Nine ISSR primers produced 101 scorable polymorphic loci with a large number of species-specific bands. UPGMA cluster analysis and nonmetric multidimensional scaling of inter-individual genetic dissimilarities were consistent in separating the three species and attributing the unidentified individuals to V. hispanica. This result was corroborated by the assignment test. ISSRs represent an attractive tool for specimen and species identification. We recommend their use, coupled with appropriate statistical analyses, in species identification when only small portions of the organisms are available.     

When physical oceanography meets population genetics: The case study of the genetic/evolutionary discontinuity in the endangered goliath grouper (Epinephelus itajara; Perciformes: Epinephelidae) with comments on the conservation of the species

Epinephelus itajara is one of the marine fish species most threatened for extinction and it is considered to be “critically endangered” by the IUCN. The present study evaluated the genetic diversity of the species and the genetic/evolutionary relationships of its populations along the Atlantic coast of South America. The results indicate relatively reduced genetic variation, re-emphasizing the low adaptive potential of the species. One of the populations presented relatively high degrees of genetic diversity and it is evolutionary isolated from the all other populations. The evidences indicate the existence of two Evolutionarily Significant Units comprising E. itajara in the Atlantic coast of South America and the conservation prospects for the species must take these evidences into account.     

Genetic variation within and between Iliamna corei and I. remota (Malvaceae): implications for species delimitation

Iliamna corei and I. remota are classified as endangered species; however, their designation as separate species has been questioned. In order to address this problem, intersimple sequence repeat (ISSR) data were generated to examine patterns of genetic differentiation within and between these two taxa. ISSRs were used to screen individuals for genetic diversity of I. corei from the single known natural population and two garden populations, and individuals of I. remota from the six natural populations and four garden populations. Using ten primers, 140 informative markers were generated. Ninety-four percent of loci detected revealed polymorphisms. Cluster analysis (neighbour-joining, NJ) revealed that the two species are genetically distinct and that the Illinois populations of I. remota were genetically distinct from the Virginia populations of I. remota . Ordination by Principal Coordinate Analysis (PCoA) supported the findings of the NJ, with a separation of I. corei and I. remota . Analysis of Molecular Variance (AMOVA) revealed that the majority of variation detected was within populations, which is consistent with other self-incompatible plants. The results indicate a correlation between the geographical distributions of the species and gene flow.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 345–354.     

Identification of microspore-derived plants in anther culture of flax (Linum usitatissimum L.) using molecular markers

The microspore origin of anther-culture-derived plants of flax was determined using inter-simple sequence repeat (ISSR) and randomly amplified polymorphic DNA (RAPD) markers. Polymorphic fragments between the two parents of the F₁ donor plants were identified and their segregation patterns in anther-culture-derived plants were used to elucidate the origin of those plants and to determine the degree of independence of plants regenerated from the same callus. Using one ISSR primer (UBC 889) and two RAPD primers (UBC 556 and 561), 12 out of 16 plants were unequivocally identified as being derived from microspores. Plants derived from the same callus had identical PCR patterns at five polymorphic loci and thus were likely derived from the same microspore. Therefore, it is proposed that the number of calli forming shoots be used to describe the anther culture efficiency in flax. Received: 3 February 1998 / Revision received: 8 June 1998 / Accepted: 8 July 1998