Ultrastructure de la spermiogenèse et du spermatozoïde de Loimosina wikoni et affinités phylétiques des Loimoidae (Plathelminthes, Monogenea, Monopisthocotylea)

In Loimosina, during spermiogenesis, the zone of differentiation of the spermatid contains two centrioles continued as two 9 +‘1’axonemes. One of the axonemes lengthens and will become the principal axoneme of the spermatozoon. The other axoneme is as long as the first one at the beginning of spermiogenesis, but is shorter in the mature sperm cell. The spermatozoon consists of several regions: (a) at the anterior end, the centriolar derivative of the principal axoneme; (b) a short region which shows cortical microtubules coinciding with external ornamentations; (c) a long uniflagellate region, with mitochondrion; (d) a biflagellate region containing the anterior slender part of the nucleus; (e) the posterior part of the nucleus, with no accompanying cytoplasmic organelles. Spermiogenesis and sperm structure in Loimosina differ from what is known in all other described monogeneans, excepting the monocotylid Heterocofyle to which they show close resemblances. However, the alteration of the second axoneme is more complete in Heterocofyle than in Loimosina. Comparative study of spermiogenesis and sperm ultrastructure thus shows an interesting coincidence with classical phylogenies of the monogeneans, in which the families Loimoidae and Monocotylidae are closely related. Chez Loimosina, pendant la spermiogenèse, la zone de différenciation de la spermatide contient deux centrioles prolongés par deux axonemes de type 9 +‘1′. L'un des axonemes s'allonge et deviendra l'axonème principal du spermatozoïde mûr. Le deuxième axontme est aussi long que le premier au début de la spermiogenèse, mais il est plus court dans le spermatozoïde mûr. Le spermatozoïde comprend: (a) à l'avant, le dérivé centriolaire de l'axonème principal; (b) une courte région contenant quelques microtubules corticaw longitudinaux coincidant avec des omementations extramembranaires; (c) une longue région miflagellée avec mitochondrie; (d) une région biflagellée contenant La partie antérieure effilée du noyau; (e) la région postérieure du noyau, sans organites cytoplasmiques accompagnateurs. La spermiogenèse et la structure du spermatozoïde de Loimosina sont différentes de ce qui est connu chez tous les autres Monogènes décrits, excepté le Monocotylidae Heterocofyle auquel elles ressemblent beaucoup. Toutefois, l'altération du deuxième axonème est moins complète chez Loimosina que chez Heterocotyle. L'étude comparée des spermatozoïdes et des spermiogenèses montre une bonne coincidence avec les phylogenèses classiques, dans lesquelles les familles Loimoidae et Monocotylidae sont proches.     

Microsatellite DNA markers for Lysiphlebus testaceipes

Microsatellite loci were isolated from the aphid parasitoid Lysiphlebus testaceipes (Hymenoptera: Braconidae). Ten loci were obtained from an enriched partial genomic library. Genetic diversity was analysed at seven of these loci and two natural populations, one on oleander and one on citrus. The observed number of alleles ranged from one to 17, and the observed heterozygosity ranged from 0.37 to 0.82. In both populations, no departure from Hardy–Weinberg equilibrium was detected except for one locus. The differentiation between the two populations was characterized by an F_ST of 0.09.     

Spatial distribution of genetic relatedness in a moorland population of red grouse (Lagopus lagopus scoticus)

Several aspects of the ecology and biology of red grouse (Lagopus lagopus scoticus) could prevent the complete admixture of genes within and between populations. Male red grouse display a high degree of natal philopatry, are territorial, and show less aggression to kin man to non-kin. Such factors acting in combination predict limited male-mediated gene flow, which will promote social structure within a population by the formation of stable kin clusters, and facilitate a rapid rise in allelic coancestry and/or inbreeding. In this study we utilize hypervariable microsatellite polymorphisms to examine the extent of social affiliation between relatives in a moorland population of grouse from NE Scodand. Levels of genetic relatedness between individual male red grouse occupying territories at Glas Choille in die spring and autumn of 1995 were examined, and kin clusters delimited. Nine kin groups (mean size = 2.4 individuals) were identified prior to breeding in the spring, which increased to 11 kin groups (mean size =4.0 individuals) when territories were reformed in the autumn. The majority of tiiose individuals that were recruited into the adult population during the autumn already had a first-order male relative established, supporting the hypothesis that recruitment is facilitated by behavioural interactions among relatives. The demographic and population genetic consequences of philopatric recruitment and kin clustering are examined and discussed.     

Ecologically heterogeneous populations of the invasive ant Wasmannia auropunctata within its native and introduced ranges

Abstract 1. The biology of most invasive species in their native geographical areas remains largely unknown. Such studies are, however, crucial in shedding light on the ecological and evolutionary processes underlying biological invasions. 2. The present study focuses on the little fire ant Wasmannia auropunctata, a species native to Central and South America that has been widely introduced and which has become invasive throughout the tropics. We characterise and compare several ecological traits of native populations in French Guiana with those in one of its introduced ranges, New Caledonia. 3. We found ecologically heterogeneous populations of W. auropunctata coexisting in the species’ native geographical area. First, we found populations restricted to naturally perturbed areas (particularly floodplains) within the primary forest, and absent from the surrounding forest areas. These populations were characterised by low nest and worker densities. Second, we found dominant populations in recent anthropogenic areas (e.g. secondary forest or forest edge along road) characterised by high nest and worker densities, and associated with low ant species richness. The local dominance of W. auropunctata in such areas can be due to the displacement of other species (cause) or the filling‐up of empty habitats unsuitable to other ants (effect). With respect to their demographic features and ant species richness, the populations of native anthropogenic habitats were to a large extent similar to the invasive populations introduced into remote areas. 4. The results point to the need for greater research efforts to better understand the ecological and demographic features of invasive species within their native ranges.     

Crepis novoana (Asteraceae), a new species restricted to coastal cliffs in northern Galicia (northwest Iberian Peninsula)

A new species of the section Lepidoseris (Rchb.) Benth. of the genus Crepis L. (Asteraceae) is described. The new species is restricted to a single known locality on near-vertical coastal cliffs of the Ria de Cedeira in northern Galicia (northwest Iberian Peninsula). Morphometric characters permitting discrimination from the most similar taxa are detailed, and possible phylogenetic relationships with other species of the section Lepidoseris (particularly those of the C. vesicaria complex) are discussed.     

Phylogeography of the marine isopod Stenosoma nadejda (Rezig, 1989) in North African Atlantic and western Mediterranean coasts reveals complex differentiation patterns and a new species

The transition zone between the Mediterranean and Atlantic basins has been extensively addressed in phylogeographical studies of marine species. However, biases exist towards the analysis of highly dispersive species, and there is a higher sampling effort in European coasts compared to North Africa. This may be hindering a detailed understanding of the historical and contemporary processes that shaped patterns of population genetic structure in the region. In the present study, we investigated the phylogeographical and phylogenetic patterns of mitochondrial cytochrome c oxidase subunit I sequences from a species with direct development and low dispersal abilities, Stenosoma nadejda (Rezig, 1989). The study area included 13 localities along the Atlantic and Mediterranean North African coasts, as well as the Alboran Sea. A new Stenosoma species, from the coasts of Algeria and Alboran Island, was discovered. For S. nadejda, phylogeographical analyses revealed three distinct clades: one in the Iberian Atlantic plus the Alboran Sea, one in the western Mediterranean, and another in the Atlantic coast of Africa. Haplotypes from the Alboran Island were more related to those from the western Mediterranean coast (east of the Almeria–Oran Front). Given the strong differentiation, it is probable that this species survived in multiple glacial refugia during the Pleistocenic glaciations. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 419–431.     

Lessons from a complex biogeographical scenario: morphological characters match mitochondrial lineages within Iberian Coronella austriaca (Reptilia: Colubridae)

Molecular evidence suggests that climatic fluctuations in the peninsulas of southern European during the Miocene and Pleistocene resulted in considerable genetic differentiation of organisms, probably following a ‘refugia within refugia’ model. We examined morphometric and meristic characters in museum specimens from the three Iberian clades of the smooth snake Coronella austriaca, previously described by molecular markers. We found sexual and interclade differences in scale counts and head shape. Sexes were dimorphic in the number of ventral and subcaudal scales, although sexual disparities in scale counts differed among clades. Moreover, discriminant and canonical analyses showed higher interclade differences in males than in females. The results obtained in the present study match those from molecular markers and confirm the population structure identified within Iberian C. austriaca. The observed sex discrepancy in this pattern suggests that males and females are subjected to different selective pressures along their Iberian distribution. In light of the above, C. austriaca may offer a useful model system in which to explore phylogeographical patterns in southern Europe, as well as the conflicts between processes driving morphological sexual divergence. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 210–223.